United States Office of Research EPA/600/R-93/187
Environmental Protection and Development December 1993
Agency (8603)
Wildlife Exposure
Factors Handbook
Volume I of II
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EPA/600/R-93/187
December 1993
WILDLIFE EXPOSURE FACTORS
HANDBOOK
Volume I of II
Office of Health and Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
Additional major funding for this Handbook was provided by the
Office of Emergency and Remedial Response,
Office of Solid Waste and Emergency Response
and by the
Office of Science and Technology, Office of Water
U.S. Environmental Protection Agency
Washington, DC 20460
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental
Protection Agency policy and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
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CONTENTS
Foreword xi
Preface xii
Authors, Managers, Contributors, and Reviewers xiii
1. INTRODUCTION 1-1
1.1. PURPOSE AND SCOPE 1-1
1.2. ORGANIZATION OF THE HANDBOOK 1-5
1.3. LIST OF SELECTED SPECIES 1-6
1.4. LIST OF EXPOSURE FACTORS 1-11
1.4.1. Normalizing Factors 1-11
1.4.1.1. Body Weight 1-13
1.4.1.2. Growth Rate 1-13
1.4.1.3. Metabolic Rate 1-14
1.4.2. Contact Rate Factors 1-14
1.4.2.1. Oral Route 1-14
1.4.2.2. Inhalation Route 1-16
1.4.2.3. Dermal Route 1-16
1.4.3. Population Dynamics 1-17
1.4.3.1. Social Organization 1-17
1.4.3.2. Home Range/Territory Size/Foraging Radius 1-17
1.4.3.3. Population Density 1-19
1.4.3.4. Annual Fecundity 1-19
1.4.3.5. Annual Mortality and Longevity 1-19
1.4.4. Seasonal Activities 1-20
1.5. DATA PRESENTATION FORMAT 1-20
1.5.1. Normalizing and Contact Rate Factors 1-21
1.5.1.1. All Animals 1-21
1.5.1.2. Birds 1-22
1.5.1.3. Mammals 1-23
1.5.1.4. Reptiles and Amphibians 1-23
MI
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CONTENTS (continued)
1.5.2. Dietary Composition 1-24
1.5.2.1. All Animals 1-24
1.5.3. Population Dynamics 1-25
1.5.3.1. All Animals 1-25
1.5.3.2. Birds 1-26
1.5.3.3. Mammals 1-27
1.5.3.4. Reptiles and Amphibians 1-27
1.5.4. Seasonal Activities 1-28
1.5.4.1. Birds 1-29
1.5.4.2. Mammals 1-29
1.5.4.3. Reptiles and Amphibians 1-29
1.5.5. Abbreviations Used in Tables 1-29
1.6. LITERATURE SEARCH STRATEGY 1-30
1.7. REFERENCES 1-32
2. EXPOSURE FACTORS AND DESCRIPTIONS OF SELECTED SPECIES 2-1
2.1. BIRDS 2-1
2.1.1. Great Blue Heron 2-3
2.1.2. Canada Goose 2-19
2.1.3. Mallard 2-39
2.1.4. Lesser Scaup 2-53
2.1.5. Osprey 2-65
2.1.6. Red-Tailed Hawk 2-79
2.1.7. Bald Eagle 2-91
2.1.8. American Kestrel 2-109
2.1.9. Northern Bobwhite 2-121
2.1.10. American Woodcock 2-137
2.1.11. Spotted Sandpiper 2-149
2.1.12. Herring Gull 2-157
2.1.13. Belted Kingfisher 2-173
2.1.14. Marsh Wren 2-183
2.1.15. American Robin 2-193
IV
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CONTENTS (continued)
2.2. MAMMALS 2-207
2.2.1. Short-Tailed Shrew 2-209
2.2.2. Red Fox 2-221
2.2.3. Raccoon 2-233
2.2.4. Mink 2-247
2.2.5. River Otter 2-261
2.2.6. Harbor Seal 2-275
2.2.7. Deer Mouse 2-291
2.2.8. Prairie Vole 2-311
2.2.9. Meadow Vole 2-323
2.2.10. Muskrat 2-337
2.2.11. Eastern Cottontail 2-351
2.3. REPTILES AND AMPHIBIANS 2-365
2.3.1. Snapping Turtle 2-367
2.3.2. Painted Turtle 2-381
2.3.3. Eastern Box Turtle 2-397
2.3.4. Racer 2-407
2.3.5. Northern Water Snake 2-419
2.3.6. Eastern Newt 2-429
2.3.7. Green Frog 2-443
2.3.8. Bullfrog 2-453
3. ALLOMETRIC EQUATIONS 3-1
3.1. FOOD INGESTION RATES 3-3
3.1.1. Birds 3-4
3.1.2. Mammals 3-5
3.1.3. Reptiles and Amphibians 3-6
3.2. WATER INTAKE RATES 3-7
3.2.1. Birds 3-8
3.2.2. Mammals 3-10
3.2.3. Reptiles and Amphibians 3-10
3.3. INHALATION RATES 3-11
3.3.1. Birds 3-11
3.3.2. Mammals 3-12
3.3.3. Reptiles and Amphibians 3-12
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CONTENTS (continued)
3.4. SURFACE AREAS 3-13
3.4.1. Birds 3-13
3.4.2. Mammals 3-14
3.4.3. Reptiles and Amphibians 3-14
3.5. ALLOMETRIC EQUATIONS FOR METABOLIC RATE 3-15
3.5.1. Birds 3-18
3.5.1.1 Basal Metabolic Rate 3-19
3.5.1.2. Existence Metabolic Rates 3-20
3.5.1.3. Free-Living Metabolic Rate 3-22
3.5.1.4. Temperature and Metabolic Rate 3-24
3.5.2. Mammals 3-26
3.5.2.1. Basal Metablic Rate 3-26
3.5.2.2. Resting Metabolism 3-27
3.5.2.3. Field Metabolic Rate 3-27
3.5.2.4. Temperature and Metabolic Rate 3-28
3.5.3. Reptiles and Amphibians 3-29
3.5.3.1. Basal and Resting Metabolic Rates 3-29
3.5.3.2. Free-Living Metabolic Rates 3-30
3.6. MATH PRIMER AND UNIT CONVERSIONS 3-32
3.6.1. Summary of Operations Involving Logarithms 3-32
3.6.2. Summary of Operations Involving Powers 3-32
3.6.3. Unit Conversions 3-33
3.6.3.1. Approximate Factors for Metabolic Equations 3-33
3.6.3.2. Exact Conversions 3-33
3.7. ESTIMATING CONFIDENCE INTERVALS 3-34
3.8. REFERENCES 3-38
4. EXPOSURE ESTIMATES 4-1
4.1. GENERAL DOSE EQUATIONS 4-1
4.1.1. Drinking Water 4-3
vi
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CONTENTS (continued)
4.1.2. Diet 4-6
4.1.2.1. Dose Equations 4-6
4.1.2.2. Energy Content and Assimilation Efficiencies 4-10
4.1.3. Soil and Sediment Ingestion 4-16
4.1.3.1. Background 4-18
4.1.3.2. Methods 4-18
4.1.3.3. Results 4-19
4.1.3.4. Dose Equations 4-21
4.1.4. Air 4-21
4.1.5. Dermal Exposure 4-23
4.2. ANALYSIS OF UNCERTAINTY 4-23
4.2.1. Natural Variation 4-24
4.2.2. Sampling Uncertainty 4-25
4.2.3. Model Uncertainty 4-26
2 4.3. REFERENCES 4-26
APPENDIX: LITERATURE REVIEW DATABASE See Volume II
VII
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LIST OF TABLES
Table 1-1. Characteristics of Selected Birds 1-8
Table 1-2. Characteristics of Selected Mammals 1-9
Table 1-3. Characteristics of Selected Reptiles and Amphibians 1-10
Table 1-4. Wildlife Exposure Factors Included in the Handbook 1-12
Table 1-5. Wildlife Contact Rate Exposure Factors 1-15
Table 1-6. Column Headers for Tables of Normalizing and Contact
Rate Factors 1-21
Table 1-7. Column Headers for Tables on Dietary Composition 1-24
Table 1-8. Column Headers for Tables of Factors for Population Dynamics 1-26
Table 1-9. Column Headers for Tables on Seasonal Activities 1-28
Table 2-1. Birds Included in the Handbook 2-2
Tables for 2.1.1. Great Blue Heron 2-8
2.1.2. Canada Goose 2-23
2.1.3. Mallard 2-43
2.1.4. Lesser Scaup 2-56
2.1.5. Osprey 2-68
2.1.6. Red-Tailed Hawk 2-82
2.1.7. Bald Eagle 2-95
2.1.8. American Kestrel 2-112
2.1.9. Northern Bobwhite 2-126
2.1.10. American Woodcock 2-140
2.1.11. Spotted Sandpiper 2-152
2.1.12. Herring Gull 2-162
2.1.13. Belted Kingfisher 2-176
2.1.14. Marsh Wren 2-186
2.1.15. American Robin 2-197
Table 2-2. Mammals Included in the Handbook 2-208
Tables for 2.2.1. Short-Tailed Shrew 2-213
2.2.2. Red Fox 2-224
2.2.3. Raccoon 2-236
2.2.4. Mink 2-251
2.2.5. River Otter 2-264
VIM
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LIST OF TABLES (continued)
2.2.6. Harbor Seal 2-280
2.2.7. Deer Mouse 2-295
2.2.8. Prairie Vole 2-314
2.2.9. Meadow Vole 2-327
2.2.10. Muskrat 2-340
2.2.11. Eastern Cottontail 2-355
Table 2-3. Reptiles and Amphibians Included in the Handbook 2-366
Tables for 2.3.1. Snapping Turtle 2-370
2.3.2. Painted Turtle 2-386
2.3.3. Eastern Box Turtle 2-400
2.3.4. Racer 2-411
2.3.5. Northern Water Snake 2-423
2.3.6. Eastern Newt 2-433
2.3.7. Green Frog 2-446
2.3.8. Bullfrog 2-456
Table 3-1. Metabolizable Energy (ME) of Various Diets for Birds
and Mammals 3-5
Table 3-2. Allometric Equations for Basal Metabolic Rate (BMR) in Birds 3-21
Table 3-3. Regression Statistics for Nagy's (1987) Allometric Equations
for Food Ingestion Rates for Free-Living Animals 3-36
Table 3-4. Regression Statistics for Nagy's (1987) Allometric Equations
for Free-Living (Field) Metabolic Rates 3-37
Table 4-1. Gross Energy and Water Composition of Wildlife Foods:
Animal Prey 4-13
Table 4-2. Energy and Water Composition of Wildlife Foods:
Plants 4-14
Table 4-3. General Assimilation Efficiency (AE) Values 4-15
Table 4-4. Percent Soil or Sediment in Diet Estimated From
Acid-Insoluble Ash of Scat 4-20
Table 4-5. Other Estimates of Percentage of Soil or Sediment in Diet 4-21
IX
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LIST OF FIGURES
Figure 3-1. Monthly Variation in Energy Budget Estimated for a
House Sparrow 3-25
Figure 4-1. Wildlife Dose Equations for Drinking Water Exposures 4-4
Figure 4-2. Wildlife Dose Equations for Dietary Exposures 4-6
Figure 4-3. Estimating NIRk When Dietary Composition Is Known on a
Wet-Weight Basis 4-8
Figure 4-4. Estimating NIRk Based on Different ME Values When
Dietary Composition Is Expressed as Percentage of
Total Prey Captured 4-9
Figure 4-5. Utilization of Food Energy by Animals 4-11
Figure 4-6. Metabolizable Energy (ME) Equation 4-12
Figure 4-7. Example of Estimating Food Ingestion Rates for
Wildlife Species From Free-Living Metabolic Rate and
Dietary Composition: Male Mink 4-17
Figure 4-8. Wildlife Oral Dose Equation for Soil or Sediment
Ingestion Exposures 4-22
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FOREWORD
The Exposure Assessment Group (EAG) of EPA's Office of Research and
Development has three main functions: (1) to conduct human health and ecological
exposure and risk assessments, (2) to review exposure and risk assessments and related
documents, and (3) to develop guidelines and handbooks for use in these assessments.
The activities under each of these functions are supported by and respond to the needs of
the various program offices, regional offices, and the technical community.
The Wildlife Exposure Factors Handbook was produced in response to the
increased interest in assessing risks to ecological systems. Its purpose is to improve
exposure assessments for wildlife and support the quantification of risk estimates. It is a
companion document to the Exposure Factors Handbook, which contains information
useful for quantifying exposure to humans. Because information and methods for
estimating exposure are continually improving, we will revise these handbooks as
necessary in the future.
Michael A. Callahan
Director
Exposure Assessment Group
XI
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PREFACE
The Exposure Assessment Group of the Office of Health and Environmental
Assessment (OHEA) has prepared the Wildlife Exposure Handbook in support of the Office
of Solid Waste and Emergency Response and the Office of Water. The Handbook provides
information on various factors used to assess exposure to wildlife. The goals of the
project are (1) to promote the application of risk assessment methods to wildlife species,
(2) to foster a consistent approach to wildlife exposure and risk assessments, and (3) to
increase the accessibility of the literature applicable to these assessments.
The bulk of the document summarizes literature values for exposure factors for 34
species of birds, mammals, amphibians, and reptiles. In addition, we include a chapter on
allometric equations that can be used to estimate some of the exposure factors when data
are lacking. Finally, we describe some common equations used to estimate exposure. The
basic literature search was completed in May 1990 and was supplemented by targeted
searches conducted in 1992.
We anticipate updating this Handbook and would appreciate any assistance in
identifying additional sources of information that fill data gaps or otherwise improve the
Handbook. Comments can be sent to:
Exposure Assessment Group
Wildlife Exposure Factors Handbook Project
USEPA (8603)
401 M Street, SW
Washington, DC 20460
XII
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AUTHORS, MANAGERS, CONTRIBUTORS, AND REVIEWERS
The Exposure Assessment Group (EAG) within EPA's Office of Health and
Environmental Assessment (OHEA) was responsible for preparing this document.
Additional major contract funding was provided by the Office of Emergency and Remedial
Response within the Office of Solid Waste and Emergency Response (OSWER) and by the
Office of Science and Technology within the Office of Water. The document was prepared
by ICF, Incorporated under contracts 68-C8-0003, 68-W8-0098, 68-DO-0101, and 68-C2-
0107. Susan Braen Norton served as the EAG project manager and provided overall
direction and coordination of the project. Thanks to Doug Norton for the cover illustration.
AUTHORS
Dr. Margaret McVey
Kimberly Hall, Peter Trenham, Alexander Soast, Leslie Frymier, and Ansara Hirst
ICF, Incorporated
PROJECT MANAGER
Susan Braen Norton
Exposure Assessment Group, Office of Health and Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
TASK MANAGERS
Cynthia Nolt
Office of Science and Technology
Office of Water
U.S. Environmental Protection Agency
Ron Preston
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
CONTRIBUTORS
Dr. Sarah Gerould
Office of Water Quality
U.S. Geological Survey
XIII
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Dr. Ronald Kirby
Office of Information Transfer
U.S. Fish and Wildlife Service (USFWS)
Department of the Interior
REVIEWERS
Dr. Cynthia Annett, USFWS, Arkansas Cooperative Fish and Wildlife Research
Unit, AR
Dr. Richard J. Aulerich, Michigan State University, Ml
Dr. Richard Bennett, USEPA, Environmental Research Laboratory (ERL),
Corvallis, OR
Dr. Christine A. Bishop, Canadian Wildlife Service, Ontario, Canada
Dr. Brad Bortner, USFWS, Office of Migratory Bird Management, MD
Dr. Steven Bradbury, USEPA, ERL-Duluth, MN
Dr. Robert Burr, USFWS, VA
Ms. Janet Burris, ABB Environmental Services, Washington, DC
Dr. Joseph Chapman, Utah State University, UT
Dr. Lewis Cowardin, USFWS, Northern Prairie Wildlife Research Center, ND
Ms. Deanna Dawson, USFWS, Patuxent Wildlife Research Center, MD
Dr. Donald L. DeAngelis, Oak Ridge National Laboratory, TN
Dr. Bruce Duncan, USEPA, Region 10, Seattle, WA
Dr. Robert Foley, USFWS, Annapolis Field Office, MD
Dr. Glen Fox, Canadian Wildlife Service, Ontario, Canada
Dr. J.H.B. Garner, USEPA, OHEA, Environmental Criteria and Assessment Office
(ECAO), Research Triangle Park, NC
Dr. J. Whitfield Gibbons, University of Georgia, Savannah River Ecology
Laboratory, GA
Mr. Keith A. Grasman, Virginia Polytechnic Institute and State University, VA
Dr. Fred Guthery, Caesar Kleberg Wildlife Research Institute, Texas A&l
University, TX
Dr. Richard S. Halbrook, Oak Ridge National Laboratory, TN
Dr. Michael J. Hamas, Central Michigan University, Ml
Dr. Charles J. Henny, USFWS, Pacific Northwest Research Station, OR
Dr. Paula F. P. Henry, USFWS, Patuxent Wildlife Research Center, MD
Dr. Gary Heinz, USFWS, Patuxent Wildlife Research Center, MD
Dr. Doug James, University of Arkansas, AR
Mr. K. Bruce Jones, USEPA, Environmental Monitoring Systems Laboratory,
EMAP Terrestrial Ecosystems, CA
Dr. Dennis G. Jorde, USFWS, Patuxent Wildlife Research Center, MD
Dr. Norm Kowal, USEPA, OHEA, ECAO, Cincinnati, OH
Dr. Gary L. Krapu, USFWS, Northern Prairie Wildlife Research Center, ND
Dr. David Krementz, USFWS, Patuxent Wildlife Research Center, MD
Dr. James Kushlan, University of Mississippi, MS
Dr. John T. Lokemoen, USFWS, Northern Prairie Wildlife Research Center, ND
Dr. Dave Ludwig, EA Engineering, Inc., MD
Dr. Drew Major, USFWS, Concord, NH
Dr. Karen Me Bee, Oklahoma State University, OK
xiv
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REVIEWERS (continued)
Dr. Linda Meyers-Schone, International Technology Corp., NM
Mr. Jerry Moore, USEPA, OHEA, Washington, DC
Dr. Lewis Oring, University of Nevada at Reno, NV
Dr. Raymond Pierotti, University of Arkansas, AR
Dr. Richard M. Poche, Genesis Laboratories, Wl
Dr. Douglas Reagan, Woodward-Clyde Consultants, CO
Dr. Lorenz Rhomberg, USEPA, OHEA, Human Health Assessment Group,
Washington, DC
Dr. Robert Ringer, Mount Dora, FL
Dr. John L. Roseberry, Southern Illinois University at Carbondale, IL
Dr. Alan Sargeant, USFWS, Northern Prairie Wildlife Research Center, ND
Dr. Edward Schafer, USDA, Denver Wildlife Research Center, CO
Dr. Laird Schutt, Canadian Wildlife Service, Quebec, Canada
Ms. Anne Sergeant, USEPA, OHEA, EAG, Washington, DC
Dr. Kim Smith, University of Arkansas, AR
Dr. Mark Sprenger, USEPA, OSWER, Environmental Response Team, Edison, NJ
Dr. George A. Swanson, USFWS, Northern Prairie Wildlife Research Center, ND
Dr. Sylvia Talmage, Oak Ridge National Laboratory, TN
Dr. Bob Trost, USFWS, Office of Migratory Bird Management, MD
Dr. D.V. (Chip) Weseloh, Canadian Wildlife Service, Ontario, Canada
Dr. Nathaniel Wheelwright, Bowdoin College, ME
Dr. Donald H. White, USFWS, Southeast Research Station, GA
Dr. Stanley N. Wiemeyer, USFWS, Patuxent Wildlife Research Center, MD
Dr. Bill Williams, Environmental Planning and Toxicology, Corvallis, OR
Dr. Dean M. Wilkinson, U.S. Department of Commerce, National Oceanic and
Atmospheric Administration, National Marine Fisheries Service
Dr. Jerry O. Wolff, USEPA, ERL, Corvallis, OR
Dr. John P. Wolfin, USFWS, Annapolis Field Station, MD
xv
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1. INTRODUCTION
The Wildlife Exposure Factors Handbook (hereafter referred to as the Handbook)
provides data, references, and guidance for conducting exposure assessments for wildlife
species exposed to toxic chemicals in their environment. It is the product of a joint effort
by EPA's Office of Research and Development (ORD), Office of Solid Waste and
Emergency Response (OSWER), and Office of Water (OW). The goals of this Handbook are
(1) to promote the application of risk assessment methods to wildlife species, (2) to foster
a consistent approach to wildlife exposure and risk assessments, and (3) to increase the
accessibility of the literature applicable to these assessments.
1.1. PURPOSE AND SCOPE
The purpose of the Handbook is to provide a convenient source of information and
an analytic framework for screening-level risk assessments for common wildlife species.
These screening-level risk assessments may be used for several purposes, including: to
assess potential effects of environmental contamination on wildlife species and to support
site-specific decisions (e.g., for hazardous waste sites); to support the development of
water-quality or other media-specific criteria for limiting environmental levels of toxic
substances to protect wildlife species; or to focus research and monitoring efforts. The
Handbook provides data (analogous to EPA's Exposure Factors Handbook for humans,
USEPA, 1989c) and methods for estimating wildlife intakes or doses of environmental
contaminants. Although the data presented in the Handbook can be used for screening
analyses, we recommend that anyone establishing a cleanup goal or criterion on the basis
of values contained herein obtain the original literature on which the values are based to
confirm that the study quality is sufficient to support the criterion. This Handbook does
not include data or extrapolation methods required to assess the toxicity of substances to
wildlife species, nor does it include any chemical-specific data (e.g., bioavailability factors).
For the Office of Water, data gathered for the Handbook were used to identify
wildlife species that are likely to be at greater risk from bioaccumulative pollutants in
surface waters and to estimate likely exposures for these species. Data on diets and on
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food and water ingestion rates can be used with chemical-specific information, such as
bioaccumulation potential and wildlife toxicity, to calculate site- or region-specific
concentrations of a chemical in water (or soil or sediment) that are unlikely to cause
adverse effects.
For the Superfund program, this Handbook supplements the existing environmental
evaluation guidance. EPA's Risk Assessment Guidance for Superfund: Volume II-
Environmental Evaluation Manual (\J.S. EPA, 1989a) provides an overview of ecological
assessment in the Superfund process. It includes a description of the statutory and
regulatory bases for ecological assessments in Superfund and fundamental concepts for
understanding ecological effects of environmental contaminants. The Environmental
Evaluation Manual a\so reviews elements of planning an ecological assessment and how to
organize and present the results of the assessment. EPA's Ecological Assessment of
Hazardous Waste Sites: A Field and Laboratory Reference (U.S. EPA, 1989b) and
Evaluation of Terrestrial Indicators for Use in Ecological Assessments at Hazardous Waste
Sites (U.S. EPA, 1992) are companion documents that describe biological assessment
strategies, field sampling designs, toxicity tests, biomarkers, biological field assessments,
and data interpretation. The ECO Update intermittent bulletin series (published by EPA's
Office of Solid Waste and Emergency Response, publication no. 9345.0-05I, available from
the National Technical Information Service, Springfield, Virginia) provides supplemental
guidance for Superfund on selected issues. Although these documents have identified
decreases in wildlife populations as potential endpoints for ecological assessments, they
do not provide guidance on how to conduct a wildlife exposure assessment that is
comparable to the guidance provided by the Superfund program for human health
exposure assessments. This Handbook provides both guidance and data to facilitate
estimating wildlife exposure to contaminants in the environment.
Exposure assessments for wildlife and humans differ in several important ways.
One key distinction is that many different wildlife species may be exposed, as compared
with a single species of concern for a human health assessment. Exposure varies between
different species and even between different populations of the same species; behavioral
attributes and diet and habitat preferences influence this variation. Second, whereas it is
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seldom possible to confirm estimated levels of human exposure without invasive sampling
of human tissues, confirmatory sampling for many chemicals can be done in wildlife
species (protected species excepted). However, the tissue sampling required to quantify
actual exposure levels can be costly, and interpretation of tissue concentrations can be
complex.
For both human health and wildlife exposure assessments, the most cost-effective
approach is often to first screen for potentially significant exposures using measures (or
estimates) of environmental contamination (e.g., in soils, water, prey species) to estimate
contaminant intakes or doses by significant routes of exposure. If estimated doses fall far
below the toxicity values associated with adverse effects, especially from chronic
exposures, further assessment may be unnecessary. If estimated doses far exceed
reference toxicity values, it may be possible to determine appropriate actions on the basis
of these estimates alone. When a screening-level exposure assessment indicates that
adverse effects are likely, additional confirmatory data may be needed in the decision-
making process. For humans, it is usually not practicable to obtain additional types of data
(e.g., tissue concentrations, biomarkers), and human exposure estimates are often refined
by using more site-specific data for exposure parameters. For wildlife, confirmatory data
may be obtained from chemical analyses of tissue samples from potentially exposed
wildlife or their prey and from observed incidence of disease, reproductive failure, or death
in exposed wildlife. These are reviewed in EPA's field and laboratory reference and
terrestrial indicators documents described above (EPA, 1989b, 1992). If this more direct
approach is not possible, the exposure analysis can be refined on the basis of more site-
specific data for the species of concern.
Wildlife can be exposed to environmental contaminants through inhalation, dermal
contact with contaminated water or soil, or ingestion of contaminated food, water, or soil.
Exposure assessment seeks to answer several questions, including:
• What organisms are actually or potentially exposed to contaminants?
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• Which organisms or life stages might be most vulnerable to environmental
contaminants (e.g., ingest the largest quantities of contaminated media
relative to body size)?
• What are the significant routes of exposure?
• To what amounts of each contaminant are organisms actually or potentially
exposed?
• How long is each exposure?
• How often does or will exposure to the environmental contaminants take
place?
• What seasonal and climatic variations in conditions are likely to affect
exposure?
• What are the site-specific geophysical, physical, and chemical conditions
affecting exposure?
The parameters for which data are presented in the Handbook are intended to help a risk
assessor answer these questions. The population parameter data (e.g., birth and death
rates) may be useful for placing estimates of risks to wildlife populations in a broader
ecological context and for planning monitoring activities.
This Handbook focuses on selected groups of mammals, birds, amphibians, and
reptiles. Fish and aquatic or terrestrial invertebrates were not included in this effort. The
profiles on amphibians and reptiles are, in general, less developed than those for birds and
mammals. We emphasized birds and mammals because methods for assessing their
exposure are more common and well developed. As more assessments are done for
amphibians and reptiles, we anticipate that additional methods and supporting factors will
be necessary. Until then, we hope the information presented here will encourage
assessors to begin considering and quantifying their exposure.
For all exposure parameters and species in the Handbook, we try to present data
indicative of the range of values that different populations of a species may assume across
North America. For site-specific ecological risk assessments, it is important to note that
the values for exposure factors presented in this Handbook may not accurately represent
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specific local populations. The species included in the Handbook have broad geographic
ranges, and they may exhibit different values for many of the exposure factors in different
portions of their range. Some species exhibit geographic variation in body size, survival,
and reproduction. Breeding and migration also influence exposure. Site-specific values
for these parameters can be determined more accurately using published studies of local
populations and assistance from the U.S. Fish and Wildlife Service, state departments of
fish and game, and organizations such as local Audubon Society chapters. In addition, The
Nature Conservancy develops and maintains wildlife databases (including endangered
species) in cooperation with all 50 states. Local information increases the certainty of a
risk assessment. Thus, for site-specific assessments, we strongly recommend contacting
local wildlife experts to determine the presence and characteristics of species of concern.
Finally, we do not intend to imply that risk assessments for wildlife should be
restricted to the species described in this Handbook, or should always be conducted for
these species. We emphasize that locally important or rare species not included in this
Handbook may still be very important for site-specific risk assessments. To assist users
who wish to evaluate other species, we list general references for birds, mammals,
reptiles, and amphibians in North America. The Handbook also provides allometric
equations to assist in extrapolating exposure factors (e.g., water ingestion rate, surface
area) to closely related species on the basis of body size.
1.2. ORGANIZATION OF THE HANDBOOK
The Handbook is organized into four chapters. The remainder of this chapter
provides an overview of the species and exposure factors included in the Handbook and
discusses the literature search strategy used to identify factors. Chapter 2 presents
exposure profiles for the selected species (described in greater detail below). Chapter 3
provides allometric models that may be used to estimate food and water ingestion rates,
inhalation rates, surface areas, and metabolic rates for wildlife species on the basis of
body size. Chapter 4 describes common equations used to estimate wildlife exposure to
environmental contaminants. Included are methods for estimating diet-specific food
1-5
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ingestion rates on the basis of metabolic rate and for estimating exposure to chemicals in
soil and sediment.
Chapter 2 is the core of the Handbook; it presents exposure profiles for selected
birds (Section 2.1), mammals (Section 2.2), and reptiles and amphibians (Section 2.3),
along with brief descriptions of their natural history. Each species profile includes an
introduction to the species' general taxonomic group, qualitative description of the
species, list of similar species, table of exposure factors, and reference list (which also
covers that species' section in Volume II, the Appendix). The values included in the
exposure factors tables are a subset of those we found in the literature and also include
values that we estimated using the allometric equations presented in Chapter 3. We
selected values for the tables in Chapter 2 based on a variety of factors including sample
size, quantification of variability (e.g., standard deviations, standard errors, ranges),
relevance of the measurement technique for exposure assessment, and coverage of
habitats, subspecies, and the variability seen in the literature. A complete listing of the
parameter values identified in our literature survey is provided in the Appendix. The
Appendix also includes more details concerning sample size, methods, and qualifying
information than the species profiles. Users are encouraged to consult the Appendix to
select the most appropriate values for their particular assessment.
The remainder of this introductory chapter describes the species and exposure
factors covered in the Handbook in greater detail. The literature search strategy is
discussed in Section 1.6.
1.3. LIST OF SELECTED SPECIES
Wildlife species were selected for the Handbook to provide several types of
coverage:
• Major taxonomic groups (major vertebrate groups, orders, and families);
• A range of diets (e.g., piscivore, probing insectivore) likely to result in
contact with contaminated environmental media;
1-6
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• A variety of habitat types (e.g., fields, marshes, woodlands, coastal areas);
and
• Small to large body sizes.
Other attributes also were considered when selecting species for the Handbook,
including:
• Species with wide geographic distribution within the United States (or
replaced regionally by similar species);
• Species of concern to EPA or other regulatory agencies (managed by state or
Federal agencies); and
• Species of societal significance (familiar or of concern to most people).
Tables 1-1, 1-2, and 1-3 list the birds, mammals, and reptiles and amphibians,
respectively, included in the Handbook. The species are listed according to diet, general
foraging habitat, and relative body size.
The species included in this Handbook were necessarily limited; however, we do
not recommend limiting wildlife exposure assessments to the species or similar species
identified in the Handbook. Instead, the Handbook should be used as a framework to
guide development of exposure factors and assessments for species of concern in a risk
assessment. Species selection criteria for site-specific risk assessments might include the
following considerations:
• Species that play important roles in community structure or function (e.g.,
top predators or major herbivores);
• Diet, habitat preferences, and behaviors that make the species likely to
contact the stressor;
• Species from different taxa that might exhibit different toxic effects from
contaminants;
• Local species that are of concern to Federal and state regulatory agencies
(e.g., endangered and threatened species);
1-7
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Table 1-1. Characteristics of Selected Birds
Diet
Insectivore3
probing/soil-dwelling invertebrates
gleaning/insects
Herbivore
gleaning/seeds
grazing/shoots
Omnivore
Carnivore"
Carnivore/Piscivore/Scavenger
small birds & mammals/fish/dead fish
fish/invertebrates/small birds/garbage
Piscivore0
Aquatic lnsectivored
probing/soil-dwelling invertebrates
diving/aquatic invertebrates
Aquatic Herbivore/lnsectivore
General Foraging Habitat
woodlands, marshes
marshes
woodlands, fields and brush
open fields
open woodland, suburbs
open fields, forest edge
most open areas
open water bodies
Great Lakes and coastal
most streams, rivers, small
lakes
most freshwater and saltwater
bodies
large water bodies
most rivers and streams
oceans and coastal areas
most wetlands, ponds
Body Size
medium
small
medium
large
small
medium
medium
large
medium
medium
large
large
small
medium
medium
Selected Bird Species
American woodcock
marsh wren
northern bobwhite
Canada goose
American robin
American kestrel
red-tailed hawk
bald eagle
herring gull
belted kingfisher
great blue heron
osprey
spotted sandpiper
lesser scaup
mallard
00
Includes consumption of insects, other arthropods, worms, and other terrestrial invertebrates.
''Includes consumption of terrestrial vertebrates and large invertebrates.
"Includes consumption of fish, amphibians, crustaceans, and other larger aquatic animals.
''Includes consumption of aquatic invertebrates and amphibian larvae by gleaning or probing.
-------
Table 1-2. Characteristics of Selected Mammals
Diet
Insectivore3
gleaning/surface-dwelling invertebrates
Herbivore
gleaning/seeds
grazing or browsing/shoots, roots, or
leaves
Omnivore
Carnivore"
Piscivore0
Aquatic Herbivore
General Foraging Habitat
most habitat types
most dry-land habitats
grassy fields, marshes, bogs
prairie grass communities
most habitat types
woodlands, suburbs
mixed woodlands and open
areas
most areas near water
rivers
coastal, estuaries, lakes
most aquatic habitats
Body Size
small
small
small
small
medium
medium
medium
medium
medium
medium
medium
Selected
Mammal Species
short-tailed shrew
deer mouse
meadow vole
prairie vole
eastern cottontail
raccoon
red fox
mink
river otter
harbor seal
muskrat
Includes consumption of insects, other arthropods, worms, and other terrestrial invertebrates.
''Includes consumption of aquatic and terrestrial vertebrates and large invertebrates.
"Includes consumption of fish, amphibians, crustaceans, molluscs, and other large aquatic animals.
-------
Table 1-3. Characteristics of Selected Reptiles and Amphibians
Adult Diet
General Foraging Habitat
for Adults
Body Size
Selected Reptile or
Amphibian Species
REPTILES
Terrestrial Carnivore3
Aquatic Piscivore"
Omnivore
Aquatic Herbivore
open woods, fields and brush
most types of water bodies
open fields, forest edge,
marshes
most freshwater bodies
most wetlands, ponds
medium
medium
medium
large
medium
racer
northern water snake
eastern box turtle
snapping turtle
painted turtle
AMPHIBIANS
Insectivore0
Aquatic Piscivore/lnsectivored
shallow freshwater bodies
lakes, ponds, bogs, streams
small lakes, ponds, streams
small
medium
small
green frog
bullfrog
eastern newt
Includes consumption of terrestrial vertebrates and invertebrates, insects, other arthropods, worms, and other terrestrial invertebrates.
''Includes consumption offish, amphibians, and crustaceans.
"Includes consumption of insects, other arthropods, worms, and other terrestrial invertebrates.
''Includes consumption offish, amphibians, crustaceans, molluscs, other aquatic animals, and terrestrial insects and other invertebrates.
-------
• Species of societal significance or concern (e.g., game species, familiar
species); and
• Species that have been shown to be particularly sensitive to the stressor
being addressed.
When species of concern for a risk assessment include species for which data are
presented in this Handbook, it can serve as a readily available source of data for
screening-level exposure analyses.
1.4. LIST OF EXPOSURE FACTORS
Three routes of exposure may be of concern for wildlife in the vicinity of
contaminated surface waters and terrestrial habitats: oral, inhalation, and dermal. Oral
exposures might occur via ingestion of contaminated food (e.g., aquatic prey) or water or
incidental ingestion of contaminated media (e.g., soils, sediments) during foraging or other
activities. Inhalation of gases or participates might be a significant route of exposure for
some animals. Dermal exposures are likely to be most significant for burrowing mammals
(i.e., via contact with contaminated soils) and animals that spend considerable amounts of
time submerged in surface waters. This Handbook tabulates selected data for all three
routes of exposure (Table 1-4), emphasizing oral exposures. It also provides quantitative
information on population parameters and qualitative information related to seasonal
activities, geographic ranges, habitats, and other life-history characteristics.
The exposure factors presented in the Handbook are conceptually separated into
four types: normalizing factors (Section 1.4.1), contact rates (Section 1.4.2), population
dynamics (Section 1.4.3), and seasonal activities (Section 1.4.4). Section 1.5 describes the
format in which values for these exposure factors are presented in Chapter 2.
1.4.1. Normalizing Factors
Normalizing factors include body weight, growth rate, and metabolic rate, which are
discussed in turn below.
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Table 1 -4. Wildlife Exposure Factors Included in the Handbook
Parameter Type
NORMALIZING FACTORS
CONTACT RATES
POPULATION DYNAMICS
SEASONAL ACTIVITIES
Exposure Route/
Factor Category
Body Weight
Metabolic Rate
Oral
Inhalation
Dermal
Distribution (by life
stage and season)
Birth, Maturation, and
Death Rates
Timing of Activities
(those that can modify
habitat preferences and
exposure)
Factor
body weight
growth rate
metabolic rate
food ingestion rate
dietary composition
water ingestion rate
soil/sediment intake
rate
inhalation rate
surface area
social organization
home range size
population density
annual fecundity
age at sexual maturity
annual mortality rates
average longevity
mating season
parturition/hatching
molt/metamorphosis
dispersal/migration/
hibernation
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1.4.1.1. Body Weight
Body weights (in units of mass) are reported as fresh weight as might be obtained
by weighing a live animal in the field. Several of the contact rate parameters are
normalized to body weight. For example, both food and water ingestion rates are reported
on a per body weight basis (e.g., gram of fresh food or water per gram of fresh body weight
per day). Using empirical models, body weight data also were used to estimate contact
rate parameters for which we could not find measured values.
Adult body weights are listed for all species. For birds, we also provide egg weight,
weight at hatching, nestling or chick weights, and weight at fledging, when available, to
assist risk assessors concerned with estimating exposures of embryos and young birds.
For mammals, we also provide gestating female weight, birth weight, pup weights at
various ages, weight at weaning, and weight at sexual maturity, when available, for a
similar purpose. Finally, for reptiles and amphibians, we also provide egg weight, larval or
juvenile weights with age, and weight at metamorphosis, if available and applicable. Body
size for reptiles and amphibians is often reported as body length instead of body weight,
so we also provide data on body length and the relationship between body length and body
weight, when available.
1.4.1.2. Growth Rate
Young animals generally consume more food (per unit body weight) than adults
because they grow and develop rapidly. Growth rates change as animals mature, whether
expressed as absolute (g/day) or relative (percent body weight) terms. Weight gain is rapid
after birth, but slows over time. Different types of animals exhibit different patterns of
growth over time. Plots of body weight versus age for some animal groups are sigmoidal
whereas others may approximate logistic functions or other shapes. As a result,
investigators often report growth rates as various constants associated with particular
mathematical models (e.g., Gompertz equation, von Bertalanffy equation; see Peters, 1983)
that fit the growth pattern for a given species. Instead of presenting a variety of growth
constants and models, however, we report growth rates for young animals, when available,
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in grams per day for specific age groups. Growth rates also can be inferred from a series
of juvenile body weights with age. These measures are included under body weight (see
Section 1.4.1.1).
1.4.1.3. Metabolic Rate
Metabolic rate is reported on the basis of kilocalories per day normalized to body
weight (e.g., kcal/kg-day). If metabolic rate was measured and reported on the basis of
oxygen consumption only, we provide those values as liters O2/kg-day. Normalized
metabolic rates based on kilocalories can be used to estimate normalized food ingestion
rates (see Section 4.1.2). Metabolic rates based on oxygen consumption can be used to
estimate metabolic rates based on kilocalories for subsequent use in estimating food
ingestion rates (see Section 3.6.3.1).
1.4.2. Contact Rate Factors
Table 1-5 summarizes the six contact rate factors included for the oral, inhalation,
and dermal routes of exposure.
1.4.2.1. Oral Route
Three environmental media are the primary contributors to wildlife exposure by the
oral route: food, water, and soils and sediments. Four contact rate exposure parameters
related to these three exposure media are discussed below.
1.4.2.1.1. Food ingestion rates. Food ingestion rates are expressed in this
Handbook as grams of food (wet weight) per gram of body weight (wet weight) per day
(g/g-day). Food ingestion rates can vary by age, size, and sex and by seasonal changes in
ambient temperature, activity levels, reproductive activities, and the type of diet consumed.
Food ingestion rates have not been measured for many wildlife species. Methods for
estimating food ingestion rates on the basis of free-living (or field) metabolic rate, energy
content of the diet, and assimilation efficiency are discussed in Section 4.1.2.
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Table 1-5. Wildlife Contact Rate Exposure Factors
Exposure
Route
ORAL
INHALATION
DERMAL
Medium
Food
Water
Soil/Sediment
Vapor or
Particulates
Water or
Soil/Sediment
Factor
ingestion rate
dietary
composition
ingestion rate
intake rate
inhalation rate
surface area
Expression
fraction body
weight
fraction of total
intake
represented by
each food type
fraction body
weight
fraction of total
food intake
daily volume
total area
potentially
exposed3
Units
6 g/g-day
g/g-day
g/g-day
m3/day
cm2
'Total unprotected or permeable surface area that might be exposed under some circumstances (e.g., dust
bathing), even though it would not be exposed under other conditions (e.g., swimming with a trapped air
layer between the feathers or fur and skin).
1.4.2.1.2. Dietary composition. Dietary composition varies seasonally and by age,
size, reproductive status, and habitat. Dietary composition (e.g., proportion of diet
consisting of various plant or animal materials), often measured by stomach-content
analyses, is expressed whenever possible as percentage of total intake on a wet-weight
basis. This convention facilitates comparison with contaminant concentrations in dietary
items reported on a wet-weight basis. Methods for converting other measures of dietary
composition (e.g., percentage of total prey items captured, proportion of intake on a dry-
weight basis) to estimates of dietary intake on a wet-weight basis are provided in Section
4.1.2.
1.4.2.1.3. Water ingestion rates. For drinking-water exposures, ingestion rates are
expressed in this Handbook as grams of water per gram of wet body weight per day (g/g-
day). Water consumption rates depend on body weight, physiological adaptations,
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diet, temperature, and activity levels. It is important to remember that, under some
conditions, some species can meet their water requirements with only the water contained
in the diet and metabolic water production (see Section 3.2).
1.4.2.1.4. Incidental soil and sediment intakes. Wildlife can incidentally ingest
soils or sediments while foraging or during other activities such as dust bathing and
preening or grooming. Data quantifying soil and sediment ingestion are limited; we
present available values for selected species in Section 4.1.3.
1.4.2.2. Inhalation Route
Average daily inhalation rates are reported in the Handbook in units of m3/day.
Inhalation rates vary with size, seasonal activity levels, ambient temperature, and daily
activities. EPA's current approach to calculating inhalation exposures requires additional
information on species' respiratory physiology to fully estimate inhalation exposures (see
Section 4.1.4).
1.4.2.3. Dermal Route
Dermal contact with contaminated soil, sediment, or water is likely to be an
exposure pathway for some wildlife species. An animal's surface area could be used to
estimate the potential for uptake of contaminants through its skin. For some exposures
(e.g., dust bathing), the entire surface area of the animal might be important. For other
types (e.g., swimming), only the uninsulated portions (e.g., no fur or feathers that create a
trapped air layer) of the animal might contact the contaminated medium. In the Handbook,
we provide measures or estimates of the entire potentially exposed surface area of an
animal, when possible. We have not attempted to determine what portions would be
exposed and protected for swimming animals.
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1.4.3. Population Dynamics
Several parameters can be used to describe the spatial distribution and abundance
of a population of animals in relation to the spatial extent of contamination. Three
parameters related to spatial distribution are social organization, home-range size, and
population density. These are important for estimating the number of individuals or
proportion of a population that might be exposed to a contaminated area. Parameters
related to population size and persistence include age at sexual maturity and maturation,
mortality, and annual fecundity rates. These parameters may be useful to assessors
planning or evaluating field studies or monitoring programs.
1.4.3.1. Social Organization
The Handbook includes a qualitative description of each species' social
organization, which influences how animals of various ages and sizes are distributed in
space. In some species, individual home ranges do not overlap. In others, all individuals
use the same home range. In between these extremes, home ranges can be shared with
mates, offspring, or extended family groups.
Social organization can vary substantially among species that appear otherwise
similar; therefore, it is not possible to extrapolate the social organization of similar species
from the selected species in this Handbook. Consult the general bibliographies for
information sources to determine the social organization of species not covered in the
Handbook.
1.4.3.2. Home Range/Territory Size/Foraging Radius
Home range size can be used to determine the proportion of time that an individual
animal is expected to contact contaminated environmental media. Home range is defined
as the geographic area encompassed by an animal's activities (except migration) over a
specified time. While home range values often are expressed in units of area, for species
dependent on riparian or coastal habitats, a more meaningful measure can be foraging
1-17
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radius, or the distances the animals are willing to travel to potential food sources. Although
home ranges may be roughly circular in homogeneous habitats, it is important to
remember that depending on habitat needs and conditions, home ranges may be irregular
in shape. The size and spatial attributes of a home range often are defined by foraging
activities, but also might depend on the location of specific resources such as dens or nest
sites in other areas. An animal might not visit all areas of its home range every day or
even every week, but over longer time periods, it can be expected to visit most of the areas
within the home range that contain needed resources such as forage, prey, or protected
resting areas.
Home range size for individuals within a population can vary with season, latitude,
or altitude as a consequence of changes in the distribution and abundance of food or other
resources. It generally varies with animal body size and age because of differences in the
distribution of preferred forage or prey. It can also depend on habitat quality, increasing as
habitat quality decreases to a condition beyond which the habitat does not sustain even
sparse populations. Finally, home ranges can vary by sex and season. For example, if a
female is responsible for most or all of the feeding of young, her foraging range might be
restricted to an area close to her nest or den when she has dependent young, whereas the
foraging range of males would not be so restricted.
Nonterritorial species may allow significant overlap of activity areas among
neighboring individuals or groups. For example, several individuals or mated pairs may
share the same area, although signalling behaviors may ensure temporal segregation. For
these species, we report a home range size or foraging radius. Other species are strongly
territorial and defend mutually exclusive areas: individuals, breeding pairs, or family units
actively advertise identifiable boundaries and exclude neighboring individuals or groups.
Foraging activities are usually restricted to the defended territories. For these species, we
report the size of the defended territory and note whether foraging occurs outside of the
territory.
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1.4.3.3. Population Density
Population density (the number of animals per unit area) influences how many
individuals (or what proportion of a local population) might be exposed within a
contaminated area. For strongly territorial species, population density can be inferred
from territory size in many cases. For species with overlapping home ranges, particularly
colonially breeding animals (e.g., most seabirds), population density cannot be inferred
from home range size.
1.4.3.4. A nnual Fecundity
Attributes related to the number of offspring produced each year that reach sexual
maturity (annual fecundity) are measured in different ways depending on the life history of
the species. For birds, data are generally available for clutch size, number of clutches per
year, nest success (generally reflecting predation pressure), number of young fledged per
successful nest (generally reflecting food availability), and number of young fledged per
active nest (reflecting all causes of mortality). For mammals, litter size in wild populations
often is determined by placenta! scars or embryo counts, and the number of young
surviving to weaning is seldom known. For reptiles that lay eggs, clutch size and percent
hatching can be measured in the field. For viviparous reptiles, we report the number born
in a litter. For amphibians, egg masses may include thousands of eggs, but these are
seldom counted.
1.4.3.5. Annual Mortality and Longevity
Longevity can influence the potential for cumulative deleterious effects and the
appropriate averaging times for chronic exposures. For birds, annual adult mortality tends
to be constant. For large mammalian species, however, annual adult mortality tends to be
constant for several years, and then increases rapidly with age. For reptiles and
amphibians, annual adult mortality can decrease with age for some time as the animals
continue to grow larger and become less susceptible to predation. In the Handbook, we
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report annual mortality rates by age category and typical or mean and maximum
longevities, when possible.
1.4.4. Seasonal Activities
Many life-cycle attributes affect an animal's activity and foraging patterns in time
and space. For example, many species of birds are present in the northern hemisphere
only during the warmer months or move seasonally between the northern and southern
parts of North America. Some species of mammals, reptiles, and amphibians hibernate or
spend a dormant period in a burrow or den during the winter months. The species profiles
describe these and other seasonal activity patterns that can influence exposure frequency
and duration.
For each species, we summarize information on the seasonal occurrence of several
activities including breeding, molting, migration, dispersal, and occurrence of
dormancy/denning (if applicable). Deposition and utilization of fat reserves are discussed
where information is available. Trends in these factors with latitude are identified.
1.5. DATA PRESENTATION FORMAT
Species-specific values for the exposure factors are presented in Chapter 2.
Quantitative data for each species are presented in tables arranged in four main sections:
• Normalizing and Contact Rate Factors;
• Dietary Composition;
• Population Dynamics; and
• Seasonal Activities.
The parameter values and units used for each exposure factor are described in the
remainder of this section. In the species profiles and in the Appendix, all values are
identified as measured or estimated, and references are provided.
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1.5.1. Normalizing and Contact Rate Factors
Normalizing and contact rate factors are presented under the heading "Factors" in
Chapter 2. Several of them apply to all animals included in the Handbook, whereas some
apply only to specific groups, as described in Sections 1.5.1.1 through 1.5.1.4. The column
headers for these factors are explained in Table 1-6.
Table 1-6. Column Headers for Tables of Normalizing and Contact Rate Factors
Age/Sex/ Age (e.g., A for adult, J for juvenile)
Cond./Seas. Sex (e.g., M for male, F for female)
Condition (e.g., I for incubating, NB for nonbreeding)
Season (e.g., SP for spring, SU for summer).
[Note: Only information needed to correctly interpret the value is
included.]
Mean
Range or
(95% Cl of
Mean)
Mean value for population sampled ± standard deviation (SD), if
reported. If SD is not reported, mean value for population sampled ±
standard error (SE) of the mean, if reported. For some studies, a
range of typical values may be presented instead of a mean value
(check the notes).
Range of values reported for the population sampled, or
(95th percent confidence interval of the mean value).
Location State(s) or province(s) in which the study was conducted
(subspecies) (subspecies studied, if reported).
Reference
Note No.
Reference for study.
Footnote number.
1.5.1.1. All Animals
Body weight (grams or
kilograms)
Measured values only. Although we use the term
weight, all data are presented in units of mass. The age
and sex of the animal are specified as appropriate, and
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Metabolic rate (liters O2/kg-day)
Metabolic rate (kcal/kg-day)
Food ingestion rate (g/g-day)
Water ingestion rate (g/g-day)
Sediment/soil ingestion rate
Inhalation rate (m3/day)
Surface area (cm2)
weights may include age-weight series for young
animals.
Included only if measured values were available. These
data can be used to estimate metabolic rate on a kcal
basis.
Measured or estimated basal and free-living (or field)
metabolic rates. Most of the free-living values were
estimated from body weight using an appropriate
allometric equation.
Measured on a wet-weight basis. For birds and
mammals, values measured in captivity are generally
lower than for free-ranging animals. For reptiles and
amphibians, food ingestion rates can be higher in
captivity than in the field. Food ingestion rates can also
be different in captivity than in the wild if the diet differs
substantially from that consumed in the wild (e.g., dry
laboratory chow has a substantially lower water content
than most natural diets).
Most of these values were estimated from body weight
using an allometric equation.
These values are not presented in the individual species
profiles in Chapter 2; instead, the limited data available
for soil/sediment ingestion rates (as percent soil or
sediment in diet on a dry weight basis) for selected
species are presented in Section 4.1.3.
Note that this value is not normalized to body weight,
but is the total volume inhaled each day. Most values
were estimated from body weight using an appropriate
allometric equation.
Most values were estimated from body weight using an
appropriate allometric equation.
1.5.1.2. Birds
Egg weight (grams)
Weight at hatching (grams)
Included only if measured values were available.
Included only if measured values were available.
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Chick or nestling growth
rate (g/day)
Weight at fledging (grams)
Included only if measured values were available. The
ages to which the growth rate applies are indicated.
Included only if measured values were available.
1.5.1.3. Mammals
Neonate weight (grams)
Pup growth rate (g/day)
Weight at weaning (grams)
Included only if measured values were available.
Included only if measured values were available. The
ages to which the growth rate applies are indicated.
Included only if measured values were available.
1.5.1.4. Reptiles and A mphibians
Body length (mm)
Egg weight (grams)
Weight at hatching (grams)
Juvenile growth rate (g/day)
Tadpole weight (grams)
Larval or eft weight (grams)
Length is the most common measure of size and growth
rate reported for reptiles and amphibians. Body length-
weight relationships are reported whenever possible.
Data for snakes include snout-to-vent lengths (SVL) and
total lengths; for frogs, SVLs only; and for turtles,
carapace (dorsal shell) and plastron (ventral shell)
lengths.
Included only if measured values were available.
Included only if measured values were available.
Included only if measured values were available. The
ages to which the growth rate applies are indicated.
For frogs only; included only if measured values were
available.
For newts only; included only if measured values were
available.
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1.5.2. Dietary Composition
1.5.2.1. All Animals
The diet of all animals is separated by season whenever possible. Up to three
months of data were combined for each of the four seasons, provided the animals were in
the same location and habitat during the 3-month period (Table 1-7). The diet components
are listed in the first column shaded in grey. The measure of dietary composition is
enclosed in parentheses under the "Location (subspecies)/Habitat (measure)" column
header.
Table 1-7. Column Headers for Tables on Dietary Composition
Dietary Composition List of food types.
Spring
Summer
Fall
Winter
Location
(subspecies)/
Habitat
(measure)
Reference
Note No.
Dietary composition during spring (March, April, May).
Dietary composition during summer (June, July, August).
Dietary composition during fall (September, October,
November).
Dietary composition during winter (December, January,
February).
State(s) or Canadian province(s) in which study was
conducted (subspecies studied, if reported).
Type of habitat associated with the reported values
(measure used to quantify dietary composition).
Reference for study.
Footnote number.
Dietary composition can be expressed in many ways. In the Appendix, we have
presented all measures of dietary composition encountered in the literature review. In the
species profiles in Chapter 2, we have emphasized dietary composition measured as the
percentage of the total food intake of each food type on a wet-weight basis. These data
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are usually determined by analysis of stomach or other digestive tract contents. For
entries based on these measures, the total of the values listed under each seasonal
column should approximate 100 percent. As Chapter 4 indicates, it is relatively simple to
estimate contaminant intakes when dietary composition is measured on a wet-weight
basis. Dietary composition may also be measured on a dry-weight basis; information on
the relative water content of the different dietary items provided in Chapter 4 can be used
to convert dry-weight composition to wet-weight composition if needed. Dietary
composition is often reported as frequency of occurrence in digestive tract contents,
scats, or regurgitated pellets. For these measures, the total of the values in the seasonal
columns can exceed 100 (e.g., fish occurred in 90 percent of scats, amphibia in 75 percent
of scats, and molluscs in 15 percent of scats). We do not provide guidance on how to
estimate contaminant intakes based on these measures; however, studies using these
measures can indicate seasonal and geographic differences in diet.
1.5.3. Population Dynamics
Distribution and mortality parameters can be defined similarly for birds, mammals,
reptiles, and amphibians (Section 1.5.3.1). Reproductive parameters, however, differ
among these groups (Sections 1.5.3.2 through 1.5.3.5). The column headers for population
dynamics are described in Table 1-8.
1.5.3.1. All Animals
Home range size (ha)/ Area usually listed in hectares, radius in kilometers. The home
Territory size (ha)/ range for species such as mink or kingfishers, which spend
Foraging radius (m) most of their time along shoreline areas, is sometimes
described as kilometers of shoreline. For some species with
extremely small breeding territories, we used m2 instead of
hectares. For colonially nesting birds, foraging radii are listed
in kilometers. For frogs, we found information only on male
breeding territory size, which does not include the foraging
range of either sex.
Population density Usually listed as number (N) of individuals per hectare,
(N/ha) although numbers of breeding pairs or nests per hectare are
used for some species.
1-25
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Table 1-8. Column Headers for Tables of Factors for Population Dynamics
Age/Sex/ Age (e.g., A for adult, J for juvenile)
Cond./Seas. Sex (e.g., M for male, F for female)
Condition (e.g., I for incubating, NB for nonbreeding)
Season (e.g., SP for spring, SU for summer).
[Note: Only information needed to correctly interpret the value is
included.]
Mean
Range
Mean value for population sampled ± standard deviation (SD), if
reported. If SD is not reported, mean value for population sampled ±
standard error (SE) of the mean, if reported. For some studies, a
range of typical values may be presented instead of a mean.
Range of values reported for the population sampled.
Location State(s) or province(s) in which the study was conducted
(subspecies)/ (subspecies studied, if reported).
Habitat Type of habitat associated with the reported values.
Reference
Note No.
Reference for study.
Footnote number.
Age at sexual maturity
Age at which first successful reproduction occurs. In many
long-lived species, only a portion of the population breeds at
this age.
Annual mortality rates
Longevity
Usually listed as percent per year. Can vary with age and sex
of the animal.
Mean longevity of adult members of the population (does not
include juvenile mortality). When available, an estimate of
maximum longevity is also provided (usually from studies of
captive individuals).
1.5.3.2. Birds
Clutch size
Number of eggs laid per active nest (usually the number laid
per female, but in some species, more than one female may lay
in a single nest).
1-26
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Clutches per year
Days incubation
Age at fledging
Number fledged per
active nest
Number of successful clutches laid per year. Additional
clutches may be laid if a clutch is lost early in incubation.
Measured from day incubation starts (often after laying of last
egg) to hatching.
Age at which young can maintain sustained flight. Parents
usually continue to feed or to accompany young for some time
after fledging.
Number fledged for each nest for which incubation was
initiated.
Percent nests
successful
Number fledged per
successful nest
Percent of active nests hatching eggs.
Number fledged for each nest for which at least one young
hatched.
1.5.3.3. Mammals
Litter size
Litters per year
Days gestation
Pup growth rate
Age at weaning
Based on embryo counts whenever possible. Use of placenta!
scars can result in overestimation of litter size and counts of
live pups in dens can result in underestimation of litter size.
Number of litters born each year.
Days of active gestation. For species with delayed
implantation, this period can be substantially shorter than the
period from mating to birth.
Usually reported as grams per day during a specified age
interval. May be reported instead as a series of weights for
pups of specified ages.
Age when the pups begin to leave the nest or den to actively
feed for most of their food.
1.5.3.4. Reptiles and A mphibians
Clutch or litter size
Number of eggs laid per female for egg-laying species; number
of live offspring born for species bearing live young (e.g., water
snake). Reported by age and size of the female when
appropriate.
1-27
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Clutches or litters Number of clutches or litters produced each year. Not limited
per year to successful clutches because there is no parental care in
most temperate species.
Days incubation Measured from laying of last egg to hatching. The duration of
incubation depends on the temperature of the substrate into
which eggs are laid.
Juvenile growth rate Usually reported as grams per day during a specified age (or
size) interval. May be reported instead as a series of weights
for juveniles of specified sizes if those are the only data
available.
Length at sexual maturity Length at which the first successful reproduction usually
occurs (see above). More commonly reported than weight or
age at sexual maturity.
1.5.4. Seasonal Activities
The meaning of most of the factors included under seasonal activities are self-
evident. Those requiring additional explanation are described in Sections 1.5.4.1 through
1.5.4.3. The column headers for this section of the table are shown in Table 1-9.
Table 1-9. Column Headers for Tables on Seasonal Activities
Begin Month that the activity usually begins.
Peak Month(s) that the activity peaks (most of the population is involved).
End Month that the activity usually ends.
Location State(s) or province(s) in which the study was conducted
(subspecies) (subspecies studied, if reported).
Reference Reference for study.
Note No. Footnote number.
1-28
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1.5.4.1. Birds
Mating/laying These two factors are combined because birds lay eggs within
a day or two of mating (they begin mating a day or two prior to
laying the first egg).
1.5.4.2. Mammals
Mating Although for most mammals the mating season corresponds to
conception and is followed immediately by gestation, some
species exhibit delayed implantation.
Parturition Birth of the pups (also known as whelping for canids).
1.5.4.3. Reptiles and Amphibians
Mating Because fertilization is external for many amphibians (i.e., most
toads and frogs and some salamanders), mating occurs at the
same time as egg-laying for these species. For reptiles,
fertilization is internal, and for some species, sperm may be
stored for months or years following mating.
Nesting Because many female reptiles can store sperm, nesting (i.e.,
egg-laying) often occurs weeks or months after mating.
1.5.5. Abbreviations Used in Tables
Age (life stage)
A adult (for all groups)
B both adults and juveniles/yearlings (for all groups)
C chick (for birds)
E eft (for newts)
F fledgling (for birds)
H hatchling (for birds, reptiles, and amphibians)
J juvenile (for all groups)
N nestling (for birds)
or
neonate (for mammals, water snakes)
P pup (for mammals)
T tadpole (for frogs)
Y yearling (for all groups)
1-29
-------
Sex
B
F
M
both sexes
female
male
Units
time:
energy:
d
wk
yr
day
week
year
cal calorie
kcal kilocalorie
mass:
area:
g
kg
length:
mm
cm
m
km
gram
kilogram
millimeter
centimeter
meter
kilometer
ha
m2
volume:
ml
1
hectare
square meter
milliliter
liter
temperature:
C degrees Centigrade
Other
NS not stated
1.6. LITERATURE SEARCH STRATEGY
The profiles in this Handbook are intended to provide a readily available
compendium of representative data for each selected species to assist in conducting
screening-level exposure assessments. They are not intended to provide complete
reviews of all available published and unpublished information or indepth biological
summaries. Moreover, the Handbook is not intended to replace field guides or natural
history or animal physiology texts. We have attempted to balance generalities, accuracy,
and coverage of each species relative to the available literature to meet our stated
purposes. We describe the process by which we identified literature for the Handbook
below.
1-30
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The U.S. Fish and Wildlife Service (USFWS) Office of Information Transfer
conducted the primary literature search for species-specific information using their Wildlife
Review/Fisheries Review database. The database is compiled by USFWS personnel from a
review of over 1,130 publication sources (largely journals, but also USFWS publications)
from the United States and other countries, most dating back to 1971. The search was
conducted in May 1990 using common and scientific species names, but no further
restrictions on search terms were applied. All titles identified for each species were
reviewed to determine potential utility for the Handbook, and promising references were
reviewed in full. Recent review articles, handbooks, and natural history texts were used to
identify other relevant literature and literature from before 1971. Commercial databases
were not searched initially. Following peer review of the Handbook in 1991 and 1992, all
references submitted or identified by peer reviewers were evaluated, and additional
relevant citations were obtained for review. Limited (1970 forward) literature searches for
some species were conducted using commercial databases in 1992.
For information concerning physiology, allometric equations, energetics, and other
general topics, literature was identified on the basis of recent review articles or books in
the field suggested by experts in the field and by peer reviewers.
Because of resource limitations, we have included some values from secondary
citations. In these cases, our intent was to carefully record the original source and to
clearly indicate from which secondary source it was obtained. Users are encouraged to
obtain the primary sources to verify these values.
We used certain field guides consistently throughout each taxonomic category to
provide greater comparability of general species characteristics. The use of a specific field
guide does not constitute endorsement.
Because our literature search strategy may not have included all journals of interest
and did not consistently cover other sources of information (e.g., books, theses,
dissertations, state wildlife reports, conference proceedings), we would appreciate any
assistance that users might provide in identifying additional sources of information that
1-31
-------
would help to fill data gaps or to improve the information in the Handbook. In particular,
Ph.D. dissertations and master's theses often contain relevant but unpublished
information.
1.7. REFERENCES
Peters, R.H. (1983) The ecological implications of body size. Cambridge, England:
Cambridge University Press.
U.S. Environmental Protection Agency. (1989a) Risk assessment guidance for Superfund:
volume II— environmental evaluation manual, interim final. Washington, DC: Office of
Solid Waste, Office of Emergency and Remedial Response; EPA report no.
EPA/540/1-89/001 A.
U.S. Environmental Protection Agency. (1989b) Ecological assessment of hazardous waste
sites: a field and laboratory reference. Corvallis, OR: Environmental Research
Laboratory; EPA report no. EPA/600/3-89/013.
U.S. Environmental Protection Agency. (1989c) Exposure factors handbook. Washington,
DC: Office of Health and Environmental Assessment; EPA report no. EPA/600/8-
89/043.
U.S. Environmental Protection Agency. (1992) Evaluation of terrestrial indicators for use in
ecological assessments at hazardous waste sites. Washington, DC: Office of
Research and Development; EPA report no. EPA/600/R-92/183.
1-32
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2. EXPOSURE FACTORS AND DESCRIPTIONS
OF SELECTED SPECIES
Chapter 2 includes exposure profiles for the selected species in three subsections:
birds (Section 2.1), mammals (Section 2.2), and reptiles and amphibians (Section 2.3).
Each species profile follows the same format, beginning with an introduction to the
taxonomic group to which the species belongs and a qualitative description of relevant
aspects of the species' natural history. Next, a list of similar species is provided to help
identify species that might share certain exposure characteristics, although they may have
different geographic ranges, diets, and habitat preferences. Each species profile then
presents a series of tables presenting values for normalizing and contact rate factors,
dietary composition, population dynamics, and seasonal activity patterns that represent
the range of values that we identified in our literature review. Table format is described in
Section 1.5. Data on soil and sediment ingestion are limited; we present these data in a
separate section (4.1.3) for easy comparison among species. Finally, each profile includes
the references cited in the species profile and in the corresponding Appendix tables.
2.1. BIRDS
Table 2-1 lists the bird species described in this section. For range maps, refer to
the general references identified in individual species profiles. The remainder of this
section is organized by species in the order presented in Table 2-1. The availability of
published information varies substantially among species, as is reflected in the profiles.
Some species include two or more subspecies; these are indicated in the profiles when
reported by the investigators. For many studies, the subspecies, although not identified,
can be inferred from the study location and geographic range of the subspecies. Average
lengths of birds are reported from museum study skins measured from bill tip to tail tip.
Body weight is reported as fresh wet weight with plumage, unless otherwise noted.
2-1
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Table 2-1. Birds Included in the Handbook
Order
Family
Ciconiformes
Ardeidae
Anseriformes
Anatidae
Falconiformes
Accipitridae
Falconidae
Galliformes
Phasianidae
Charadriiformes
Scolopacidae
Laridae
Coraciiformes
Alcedinidae
Passeriformes
Troglodytidae
Muscicapidae
Common name
great blue heron
Canada goose
mallard
lesser scaup
os prey
red-tailed hawk
bald eagle
American kestrel
northern bobwhite
American woodcock
spotted sandpiper
herring gull
belted kingfisher
marsh wren
American robin
Scientific name
Ardea herodias
Branta canadensis
Anas platyrhynchos
Aythya affinis
Pandion haliaetus
Buteo jamaicensis
Haliaeetus leucocephalus
Falco sparverius
Colinus virginianus
Scolopax minor
Actitis macularia
Larus argentatus
Ceryle alcyon
Cistothorus palustris
Turdus migratorius
Section
2.1.1
2.1.2
2.1.3
2.1.4
2.1.5
2.1.6
2.1.7
2.1.8
2.1.9
2.1.10
2.1.11
2.1.12
2.1.13
2.1.14
2.1.15
2-2
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2.1.1. Great Blue Heron (herons)
Order Ciconiiformes, Family Ardeidae. Herons, egrets, and bitterns are medium to
large wading birds with long necks and spear-like bills. Nearly all species feed primarily on
aquatic animal life (e.g., fish, frogs, crayfish, insects) and are common along the margins
of most freshwater and saltwater bodies and wetlands (Kushlan, 1978). Their long legs,
necks, and bills are adapted for wading in shallow water and stabbing prey. Most species
build their nests in trees near their foraging habitat, and many nest colonially. Members of
this group range in size from the least bittern (28 to 36 cm bill tip to tail tip) to the great
blue heron (106 to 132 cm tall). The sexes are similar in size and appearance.
Selected species
The great blue heron (Ardea herodias) is the largest member of the group in North
America and feeds primarily on aquatic animals. It is widely distributed in both saltwater
and freshwater environments. There are four subspecies in the United States and Canada:
A. h. wardi (Kansas and Oklahoma across the Mississippi River to Florida), A. h. herodias
(remainder of the North and Central American range), A. h. fannini (Pacific coast of North
America from Alaska to Washington), and A. h. occidentalis (extreme south of Florida)
(Bancroft, 1969, cited in Hancock and Kushlan, 1984). A. h. occidentalis (the great white
heron) is an all white color morph that was formerly considered a separate species
(National Geographic Society, 1987).
Body size. Males average slightly heavier in weight than females (Hartman, 1961;
Palmer, 1962). Northern continental herons are somewhat smaller than those found in the
south (Palmer, 1962). Quinney (1982) determined a relationship between age and body
weight for nestling great blue herons (r = 0.996, N = 16 nestlings, and 274 measurements):
BW = 55.6 x A - 47.4
where BW equals body weight in grams and A equals age in days.
Habitat. Great blue herons inhabit a variety of freshwater and marine areas,
including freshwater lakes and rivers, brackish marshes, lagoons, mangroves, and coastal
wetlands, particularly where small fish are plentiful in shallow areas (Spendelow and
Patton, 1988; Short and Cooper, 1985). They are often seen on tidal flats and sandbars and
occasionally forage in wet meadows, pastures, and other terrestrial habitats (Palmer,
1962). Great blue herons tend to nest in dense colonies, or heronries. The location of the
heronry is generally close to foraging grounds, and tall trees are preferred over shorter
trees or bushes for nest sites (Bent, 1926; Palmer, 1962; Gibbs et al., 1987). They also may
nest on the ground, on rock ledges, or on sea cliffs (Palmer, 1962).
Food habits. Fish are the preferred prey, but great blues also eat amphibians,
reptiles, crustaceans, insects, birds, and mammals (Alexander, 1977; Bent, 1926; Hoffman,
1978; Kirkpatrick, 1940; Peifer, 1979). When fishing, they mainly use two foraging
techniques: standing still and waiting for fish to swim within striking distance or
2-3 Great Blue Heron
-------
slow wading to catch more sedentary prey (such as flounder and sculpin) (Bent, 1926;
Willard, 1977). To fish, they require shallow waters (up to 0.5 m) with a firm substrate
(Short and Cooper, 1985). Fish up to about 20 cm in length were dominant in the diet of
herons foraging in southwestern Lake Erie (Hoffman, 1978), and 95 percent offish
consumed by great blues in a Wisconsin population were less than 25 cm in length
(Kirkpatrick, 1940). Great blues sometimes forage in wet meadows and pastures in pursuit
of lizards, small mammals, and large insects (Palmer, 1962; Peifer, 1979). In northern
areas, small mammals such as meadow voles may be an important part of the diet early in
the breeding season, possibly because some aquatic foraging areas may still be partially
frozen when the herons arrive (Collazo, 1985). Consumption of larger prey (fish, frogs,
rodents) is often followed by drinks of water (Hedeen, 1967); terrestrial prey such as voles
are usually dunked in water before they are swallowed (Peifer, 1979). Adult herons tend to
deliver the same type and size of food to their nestlings that they consume themselves, but
they deliver it well digested for young nestlings and less well digested as the nestlings
grow (Kushlan, 1978). Adults tend to feed solitarily, although they may feed in single or
mixed species flocks where there are large concentrations of prey (Bayer, 1978; Krebs,
1974; Kushlan, 1978; Willard, 1977); fledglings are frequently seen foraging together (Dowd
and Flake, 1985). Kushlan (1978) developed a regression equation relating the amount of
food ingested per day to body weight for wading birds (N = seven species):
log(FI) = 0.966 log(BW) - 0.640
where Fl equals food ingestion in grams per day and BW equals body weight in grams.
Molt. Adults undergo a complete molt in the late summer and fall and a partial molt
of the contour feathers in the late winter and early spring (Bent, 1926). Young herons
attain full adult plumage in the summer/fall molt at the end of their second year (Bent,
1926).
Migration. In the northern part of its range, most great blues are migratory, some
moving to the southern Atlantic and Gulf States to overwinter with the resident populations
of herons (Bent, 1926; Palmer, 1962), others continuing on to Cuba and Central and South
America (Hancock and Kushlan, 1984). Most migrating herons leave their breeding
grounds by October or November and return between February and April (Bent, 1926).
Breeding activities and social organization. The male great blue heron selects the
site for the breeding territory, and nests generally consist of a stick platform over 1 m in
diameter (Palmer, 1962). Great blues often use a nest for more than 1 year, expanding it
with each use (Palmer, 1962). Mean clutch sizes range from three to five (see table); in
general, clutch size tends to increase with latitude (Pratt, 1972). Only one brood is raised
per year; however, if a clutch is destroyed, great blues may lay a replacement clutch,
usually with fewer eggs than the initial clutch (Palmer, 1962; Pratt and Winkler, 1985). Both
parents incubate and feed the young (Palmer, 1962; Hancock and Kushlan, 1984). During
the breeding season, great blues are monogamous and colonial, with from a few to
hundreds of pairs nesting in the same area or heronry (Gibbs et al., 1987). Colonies may
2-4 Great Blue Heron
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include other species, such as great egrets or double-crested cormorants (Pratt and
Winkler, 1985; Mock et al., 1987).
Home range and resources. Breeding colonies are generally close to foraging
grounds (Bent, 1926; Palmer, 1962; Gibbs et al., 1987). Mathisen and Richards (1978)
found the distance between heronries and possible feeding areas in Minnesota lakes to
range from 0 to 4.2 km, averaging 1.8 km. Another study found that most heronries along
the North Carolina coast were located near inlets with large concentrations of fish, an
average of 7 to 8 km away (Parnell and Soots, 1978, cited in Short and Cooper, 1985).
Fifteen to 20 km is the farthest great blue herons regularly travel between foraging areas
and colonies (Gibbs et al., 1987; Gibbs, 1991; Peifer, 1979). In the northern portion of their
range, great blue herons often build nests in tall trees over dry land, whereas in the
southern part of their range, they usually nest in swamp trees, including mangroves
(Palmer, 1962). Each breeding pair defends a small territory around the nest, the size of
which depends on local habitat and the birds' stage of reproduction (Hancock and Kushlan,
1984). Herons in some areas also defend feeding territories (Peifer, 1979). In other areas,
great blues appear to be opportunistic foragers, lacking strict fidelity to particular feeding
sites (Dowd and Flake, 1985). A study in North Dakota found that herons often returned to
the same general areas, but different individuals often used the same areas at different
times (Dowd and Flake, 1985).
Population density. Because great blues nest colonially, local population density
(i.e., colony density, colony size, and number of colonies) varies with the availability of
suitable nesting habitat as well as foraging habitat. On islands in coastal Maine, Gibbs and
others (1987) found a significant correlation between colony size and the area of tidal and
intertidal wetlands within 20 km of the colonies, which was the longest distance herons in
the study colonies traveled on foraging trips. In western Oregon, the size of heronries was
found to range from 32 to 161 active nests; the area enclosed by peripheral nest trees
within the colonies ranged from 0.08 to 1.21 ha (Werschkul et al., 1977).
Population dynamics. Most nestling loss is a result of starvation, although some
losses to predation do occur (Collazo, 1981; Hancock and Kushlan, 1984). In a study of 243
nests in a coastal California colony, 65 percent of the chicks fledged, 20 percent starved, 7
percent were taken by predators, and 7 percent were lost to other causes (Pratt and
Winkler, 1985). Estimates of the number of young fledged each year by breeding pairs
range from 0.85 to 3.1 (Pratt, 1970; Pratt, 1972; McAloney, 1973; Pratt and Winkler, 1985;
Quinney, 1982). Based on banding studies, about two-thirds of the fledglings do not
survive more than 1 year, although they may survive better in protected wildlife refuges
(Bayer, 1981 a). Values for later years indicate that about one-third to one-fifth of the 2-
year-old and older birds are lost each year (Bayer, 1981 a; Henny, 1972; Owen, 1959).
Similar species (from general references)
• The great egret (Casmerodius albus) is almost the same size (96 cm length)
as the great blue heron and is found over a limited range in the breeding
season, including areas in the central and eastern United States and the east
and west coasts. It winters in coastal areas of the United States and in
2-5 Great Blue Heron
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Mexico and farther south. The great egret's habitat preferences are similar
to those of the great blue heron.
• The snowy egret (Egretta thula), one of the medium-sized herons (51 to 69
cm), shuffles its feet to stir up benthic aquatic prey. It is found mostly in
freshwater and saltwater marshes but also sometimes follows cattle and
other livestock as does the cattle egret. It breeds in parts of the western,
southeastern, and east coasts of the United States and winters along both
coasts of the southern United States and farther south.
• The cattle egret (Bubulcus ibis) is seen in agricultural pastures and fields,
where it follows livestock to pick up insects disturbed by grazing. An Old
World species, it was introduced into South America and reached Florida in
the 1950's. It reached California by the 1960's and has been continuing to
expand its range.
• The green-backed heron (Butorides striatus), one of the smaller herons (41
to 56 cm), breeds over most of the United States except for the northwest
and southern midwest. It has a winter range similar to that of the snowy
egret and seems to prefer water bodies with woodland cover.
• The tricolored heron (Egretta tricolor) (formerly known as the Louisiana
heron) is common in salt marshes and mangrove swamps of the east and
gulf coasts, but it is rare inland.
• The little blue heron (Egretta caerulea) is common in freshwater ponds,
lakes, and marshes and coastal saltwater wetlands of the Gulf Coast States.
Juveniles are easily confused with juvenile snowy egrets. This species
hunts by walking slowly in shallow waters, and its diet typically includes fish,
amphibians, crayfish, and insects.
• The black-crowned night heron (Nycticorax nycticorax), characterized by a
heavy body, short thick neck, and short legs (64 cm), is a common heron of
freshwater swamps and tidal marshes, roosting by day in trees. It typically
feeds by night, predominantly on aquatic species, fish, amphibians, and
insects. This heron is extremely widespread, occurring in North and South
America, Eurasia, and Africa. It breeds over much of the United States and
parts of central Canada and winters along both coasts of the United States
and farther south.
• The yellow-crowned night heron (Nyctanassa violacea) (61 cm) is similar to
the black-crowned but is more restricted in its range to the southeastern
United States. It roosts in trees in wet woods, swamps, and low coastal
shrubs.
• The American bittern (Botaurus lentiginosus), another of the medium-sized
herons (58 to 70 cm), is a relatively common but elusive inhabitant of
freshwater and brackish marshes and reedy lakes. It is a solitary feeder,
2-6 Great Blue Heron
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consuming fish, crayfish, reptiles, amphibians, insects, and even small
mammals. Its breeding range includes most of Canada and the United
States, although much of the southern United States is inhabited only during
the winter.
• The least bittern (Ixobrychus exilis), the smallest of the North American
herons (33 cm), also is an elusive inhabitant of reedy areas. Its breeding
range is restricted largely to the eastern half of the United States.
General references
Hancock and Kushlan (1984); Robbins et al. (1983); National Geographic Society
(1987); Palmer (1962); Short and Cooper (1985).
2-7 Great Blue Heron
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Great Blue Heron (Ardea herodias)
Factors
Body Weight
(g)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion Rate
(g/g-day)
Inhalation Rate
(m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
AF
AM
yearlings
juveniles
nestlings:
dayl
dayS
day 10
day 15
day 20
day 25
day 30
day 35
day 40
A B basal
A B free-living
AB
AB
AB
AB
Mean
2,229 ± 762 SD
2,204 ± 337 SD
2,576 ± 299 SD
2,340 ± 490 SD
1,990±550SD
86
170
567
983
1,115
1,441
1,593
1,786
2,055
62
165
0.18
0.045
0.76
1,711
Range or
(95% Cl of mean)
1,940-2,970
1,370-2,750
(78 - 353)
Location
eastern North America
NS
central Oregon
Nova Scotia, Canada
NS
Reference
Quinney, 1982
Hartman, 1961
Bayer, 1981b
McAloney, 1973
estimated
estimated
Kushlan, 1978
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
7
10
00
0)
I-K
CD
(D
(D
3
-------
Great Blue Heron (Ardea herodias)
Dietary Composition
trout
non-trout fish
crustaceans/amphibian
s
trout
non-trout fish
crustaceans
amphibians
birds and mammals
Atlantic silverside
mummichog
American eel
Gaspereaux
pollack
yellow perch
staghorn sculpin
small
medium
large
starry flounder
small
medium
large
other
small
medium
Spring
Summer
59
39
2
89
5
1
4
1
3.6
2.4
52.6
29.9
8.9
2.6
27.8
7.6
2.2
15.0
8.1
5.2
30.6
3.5
Fall
Winter
Location/Habitat
(measure)
lower Michigan/lake
(% wet weight; stomach
contents)
lower Michigan/river
(% wet weight; stomach
contents)
Nova Scotia/Boot Island
(% wet weight; items
regurgitated by nestlings)
Vancouver, BC/coastal
island
(% offish observed caught;
small = less than 1/3 beak
length; medium = about 1/2
beak length; large = longer
than beak; other includes
shiner sea perch and
penpoint gunnels)
Reference
Alexander, 1977
Alexander, 1977
Quinney, 1982
Krebs, 1974
Note
No.
10
CD
0)
I-K
CD
(D
(D
3
-------
Great Blue Heron (Ardea herodias)
Population
Dynamics
Size Feeding
Territory
Foraging
Distance from
Colony
Population
Density
Clutch Size
Clutches/Year
Days
Incubation
Age at Fledging
(days)
Number Fledge
per Pair
Age/Sex
Cond./Seas.
A B fall
A B winter
A B summer
A B summer
summer
along stream
along river
summer
summer
Mean
0.6 ±0.1 SDha
8.4 ± 5.4 SD ha
3.1 km
7 to 8 km
2.3 birds/km
3.6 birds/km
149±53SD
nests/ha
461 nests/ha
3.16 ± 0.04 SE
4.17 ± 0.85 SD
4.37
1
27.1
28
45
60
49 to 56
1.7
1.96
2.8
Range
up to 24.4 km
447 - 475
1 -5
3-6
3-6
25-30
Location/Habitat
Oregon/freshwater marsh
Oregon/estuary
South Dakota/river &
streams
North Carolina/coastal
North Dakota/rivers &
streams
Maine/coastal islands
Oregon/coastal island
California/coastal canyon
Nova Scotia/island
Pennsylvania/NS
Pennsylvania; Oregon/NS
Nova Scotia/island
United States/NS
Nova Scotia/island
NS/NS
Nova Scotia/island
central California/coastal
northwest Oregon/river
Nova Scotia/island
Reference
Bayer, 1978
Dowd & Flake, 1985
Parnell & Soots, 1978
Dowd & Flake, 1985
Gibbsetal., 1987
Werschkuletal., 1977
Pratt &Winkler, 1985
McAloney, 1973
Miller, 1943
Miller, 1943; English, 1978
McAloney, 1973
Bent, 1926
McAloney, 1973
Hancock & Kushlan, 1984
Quinney, 1982
Pratt, 1972
English, 1978
Quinney, 1982
Note
No.
8
9
10
11
10
_1
o
0
fi)
l-K
CD
c
(D
I
(D
O
3
-------
Population
Dynamics
Number
Fledge per
Successful
Nest
Age at Sexual
Maturity
Annual
Mortality Rates
(percent)
Seasonal
Activity
Mating/Laying
Age/Sex
Cond./Seas.
B
during 1st yr
during 2nd yr
during 3rd yr
Begin
Nov. to Dec.
mid-February
mid-March
late March
mid-April
mid-April
mid-May
mid-Sept.
mid-February
mid-March
late March
Mean
2.19 ± 0.25 SD
2.43
3.09
2 years
64
36
22
Peak
mid-March
early May
early May
Range
2-3
End
April
June
early April
late May
mid-July
late October
mid-March
Location/Habitat
central California/coastal
northwest Oregon/river
Nova Scotia/island
NS
United States and
Canada/NS
Location
Florida
central California
northwest Oregon
Pennsylvania
Nova Scotia
northwest Oregon
Idaho
Ohio
northern US
western Oregon
Wisconsin; Minnesota
Nova Scotia
Reference
Pratt &Winkler, 1985
English, 1978
McAloney, 1973
Bent, 1926
Henny, 1972
Reference
Howell, 1932
Pratt &Winkler, 1985
English, 1978
Miller, 1943
McAloney, 1973
English, 1978
Collazo, 1981
Hoffman & Curnow, 1979
Palmer, 1962
Werschkuletal., 1977
Bent, 1926
Bent, 1926
Note
No.
Note
No.
9
9
0
fi)
l-K
CD
c
(D
I
(D
O
3
1 As cited in Dunning, 1984.
2 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and body weights from Quinney (1982).
3 Estimated using equation 3-37 (Nagy, 1987) and body weights from Quinney (1982).
4 Estimated from Kushlan's (1978) allometric equation for wading birds, assuming a body weight of 2,230 g.
5 Estimated using equation 3-15 (Calderand Braun, 1983) and body weights from Quinney (1982).
6 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Quinney (1982).
Great Blue Heron (Ardea herodias)
-------
7 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Quinney
(1982).
8 Cited in Short and Cooper (1985).
9 Cited in Palmer (1962).
10 May replace clutch if eggs are lost, but only rear one brood (Henny, 1972).
11 Young fed around colony for 10 days after leaving nest at 45 days of age.
10
_i
10
0
fi)
l-K
CD
c
(D
I
(D
O
3
Great Blue Heron (Ardea herodias)
-------
References (including Appendix)
Alexander, G. (1977) Food of vertebrate predators on trout waters in north central lower
Michigan. Michigan Academician 10: 181-195.
Altman, P. L.; Dittmer, D. S., eds. (1968) Biology data book. 2nd ed., 3v. Bethesda, MD:
Federation of American Societies for Experimental Biology.
Baird, S. F.; Brewer, T. M.; Ridgeway, R. (1884) Water birds of North America. Boston, MA:
Little, Brown & Co.
Bancroft, G. (1969) (as cited in Hancock and Kushlan, 1984). Auk 86: 141-142.
Bayer, R. D. (1978) Aspects of an Oregon estuarine great blue heron population. In: Sprunt,
A.; Ogden, J.; Winckler, S., eds. Wading birds. Natl. Audubon Soc. Res. Rep. 7; pp.
213-217.
Bayer, R. D. (1981 a) Regional variation of great blue heron Ardea herodias longevity. J.
Field Ornithol. 52: 210-213.
Bayer, R. D. (1981b) Weights of great blue herons (Ardea herodias) at the Yaquina Estuary,
Oregon. Murrelet 62: 18-19.
Benedict, F. G.; Fox, E. L. (1927) (cited in Altman and Dittmer, 1968). Proc. Am. Phil. Soc.
66:411.
Bent, A. C. (1926) Life histories of North American marsh birds. Washington, DC: U.S.
Government Printing Office; Smithsonian Inst. U.S. Nat. Mus., Bull. 135.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Collazo, J. A. (1981) Some aspects of the breeding ecology of the great blue heron at
Heyburn State Park. Northwest Sci. 55: 293-297.
Collazo, J. A. (1985) Food habits of nestling great blue herons (Ardea herodias) at Heyburn
State Park, Idaho. Northwest Sci. 59: 144-146.
Cottam, C. A.; Uhler, F. M. (1945) Birds in relation to fishes. U.S. Fish Wildl. Serv. Leaflet
272.
Cottam, C. A.; Williams, J. (1939) (as cited in Palmer, 1962). Wilson Bull. 51: 150-155.
Dowd, E.; Flake, L. D. (1985) Foraging habitats and movements of nesting great blue
herons in a prairie river ecosystem, South Dakota. J. Field Ornithol. 56: 379-387.
2-13 Great Blue Heron
-------
Dunning, J. B., Jr. (1984) Body weights of 686 species of North American birds. Western
Bird Banding Association, Monograph No. 1. Cave Creek, AZ: Eldon Publishing.
English, S. M. (1978) Distribution and ecology of great blue heron colonies on the
Willamette River, Oregon. In: Sprunt, A.; Ogden, J.; Winckler, S., eds. Wading birds.
Natl. Audubon Soc. Res. Rep. 7; pp. 235-244.
Forbes, L. S.; Simpson, K.; Kelsall, J. P., et al. (1985) Reproductive success of great blue
herons in British Columbia. Can. J. Zool. 63: 1110-1113.
Gibbs, J. P. (1991) Spatial relationships between nesting colonies and foraging areas of
great blue herons. Auk 108: 764-770.
Gibbs, J. P.; Woodward, S.; Hunter, M. L., et al. (1987) Determinants of great blue heron
colony distribution in coastal Maine. Auk 104: 38-47.
Hancock, J.; Kushlan, J. (1984) The herons handbook. New York, NY: Harper & Row.
Hart man, F. A. (1961) Locomotor mechanisms in birds. Washington, DC: Smithsonian Misc.
Coll. 143.
Hedeen, S. (1967) Feeding behavior of the great blue heron in Itasca State Park, Minnesota.
Loon 39: 116-120.
Henny, C. J. (1972) An analysis of the population dynamics of selected avian species with
special reference to changes during the modern pesticide era. Washington, DC: Bur.
Sport. Fish. Wildl.; Wildl. Res. Rep. 1.
Henny, C. J.; Bethers, M. R. (1971) Ecology of the great blue heron with special reference
to western Oregon. Can. Field-Nat. 85: 205-209.
Hoffman, R. D. (1978) The diets of herons and egrets in southwestern Lake Erie. In: Sprunt,
A.; Ogden, J.; Winckler, S., eds. Wading birds. Natl. Audubon Soc. Res. Rep. 7:
365-369.
Hoffman, R. D.; Curnow, R. D. (1979) Mercury in herons, egrets, and their foods. J. Wildl.
Manage 43: 85-93.
Howell, A. H. (1932) Florida bird life. Florida Dept. Game and Freshwater Fish and Bur. Biol.
Survey, USDA.
Kelsall, J. P.; Simpson, K. (1979) A three year study of the great blue heron in
southwestern British Columbia. Proc. Col. Waterbird Group 3: 69-74.
Kirkpatrick, C. M. (1940) Some foods of young great blue herons. Am. Midi. Nat. 24:
594-601.
2-14 Great Blue Heron
-------
Krebs, J. R. (1974) Colonial nesting and social feeding as strategies for exploiting food
resources in the great blue heron (Ardea herodias). Behaviour 51: 93-134.
Kushlan, J. A. (1978) Feeding ecology of wading birds. In: Sprunt, A.; Ogden, J.; Winckler,
S., eds. Wading birds. Natl. Audubon Soc. Res. Rep. 7; pp. 249-296.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
Lasiewski, R. C.; Dawson, W. R. (1967). A reexamination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Mathisen, J.; Richards, A. (1978) Status of great blue herons on the Chippewa National
Forest. Loon 50: 104-106.
McAloney, K. (1973) The breeding biology of the great blue heron on Tobacco Island, Nova
Scotia. Can. Field-Nat. 87: 137-140.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Miller, R. F. (1943) The great blue herons: the breeding birds of the Philadelphia region
(Part II). Cassinia 33: 1-23.
Mitchell, C. A. (1981) Reproductive success of great blue herons at Nueces Bay, Corpus
Christi, Texas. Bull. Texas Ornithol. Soc. 14: 18-21.
Mock, D. W.; Lamey, T. C.; Williams, C. F.; et al. (1987) Flexibility in the development of
heron sibling aggression: an interspecific test of the prey-size hypothesis. Anim.
Behav. 35: 1386-1393.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Owen, D. F. (1959) Mortality of the great blue heron as shown by banding recoveries. Auk
76: 464-470.
Page, P. J. (1970) Appendix. San Joaquin River rookery study 1970. Sacramento, CA: Calif.
Dept. Fish and Game; statewide heron rookery survey progress report.
Palmer, R. S. (1949) Marine birds. Bull. Mus. Comp. Zool. Harvard 102.
Palmer, R. S. (1962) Handbook of North American birds: v. 1. New Haven, CT: Yale
University Press.
2-15 Great Blue Heron
-------
Parnell, J. F.; Soots, R. F. (1978) The use of dredge islands by wading birds. Wading birds.
Nat. Audubon Soc. Res. Rep. 7: 105-111.
Peifer, R. W. (1979) Great blue herons foraging for small mammals. Wilson Bull. 91:
630-631.
Poole, E. L. (1938) Weights and wing areas in North American birds. Auk 55: 511-517.
Powell, G. V.; Powell, A. H. (1986) Reproduction by great white herons Ardea herodias in
Florida Bay as an indicator of habitat quality. Biol. Conserv. 36: 101-113.
Pratt, H. M. (1970) Breeding biology of great blue herons and common egrets in central
California. Condor 72: 407-416.
Pratt, H. M. (1972) Nesting success of common egrets and great blue herons in the San
Francisco Bay region. Condor 74: 447-453.
Pratt, H. M.; Winkler, D. W. (1985) Clutch size timing of laying and reproductive success in
a colony of great blue herons (Ardea herodias) and great egrets (Casmerodius
a/dus). Auk 102: 49-63.
Quinney, T. E. (1982) Growth, diet, and mortality of nestling great blue herons. Wilson Bull.
94: 571-577.
Robbins, C. S.; Bruun, B.; Zim, H. S. (1983) A guide to field identification: birds of North
America. New York, NY: Golden Press.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Short, H. L.; Cooper, R. J. (1985) Habitat suitability index models: great blue heron. U.S.
Fish Wildl. Serv. Biol. Rep. No. 82(10.99); 23 pp.
Spendelow, J. A.; Patton, S. R. (1988) National atlas of coastal waterbird colonies:
1976-1982. U.S. Fish Wildl. Serv. Biol. Rep. No. 88(5).
Thompson, D. H. (1978) Feeding areas of great blue herons and great egrets nesting within
the floodplain of the upper Mississippi River. Colonial Waterbirds 2: 202-213.
Vermeer, K. (1969) Great blue heron colonies in Alberta. Can. Field-Nat. 83: 237-242.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Werschkul, D. F.; McMahon, E.; Leitschuh, M.; et al. (1977) Observations on the
reproductive ecology of the great blue heron (Ardea herodias) in western Oregon.
Murrelet58:7-12.
2-16 Great Blue Heron
-------
Willard, D. E. (1977) The feeding ecology and behavior of five species of herons in
southeastern New Jersey. Condor 79: 462-470.
Wood (1951) (cited in Palmer, 1962). Univ. Mich. Mus. Misc. Publ. No. 75.
2-17 Great Blue Heron
-------
2.1.2. Canada Goose (geese)
Order Anseriformes, Family Anatidae. Geese are large herbivorous waterfowl that
feed on grains, grass sprouts, and some aquatic vegetation. Although adapted for life on
the water, they forage primarily in open fields. They breed in open forested areas near lake
shores and coastal marshes from the arctic tundra through temperate climates. These
birds migrate in noisy flocks in the familiar V-formation, stopping in cultivated fields,
wetlands, and grasslands to feed. Geese show a wide variation in size even within a
species; the sexes look alike.
Selected species
The Canada goose (Branta canadensis) is the most widespread and abundant goose
in North America. It is a popular game species and is commonly encountered on cultivated
fields, golf courses, other parklands, and wetland refuge areas. Depending on subspecies,
these geese can range in size from 64 to 114 cm (bill tip to tail tip), the larger geese
breeding in more southerly locations than the smaller subspecies. The reverse is true in
winter, with the larger subspecies wintering in the more northerly parts of the range
(Palmer, 1962). The number of existing recognized subspecies varies, but most
ornithologists agree that there are 11: canadensis (Atlantic Canada goose), fulva
(Vancouver Canada goose), hutchinsii (Richardson's Canada goose), interior (interior
Canada goose), leucopareia (Aleutian Canada goose), maxima (giant Canada goose),
minima (cackling Canada goose), moffitti (Great Basin or western Canada goose),
occidentalis (dusky Canada goose), parvipes (lesser Canada goose), and taverneri
(Taverner's Canada goose) (Bellrose, 1976; Johnson et al., 1979; Palmer, 1962). Several
subspecies usually mingle during migration and in wintering areas, but they breed in
geographically distinct ranges. Six of the subspecies breed in Alaska (fulva, leucopareia,
minima, occidentalis, parvipes, and taverni) (Johnson et al., 1979). The leucopareia
subspecies, found in Oregon, Washington, California, and Alaska, currently is a United
States federally designated threatened species (50 CFR 17.11, 1992). It is only known to
breed on one of the western Aleutian islands off Alaska (Byrd and Woolington, 1983). See
Bellrose (1976) for ranges, migration corridors, and wintering areas of specific subspecies
and populations.
Body size. Canada geese subspecies vary greatly in size, but males are on average
larger than females (see table). Body weight reaches its maximum just prior to or during
the spring migration and then declines during egg-laying and incubation, sometimes by as
much as 20 percent (Mainguy and Thomas, 1985; McLandress and Raveling, 1981). Most of
the weight lost during incubation reflects loss of fat, which can provide over 80 percent of
the energy requirements for the incubating females (Mainguy and Thomas, 1985; Murphy
and Boag, 1989). Young are similar to parents in size by 2 months of age (Palmer, 1962).
Habitat. Breeding habitat includes tundra, forest muskeg in the far north, tall- and
shortgrass prairie, marshes, ponds, and lakes. Most nesting sites are close to open water
with high visibility in all directions (Palmer, 1962; Steel et al., 1957). In many areas, Canada
geese nest predominantly on islands in ponds or lakes (Geis, 1956). Former
2-19 Canada Goose
-------
muskrat houses often serve as nest sites in marshes (Steel et al., 1957). Brood-rearing
habitats, on the other hand, require adequate cover, and riparian areas are used more
frequently than open water (Eberhardt et al., 1989a). During the fall and winter in Maryland,
Harvey et al. (1988) found Canada geese to spend 57 percent of their time in farmlands
(mostly corn, soybeans, and winter wheat fields) and 24 percent in forested areas.
Food habits. Canada geese are almost exclusively vegetarian, and feeding activity
is concentrated in areas where food is plentiful (e.g., standing crops, scattered whole
grain) (Palmer, 1962). They are primarily grazers, but must consume grit at some point to
assure proper digestion (Palmer, 1962). They prefer certain foods, but will change their
diet depending on the availability of a food type (Coleman and Boag, 1987). For example,
when water levels are low in the south Yukon (Canada) river delta, Canada geese forage on
rhizomes of Potamogeton richardsonii even though other forage is available; at higher
water levels when the Potamogeton is unreachable, the geese will feed on other plants
(Coleman and Boag, 1987). During fall, geese often consume green crops (e.g., winter
wheat). During winter, however, they consume more energy-rich foods such as corn
(Harvey et al., 1988; McLandress and Raveling, 1981). In late winter and early spring, green
crops that are high in nitrogen and other important nutrients again constitute an important
part of the diet (McLandress and Raveling, 1981). Canada geese often feed preferentially
on the blade tips of many plants, which are higher in nitrogen than other parts of the plant
(Buchsbaum et al., 1981). In Minnesota, Canada geese begin consuming green grasses as
soon as they are exposed by the melting snow (McLandress and Raveling, 1981). In
Maryland, on the other hand, Harvey et al. (1988) found that Canada geese did not begin
consuming green crops before migration to the breeding grounds, indicating that this
population may rely on green forage available at staging areas to obtain the protein and
lipids required for reproduction. In the spring in Falmouth Harbor, Massachusetts, Canada
geese initially consume predominantly the marsh grasses Spartina spp. and rushes
Juncus gerardi, which are high in protein (Buchsbaum and Valiela, 1987). As the summer
progresses, however, they feed increasingly on submerged eelgrass, Zostera marina,
which provides more carbohydrates (Buchsbaum and Valiela, 1987).
Molt. Nonbreeders and yearlings migrate to a separate molting ground soon after
arrival at the breeding grounds, while breeding birds molt on the brood-rearing grounds
(Bellrose, 1976). Molting occurs earlier in nonbreeders, at least a month earlier in the
larger subspecies (Palmer, 1962). Molting parents do not regain flight feathers until just
prior to the time when their young first attain flight (Palmer, 1962). The flightless period of
B. c. interior is estimated to be 32 days. For B. c. maxima and B. c. moffitti, the flightless
period lasts from 39 to 40 days (Balham, 1954; Hanson, 1965, as cited in Palmer, 1962).
Migration. Migratory Canada geese leave their breeding grounds during late
summer and early autumn; they return in the spring around the time the first water is
opening (i.e., ice melting) but well before snow cover has disappeared (Bellrose, 1976).
Spring migration begins later for northerly populations, with geese that winter in mild
climates departing as early as mid-January, while those wintering in the coldest areas do
not move northward until the beginning of March (Bellrose, 1976). The bulk of the migrants
typically arrive on the summer breeding grounds 3 weeks after the first birds
2-20 Canada Goose
-------
(Bellrose, 1976). Some populations have become resident year-round, for example,
B. c. maxima in Missouri (Brakhage, 1965) and in southeast Georgia and southwest
Alabama (Combs et al., 1984). During both the spring and fall migrations, geese tend to
gather in large flocks and feed for several weeks in "staging" areas along major waterfowl
flyways (Bellrose, 1976).
Breeding activities and social organization. Canada geese arrive on the breeding
grounds in flocks, and soon after, the male becomes territorial and aggressive toward
other birds (Palmer, 1962). Lifelong monogamy following their first breeding is the general
rule with these geese (Palmer, 1962). Nests are built on the ground in a position with good
visibility (Palmer, 1962). During incubation the male stands guard, while the female
incubates the eggs, which she normally leaves two or three times daily to feed, bath, drink,
and preen (Murphy and Boag, 1989). Both parents accompany the young through the
brood period (Bellrose, 1976; Brakhage, 1965). Canada geese return to the breeding
grounds as family units, but the yearlings leave their parents soon after arrival (Bellrose,
1976).
Home range and resources. The foraging home range of Canada geese varies with
season, latitude, and breeding condition. Soon after hatching, goose families move away
from the nesting sites to other areas with adequate cover and forage to rear their broods
(Byrd and Woolington, 1983). Newly hatched families may have to travel 10 to 20 km from
the nest site to reach areas with adequate aquatic vegetation or pasture grasses (Geis,
1956). Although the families stay predominantly on land, often in riparian areas, they
usually are close to water. Eberhardt et al. (1989a) found goslings within 5 m of water
most of the time; only 7 percent of sightings were farther than 50 m away. During the
spring and fall migrations and in winter, Canada geese can be found on open water or
refuges near grain fields or coastal estuaries (Leopold et al., 1981).
Population density. Breeding population densities of Canada geese vary widely.
Low nesting densities (i.e., less than 0.005 per hectare) are common in the Northwest
Territories of Canada (Smith and Sutton, 1953, 1954) and intermediate densities (i.e., 0.02
to 0.7 per hectare) have been reported for Alaska (Cornley et al., 1985). In some more
southerly locations (e.g., California), colonial nesting situations have been reported, with
as many as 32 nests located on half an acre (Naylor, 1953, as cited in Palmer, 1962).
Population dynamics. The earliest Canada geese begin breeding is around 2 to 3
years of age (Maclnnes and Dunn, 1988; Brakhage, 1965). In the larger subspecies, only a
small proportion of the birds under 4 years may attempt to breed. For example, in
Manitoba, Moser and Rusch (1989) found that only 7 percent of 2-year-old and 15 percent
of 3-year-old B. c. interior laid eggs. Canada geese only attempt to rear one brood per
year. In the more southerly latitudes, Canada geese will renest if a clutch is lost prior to
incubation (Brakhage, 1965; Geis, 1956). In general, both clutch size and success at
rearing goslings increase with the age of the breeder (Brakhage, 1965). Raveling (1981)
found that older B. c. maxima (4 plus years) raised more than twice as many goslings to
fledging as did younger (2 to 3 years) birds. Population age structure and annual mortality
vary with hunting pressure as well as natural factors.
2-21 Canada Goose
-------
Similar species (from general references)
• The Brant goose (Branta bernicla) is approximately the size of the smaller
Canada geese subspecies (length 25 cm). It is primarily a sea goose and is
rare inland. It winters along both the east and west coasts of the United
States, where it feeds on aquatic plants in shallow bays and estuaries. It
breeds in the high arctic.
• The greater white-fronted goose (Anser albifrons) is limited to certain areas
west of the Mississippi River and averages 71 cm in length. Its habits are
similar to those of other geese.
• The snow goose (Chen caerulescens) breeds in the Arctic and winters in
selected coastal areas across the United States. However, this average-
sized goose (71 cm) is a migratory visitor to much of the central United
States.
• The Ross' goose (Chen rosii) breeds in the high arctic tundra and winters in
some areas of the southwest United States. This relatively small (58 cm)
goose is a rare visitor to the mid-Atlantic States and is always seen with
snow geese.
General references
Bellrose (1976); Kortright (1955); National Geographic Society (1987); Palmer (1962).
2-22 Canada Goose
-------
Canada Goose (Branta canadensis)
Factors
Body Weight (g)
Age/Sex/
Cond./Seas.
A M late sum.
A F late sum.
A M winter
A F winter
A M not spec.
A F not spec.
A M fall
A F fall
A M late sum.
A F late sum.
M at hatching
F at hatching
B day 10
B day 20
B day 30
B day 40
B day 47
B day 0
Bday9
B day 16
B day 30
B day 44
B day 51
M at fledging
F at fledging
Mean
1,443±32SE
1,362±54SE
2,769 ± 30 SE
2,472 ± 23 SE
3,992
3,447
4,212 ± 35 SE
3,550 ± 31 SE
4,960
4,160
108.7
109.5
150
450
755
950
1,050
110
240
440
1,400
2,400
2,600
87%adultwt
89%adultwt
Range or
(95% Cl of mean)
1,260-1,605
1,195-1,590
3,799 - 4,727
3,147-3,856
Location (subspecies)
Alaska (minima)
Colorado (parvipes)
NS (canadensis)
Illinois (interior)
Missouri (maxima)
Alberta (moffitti)
Alaska (minima)
NS (moffitti)
Alaska (minima)
Reference
Raveling, 1979
Grieb, 1970
Webster (unpublished) in
Bellrose, 1976
Raveling, 1968
Brakhage, 1965
LeBlanc, 1987b
Sedinger, 1986
Williams (unpublished) in
Palmer, 1976
Sedinger, 1986
Note
No.
1
10
ISJ
CO
O
0)
3
0)
Q.
0)
Q
O
O
-------
Canada Goose (Branta canadensis)
Factors
Body Fat
(g lipid)
Egg Weight
(g)
Metabolic Rate
(kcal/kg-day)
Age/Sex/
Cond./Seas.
F fall migr.
F winter
F spring migr.
F prelaying
F end incub.
F early molt
F prelaying
F incubating
F late incub.
F molting
free-living:
A M winter
A M spring
A M summer
A M fall
A F spring
A F summer
free-living:
AM
AF
AM
AF
AM
AF
Mean
182±24SE
57 ± 6 SE
172±25SE
171 (noSE; N=2)
33 ± 5 SE
108±13SE
751 ± 45 SE
611 ±40SE
166±18SE
485 ± 37 SE
96
127
163
185
187
141
147
135
142
Range or
(95% Cl of mean)
117-264
34-71
68 - 362
136-205
14-51
62-179
105-209
105-203
115-253
100-209
130-220
143-274
(87-391)
(88 - 397)
(65 - 304)
(69-316)
(63 - 292)
(66 - 305)
Location (subspecies)
Alaska in winter (minima)
California in summer
Ontario, Canada (maxima)
NS (minima)
NS (leucopa)
Alberta, Canada (moffitti)
Illinois in winter (interior)
Ontario, Canada in
summer
(interior)
(minima)
(interior)
(maxima)
Reference
Raveling, 1979
Thomas etal., 1983
Owen, 1980
Owen, 1980
LeBlanc, 1987a
Williams & Kendeigh, 1982
Williams & Kendeigh, 1982
estimated
estimated
estimated
Note
No.
2
2
3
3
4a
4b
4c
10
ISJ
o
0)
3
0)
Q.
0)
Q
O
O
-------
Canada Goose (Branta canadensis)
Factors
Food Ingestion
Rate (g/g-day)
Water Ingestion
Rate
(g/g-day)
Inhalation Rate
(m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
A M winter
A F winter
A M spring
A F spring
AM
AF
AM
AF
AM
AF
AM
AF
AM
AF
AM
AF
Dietary Composition
sedges
native grasses
corn kernels
animal
other
Mean
0.030
0.033
0.030
0.031
0.052
0.053
0
0
0
.035
.037
.54
0.52
1
1
1
1
.40
.22
,280
,230
2,920
2,590
Range or
(95%
Cl of mean)
Winter
63
11
22
0.01
4
Location (subspecies)
(interior) captive
(interior) captive
(minima)
(maxima)
(minima)
(maxima)
(minima)
(maxima)
North Carolina/lake
(% volume; crop and gizzard
contents)
Reference
Joyneretal., 1984
Joyneretal., 1984
estimated
estimated
estimated
estimated
estimated
estimated
Note
No.
5
5
6a
6b
7a
7b
8a
8b
Note
Reference No.
Yelverton & Quay, 1959
10
ISJ
Ol
O
0)
3
0)
Q.
0)
Q
O
O
-------
Canada Goose (Branta canadensis)
Dietary Composition
Equisetum sp.
(shoot)
Triglochin paiustris
(root)
grasses (root)
(shoot)
sedges (shoot)
(root)
(reed)
Plantago maritima
(root)
unidentified plants
invertebrates
corn
unidentified plants
alfalfa
Gramineae
oats
Setaria iutescens
Trifolium repens
Population
Dynamics
Home Range
Size
Spring
9.2
3.4
23.4
2.1
25.3
5.3
17.9
6.5
6.1
0.7
A F & brood
A F & brood
Summer
Fall
23
8.6
10.4
12.6
25.1
8.4
10.9
983 ± 822 SD ha
8.8±4.4SDkm
Winter
Range
290 - 2,830
2.8-18.1
Location/Habitat
(measure)
Ontario, Canada/bay
(% dry weight; esophagus
and proventriculus
contents)
Wisconsin/marsh
(% dry volume; gizzard
and proventriculus
contents)
Location (subspecies)/
habitat1
Washington (moffitti)lr\ver
Washington (moffitti)lr\ver
Reference
Prevettetal., 1985
Craven & Hunt, 1984
Reference
Eberhardtetal., 1989a
Eberhardtetal., 1989a
Note
No.
Note
No.
10
ISJ
o>
O
0)
3
0)
Q.
0)
Q
O
O
-------
Canada Goose (Branta canadensis)
Population
Dynamics
Population
Density
Clutch Size
Clutches/Year
Days
Incubation
Age at
Fledging
(days)
Percent Nests
Successful
Number
Fledge per
Active Nest
Age/Sex/
Co nd. /Seas.
summer
fall
winter
Mean
16.6 nests/ha
1.3 nests/ha
0.35 nests/ha
22 birds/ha
4 birds/ha
4.7
5.6 ±0.1 SE
4.6
5.6
1
25
28
40-46
55
63
71-73
91
44
2.19 ± 2.42 SD
Range
0.02-12.4 nests/ha
2-8
89-93
27-64
0-7
Location (subspecies)/
habitat1
various locations
Montana (moffitti)!
on 0.2-0.8 ha island
Montana (moffitti)!
on 8-121 ha island
Alaska (leucopus)!
island preferred habitat
Missouri/wildlife refuge
Missouri/wildlife refuge
Alaska (minima)
Alaska (leucopa)
Ontario, Canada (interior)
Alabama, Georgia (maxima)
Missouri
NS (minima)
Missouri (maxima)
Alaska (minima)
NS (leucopa)
Ontario, Canada (interior)
Michigan (maxima)
Alaska/island (leucopa)
Alabama, Georgia (maxima)
Washington (moffitti)
Reference
Cooper, 1978
Geis, 1956
Byrd & Woolington, 1983
Humburg etal., 1985
Humburg etal., 1985
Spencer etal., 1951
Byrd & Woolington, 1983
Raveling & Lumsden, 1977
Combs etal., 1984
Brakhage, 1985
Laid ley, 1939
Brakhage, 1965
Mickelson, 1973
Lee (pers. comm.) in Byrd
& Woolington, 1983
Hanson, 1965
Sherwood, 1965
Byrd & Woolington, 1983
Combs etal., 1984
Eberhardt et al., 1989b
Note
No.
9
10
2
10
11
11
11
10
ISJ
O
0)
3
0)
Q.
0)
Q
O
O
-------
Canada Goose (Branta canadensis)
Population
Dynamics
Number
Fledge per
Successful
Nest
Age at Sexual
Maturity
Annual
Mortality Rates
(percent)
Seasonal
Activity
Mating/Laying
Hatching
Age/Sex/
Co nd. /Seas.
B
F
M
F
AB
JB
AB
JB
AB
JB
late February
early March
mid-March
early April
early April
late May
March
mid-April
early May
Mean
4.0 ± 0.008 SE
2.2
3.9±1.9SD
2-3
4-5
2-3
2-3
35.9
46.0
28 ± 0.8 SD
49 ± 3.7 SD
22.9
37.0
March - April
late March
late March - April
mid-April
late May
April - May
late April - May
mid-May
early July
Range
1 -7
1 -7
>2
>1
>2
End
mid-May
May
early May
mid-April
early June
early June
late May
late June
Location (subspecies)/
habitat1
Alaska (leucopa)
IL, Wl (interior)
Washington (moffitti)
Northwest Territories
(smaller subspecies)
Manitoba, Canada (interior)
Missouri (maxima)
Alaska (minima)
California, Nevada (moffitti)
Ohio (maxima)
Location (subspecies)
Georgia, Alabama (maxima)
OR, WA, CA (moffitti)
Montana (moffitti)
Idaho (moffitti)
Ontario, Canada (maxima)
Alaska (leucopa)
Georgia, Alabama (maxima)
Montana (moffitti)
Idaho (moffitti)
Alaska (leucopa)
Reference
Byrd & Woolington, 1983
Hardy & Tacha, 1989
Eberhardtetal., 1989b
Maclnnes & Dunn, 1988
Moser& Rusch, 1989
Brakhage, 1965
Nelson & Hansen, 1959
Rienecker, 1987
Cummings, 1973
Reference
Combs etal., 1984
McCabe, 1979; Bellrose,
1976
Geis, 1956
Steel etal., 1957
Mainguy & Thomas, 1985
Byrd & Woolington, 1983
Combs etal., 1984
Geis, 1956
Steel etal., 1957
Byrd & Woolington, 1983
Note
No.
12
11
11
Note
No.
10
ISJ
00
O
0)
3
0)
Q.
0)
Q
O
O
-------
Canada Goose (Branta canadensis)
Seasonal
Activity
Molt (fall)
Begin
mid-June
mid-July
late June
mid-Sept.
October
February
late March
Peak
mid-August
November
early November
early March
early April
End
late August
late October
mid-December
Location (subspecies)
Idaho (moffitti)
Alaska (leucopa)
Illinois (interior)
arrive south Illinois (interior)
arrive CO, TX (parvipes)
leave Illinois (interior)
leave Minnesota (maxima)
Reference
Steel etal., 1957
Byrd & Woolington, 1983
Williams & Kendeigh, 1982
Bell &Klimstra, 1970
Grieb, 1970
Bell &Klimstra, 1970
Raveling, 1978b
Note
No.
10
ISJ
1 Weights estimated from graph.
2 Cited in Dunn and Maclnnes (1987).
3 Estimated range of existence to maximum free-living metabolism at typical breeding ground (Ontario, Canada in spring and summer) and at
typical wintering ground (south Illinois in fall and winter). Estimated using regression equations developed by the authors, measures of
metabolic rates at temperatures from -40 to 41 C, and temperatures typical for the season and location.
4 Estimated using equation 3-37 (Nagy, 1987) and body weights from (a) Raveling (1979); (b) Raveling (1968); and (c) Brakhage (1965).
5 Reported as grams dry weight of feed; corrected to grams wet weight of feed using the measured moisture content of 11 percent (on average) of
the feed items (i.e., corn, sunflower seeds, wheat, and milo).
6 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from (a) Raveling (1979) and (b) Brakhage (1965).
7 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from (a) Raveling (1979) and (b) Brakhage (1965).
8 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from (a) Raveling (1979)
and (b) Brakhage (1965).
9 Summarizing several studies, cited in Byrd & Woolington (1983).
10 Cited in Palmer (1976).
11 Cited in Bellrose (1976).
12 For parents older than 5 years of age.
O
0)
3
0)
Q.
0)
Q
O
O
-------
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2-31 Canada Goose
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2-32 Canada Goose
-------
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2-33 Canada Goose
-------
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2-34 Canada Goose
-------
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Palmer, R. S. (1962) Handbook of North American birds: v. 1. New Haven, CT: Yale
University Press.
Palmer, R. S. (1976) Handbook of North American birds: v. 2. New Haven, CT: Yale
University Press.
Peach, H. C.; Thomas, V. G. (1986) Nutrient composition of yolk in relation to early growth
of Canada geese. Physiol. Zool. 59: 344-356.
Prevett, J. P.; Marshall, I. F.; Thomas, V. G. (1985) Spring foods of snow and Canada geese
at James Bay. J. Wildl. Manage. 49: 558-563.
Ratti, J. T.; Timm, D. E.; Robards, F. L. (1977) Weights and measurements of Vancouver
Canada geese. Bird Banding 48: 354-357.
Raveling, D. G. (1968) Weights of Branta canadensis interior during winter. J. Wildl.
Manage. 32: 412-414.
Raveling, D. G. (1978a) Morphology of the cackling Canada goose. J. Wildl. Manage. 42:
897-900.
Raveling, D. G. (1978b) Dynamics of distribution of Canada geese in winter. Trans. North
Am. Wildl. Nat. Resour. Conf. 43: 206-225.
Raveling, D. G. (1979) The annual cycle of body composition of Canada geese with special
reference to control of reproduction. Auk 96: 234-252.
Raveling, D. G. (1981) Survival, experience, and age in relation to breeding success of
Canada geese. J. Wildl. Manage. 45: 817-829.
Raveling, D. G.; Lumsden, H. G. (1977) Nesting ecology of Canada geese in the Hudson Bay
lowlands of Ontario: evolution and population regulation. U.S. Fish Wildl. Res. Rep.
98; pp. 1-77.
Rienecker, W. C. (1987) Population trends, distribution, and survival of Canada geese in
California and western Nevada. Calif. Fish and Game 73: 21-36.
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Klamath National Wildlife Refuges, 1957. Calif. Fish and Game 46: 481-506.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
2-35 Canada Goose
-------
Samuel, M. D.; Rusch, D. H.; Craven, S. (1990) Influence of neck bands on recovery and
survival rates of Canada geese. J. Wildl. Manage. 54: 45-54.
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169-180.
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2-36 Canada Goose
-------
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2-37 Canada Goose
-------
2.1.3. Mallard (surface-feeding ducks)
Order Anseriformes, Family Anatidae. Surface-feeding ducks are the most familiar
ducks of freshwater and saltwater wetlands. They feed by dabbling and tipping up in
shallow water, often filtering through soft mud for food. They feed primarily on seeds of
aquatic plants and cultivated grains, although they also consume aquatic invertebrates,
particularly during the breeding season (Jorde et al., 1983; Swanson et al., 1985). All
species have a bright colored patch of feathers on the trailing edge of each wing, and the
overall plumage of the males is more colorful than that of the females. Dabbling ducks
range in size from the green-winged teal (average 37 cm bill tip to tail tip) to the northern
pintail (average 66 cm).
Selected species
The mallard (Anas platyrhynchos) feeds mostly on aquatic plants, seeds, and
aquatic invertebrates, depending on the season, and forages in ponds and wetlands by
dabbling and filtering through sediments. It is widespread throughout most of the United
States and is the most abundant of the United States ducks (USFWS, 1991). In the past
decade, however, its numbers have declined markedly across its principal range in the
mid-continental region because of habitat degradation and drought (USFWS, 1991).
Mallards interbreed with domestic ducks and black ducks (Anas rubripes).
Body size. Mallards average 58 cm from bill tip to tail tip. Male mallards are
generally heavier than females (Delnicki and Reinecke, 1986; Whyte and Bolen, 1984; see
table). Female mallards lose weight during the laying and incubation periods; males lose
weight from their spring arrival through the peak of the breeding season and then gain
weight while the females are incubating (Lokemoen et al., 1990a).
Habitat. Wintering mallards prefer natural bottomland wetlands and rivers to
reservoirs and farm ponds (Heitmeyer and Vohs, 1984); water depths of 20 to 40 cm are
optimum for foraging (Heitmeyer, 1985, cited in Allen, 1987). The primary habitat
requirement for nesting appears to be dense grassy vegetation at least a half meter high
(Bellrose, 1976). Mallards prefer areas that provide concealment from predators such as
seeded cover (fields established on former croplands) (Klett et al., 1988; Lokemoen et al.,
1990b), cool-season introduced legumes and grasses (Duebbert and Lokemoen, 1976), and
idle grassland with tall, dense, rank cover in the area (Duebbert and Kantrud, 1974). Nests
usually are located within a few kilometers of water, but if choice nesting habitat is not
available nearby, females may nest further away (Bellrose, 1976; Duebbert and Lokemoen,
1976).
Food habits. In winter, mallards feed primarily on seeds but also on invertebrates
associated with leaf litter and wetlands, mast, agricultural grains, and to a limited extent,
leaves, buds, stems, rootlets, and tubers (Goodman and Fisher, 1962; Heitmeyer, 1985,
cited in Allen, 1987). In spring, females shift from a largely herbivorous diet to a diet of
mainly invertebrates to obtain protein for their prebasic molt and then for egg production
(Swanson and Meyer, 1973; Swanson et al., 1979; Swanson et al., 1985; Heitmeyer, 1988b).
Laying females consume a higher proportion of animal foods on the breeding
2-39 Mallard
-------
grounds than do males or nonlaying females (Swanson et al., 1985). The animal diet
continues throughout the summer, as many females lay clutches to replace destroyed
nests (Swanson et al., 1979; Swanson et al., 1985). Ducklings also consume aquatic
invertebrates almost exclusively, particularly during the period of rapid growth (Chura,
1961). Mallards concentrate in wetlands at night, apparently feeding on emerging insects
(Swanson and Meyer, 1973). Flocks may feed in unharvested grain fields and stubble fields
during fall and winter (Dillon, 1959). During periods of food shortage, fat reserves are used
as an energy source. During breeding, females continue to feed but also use fat to meet
the demands of egg production; females may lose 25 percent of their body mass (in fat)
during laying and early incubation (Krapu, 1981).
Molt. Female mallards molt into basic plumage in late winter or early spring, except
for the wing molt, which is delayed until about the time broods are fledged. In males, head-
body-tail molt commences in early summer and overlaps or is followed by the wing molt.
Mallards generally are flightless for about 25 days during the wing molt (Palmer, 1976).
Migration. Although the mallard winters in all four waterfowl flyways of North
America (i.e., Pacific, Central, Mississippi, and Atlantic), the Mississippi flyway (alluvial
valley from Missouri to the Gulf of Mexico) contains the highest numbers (Bellrose, 1976).
Human creation and alteration of water bodies and plant communities have changed the
migration and wintering patterns of mallards; in North America the ducks winter farther
north than in the past (Jorde et al., 1983). Mallards tend to arrive at their wintering grounds
in the Mississippi Valley in mid-September through early November and depart for their
northerly breeding grounds again in March (Fredrickson and Heitmeyer, 1988). Adult
females that reproduce successfully are likely to return to the same nesting ground the
following year (Lokemoen et al., 1990a, 1990b).
Breeding activities and social organization. Older females arrive at breeding
grounds earlier than yearling birds, which probably increases their chances of
reproductive success because they can select the best nest sites (Lokemoen et al., 1990b).
First clutches are generally finished by mid-April in the southern part of the breeding range
and late April to May in the northern United States (Palmer, 1976). High rates of nest failure
require females to renest persistently to reproduce successfully (Swanson et al., 1985).
Average clutch size decreases as the season progresses because the clutch size of
renesting females is smaller than initial clutches (Eldridge and Krapu, 1988; Lokemoen et
al., 1990b). Older females produce larger clutches than do yearlings (Lokemoen et al.,
1990a). Mallards mate for one breeding season, and males typically leave the females at
the onset of incubation (Palmer, 1976). Females remain with the brood until fledging.
Mallards are serially monogamous and thus remate annually (Palmer, 1976).
Home range and resources. Each pair of mallards uses a home range, and the
drake commonly establishes a territory that he defends against other mallards (Bellrose,
1976). Home-range size depends on habitat, in particular the type and distribution of water
habitats (e.g., prairie potholes, rivers), and population density (Bellrose, 1976; Dwyer et al.,
1979; Kirbyetal., 1985).
2-40 Mallard
-------
Population density. Mallard densities during the breeding season are positively
correlated with availability of terrestrial cover for nesting and with availability of wetlands
and ponds that provide the aquatic diet of mallards (Pospahala et al., 1974). Availability of
suitable wetland habitat for breeding and wintering depends on environmental conditions
(e.g., rainfall) (Heitmeyer and Vohs, 1984; Lokemoen et al., 1990a). Average densities of
breeding mallards in the prairie pothole region range from 0.006 to 0.67 pairs per hectare
(Duebbert and Kantrud, 1974; Duebbert and Lokemoen, 1976; Kantrud and Stewart, 1977;
Lokemoen et al., 1990b). Mallards attain their highest densities in prairie and parkland of
the southern prairie provinces and in the Cooper River and Athabasca River deltas of
Canada (Johnson and Grier, 1988).
Population dynamics. Nest success or failure is an important factor affecting
mallard populations. Mammalian predation is the main cause of nest failure, followed by
human disturbance (e.g., farming operations) and adverse weather conditions (Klett et al.,
1988; Lokemoen et al., 1988). Mammalian predators include fox, badger, and skunk; crows
also prey on mallard nests (Johnson et al., 1988). Mallards usually renest if the first nest
fails (Palmer, 1976). Juvenile survival depends on food and preferred habitat availability,
factors that in turn are affected by environmental conditions. For example, high rainfall is
related to increased wetland area, which is positively correlated with duckling growth
(Lokemoen et al., 1990a). Annual adult mortality rates vary with year, location, hunting
pressure, age, and sex. Females suffer greater natural mortality rates (e.g., typical values
of 40 to 50 percent) than do males (e.g., typical values of 30 to 40 percent) (Chu and
Hestbeck, 1989). By fall, there is a higher proportion of males than females in most
populations (Bellrose, 1976). Immature mortality rates of 70 percent have been recorded in
many areas, although lower immature mortality rates are more common (Bellrose, 1976;
Chu and Hestbeck, 1989). Annual mortality rates also are greater in areas with higher
hunting pressure (Bellrose, 1976).
Similar species (from general references)
• The American black duck (Anas rubripes) is only present in the wooded
parts of northeastern and north central United States. It nests near
woodland lakes and streams or in freshwater and tidal marshes. It is similar
in size (58 cm) to mallards using the same habitats.
• The northern pintail (Anas acuta) is widespread, occurring in most parts of
North America and breeding throughout Canada and the north central United
States. Although formerly farily abundant, North American pintail
populations have declined dramatically during the past decade (USFWS,
1991). It prefers marshes and open areas with ponds and lakes. Pintails
average slightly longer (66 cm) than mallards.
• The gadwall (Anas strepera) (51 cm) occurs throughout most of the United
States. In Canada, its breeding range is limited to the south central potholes
region. It is more common in the west than in the east.
• The American wigeon (Anas americana) (48 cm) breeds throughout most of
Canada and in the prairie pothole regions of the United States. It winters
2-41 Mallard
-------
along both the east and west coasts of the United States as well as farther
south into Mexico.
• Northern shovelers (Anas clypeata) (48 cm), inhabitants of marshes, ponds,
and bays, breed throughout mid to western Canada and the prairie pothole
regions of the United States. They winter along the gulf coast, southern
Atlantic coast, in Texas, and a few other southwestern states as well as
throughout Mexico.
• Blue-winged teal (Anas discors) (39 cm) are fairly common in open country
in marshes and on ponds and lakes. Breeding populations occur throughout
the central United States and Canada, but wintering populations are
restricted to Atlantic and Pacific coastal areas.
• The green-winged teal (Anas crecca) (37 cm) is the smallest of the dabbling
ducks. A. c. carolinensis is the most common subspecies in the United
States. It breeds throughout most of Canada and the prairie pothole region
of the United States. It overwinters in the southern half of the United States
and in Mexico.
• Cinnamon teal (Anas cyanoptera) (41 cm) breeding populations are restricted
to the western United States and Mexico, with few reaching southern
Canada. Some populations in California and Mexico are year-round
residents.
General references
Allen (1987); National Geographic Society (1987); Pospahala et al. (1974); Palmer
(1976); Bellrose(1976).
2-42 Mallard
-------
Mallard Duck (Anas platyrhynchos)
Factors
Body Weight
(g)
Body Fat
(g lipid)
Age/Sex/
Cond./Seas.
AM
AF
A M winter
A F winter
A M winter
A F winter
A F spring
egg
at hatching
B at 3.5 days
F at 9. 5 days
F at 15.5 days
F at 30.5 days
F fledging at
56.0 days
M at 9.5 days
Mat 15.5 days
M at 30.5 days
M fledging at
56.0 days
A M winter
A F winter
A F April
Y F April
A F June
YFJune
Mean
1,225
1,043
1,246±108SD
1,095 ± 106 SD
1,237 ± 118 SD
1,088 ± 105 SD
1,197±105SD
52.2
32.4 ± 2.4 SD
32.4 ± 2.4 SD
115±37 SD
265 ±92 SD
401 ± 92 SD
740±115SD
92 ±12 SD
215±5 SD
460 ±93 SD
817 ±91 SD
174±66SD
171 ±56SD
106±34SD
82 ± 37 SD
22 ± 22 SD
9.6±8.3SD
Range or
(95% Cl of mean)
up to 1,814
up to 1,633
32.2 - 66.7
Location
throughout North America
western Mississippi
(alluvial valley)
Texas
North Dakota
North Dakota
central North Dakota
central North Dakota
central North Dakota
central North Dakota
Texas
North Dakota
Reference
Nelson & Martin, 1953
Delnicki & Reinecke, 1986
Whyte&Bolen, 1984
Krapu & Doty, 1979
Eldridge & Krapu, 1988
Lokemoen et al., 1990a
Lokemoen et al., 1990b
Lokemoen etal., 1990b
Lokemoen et al., 1990b
Whyte&Bolen, 1984
Krapu & Doty, 1979
Note
No.
10
A.
CO
u.
5T
o.
-------
Mallard Duck (Anas platyrhynchos)
Factors
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (mVday)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
A F basal
A M basal
A F winter
A M winter
A F free-living
A M free-living
AF
AM
AF
AM
AF
AM
Dietary
Composition
adults:
rice
jungle rice
brownseed paspalum
barnyard grass
red rice
knot grass
signal grass
coast cockspur
Mamaica sawgrass
snails
other
Mean
77
73
280
220
200
192
0.058
0.055
0.42
0.48
1,030
1,148
Range or
(95% Cl of mean)
(94 - 424)
(91 - 408)
Winter
24
21
19
8.0
8.0
6.5
2.5
1.9
1.3
1.0
6.8
Location
Texas
Location/Habitat
(measure)
Louisiana/coastal marsh
and prairie
(% volume; gullet contents)
Reference
estimated
Whyte & Bolen, 1984
estimated
estimated
estimated
estimated
Reference
Dillon, 1959
Note
No.
1
2
3
4
5
6
7
Note
No.
10
U.
5T
Q.
-------
Mallard Duck (Anas platyrhynchos)
Dietary
Composition
breeding female:
(total animal)
gastropods
insects
crustacea
annelids
misc. animal
(total plant)
seeds
tubers
stems
Population
Dynamics
Home Range
Size (ha)
Population
Density
(pairs/ha)
Clutch
Size
Clutches
/Year
Days
Incubation
April
(67.8)
trace
13.1
7.9
38.3
8.5
(32.2)
28.7
2.4
1.1
spring:
A F total
A F laying
spring:
AF
AM
A B spring
(area 1)
A B spring
(area 2)
yearling
A
if lost
if successful
May
(66.8)
24.9
25.6
15.1
0.2
1.0
(33.2)
28.7
4.3
0.2
Mean
468±159SD
111 ±76 SD
540
620
0.036
0.047
9.3±1.7SE
10.3 ±1.1 SE
9
1
26
25
June
(89.4)
16.5
48.1
13.9
10.9
-
(10.6)
10.6
-
-
Range
307-719
38 - 240
40-1,440
70-1,140
0.006 - 0.076
0.031 - 0.087
1 -18
up to 4.5
23-29
Location/Habitat
(measure)
south central North
Dakota/prairie potholes
(% wet volume; esophagus
contents)
Location/Habitat
North Dakota/prairie
potholes
Minnesota/wetlands, river
central North Dakota/range
of 6 years of data from
two different pothole
areas
North Dakota/prairie
potholes
NS/NS
North Dakota/experimental
ponds (nests purposely
destroyed)
North America/NS
NS/NS
North Dakota/wetlands
Reference
Swanson etal., 1985
Dwyeretal., 1979
Kirby etal., 1985
Lokemoen et al., 1990a
Krapu & Doty, 1979
Bellrose, 1976
Swanson, unpublished in
Swanson etal., 1985
Bellrose, 1976
Bent, 1923
Klett& Johnson, 1982
Note
No.
Note
No.
8
10
^
Ul
u.
5T
o.
-------
Mallard Duck (Anas platyrhynchos)
Population
Dynamics
Age at
Fledging
(days)
Percent Nests
Successful
Number
Fledge per
Successful
Nest
Age at
Sexual
Maturity
Annual
Mortality
Rates
(percent)
Seasonal
Activity
Mating
Hatching
Age/Sex
Cond./Seas.
AM
AF
AM fall
J M fall
A F fall
J F fall
AM fall
J M fall
A F fall
J F fall
early April
Mean
52-60
56
51 -61
9-10
4.9
8.4
1 yr
27.2
38.2
40.1 ±3.1 SE
41.1 ±7.2SE
49.9 ± 3.3 SE
48.8 ± 6.0 SE
39.0 ± 2.3 SE
48.1 ± 5.3 SE
51.5 ± 1.9 SE
56.8 ± 3.2 SE
May
early May
June
Range
22-51
31 -59
20-72
15-68
9-60
7-69
33-64
38-68
End
mid-July
Location/Habitat
NS/NS
central North Dakota/
potholes
South Dakota/prairie
potholes and fields
eastern South Dakota/
potholes
NS/NS
United States/NS
United States/NS
eastern-central flyway/NS
western mid-Atlantic/NS
1971 to 1985
northeastern United
States/NS
1971 to 1985
CA, UT, MT, SD, NY, VT
south central N Dakota
NW Territory, Canada
Reference
Bellrose, 1976
Lokemoen et al., 1990a
Duebbert& Lokemoen, 1976
Klettetal., 1988
Cowardin & Johnson, 1979
Bellrose, 1976
Krapu & Doty, 1979
Bellrose, 1976
Chu & Hestbeck, 1989
Chu & Hestbeck, 1989
Bellrose, 1976
Krapu & Doty, 1979
Toft etal., 1984
Note
No.
9
Note
No.
10
^
o>
u.
5T
o.
-------
Mallard Duck (Anas platyrhynchos)
Seasonal
Activity
Molt
spring
fall
Begin
December
mid-Sept.
mid-March
mid-October
Peak
November
End
March
November
mid-May
Location
Mississippi Valley
arrive north central US
leave northern US
Reference
Fredrickson & Heitmeyer, 1988
Johnson etal., 1987
Palmer, 1976
Note
No.
1 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and body weights from Nelson and Martin (1953).
2 Estimated daily existence energy at 0 C.
3 Estimated using equation 3-37 (Nagy, 1987) and body weights from Nelson and Martin (1953).
4 See Chapters 3 and 4 for methods of estimating food ingestion rates from free-living metabolic rate and dietary composition.
ho 5 Estimated using equation 3-15 (Calderand Braun, 1983) and body weights from Nelson and Martin (1953).
^ 6 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Nelson and Martin (1953).
7 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Nelson and Martin
(1953).
8 Cited in Palmer (1976).
9 Cited in Johnson et al. (1987).
u.
5T
o.
-------
References (including Appendix)
Allen, A. W. (1987) Habitat suitability index models: mallard (winter habitat, lower
Mississippi Valley). U.S. Fish Wildl. Serv. Biol. Rep. No. 82(10.132).
Bellrose, F. C. (1976) Ducks, geese, and swans of North America. Harrisburg, PA: The
Stackpole Co.; pp. 229-243.
Bellrose, F. C.; Hawkins, A. S. (1947) (cited in Palmer, 1976). Auk 64: 422-430.
Bent, A. C. (1923) Life histories of North American wild fowl. Washington, DC: U.S.
Government Printing Office; Smithsonian Inst. U.S. Nat. Mus., Bull. 126.
Brownie, C.; Anderson, D. R.; Burnham, K. P.; et al. (1978) Statistical inference from band
recovery data—a handbook. U.S. Fish Wildl. Serv. Resour. Publ. 131.
Brownie, C.; Anderson, D. R.; Burnham, K. P.; et al. (1985) Statistical inference from band
recovery data—a handbook. U.S. Fish Wildl. Serv. Resour. Publ. 156.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Chu, D. S.; Hestbeck, J. B. (1989) Temporal and geographic estimates of survival and
recovery rates for the mallard, 1950 through 1985. Washington, DC: U.S. Fish Wildl.
Serv. Tech. Rep. No. 20.
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2-50 Mallard
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2-51 Mallard
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2-52 Mallard
-------
2.1.4. Lesser Scaup (bay ducks)
Order Anseriformes, Family Anatidae. Bay ducks are adapted for diving and
characteristically need a running start to become airborne because their legs are located
further back on their body than on other ducks. They breed at mid to high latitudes and
winter in flocks on large water bodies and in protected coastal bays and river mouths. Bay
ducks dive for their food, and their diet is omnivorous (i.e., both plant and animal matter)
and depends on the seasonal and regional abundance of food resources. Because of their
food habits, bay ducks prefer deeper, more permanent ponds than dabbling ducks
(Bellrose, 1976). The sexes vary in coloration, and different bay duck species range in
length from 42 to 53 cm (bill tip to tail tip).
Selected species
The lesser scaup (Aythya affinis) is one of the most abundant North American
ducks (Allen, 1986). They breed principally throughout western Canada and Alaska,
although their breeding range extends into the western United States as far south as
Colorado and Ohio. Lesser scaup winter in the United States in the Mississippi flyway and
the Atlantic flyway (Bellrose, 1976). They also winter along all coastal areas in the
southern states and into Mexico (National Geographic Society, 1987).
Body size. The lesser scaup averages 42 cm from bill tip to tail tip. Males are
larger and more colorful than the brown females (Bellrose, 1976; see table). Following their
postbreeding molt, scaups increase their fat reserves in preparation for migration (Austin
and Fredrickson, 1987; see table).
Habitat. Lesser scaup are found on large lakes and bays during the fall and winter
and are common on smaller bodies of water (e.g., ponds) during the spring. They breed in
the prairie potholes region, most often on permanent or semipermanent wetlands of 0.85 to
2.0 ha with trees and shrubs bordering at least half of the shorelines (Bellrose, 1976;
Smith, 1971, cited in Allen, 1986). Primary brood habitat is characterized by permanent
wetlands dominated by emergent vegetation (Smith, 1971, cited in Allen, 1986). In a study
of ducks wintering in South Carolina, Bergan and Smith (1989) found lesser scaup would
forage primarily in areas with submergent vegetation but also in areas of emergent
vegetation, shallow open water, and floating-leaved vegetation. They found some
differences in foraging habitat use by season and between males and females. In
particular, females tended to use more shallow habitats than males, and males preferred
open water in late fall (Bergan and Smith, 1989).
Food habits. Most populations of lesser scaup consume primarily aquatic
invertebrates, both from the water column and from the surfaces of aquatic vegetation and
other substrates (Tome and Wrubleski, 1988; Bartonek and Mickey, 1969). Common prey
include snails, clams, scuds (amphipods), midges, chironomids, and leeches (see table).
Scaup are omnivorous, however, and the percentage of plant materials (almost exclusively
seeds) in the diet varies seasonally as the availability of different foods changes (Afton et
al., 1991; Dirschl, 1969; Rogers and Korschgen, 1966). When seeds are locally abundant,
they may be consumed in large quantities (Dirschl, 1969). Breeding females and ducklings
2-53 Lesser Scaup
-------
eat mostly aquatic invertebrates (Sugden, 1973). Young ducklings feed primarily on water-
column invertebrates (e.g., phantom midges, clam shrimps, water mites), whereas older
ducklings forage mainly on bottom-dwelling invertebrates (e.g., scuds or amphipods,
dragonflies, caddisflies) (Bartonek and Murdy, 1970). During the winter, there are no
significant differences in diet between juveniles and adults or between males and females
(Aftonetal., 1991).
Molt. Nonbreeding and postbreeding males and nonbreeding females generally
leave the breeding grounds in June to molt on lakes. However, some males complete their
molt on the breeding grounds (Trauger, 1971, cited in Bellrose, 1976). Large flocks of
molting birds become flightless during the wing molt phase, which begins in July and is
usually complete by late August (McKnight and Buss, 1962).
Migration. The axis of the main migration corridor extends from the breeding
grounds on the Yukon Flats, Alaska, to wintering areas in Florida (Bellrose, 1976). Most
scaup winter in the United States, with the greatest numbers in the Mississippi flyway and
the Atlantic flyway. They start to arrive at their wintering areas in mid-October (Bellrose,
1976). The timing of northward migration in the spring varies from February to May
(Bellrose, 1976). Before migration, scaup gain weight by increasing their body fat content
(Austin and Fredrickson, 1987).
Breeding activities and social organization. Scaup build nests on the ground
among tall grasses, shrubs, or forbs where plant heights range from 20 to 60 cm (Mines,
1977). Nests can be located along the edge of shorelines to upland areas (Bellrose, 1976).
Courtship and pair bonds start to form on the wintering grounds, and pairs typically remain
together for only one season. Males do not remain long after incubation commences
(Trauger, 1971, cited in Bellrose, 1976). The female and her brood leave the vicinity of the
nest shortly after the ducklings have hatched. Most broods are on their own by 4 to 5
weeks of age (Gehrman, 1951, cited in Bellrose, 1976) and fledge between 7 and 9 weeks of
age (Bellrose, 1976; Lightbody and Ankney, 1984). Females of this species often lay eggs
in other lesser scaup nests (nest parasitism), which can result in large compound clutches
of lesser scaup eggs in a single nest (Mines, 1977). Mines (1977) also found that mixing of
broods was common in Saskatchewan; by August, groups of 15 to 40 ducklings led by two
to three hens would be common. Female lesser scaup also occasionally lay eggs in the
nests of other ducks (e.g., gadwall; Mines, 1977).
Home range and resources. Relatively small nesting territories and large highly
overlapping foraging ranges are characteristic of lesser scaup (Hammel, 1973, cited in
Allen, 1986). Several pairs can nest in close proximity without aggression, each defending
only a small area immediately surrounding the nest (Bellrose, 1976; Vermeer, 1970). In
Manitoba, Hammel (1973) estimated the mean minimum foraging home range to be 89 ± 6.5
ha. Initial areas occupied by pairs usually contain stumps, logs, boulders, or beaches as
loafing sites, but later lesser scaup rely solely on open water (Gehrman, 1951, cited in
Bellrose, 1976).
Population density. In winter, local densities of scaup can be very high, as large
flocks float on favored feeding areas (Bellrose, 1976). In summer, the density of breeding
2-54 Lesser Scaup
-------
pairs increases with the permanence and size of the ponds (Kantrud and Stewart, 1977;
see table).
Population dynamics. In some populations, many yearling and some 2-year-olds do
not breed; the proportion breeding tends to increase with improving water and habitat
conditions (Afton, 1984; McKnight and Buss, 1962). In a 4-year study in Manitoba, Afton
(1984) found that, on average, 30 percent of 1-year-olds and 10 percent of 2-year-olds, did
not breed. Clutch size and reproductive performance of adult females generally increase
with age (Afton, 1984). Most nest failures are due to predation (e.g., by mink, raccoons, red
fox), and scaup often attempt to renest if the initial nest fails (Afton, 1984; Bellrose, 1976).
Annual mortality for juveniles is higher than that for adults, and adult female mortality
exceeds adult male mortality (Smith, 1963; see table).
Similar species (from general references)
• The redhead (Aythya americana), a larger bay duck (48 cm), breeds on lakes
and ponds in the northwestern United States and in midwestern Canada.
They winter in coastal areas and the southern United States and Mexico. In
summer, adult female and juvenile redheads consume predominantly animal
matter (e.g., caddis flies, midges, water fleas, snails), while males include
more plant materials in their diet.
• The canvasback (Aythya valisineria) is the largest bay duck (53 cm). They
are common on lakes and ponds in the northern United States and southern
Canada during the breeding season and along coastal areas of the United
States during winter. Studies during the winter in North and South Carolina
have found varying diets for canvasbacks, consuming mostly animal matter
(e.g., clams); others eat only vegetation. In summer, adult female and
juvenile canvasbacks eat predominantly animal material (e.g., caddis flies,
snails, mayflies, midges), whereas adult males may eat predominantly
vegetable material, particularly tubers of Potamogeton.
• The ring-necked duck (Aythya collaris) is similar in size (43 cm) to the lesser
scaup and prefers freshwater wetlands. They are commonly seen on
woodland lakes and ponds, but in winter also use southern coastal marshes.
During the winter, ring-necked ducks eat mostly plant materials (81 percent)
and a variety of animal matter (19 percent).
• The greater scaup (Aythya marila) (46 cm) is common in coastal areas and
the Great Lakes during winter. They are omnivorous, eating 50 to 99 percent
animal matter and the remainder plant foods during the winter.
General references
Allen (1986); Bartonek and Mickey (1969); Bellrose (1976); National Geographic
Society (1987); Perry and Uhler (1982).
2-55 Lesser Scaup
-------
Lesser Scaup (Aythya affinis)
Factors
Body Weight
(g)
Adult Body Fat
(grams lipid:
% of total body
weight)
Duckling
Growth Rate
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Age/Sex/
Co nd. /Seas.
F preflightless
F flightless
F postflightless
F migratory
F
M
F preflightless
F flightless
F postflightless
F migratory
age in weeks
0-3
3-6
6-9
9-12
A F basal
A M basal
A B resting
20 to 30°C
A F free-living
A M free-living
juveniles,
both sexes:
1 - 5 weeks
6 - 12 weeks
AF
AM
AF
AM
Mean
688
647
693
842
770
860
50.7 (7.4%)
37.2 (5.7%)
46.5 (6.7%)
188.1 (22.3%)
growth in g/day
6.9
14
1.5
1.2
83
81
90
216
211
dry matter intake/
wet body weight
0.162
0.077
0.064
0.062
0.34
0.36
Range or
(95% Cl of mean)
up to 950
up to 1,100
(final body weight)
(190 g)
(485 g)
(516 g)
(542 g)
(102-457)
(99 - 445)
Location or
subspecies
Manitoba, Canada
United States
Manitoba, Canada
Utah or Canada
Canada
Saskatchewan/captive:
reared in large brooder
and in outdoor pens
Reference
Austin & Fredrickson, 1987
Nelson & Martin, 1953
Austin & Fredrickson, 1987
Sugden & Harris, 1972
estimated
McEwan & Koelink, 1973
estimated
Sugden & Harris, 1972
estimated
estimated
Note
No.
1
1
2
3
4
5
6
7
Ol
o>
(D
(D
T
CO
o
0)
c
-o
-------
Lesser Scaup (Aythya affinis)
Factors
Surface Area
(cm2)
Dietary
Composition
(animal)
midges
snails
grass shrimp
(plant - seeds)
bulrush
Age/Sex/
Co nd. /Seas.
AF
AM
(plant - vegetative)
green algae
juveniles only:
(animal)
scuds
phantom midges
clam shrimps
dragon/damselflies
water bugs
water mites
caddis flies
water beetles
mayflies
(plants)
Mean
842
906
(100)
1 ±1
54 ±8
30 ±8
-
4±3
8±3
-
1 ±1
2±1
(trace)
Range or
(95% Cl of mean)
(100)
57 ±9
1 ±1
2±2
17 ±8
11 ±7
-
6±5
4±3
-
(trace)
Winter
(60.9)
45.9
7.7
7.3
(36.1)
36.0
(3.0)
2.3
Location or
subspecies
Location/Habitat
(measure)
Louisiana/lakes, marshes
(% dry weight;
esophageal & proventricular
contents)
Northwest Territories/lake
(% wet volume ±SE;
esophageal contents)
Reference
estimated
Aftonetal., 1991
Bartonek & Murdy, 1970
Note
No.
8
Note
No.
Ol
(0
(D
T
CO
o
0)
c
-o
-------
Lesser Scaup (Aythya affinis)
Dietary
Composition
adults only:
(animal)
scuds (amphipods)
dragonflies
caddis flies
midges
other insects
snails
fingernail clams
brook stickleback
fathead minnow
other fish
(plants - seeds)
(plants - vegetative)
(animal)
scuds
diptera
leeches
fingernail clams
cyprinid fish
caddis flies
clam shrimps
(plant - seeds)
Nuphar variegatum
other seeds
Spring
(91.8)
33.2
-
8.8
2.3
4.9
31.9
6.0
-
-
3.5
(6.0)
(2.2)
(90.9)
66.0
-
12.0
12.7
-
0.2
-
(9.1)
-
9.1
Summer
(75.1)
9.8
1.3
23.7
25.7
2.9
1.6
3.1
(24.9)
13.2
11.7
Fall
(90.5)
54.9
2.4
7.6
-
-
10.2
5.1
4.1
5.0
(9.4)
(0.1)
(49.6)
42.5
0.1
1.6
-
-
1.9
0.5
(50.4)
42.8
7.6
Winter
Location/Habitat
(measure)
nw Minnesota: spring and fall
migrations/lakes, marshes,
pools
(% dry weight;
esophageal & proventricular
contents)
Saskatchewan,
Canada/shallow lakes
(% dry weight; esophagus
and proventriculus contents)
Reference
Aftonetal., 1991
Dirschl, 1969
Population Age/Sex
Dynamics Cond./Seas. Mean Range Location/Habitat
Home Range breeding 89±6.5SE Manitoba, Canada Hammel, 1973
Size (ha)
Note
No.
Note
No.
9
Ol
CO
(D
(D
T
CO
o
0)
c
-o
-------
Lesser Scaup (Aythya affinis)
Population
Dynamics
Population
Density
(pairs/ha)
Clutch
Size
Clutches
/Year
Days
Incubation
Age at
Fledging
(days)
Percent Nests
Hatching
Percent
Broods
Surviving
Age at First
Breeding
Annual
Mortality Rates
(percent)
Age/Sex
Cond./Seas.
A B seasonal
wetland
A B permanent
wetland
A B island in
lake
2nd yr female
4th yr female
B
1st yr female
2nd yr female
3rd yr female
up to 20 days
of age
M
F
juveniles
A males
A females
Mean
0.029
0.061
28.9
9.47 ± 0.18 SE
10.0 ± 0.2 SE
12.1 ±0.2SE
1 , but often
renest if lost
24.8
65 ±0.91 SE
26.3
22.2
45.5
76
67.5 ± 4.9 SE
most in 2nd yr
1-2 years
68-71
38-52
49-60
Range
13.1 -58.5
7-12
8-12
11 -14
21 -27
Location/Habitat
North Dakota/
prairie potholes
Alberta, Canada/islands in
lakes of parklands and
boreal forest
Saskatchewan/marsh island
Manitoba/lake
NS/NS
NS/NS
Manitoba/captive
Manitoba/lake
Saskatchewan/marsh islands
Manitoba/lake
NS/NS
Manitoba/lake
NS/NS
Reference
Kantrud& Stewart, 1977
Vermeer, 1970
Mines, 1977
Afton, 1984
Afton, 1984
Vermeer, 1968
Lightbody & Ankney, 1984
Afton, 1984
Mines, 1977
Afton, 1984
Palmer, 1976
Palmer, 1976; Afton, 1984
Smith, 1963
Note
No.
10
10
Ol
-------
Lesser Scaup (Aythya affinis)
Seasonal
Activity
Mating/Laying
Begin
early June
early May
early July
July
early February
mid-April
September
mid-October
Peak
early June
mid-July
March - April
mid-
November
End
early July
early August
September
May
mid-November
December
Location
Manitoba, Canada
Montana
NW Territory and
Saskatchewan, Canada
Manitoba, Canada
departing United States
arriving Manitoba, Canada
Pacific flyway (s OR, n CA)
arriving United States
Reference
Afton, 1984
Ellig, 1955
Toftetal., 1984; Mines, 1977
Austin & Fredrickson, 1987
Bellrose, 1976
Afton, 1984
Gammonley & Heitmeyer, 1990
Bellrose, 1976
Note
No.
10
o>
o
(D
-------
References (including Appendix)
Afton, A. D. (1984) Influence of age and time on reproductive performance of female lesser
scaup. Auk 101: 255-265.
Afton, A. D.; Hier, R. H.; Paulus, S. L. (1991) Lesser scaup diets during migration and winter
in the Mississippi flyway. Can. J. Zool. 69: 328-333.
Allen, A. W. (1986) Habitat suitability index models: lesser scaup. U.S. Fish Wildl. Serv.
Biol. Rep. 82(10.117).
Austin, J. E.; Fredrickson, L. H. (1987) Body and organ mass and body composition of
postbreeding female lesser scaup. Auk 104: 694-699.
Bartonek, J. C.; Mickey, J. J. (1969) Food habits of canvasbacks, redheads, and lesser
scaup in Manitoba. Condor 71: 280-290.
Bartonek, J. C.; Murdy, H. W. (1970) Summer foods of lesser scaup in subarctic taiga.
Arctic 23: 35-44.
Bellrose, F. C. (1976) Ducks, geese, and swans of North America. Harrisburg, PA: The
Stackpole Co.
Bergan, J. F.; Smith, L. M. (1989) Differential habitat use by diving ducks wintering in South
Carolina. J. Wildl. Manage. 53: 1117-1126.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Chabreck, R. H.; Takagi, T. (1985) Foods of lesser scaup in crayfish impoundments in
Louisiana. Proc. Annu. Conf. Southeast. Assoc. Fish Wildl. Agencies 39: 465-470.
Chappel, W. A.; Titman, R. D. (1983) Estimating reserve lipids in greater scaup (Aythya
marila) and lesser scaup (A. affinis). Can. J. Zool. 61: 35-38.
Dirschl, H. J. (1969) Foods of lesser scaup and blue-winged teal in the Saskatchewan River
Delta. J. Wildl. Manage. 33: 77-87.
Dunning, J. B., Jr. (1984) Body weights of 686 species of North American birds. Western
Bird Banding Association, Monograph No. 1. Cave Creek, AZ: Eldon Publishing.
Ellig, L. J. (1955) Waterfowl relationships to Greenfields Lake, Teton County, Montana.
Mont. Fish, and Game Comm. Tech. Bull. 1.
Gammonley, J. H.; Heitmeyer, M. E. (1990) Behavior, body condition, and foods of
buffleheads and lesser scaups during spring migration through the Klamath Basin,
California. Wilson Bull. 102: 672-683.
2-61 Lesser Scaup
-------
Gehrman, K. H. (1951) An ecological study of the lesser scaup duck (Athaya affinis Eyton)
at West Medical Lake, Spokane County, Washington [master's thesis]. Pullman, WA:
Washington State College.
Gollop, J. B.; Marshall, W. H. (1954) A guide for aging duck broods in the field (mimeo). MS:
Mississippi Flyway Council Tech. Sect.
Hammel, G. S. (1973) The ecology of the lesser scaup (Athaya affinis Eyton) in
southwestern Manitoba [master's thesis]. Guelph, Ontario: University of Guelph.
Mines, J. E. (1977) Nesting and brood ecology of lesser scaup at Waterhen Marsh,
Saskatchewan. Can. Field-Nat. 91: 248-255.
Hoppe, R. T.; Smith, L. M.; Wester, D. B. (1986) Foods of wintering diving ducks in South
Carolina. J. Field Ornithol. 57: 126-134.
Hunt, E. G.; Anderson, W. (1966) Renesting of ducks at Mountain Meadows, Lassen
County, California. Calif. Fish and Game 52: 17-27.
Kantrud, H. A.; Stewart, R. E. (1977) Use of natural basin wetlands by breeding waterfowl in
North Dakota. J. Wildl. Manage. 41: 243-253.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
Lasiewski, R. C.; Dawson, W. R. (1967). A reexamination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Lightbody, J. P.; Ankney, C. D. (1984) Seasonal influence on the strategies of growth and
development of canvasback and lesser scaup ducklings. Auk 101: 121 -133.
McEwan, E. H.; Koelink, A. F. (1973) The heat production of oiled mallards and scaup. Can.
J.Zool. 51:27-31.
McKnight, D. E.; Buss, I. O. (1962) Evidence of breeding in yearling female lesser scaup. J.
Wildl. Manage. 26: 328-329.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
Nasser, J. R. (1982) Management of impoundments for crayfish and waterfowl [master's
thesis]. Baton Rouge, LA: Louisiana State University.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
2-62 Lesser Scaup
-------
Nelson, A. L; Martin, A. C. (1953) Gamebird weights. J. Wildl. Manage. 17: 36-42.
Palmer, R. S. (1976) Handbook of North American birds: v. 2, 3. New Haven, CT: Yale
University Press.
Perry, M. C.; Uhler, F. M. (1982) Food habits of diving ducks in the Carolinas. Proc. Annu.
Conf. Southeast. Assoc. Fish Wildl. Agencies 36: 492-504.
Poole, E. L. (1938) Weights and wing areas in North American birds. Auk 55: 511-517.
Rienecker, W. C.; Anderson, W. (1960) A waterfowl nesting study on Tule Lake and Lower
Klamath National Wildlife Refuges, 1957. Calif. Fish and Game 46: 481-506.
Ringelman, J. K.; Eddleman, W. R.; Miller, H. W. (1989) High plains reservoirs and sloughs.
In: Smith, L. M.; Pederson, R. L.; Kaminski, R. M., eds. Habitat management for
wintering waterfowl in North America. Lubbock, TX: Texas Tech University Press;
pp. 311-340.
Rogers, J. P. (1962) The ecological effects of drought on reproduction of the lesser scaup,
Aythya affinis (Eyton) [Ph.D. dissertation]. Columbia, MO: University of Missouri.
Rogers, J. P.; Korschgen, L. J. (1966) Foods of lesser scaups on breeding, migration, and
wintering areas. J. Wildl. Manage. 30: 258-264.
Rowinski, L. J. (1958) A review of waterfowl investigations and a comparison of aerial and
ground censusing of waterfowl at Minto Flats, Alaska. Mimeogr. Rep.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Rutherford, W. H. (1966) Chronology of waterfowl migration in Colorado. Colo. Div. Wildl.;
Game Inf. Leafl. No. 42.
Siegfried, W. R. (1974) Time budget of behavior among lesser scaups on Delta Marsh. J.
Wildl. Manage. 38: 708-713.
Smith, A. G. (1971) Ecological factors affecting waterfowl production in Alberta parklands.
U.S. Fish Wildl. Serv. Resour. Publ. 92.
Smith, R. I. (1963) Lesser scaup and ring-necked duck shooting pressure and mortality
rates. Bur. Sport Fish & Wildl. Adm. Rep. 20.
Sugden, L. G. (1973) Feeding ecology of pintail, gadwall, American widgeon and lesser
scaup ducklings in Southern Alberta. Can. Wildl. Serv. Rep. Ser. No. 24.
Sugden, L. G.; Harris, L. E. (1972) Energy requirements and growth of captive lesser scaup.
Poultry Sci. 51: 625-633.
2-63 Lesser Scaup
-------
Swanson, G. A.; Krapu, G. L.; Bartonek, J. C.; et al. (1974) Advantages in mathematically
weighting waterfowl food habits data. J. Wildl. Manage. 38: 302-307.
Toft, C. A.; Trauger, D. L.; Murdy, H. W. (1984) Seasonal decline in brood sizes of sympatric
waterfowl (Anas and Athya, Anatidae) and a proposed evolutionary explanation. J.
Anim. Ecol. 53: 75-92.
Tome, M. W.; Wrubleski, D. A. (1988) Underwater foraging behavior of canvasbacks, lesser
scaups, and ruddy ducks. Condor 90: 168-172.
Townsend, G. H. (1966) A study of waterfowl nesting on the Saskatchewan River delta.
Can. Field. Nat. 80: 74-88.
Trauger, D. L. (1971) Population ecology of lesser scaup (Athaya affinis) in subarctic taiga
[Ph.D. dissertation]. Ames, IA: Iowa State University.
Vermeer, K. (1968) Ecological aspects of ducks nesting in high densities among larids.
Wilson Bull. 80: 78-83.
Vermeer, K. (1970) Some aspects of the nesting of ducks on islands in Lake Newell,
Alberta. J. Wildl. Manage. 34: 126-129.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
2-64 Lesser Scaup
-------
2.1.5. Os p rey (Pandion haliaetus)
Order Falconiformes, Family Accipitridae. The only North American member of the
subfamily Pandioninae, these large birds of prey have long narrow wings, a sharp hooked
bill, and powerful talons. Osprey are found near freshwater or saltwater, and their diet is
almost completely restricted to fish. They are adapted for hovering over the water and
dive feet-first, seizing fish with their talons (Robbins et al., 1983). Once very rare owing to
DDT accumulation in their food (1950's to early 1970's), osprey now are increasing in
numbers. In the United States, there are five regional populations of osprey (in order of
abundance): Atlantic coast, Florida and gulf coast, Pacific Northwest, western interior, and
Great Lakes (Henny, 1983). In North America, osprey breed primarily in a wide band from
coast to coast across Canada and the southern half of Alaska, where they are not
restricted to coastal and Great Lake areas as they are in the United States. However,
osprey are reported from all States during the fall and spring migrations (Henny, 1986).
Body size. The various subspecies of osprey around the world differ in size, and in
general females are heavier than males (Poole, 1989a; see table). Osprey found in the
United States are considered to be of the subspecies carolinenesis and average 56 cm
from bill tip to tail tip (Robbins et al., 1983) and weigh between 1.2 and 1.9 kg (see table).
Habitat. In the United States, the majority of osprey populations are associated with
marine environments, but large inland rivers, lakes, and reservoirs also may support
osprey (Henny, 1986, 1988b). Good nesting sites in proximity to open, shallow water and a
plentiful supply of fish are the primary resources required for osprey success (Poole,
1989a). The tops of isolated and often dead trees and man-made structures are preferred
nesting sites. Osprey often nest in colonies (Poole, 1989a).
Food habits. Osprey are almost completely piscivorous, although they have been
observed on occasion taking other prey including birds, frogs, and crustaceans (Brown
and Amadon, 1968). Their prey preferences change seasonally with the abundance of the
local fish (Edwards, 1988; Greene et al., 1983). Osprey occasionally will pick up dead fish
but only if fresh (Bent, 1937). Osprey are most successful catching species of slow-
moving fish that eat benthic organisms in shallow waters and fish that remain near the
water's surface (Poole, 1989a). Osprey consume all parts of a fish except the larger bones;
later, bones and other undigestible parts are ejected in fecal pellets (Bent, 1937).
Molt. Juvenile plumage is fully developed by fledging at about 60 days of age
(Henny, 1988b). Juveniles undergo a gradual molt to adult plumage at approximately 18
months of age (Brown and Amadon, 1968). For adults, the basic molt takes place in two
phases; the first phase occurs primarily on the wintering grounds prior to spring migration.
Completion of the molt occurs in the summer range prior to fall migration (Henny, 1988b).
Migration. Osprey are year-round residents in the most southern parts of their
range (e.g., south Florida, Mexico) but are migratory over the rest of their range in the
United States and Canada (Poole, 1989a). Studies of banded osprey have shown that the
fall migration begins in late August in the north temperate zone, with adults and juveniles
2-65 Osprey
-------
from the eastern and central United States comprising a broad front flying south and then
directly across open ocean to their wintering grounds in Central and South America (Poole,
1989a). Spring migration appears to follow the same routes with birds reaching, for
example, the Chesapeake Bay area in mid-March (Reese, 1977) and Minnesota by the first
half of April (Dunstan, 1973; Henny and Van Velzen, 1972). The majority of migrating
osprey appear to follow the coastline, perhaps because they come from coastal colonies or
because the coast offers abundant food (Poole, 1989a). After their first migration south,
juveniles remain in their wintering grounds for about a year and a half, returning north to
the breeding grounds as 2-year-olds (Henny and Van Velzen, 1972).
Breeding activities and social organization. Nonmigratory (i.e., year-round resident)
populations breed during the winter; whereas migratory populations breed during the
summer (Poole, 1989a). Monogamy is the general rule for osprey; breeding pairs remain
together and return to the same nest site year after year (Fernandez and Fernandez, 1977;
Henny, 1988b). Colonies of osprey occur in areas such as islands, reservoirs, or lakes that
offer secure nesting sites and abundant food (Henny, 1986), but most osprey are solitary
nesters, often separated from other nests by tens to hundreds of kilometers (Poole, 1989a).
The female performs most of the incubation and relies completely on the male for food
from just after mating until the young have fledged (Poole, 1989a). Van Daele and Van
Daele (1982) found that ospreys at successful nests incubated 99.5 to 100 percent of the
daylight hours; disturbance of the nest during this time can kill the eggs if the adults are
kept from returning to the nest for some time. After hatching, the female is in constant
attendance at the nest for the first 35 days but may perch nearby at intervals after that
(Henny, 1988b). The female distributes the food delivered by the male by biting off pieces
to feed to the young (Poole, 1989a). By 30 days, the nestlings have reached 70 to 80
percent of their adult weight and begin to be active in the nest (Poole, 1989a). The young
fledge by age 60 to 65 days in nonmigratory populations and by about 50 to 55 days in
migratory populations (Henny et al., 1991). After fledging, the young remain dependent on
both parents for food usually for an additional 2 to 3 weeks (Poole, 1989a), but dependency
can continue up to 6 weeks in the more southern populations (Henny, 1986).
Home range and resources. Osprey build large stick nests in the tops of tall trees
or artificial structures such as buoys and radio towers (Poole, 1989a). In the Chesapeake
Bay area, less than one third of the 1,450 breeding pairs built their nests in trees, while
over half nested on channel markers and duck blinds, and the remainder on miscellaneous
man-made structures (Henny et al., 1974). Osprey build their nest at the top of the chosen
site, which can make it vulnerable to destruction from high winds (Henny, 1986). If not lost,
the same nest often is used year after year, and it can become quite large (e.g., over 2 m
tall and 1.5 m across) (Dunstan, 1973; Henny, 1988a). On islands where no predators are
present, osprey will nest on the ground (Poole, 1989b). The distance osprey travel from
their nests to forage (i.e., foraging radius) depends on the availability of appropriate nest
sites near areas with sufficient fish; osprey will travel up to 10 to 15 km to obtain food (Van
Daele and Van Daele, 1982).
Population density. Population density depends on the availability and distribution
of resources and can be highly variable. Henny (1988a) reported as many as 1.9 nests per
hectare in one of the largest osprey colonies in the western United States in 1899, with an
2-66 Osprey
-------
estimated 1.0 to 1.2 nests per hectare occupied that year. Lower densities on the order of
0.005 to 0.1 nests per hectare are more common (see table).
Population dynamics. Breeding data from many locations in the United States and
Canada during the years 1950 to 1976 show low productivity (fewer than one chick fledged
per active nest on average). Evidence indicates the cause to be egg-shell thinning that
resulted from the ospreys' exposure to DDT that had bioaccumulated in fish (Henny and
Anthony, 1989; Henny et al., 1977; Poole, 1989a). Thus, data from reproductive studies
conducted during this time can only be used with this in mind (Spitzer et al., 1978).a
Because of their terminal position in the aquatic food chain, osprey can be a sensitive
indicator of toxic contaminants that bioaccumulate (Henny et al., 1978; Henny, 1988b).
Osprey are only known to start a second clutch if the first one is destroyed (Poole,
1989a). Juveniles do not return to their place of birth until 2 years of age, and they do not
breed until their third season (Henny and Van Velzen, 1972). Often, breeding is delayed
until 4 to 7 years of age in areas such as the Chesapeake Bay, where good nesting sites
are scarce (Poole, 1989b).
General references
Poole (1989a); Brown and Amadon (1968); Henny (1986); Henny (1988b).
aln the table beginning on the next page, data on the number fledged per active nest and the
number fledged per successful nest are provided only for studies of populations that appeared
to be unaffected by DDT.
2-67 Osprey
-------
Osprey (Pandion haliaetus)
Factors
Body Weight
(g)
Egg Weight (g)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water Ingest.
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AF
AM
A F courtship
A F incubation
A F late nestl.
A M courtship
A M late nestl.
F at fledging
M at fledging
A F basal
A M basal
A F free-living
A M free-living
A F courtship
period
AF
AM
AF
AM
AF
Mean
1,568
1,403
1,880±20SE
1,925±25SE
1,725±25SE
1,480 ± 15 SE
1,420 ± 15 SE
1,510
1,210
72.2 ± 5.35 SD
69
71
181
186
0.21
0.051
0.053
0.578
0.531
1,353
Range or
(95% Cl of mean)
1,250-1,900
1,220-1,600
66.0-81.3
(85 - 384)
(87 - 395)
Location (subspecies)
NS
se Massachusetts
Maryland, Virginia
North Carolina
(carolinensis)
se Massachusetts
Reference
Brown & Amadon, 1968
Poole, 1984
McLean, 1986
Whittemore, 1984
estimated
estimated
Poole, 1983
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
10
0>
00
-------
Osprey (Pandion haliaetus)
Dietary
Composition
alewife
smelt
pollock
winter flounder
starry flounder
cutthroat trout
carp
crappie
gizzard shad
sunfish
largemouth bass
golden shiner
brown bullhead
salmonids
northern squawfish
yellow perch
largescale sucker
Size of fish caught:
< 10 cm
11 -20cm
21 -30cm
31 - 40 cm
41 + cm
Spring
63
29
5
3
37.7
20.8
19.3
11.6
10.6
Summer
32
5
53
10
95
5
67
33
3.3
42.1
46.7
6.6
1.3
Fall
Winter
Location/Habitat
(measure)
Nova Scotia, Canada/
harbor, bay
(% wet weight; observed
captures)
se Alaska/NS
(% wet weight; observed
captures, noting fish length)
w Oregon/NS
(% wet weight; observed
captures, noting fish length)
Florida/lake
(% of prey caught; identified
at nests)
Idaho/reservoir
(% offish caught; observed
captures)
Idaho/reservoir
(% offish in each size class;
determined from remains at
nest)
Reference
Greene etal., 1983
Hughes, 1983
Hughes, 1983
Collopy, 1984
Van Daele & Van Daele, 1982
Van Daele & Van Daele, 1982
Note
No.
7
7
7
10
0>
-------
Osprey (Pandion haliaetus)
Population
Dynamics
Foraging
Radius (km)
Population
Density
(nests/ha)
Clutch
Size
Clutches/Year
Days
Incubation
Age at
Fledging
(days)
Number
Fledge per
Active Nest
Age/Sex
Cond/Seas
AM
A B spring
AB
A B summer
A B spring
A B spring
A B spring
non-migr.
pop.
migratory
pop.
Mean
1.7
10
3 to 8
1.9
0.028
0.10
0.005
3.23 ± 0.03 SE
2.84 ± 0.07 SE
2.67 ± 0.07 SE
3.23 ± 0.09 SE
2.82
1
38.1 ±3.2SD
62.5 ± 4.9 SD
54 ±3.0SD
1.16
1.34
1.58
1.92
Range
0.7-2.7
>1
1 -4
32-42
35-43
52-76
48-59
0.79-1.47(10yrs)
1.17 -1.89 (3 yrs)
Location/Habitat
Minnesota/lakes
Nova Scotia/coastal
nw California/coastal, bay
Oregon/lake in 1899 only
Florida/wetland
North Carolina/reservoir
North Carolina/lake
Atlantic Seaboard/NS
Georgia, Florida/NS
s California, n Mexico/NS
ne United States/NS
Idaho/river, lakes
NS/NS
Baja California,
Mexico/coastal islands
Massachusetts/NS
Baja California,
Mexico/coastal islands
Maryland/Cheasapeake Bay
N. Carolina/lake
S. Carolina/lake
Idaho/reservoir
e United States/coastal
Reference
Dunstan, 1973
Greene etal., 1983
Koplin, 1981
Henny, 1988a
Eichholz, 1980
Henny & Noltemeier, 1975
Henny & Noltemeier, 1975
Judge, 1983
Judge, 1983
Judge, 1983
Spitzer, 1980
Henny etal., 1991
Poole, 1989a
Judge, 1983
Poole, 1989a
Judge, 1983
Stotts& Henny, 1975
Whittemore, 1984
Henny & Noltemeier, 1975
Van Daele & Van Daele, 1982
Poole, 1984
Note
No.
8
9
9
10
•ij
o
-------
Osprey (Pandion haliaetus)
Population
Dynamics
Number
Fledge per
Successful
Nest
Age at
Sexual
Maturity
Annual
Mortality
Rates (percent)
Average
Longevity
Seasonal
Activity
Mating
Hatching
Migration fall
spring
Age/Sex
Cond/Seas
B
B
1st year
years 2-18
JB
AB
if reach sex.
maturity
late April
early Dec.
early January
mid-March
late April
February
late August
early April
early March
Mean
1.7
2.14
1.83
1.79
2.05
3yrs
57.3
18.5 ±1.8
41
15
4.8
Peak
May
May
early May
mid-May
September
Range
3 - 5 yrs
End
mid-June
late February
early March
late May
mid-June
late April
November
Location/Habitat
Baja California,
Mexico/coastal islands
Idaho/river
Florida/lake
Delaware/coastal bay
Montana/lake
New York,
Massachusetts/NS
North America/NS
New York, New Jersey/NS
NS/NS
NS/NS
Delaware, New Jersey
Minnesota
Florida (non migratory)
Baja California, Mexico
(non migratory)
Maryland, Virginia
New York/New England
Baja California, Mexico
(non migratory)
most of United States
Minnesota
North Carolina
Reference
Judge, 1983
Hennyetal., 1991
Collopy, 1984
Hennyetal., 1977
Hennyetal., 1991
Spitzer, 1980
Henny& Wight, 1969
Henny& Wight, 1969
Spitzer, 1980
Brown & Amadon, 1968
Reference
Bent, 1937
Dunstan, 1973
Poole, 1989a
Judge, 1983
Bent, 1937
Bent, 1937
Judge, 1983
Henny, 1986
Dunstan, 1973
Parnell& Walton, 1977
Note
No.
10
Note
No.
11
10
-------
10
•ij
10
Osprey (Pandion haliaetus)
1 Late nestl. indicates late nestling stage of the breeding season. Cited in Poole (1989a).
2 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and body weights from Brown and Amadon (1968).
3 Estimated using equation 3-37 (Nagy, 1987) and body weights from Brown and Amadon (1968).
4 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Brown and Amadon (1968).
5 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Brown and Amadon (1968).
6 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, cited in Walsberg and King, 1978) and body weights from Brown and Amadon
(1968).
7 Percent wet weight of food ingested by free-flying osprey estimated by identifying species offish captured (using binoculars), estimating the
length of each fish captured by comparison with osprey, and using laboratory measures of weights and lengths of samples of these fish species.
8 Second clutch produced only if first is lost.
9 Nestlings in migratory populations fledge at an earlier age than nestlings in nonmigratory populations, such as those in Mexico and south
Florida.
10 Cited in Henny (1988b).
11 Cited in Henny (1986).
-------
References (including Appendix)
Bent, A. C. (1937) Life histories of North American birds of prey. Part 1: Order
Falconiformes. Washington, DC: U.S. Government Printing Office; Smithsonian Inst.
U.S. Nat. Mus., Bull. 167.
Brown, L.; Amadon, D. (1968) Eagles, hawks, and falcons of the world, v. 1. New York, NY:
McGraw-Hill.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Collopy, M. W. (1984) Parental care, productivity, and predator-prey relationships of
ospreys in three North Florida Lakes: preliminary report. In: Westall, M. A., ed. Proc.
southeastern U.S. and Caribbean osprey symposium; pp. 85-98.
Cramp, S., chief ed. (1980) Handbook of the birds of Europe, the Middle East and North
Africa: v. 2. Oxford, UK: Oxford University Press.
Dunstan, T. C. (1968) Breeding success of osprey in Minnesota from 1963-1968. Loon 40:
109-112.
Dunstan, T. C. (1973) The biology of ospreys in Minnesota. Loon 45: 108-113.
Edwards, T. C., Jr. (1988) Temporal variation in prey preference patterns of adult ospreys.
Auk 105: 244-251.
Eichholz, N. F. (1980) Osprey nest concentrations in northwest Florida. Fla. Field Nat. 8:
18-19.
Fernandez, G.; Fernandez, J. (1977) Some instant benefits and long range hopes of color
banding ospreys. Transactions of the North American osprey research conference.
U.S. Natl. Park Serv. Trans. Proc. Ser. 2.
French, J. M. (1972) Distribution, abundance, and breeding status of ospreys in
northwestern California [master's thesis]. Arcata, CA: Humboldt State University.
French, J. M.; Koplin, J. R. (1977) Distribution, abundance, and breeding status of ospreys
in northwestern California. Transactions of the North American osprey research
conference. U.S. Natl. Park Serv. Trans. Proc. Ser. 2: 223-240.
Garber, D. P. (1972) Osprey nesting ecology in Lassen and Plumas Counties, California
[master's thesis]. Arcata, CA: Humboldt State University.
2-73 Osprey
-------
Greene, E. P.; Greene, A. E.; Freedman, B. (1983) Foraging behavior and prey selection by
ospreys in coastal habitats in Nova Scotia, Canada. In: Bird, D. M.; Seymour, N. R.;
Gerrard, J. M., eds. Biology and management of bald eagles and ospreys. St. Anne
de Bellvue, Quebec: Harpell Press; pp. 257-267.
Grubb, T. C., Jr. (1977) Weather dependent foraging in ospreys. Auk 94: 146-149.
Hagan, J. M. (1984) North Carolina osprey population: social group or breeding
aggregation? In: Westall, M. A., ed. Proc. southeastern U.S. and Caribbean osprey
symposium.
Henny, C. J. (1977) Research, management and status of the osprey in North America. In:
Chancellor, R. D., ed. Proc. world birds of prey conf. Internat. Council Bird Preserv.;
Vienna, Austria; pp. 199-222.
Henny, C. J. (1983) Distribution and abundance of nesting ospreys in the United States. In:
Bird, D. M.; Seymour, N. R.; Gerrard, J. M., eds. Biology and management of bald
eagles and ospreys. St. Anne de Bellvue, Quebec: Harpell Press; pp. 175-186.
Henny, C. J. (1986) Osprey (Pandion haliaetus), Section 4.3.1, US Army Corps of Engineers
Wildlife Resources Management Manual. Prepared by U.S. Fish Wildl. Serv.,
Patuxent Wildl. Res. Center, Corvallis, OR for US Army Engineer Waterways
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Henny, C. J. (1988a) Large osprey colony discovered in Oregon. Murrelet 69: 33-36.
Henny, C. J. (1988b) Osprey [sections]. In: Palmer, R. S., ed. Handbook of North American
birds: v. 4. New Haven, CT: Yale University Press.
Henny, C. J.; Anthony, R. G. (1989) Bald eagle and osprey. Natl. Wildl. Fed. Sci. Tech. Ser.
No. 12: 66-82.
Henny, C. J.; Noltemeier, A. P. (1975) Osprey nesting populations in the coastal Carolinas.
Amer. Birds 29: 1073-1079.
Henny, C. J.; Van Velzen, W. T. (1972) Migration patterns and wintering localities of
American ospreys. J. Wildl. Manage. 36: 1133-1141.
Henny, C. J.; Wight, H. M. (1969) An endangered osprey population: estimates of mortality
and production. Auk 86: 288-198.
Henny, C. J.; Smith, M. M.; Stotts, V. D. (1974) The 1973 distribution and abundance of
breeding ospreys in the Chesapeake Bay. Chesapeake Sci. 15: 125-133.
Henny, C. J.; Byrd, M. A.; Jacobs, J. A.; et al. (1977) Mid-Atlantic coast osprey population:
present numbers, productivity, pollutant contamination, and status. J. Wildl.
Manage. 41:254-265.
2-74 Osprey
-------
Henny, C. J.; Collins, J. A.; Deibert, W. J. (1978) Osprey distribution, abundance, and status
in western North America. Murrlet 59: 14-25.
Henny, C. J.; Blus, L. J.; Hoffman, D. J.; et al. (1991) Lead accumulation and osprey
production near a mining site on the Coeur d'Alene River, Idaho. Arch. Environ.
Contam. Toxicol. 21: 415-424.
Hughes, J. (1983) On osprey habitat and productivity: a tale of two habitats. In: Bird, D. M.;
Seymour, N. R.; Gerrard, J. M., eds. Biology and management of bald eagles and
ospreys. St. Anne de Bellvue, Quebec: Harpell Press; pp. 269-273.
Judge, D. S. (1983) Productivity of ospreys in the gulf of California. Wilson Bull. 95:
243-255.
Kennedy, R. S. (1973) Notes on the migration of juvenile ospreys from Maryland and
Virginia. Bird-Banding 44: 180-186.
Koplin, J. R. (1981) Reproductive performance of ospreys (Pandion haliaetus) in
northwestern California. Natl. Geogr. Soc. Res. Rep. 13: 337-344.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
Lasiewski, R. C.; Dawson, W. R. (1967) A re-examination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Lind, G. S. (1976) Production, nest site selection, and food habits of ospreys in Deschutes
National Forest, Oregon [master's thesis]. Corvallis, OR: Oregon State University.
MacCarter, D. S. (1972) Food habits of osprey at Flathead Lake, Montana [master's thesis].
Arcata, CA: Humboldt State University.
MacNamara, M. (1977) Sexing the American osprey using secondary sexual characteristics.
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Serv. Trans. Proc. Ser. 2: 43-45.
McLean, P. K. (1986) The feeding ecology of Chesapeake Bay ospreys and the growth and
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Melquist, W. E.; Johnson, D. R.; Carrier, W. D. (1978) Migration patterns of northern Idaho
and eastern Washington ospreys. Bird-Banding 49: 234-236.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
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2-75 Osprey
-------
Nesbitt, S. (1974) Foods of the osprey at Newnans Lake. Fla. Field Nat. 2: 45.
Ogden, J. C. (1977) Preliminary report on a study of Florida ospreys. In: Ogden, J. C., ed.
Transactions of the North American osprey research conference; pp. 143-151.
Parnell, J. F.; Walton, R. (1977) Osprey reproductive success in southeastern North
Carolina. Transactions North American osprey research conference. U.S. Natl. Park
Serv. Trans. Proc. Ser. 2: 139-142.
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North America. In: Toxic contamination in large lakes; v. 1; pp. 39-54.
Poole, A. F. (1982) Brood reduction in temperate and subtropical ospreys. Oecologia (Berl.)
53: 111-119.
Poole, A. F. (1984) Reproductive limitation in coastal ospreys: an ecological and
evolutionary perspective [Ph.D. dissertation]. Boston, MA: Boston University.
Poole, A. F. (1983) Courtship feeding, clutch size, and egg size in ospreys: a preliminary
report. In: Bird, D. M.; Seymour, N. R.; Gerrard, J. M., eds. Biology and management
of bald eagles and ospreys. St. Anne de Bellvue, Quebec: Harpell Press; pp.
243-256.
Poole, A. F. (1989a) Ospreys: a natural and unnatural history. Cambridge, MA: Cambridge
University Press.
Poole, A. F. (1989b) Regulation of osprey Pandion haliaetus populations: the role of nest
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world: proceedings of the 3rd world conference on birds of prey and owls; 22-27
March 1987; Eilat, Israel. Berlin, London, Paris: World Working Group on Birds of
Prey and Owls; pp. 227-234.
Prevost, Y. A. (1977) Feeding ecology of ospreys in Antigonish County, Nova Scotia
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202-221.
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2-76 Osprey
-------
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
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Stinson, C. H. (1977) Familial longevity in ospreys. Bird-Banding 48: 72-73.
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Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Whittemore, R. E. (1984) Historical overview of osprey at the Mattamuskeet National
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2-77 Osprey
Page 2-78 left blank.
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2.1.6. Red-Tailed Hawk (buteo hawks)
Order Falconiformes, Family Accipitridae. The family Accipitridae includes most
birds of prey except falcons, owls, and American vultures. Buteo hawks are covered in
this section.b Buteo hawks are moderately large soaring hawks that inhabit open or semi-
open areas. They are the most common daytime avian predators on ground-dwelling
vertebrates, particularly rodents and other small mammals. They range in size from the
broad winged hawk (41 cm bill tip to tail tip) to the ferruginous hawk (58 cm). Hawks egest
pellets that contain undigestible parts of their prey, such as hair and feathers, that can be
useful in identifying the types of prey eaten (bones usually are digested completely; Duke
etal., 1987).
Selected species
The red-tailed hawk (Buteo jamaicensis) is the most common Buteo species in the
United States (National Geographic Society, 1987). Breeding populations are distributed
throughout most wooded and semiwooded regions of the United States and Canada south
of the tundra (Adamcik et al., 1979), although some populations are found in deserts and
prairie habitats. Six subspecies are recognized (Brown and Amadon, 1968). Nesting
primarily in woodlands, red-tails feed in open country on a wide variety of small- to
medium-sized prey.
Body size. Males of this medium-sized buteo (46 cm) weigh about 1 kg, and females
are approximately 20 percent heavier than the males (see table). Otherwise, the sexes look
alike (Brown and Amadon, 1968).
Habitat. Red-tails are found in habitats ranging from woodlands, wetlands,
pastures, and prairies to deserts (Bohm 1978b; Gates, 1972; MacLaren et al., 1988; Mader,
1978). They appear to prefer a mixed landscape containing old fields, wetlands, and
pastures for foraging interspersed with groves of woodlands and bluffs and streamside
trees for perching and nesting (Brown and Amadon, 1968; Preston, 1990). Red-tails build
their nests close to the tops of trees in low-density forests and often in trees that are on a
slope (Bednarz and Dinsmore, 1982). In areas where trees are scarce, nests are built on
other structures, occasionally in cactus (Mader, 1978), on rock pinnacles or ledges, or
man-made structures (Brown and Amadon, 1968; MacLaren et al., 1988). In winter, night
roosts usually are in thick conifers if available and in other types of trees otherwise (Brown
and Amadon, 1968).
Food habits. Red-tails hunt primarily from an elevated perch, often near woodland
edges (Bohm, 1978a; Janes, 1984; Preston, 1990). Small mammals, including mice,
shrews, voles, rabbits, and squirrels, are important prey, particularly during winter. Red-
tails also eat a wide variety of foods depending on availability, including birds, lizards,
snakes, and large insects (Bent, 1937; Craighead and Craighead, 1956; Fitch et al., 1946).
In general, red-tails are opportunistic and will feed on whatever species are most abundant
"Other members of the family Accipitridae, eagles and the osprey, are covered in Sections 2.1.7
and 2.1.5, respectively.
2-79 Red-Tailed Hawk
-------
(Brown and Amadon, 1968). Winter food choices vary with snow cover; when small
mammals such as voles become unavailable (under the snow), red-tails may concentrate
on larger prey, such as pheasants (Gates, 1972).
Molt. Juveniles molt into adult plumage in a gradual process from the spring (age
about 14 months) to summer or early fall (Bent, 1937).
Migration. The more northerly red-tailed hawk populations are migratory while the
more southerly are year-round residents (Bent, 1937).
Breeding activities and social organization. Red-tails lay one clutch per year
consisting of one to three eggs, although a replacement clutch is possible if the initial
clutch is lost early in the breeding season (Bent, 1937). Their nests are large and built of
twigs (Bohm, 1978b). Both sexes incubate, but the male provides food for the female
during incubation and the entire family following hatching (Brown and Amadon, 1968). The
parents continue to feed their young after fledging while they are learning to hunt (Brown
and Amadon, 1968).
Home range and resources. Red-tailed hawks are territorial throughout the year,
including winter (Brown and Amadon, 1968). Trees or other sites for nesting and perching
are important requirements for breeding territories and can determine which habitats are
used in a particular area (Preston, 1990; Rothfels and Lein, 1983). Home range size can
vary from a few hundred hectares to over 1,500 hectares, depending on the habitat
(Andersen and Rongstad, 1989; Petersen, 1979). In a 10-year study in Oregon, Janes
(1984) found that the size of red-tail territories and the location of boundaries between
territories varied little from year to year, even though individual birds or pairs died and
were replaced.
Population density. Population densities generally do not exceed 0.03 pairs per
hectare, and usually are lower than 0.005 pairs per hectare (see Appendix). Populations in
southern areas such as Florida can increase substantially in the winter with the influx of
migrants from the more northerly populations (Bohall and Collopy, 1984).
Population dynamics. Beginning at 2 years of age, most red-tailed hawks attempt to
breed, although the proportion breeding can vary by population and environmental
conditions (Henny and Wight, 1970, 1972). Average clutch size varies regionally, tending to
increase from east to west and from south to north (Henny and Wight, 1970, 1972). In a 10-
year study of red-tails in Alberta, Canada, Adamcik et al. (1979) found that the breeding
population of adults remained stable despite strong cyclical fluctuations in the density of
their main prey, the snowshoe hare, over the years. The mean clutch size for the red-tail
population, however, appeared to vary with prey density, from 1.7 to 2.6 eggs/nest
(Adamcik et al., 1979). Over the course of the study, about 50 percent of observed nestling
losses occurred within 3 to 4 weeks after hatching due to starvation. Most of the variance
in yearly mortality of nestlings could be attributed to the amount of food supplied and the
frequency of rain. Large raptors such as horned owls also can be important sources of
mortality for red-tail nestlings in some areas (Adamcik et al., 1979).
2-80 Red-Tailed Hawk
-------
Similar species (from general references)
• The ferruginous hawk (Buteo regalis), one of the larger buteos (58 cm),
inhabits the dry open country of the western United States.
• The red-shouldered hawk (Buteo lineatus) is slightly smaller (53 cm) and
feeds on snakes, frogs, crayfish, mice, and some small birds. Its range is
east of the Rocky Mountains and in California, with moist mixed woodlands
preferred.
• Swainson's hawk (Buteo swainsoni) is restricted to the open plains of the
western United States. Although it is as large (53 cm) as the red-tail, it preys
mostly on insects.
• The broad-winged hawk (Buteo platypterus) is one of the smaller buteos (41
cm) and preys on mice, frogs, snakes, and insects. It prefers woodlands and
is found almost exclusively east of the Mississippi River.
• Harris' hawk (Parabuteo unicinctus) is similar in size (53 cm) to the red-tailed
hawk but is restricted to the semiarid wood and brushlands of the southwest.
This bird nests in saguaro, mesquite, and yucca and preys on rodents,
lizards, and small birds.
• The rough-legged hawk (Buteo lagopus) is one of the larger buteos
(56 cm). It winters throughout most of the United States in open
country but breeds only in the high arctic of North America.
• The zone-tailed hawk (Buteo albonotatus) is slightly smaller (51 cm)
than most buteos and feeds on rodents, lizards, fish, frogs, and small
birds. It can be found in mesa and mountain country within its limited
range between the southwest United States and Mexico.
• The short-tailed hawk (Buteo brachyurus) is the smallest buteo (39
cm) and can only be found in the southern tip of Florida in mixed
woodland and grassland habitats.
General references
Brown and Amadon (1968); Craighead and Craighead (1956); Fitch et al. (1946);
National Geographic Society (1987).
2-81 Red-Tailed Hawk
-------
Red-Tailed Hawk (Buteo jamaicensis)
Factors
Body Weight
(g)
Metabolic Rate
(I02/kg-day)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AF
AM
AF
AM
AF
AM
hatchling F
hatchling M
juvenile F
juvenile M
A B standard
MR /spring
A F basal
A M basal
A M breeding
A F breeding
A F free-living
A M free-living
A F winter
A M winter
A M summer
AF
AM
AF
AM
AF
AM
Mean
1,224
1,028
1,154
957
1,235
1,204
58
57
1,149
962
17.7 ± 5.9 SD
73
77
109
102
192
201
0.11
0.10
0.086
0.055
0.059
0.48
0.42
1,147
1,021
Range or
(95% Cl of mean)
(91 - 408)
(95 - 426)
Location
Michigan, Pennsylvania
sw Idaho
Ohio
Michigan/metabolism
chamber
California/mountains
Michigan/captive outdoors
Reference
Craighead & Craighead, 1956
Steenhof, 1983
Springer & Osborne, 1983
Pakpahan et al., 1989
estimated
Soltz, 1984
estimated
Craighead & Craighead, 1956
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
7
8
10
00
10
0)
CD"
Q.
I
0)
-------
Red-Tailed Hawk (Buteo jamaicensis)
Dietary
Composition
summary of 10 years:
snowshoe hare
Richard's ground
squirrel
Franklin's ground
squirrel
voles & mice
other mammals
waterfowl
ruffed grouse
sharp-tailed grouse
other grouse
other birds
(mammals)
Belding's ground
squirrel
mtn cottontail
pocket gopher
Townsend's ground
squirrel
(birds)
Alectoris graeca
western meadowlark
(snakes)
gopher snake
ground squirrel
rabbit
pocket gopher
other mammals
gopher snake
whiptail lizard
birds
Spring
(78.5)
52.8
13.1
7.3
2.9
(8.5)
3.5
1.8
(13.1)
6.1
Summer
mean ± SD
25.6 ±19
30.4 ±10
5.1 ± 2
4.8 ± 2
7.8 ± 6
16.2 ±10
2.0 ± 2
1.2 ± 1
0.9 ± 1
6.3 ± 3
60.8
26.5
4.3
2.6
3.8
0.3
1.3
Fall
Winter
Location/Habitat
(measure)
Alberta, Canada/
farm & woodlands
(% wet weight of prey
brought to chicks)
nc Oregon/
pasture and wheat fields
(% wet weight of prey
brought to nests; March to
June)
c California/foothills
(% wet weight of prey
brought to nests)
Reference
Adamciketal., 1979
Janes, 1984
Fitch etal., 1946
Note
No.
9
9
9
10
00
CO
0)
CD"
Q.
I
0)
-------
Red-Tailed Hawk (Buteo jamaicensis)
Population
Dynamics
Territory
Size (ha)
Population
Density
Clutch
Size
Clutches/Year
Days
Incubation
Age/Sex
Cond./Seas.
A B spring
A B winter
A B fall
summer:
AB
A B area a
A B area b
AB
winter:
BB
BB
Mean
60-160
697±316SD
1,770
pairs/ha:
0.0017 -
0.0050
0.0004
0.0012
0.0012
N/ha:
0.014
0.001 5 ±
0.0003
SD
2.0 ± 0.77 SD
2.32
2.2
2.11
2.96
1
32
Range
381 - 989
957 - 2,465
0.0002 - 0.0005
0.0010-0.0013
0.0010-0.0015
0.0012-0.0018
1 -3
1.9-2.6/10yrs
Location/Habitat
c California/foothills
s Michigan/fields, wood lots
Colorado/upland prairie,
pinyon-juniper woodlands
Colorado/open aspen
s Michigan/fields, wood lots
Alberta, Canada/farm,
woodlands
Toronto, Canada/mixed old
fields
s Michigan/fields, wood lots
c California/foothills
Arizona/desert
Alberta, Canada/farm,
woodlands
Florida/NS
Oregon, Washington/NS
Alberta, Canada
Reference
Fitch etal., 1946
Craighead & Craighead, 1956
Andersen & Rongstad, 1989
McGovern & McNurney, 1986
Craighead & Craighead, 1956
Adamcik etal., 1979
Baker & Brooks, 1981
Craighead & Craighead, 1956
Fitch etal., 1946
Mader, 1978
Adamcik etal., 1979
Henny& Wight, 1972
Henny& Wight, 1970
Bent, 1937
Adamcik etal., 1979
Note
No.
10
10
00
0)
CD"
Q.
I
0)
-------
Red-Tailed Hawk (Buteo jamaicensis)
Population
Dynamics
Growth Rate
Age at
Fledging
Number
Fledge
per Active Nest
Number
Fledge per
Successful
Nest
Age at
Sexual
Maturity
Annual
Mortality
Rates (percent)
Longevity
Seasonal
Activity
Mating
Age/Sex
Cond./Seas.
to 1 week
1 to 2 weeks
2 to 3 weeks
3 to 4 weeks
4 to 5 weeks
high prey
low prey
B
J B 1st year
AB
J B 1st year
AB
mid-February
mid-April
late March
Mean
20 g/day
34 g/day
39 g/day
26 g/day
10 g/day
4 5 to 46 days
1.47±0.25SE
1.15
1.9
1.2
2.12
1.85
2 years
62.4
20.6 ±1. 3 SE
66.0
23.9 ± 2.2 SE
early May
Range
0.28-1.90/
10yrs
maximum 18 yrs
early April
mid-May
early April
Location/Habitat
Ohio/free-living, habitat NS
California/foothills
Oregon/pasture
Alberta, Canada/farm,
woodlands
Idaho/canyon, shrub steppe
north of 42 N latitude/
North America
south of 42 N latitude/
North America
throughout range
north of 42 °N latitude/
North America
south of 42 N latitude/
North America
North America/NS
Location
Arizona
Alberta Canada
south Michigan
Reference
Springer and Osborne, 1983
Fitch etal., 1946
Janes, 1984
Adamciketal., 1979
Steenhof & Kochert, 1985
Henny& Wight, 1970
Henny& Wight, 1970
Henny& Wight, 1970
Henny& Wight, 1970, 1972
Henny& Wight, 1970, 1972
Henny& Wight, 1970, 1972
Mader, 1978
Luttich et al., 1971
Craighead & Craighead, 1956
Note
No.
11
12
12
13
13
Note
No.
10
00
01
0)
CD"
Q.
I
0)
-------
Red-Tailed Hawk (Buteo jamaicensis)
Seasonal
Activity
Hatching
Begin
late March
mid-May
late April
late February
mid-March
early April
Peak
early June
early March
End
early May
mid-June
early May
mid-October
late October
late November
Location
Arizona
Alberta, Canada
south Michigan
Montana, Alberta, Canada
North Dakota
Minnesota
south Michigan
Maine, Montana
Alberta, Canada
Reference
Mader, 1978
Luttichetal., 1971
Craighead & Craighead, 1956
Bent, 1937; Luttichetal.,
1971
Bent, 1937
Bent, 1937
Craighead & Craighead, 1956
Bent, 1937
Luttichetal., 1971
Note
No.
14
15
10
00
o>
0)
CD"
Q.
I
0)
1 Estimated from data provided by authors.
2 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and body weights from Craighead and Craighead (1956).
3 Estimated from time and energy budgets for breeding season only.
4 Estimated using equation 3-37 (Nagy, 1987) and body weights from Craighead and Craighead (1956).
5 Hawks maintained outdoors using falconer's techniques; fed lean raw beef supplemented with natural prey. Overall activity levels not described.
Winter temperatures averaged 3 to 5 C and summer temperatures averaged 15 C during trials. Females weighed 1,218 g; males in winter
weighed 1,147 g; males in summer weighed 855 g.
6 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Craighead and Craighead (1956).
7 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Craighead and Craighead (1956).
8 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Craighead and
Craighead (1956).
9 Percent biomass (wet weight) estimated from observations of prey brought to the nest (identified to species) and remains of prey found at the
nests, using standard wet weights for each species of prey from other studies or measured in the lab.
10 Home range determined by 95 percent ellipse method; radio-tagged hawks, two of each sex.
11 Estimated from figure.
12 Summarizing data from several studies.
13 Summarizing banding recoveries prior to 1951.
14 Late departure dates.
15 Early arrival dates.
-------
References (including Appendix)
Adamcik, R. S.; Tood, A. W.; Keith, L. B. (1979) Demographic and dietary responses of
red-tailed hawks during a snowshoe hare fluctuation. Can. Field-Nat. 93: 16-27.
Andersen, D. E.; Rongstad, O. J. (1989) Home-range estimates of red-tailed hawks based
on random and systematic relocations. J. Wildl. Manage. 53: 802-807.
Baker, J. A.; Brooks, R. J. (1981) Distribution patterns of raptors in relation to density of
meadow voles. Condor 83: 42-47.
Bednarz, J. C.; Dinsmore, J. J. (1982) Nest-sites and habitat of red-shouldered and
red-tailed hawks in Iowa. Wilson Bull. 94: 31-45.
Bent, A. C. (1937) Life histories of North American birds of prey. Part 1: Order
falconiformes. Washington, DC: U.S. Government Printing Office; Smithsonian Inst.
U.S. Nat. Mus., Bull. 167.
Bohall, P. G.; Collopy, M. W. (1984) Seasonal abundance, habitat use, and perch sites of
four raptor species in north-central Florida. J. Field Ornithol. 55: 181-189.
Bohm, R. T. (1978a) Observation of nest decoration and food habits of red-tailed hawks.
Loon 50: 6-8.
Bohm, R. T. (1978b) A study of nesting red-tailed hawks in central Minnesota. Loon 50:
129-137.
Bosakowski, T.; Smith, D. G. (1992) Comparative diets of sympatric nesting raptors in the
eastern deciduous forest biome. Can. J. Zool 70: 984-992.
Brown, L.; Amadon, D. (1968) Eagles, hawks, and falcons of the world: v. 1. New York, NY:
McGraw-Hill.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Craighead, J. J.; Craighead, F. C. (1956) Hawks, owls and wildlife. Harrisburg, PA: The
Stackpole Co. and Washington, DC: Wildl. Manage. Inst.
Duke, G. E.; Evanson, O. A.; Jegers, A. A. (1976) Meal to pellet intervals in 14 species of
captive raptors. Comp. Biochem. Physiol. 53A: 1-6.
Duke, G. E.; Mauro, L.; Bird, D. M. (1987) Physiology. In: Pendleton, B. A.; Millsap, B. A.;
Cline, K. W.; et al., eds. Raptor management techniques manual. Washington, DC:
Institute for Wildlife Research, National Wildlife Federation; Sci. Tech. Ser. No. 10;
pp. 262-267.
2-87 Red-Tailed Hawk
-------
Fitch, H. S.; Swenson, F.; Tillotson, D. F. (1946) Behavior and food habits of the red-tailed
hawk. Condor 48: 205-237.
Gates, J. M. (1972) Red-tailed hawk populations and ecology in east-central Wisconsin.
Wilson Bull. 84: 421-433.
Gatz, T. A.; Hegdal, P. L. (1987) Local winter movements of four raptor species in central
Colorado. West. Birds 17: 107-114.
Hagar, D. C., Jr. (1957) Nesting populations of red-tailed hawks and horned owls in central
New York state. Wilson Bull. 69: 263-272.
Hardy, R. (1939) Nesting habits of the western red-tailed hawk. Condor 41: 79-80.
Henny, C. J.; Wight, H. M. (1970) Population ecology and environmental pollution: red-tailed
and Cooper's hawks. Symposium: Population ecology of migratory birds; Patuxent
Wildlife Research Center; pp. 229-249.
Henny, C. J.; Wight, H. M. (1972) Population ecology and environmental pollution: red-tailed
and Cooper's hawks. U.S. Bur. Sport Fish. Wildl., Wildl. Res. Rep. 2: 229-250.
Janes, S. W. (1984) Influences of territory composition and interspecific competition on
red-tailed hawk reproductive success. Ecology 65: 862-870.
Johnson, S. J. (1975) Productivity of the red-tailed hawk in southwestern Montana. Auk 92:
732-736.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
Lasiewski, R. C.; Dawson, W. R. (1967). A reexamination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Luttich, S. N.; Keith, L. B.; Stephenson, J. D. (1971) Population dynamics of the red-tailed
hawk (Buteo jamaicensis) at Rochester, Alberta. Auk 88: 75-87.
MacLaren, P. A.; Anderson, S. H.; Runde, D. E. (1988) Food habits and nest characteristics
of breeding raptors in southwestern Wyoming. Great Basin Nat. 48: 548-553.
Mader, W. J. (1978) A comparative nesting study of red-tailed hawks and Harris' hawks in
southern Arizona. Auk 95: 327-337.
McGovern, M.; McNurney, J. M. (1986) Densities of red-tailed hawk nests in aspen stands in
the Piceance Basin, Colorado. Raptor Res. 20: 43-45.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
2-88 Red-Tailed Hawk
-------
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Nice, M. M. (1954) Problems of incubation periods in North American birds. Condor 56:
173-197.
Orians, G.; Kuhlman, J. (1956) The red-tailed hawk and great horned owl populations in
Wisconsin. Condor 58: 371-385.
Pakpahan, A. M.; Haufler, J. B.; Prince, H. H. (1989) Metabolic rates of red-tailed hawks and
great horned owls. Condor 91: 1000-1002.
Petersen, L. (1979) Ecology of great horned owls and red-tailed hawks in southeastern
Wisconsin. Wise. Dept. Nat. Resour. Tech. Bull. No. 111.
Poole, E. L. (1938) Weights and wing areas in North American birds. Auk 55: 511-517.
Preston, C. R. (1990) Distribution of raptor foraging in relation to prey biomass and habitat
structure. Condor 92: 107-112.
Rothfels, M.; Lein, M. R. (1983) Territoriality in sympatric populations of red-tailed and
Swainson's hawks. Can. J. Zool. 61: 60-64.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Smith, D. G.; Murphy, J. R. (1973) Breeding ecology of raptors in the eastern Great Basin of
Utah. Brigham Young Univ. Sci. Bull., Biol. Ser. 18: 1-76.
Soltz, R. L. (1984) Time and energy budgets of the red-tailed hawk (Buteo jamaicensis) in
southern California. Southwest Nat. 29: 149-156.
Springer, M. A.; Kirkley, J. S. (1978) Inter-and intraspecific interactions between red-tailed
hawks and great horned owls in central Ohio. Ohio J. Sci. 78: 323-328.
Springer, M. A.; Osborne, D. R. (1983) Analysis of growth of the red-tailed hawk (Buteo
jamaicensis). Ohio J. Sci 83: 13-19.
Steenhof, K. (1983) Prey weights for computing percent biomass in raptor diets. Raptor
Res. 17: 15-27.
Steenhof, K. (1987) Assessing raptor reproductive success and productivity. In: Giron
Pendleton, B. A.; Millsap, B. A.; Cline, K. W., et al., eds. Raptor management
techniques manual. Washington, DC: National Wildlife Federation; pp. 157-170.
2-89 Red-Tailed Hawk
-------
Steenhof, K.; Kochert, M. N. (1985) Dietary shifts of sympatric buteos during a prey decline.
Oecologia 66: 6-16.
U. S. Department of Interior. (1979) Snake River birds of prey special research report.
Boise, ID: Bureau of Land Management.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
2-90 Red-Tailed Hawk
-------
2.1.7. Bald Eagle (eagles)
Order Falconiformes, Family Accipitridae. Eagles have long rounded wings, large
hooked bills, sharp talons, and are the largest birds of prey in the United States. They
swoop down on their prey at high speeds, and their diet varies by species and
considerably by habitat. In most species, the male is smaller than the female, but
otherwise the sexes are similar in appearance. This family also includes kites and hawks.
Selected species
The bald eagle (Haliaeetus leucocephalus), our national symbol, is a federally
designated endangered species. Relatively common in Alaska, populations in the lower 48
States have been seriously diminished, although they are recovering in some areas. Bald
eagles are most commonly sighted in coastal areas or near rivers or lakes. Bald eagles are
primarily carrion feeders.
Body size. Females are significantly larger than males, but otherwise the sexes
look alike (Brown and Amadon, 1968). Body size increases with latitude and is the sole
basis by which the northern and southern subspecies are divided (Snow, 1973). Length
from bill tip to tail tip averages 81 cm in the more northerly populations.
Habitat. Bald eagles generally are restricted to coastal areas, lakes, and rivers
(Brown and Amadon, 1968), although some may winter in areas not associated with water
(Platt, 1976). Preferred breeding sites include proximity to large bodies of open water and
large nest trees with sturdy branches (often conifers) and areas of old-growth timber with
an open and discontinuous canopy (Andrew and Mosher, 1982; Anthony et al., 1982;
Grubb, 1980; Peterson, 1986). In an analysis of more than 200 nests, Grubb (1980) found
55 percent within 46 m of a shoreline and 92 percent within 183 m of shore. During
migration and in winter, conifers often are used for communal roosting both during the day
and at night, perhaps to minimize heat loss (Anthony et al., 1982; Stalmaster, 1980).
Mature trees with large open crowns and stout, horizontal perching limbs are preferred for
roosting in general (Anthony et al., 1982; Chester et al., 1990). Bald eagles reach maximum
densities in areas of minimal human activity and are almost never found in areas of heavy
human use (Peterson, 1986).
Food habits. Primarily carrion feeders, bald eagles eat dead or dying fish when
available but also will catch live fish swimming near the surface or fish in shallow waters
(Brown and Amadon, 1968). In general, bald eagles can be described as opportunistic
feeders, taking advantage of whatever food source is most plentiful and easy to scavenge
or to capture, including birds and mammals (Brown and Amadon, 1968; Green, 1985;
Watson et al., 1991). In many areas, especially in winter, waterfowl, killed or injured by
hunters, and shore birds are an important food source (Todd et al., 1982). Eagles forage in
upland areas in the winter when surface waters are frozen over, consuming carrion
including rabbits, squirrels, and dead domestic livestock such as pigs and chickens
(Brown and Amadon, 1968; Harper et al., 1988). Bald eagles also have been known to steal
food from other members of their own species as well as from hawks, osprey, gulls, and
mergansers (Grubb, 1971; Jorde and Lingle, 1988; Sobkowiak and Titman, 1989). This
2-91 Bald Eagle
-------
may occur when there is a shortage of a primary food source, such as fish, and an
abundance of other prey such as waterfowl being used by other predatory birds (Jorde and
Lingle, 1988). Some prey are important to a few populations; for example, in the
Chesapeake Bay region, turtles are consumed during the breeding season (Clark, 1982),
and at Amchitka Island in Alaska, sea otter pups are found regularly in bald eagle nests
(Sherrod et al., 1975). In the Pacific Northwest during the breeding season, Watson et al.
(1991) found that bald eagles hunted live prey 57 percent of the time, scavenged for 24
percent of their prey, and pirated 19 percent (mostly from gulls or other eagles). Because
bald eagles scavenge dead or dying prey, they are particularly vulnerable to environmental
contaminants and pesticides (e.g., from feeding on birds that died from pesticides,
consuming lead shot from waterfowl killed or disabled by hunters) (Henny and Anthony,
1989; Harper et al., 1988; Lingle and Krapu, 1988). Bald eagles also are vulnerable to
biomagnification of contaminants in food chains. For example, near Lake Superior (Wl),
herring gulls, which were consumed by over 20 percent of nesting bald eagle pairs, were
found to be a significant source of DDE and PCB intake by the eagles (Kozie and Anderson,
1991). The gulls contained higher contaminant levels than the local fish because of their
higher trophic level.
Molt. Adult eagles molt yearly. In northern populations, molting occurs from late
spring to early fall; in southern populations, molting may be initiated earlier (McCollough,
1989). It is likely that the molt is not complete, and that some feathers are retained for 2
years. Young bald eagles generally molt into their adult plumage by their fifth year
(McCollough, 1989).
Migration. Bald eagles migrate out of areas where lakes are completely frozen over
in winter, but will remain as far north as the availability of open water and a reliable food
supply allow (Brown and Amadon, 1968). Areas with ice-free waterways, such as the
Columbia River estuary in Washington and Oregon, may support both resident and
migratory populations in the winter (Watson et al., 1991). The far northern breeding
populations migrate south for the winter and often congregate in areas with abundant food,
particularly the Mississippi Valley and the northwestern States (Snow, 1973). Some
populations of eagles that breed in southern latitudes (e.g., Arizona, Florida) show a
reverse migration and migrate north in midsummer (following breeding), returning south in
early autumn or winter (Brown and Amadon, 1968; Grubb et al., 1983).
Breeding activities and social organization. Bald eagles have been observed to
nest successfully at 4 years of age, but most do not breed until at least their fifth year (Nye,
1983). Breeding pairs remain together as long as both are alive (Brown and Amadon,
1968). Large stick nests (approximately 1.5 m across and 0.6 m deep) are built near water
and most often in a large tree, but sometimes on rocky outcrops or even on the ground on
some islands (Brown and Amadon, 1968; Grubb, 1980). In the absence of disturbance, the
same nest site may be used for many years (Nash et al., 1980). In Florida, eggs are laid in
late autumn or winter, while over the rest of the eagle's range, mating and egg laying occur
in spring (Brown and Amadon, 1968). Clutch sizes are larger in the north, and both sexes
take responsibility for feeding the young (Brown and Amadon, 1968). Young fledge at
about 10 to 12 weeks of age; after leaving the nest, they are still dependent on their parents
for several weeks and often return to the nest for food (Sprunt et al., 1973). After nesting,
large groups will often gather at sites with plentiful food
2-92 Bald Eagle
-------
resources, such as along rivers following a salmon spawn (Fitzner and Hanson, 1979;
Keister et al., 1987; McClelland, 1973).
Home range and resources. During the breeding season, eagles require large areas
in the vicinity of open water, with an adequate supply of nesting trees (Brown and Amadon,
1968). Distance from human disturbance is an important factor in nest site selection, and
nests have been reported to fail as a result of disturbance (Andrew and Mosher, 1982).
During incubation and brooding, eagles show territorial defense of an area around the nest
site. Following fledging, there is little need for nest defense, and eagles are opportunistic
in their search for abundant sources of prey (Mahaffy and Frenzel, 1987). During winter,
eagles roost communally in large aggregations and share a foraging home range. For
example, Opp (1980) described a population of 150 eagles that fed on meadow voles in a
250-ha flooded field for a 4-week period. This group also established a communal night
roost in the vicinity.
Population density. Because population density depends strongly on the
configuration of the surface water bodies used for foraging, few investigators have
published explicit density estimates on an area basis; most report breeding densities along
a shoreline on a linear basis. During the breeding season, 0.03 to 0.4 pairs have been
recorded per km shore (see table). Eagles migrating south from their summer territories in
Canada have aggregated in communal roosts of up to 400 eagles in a 40-ha area
(Crenshaw and McClelland, 1989). In the winter, communal roost sites may also contain
large numbers of eagles. Opp (1980) described a group of 150 eagles that roosted and
foraged together in the Klamath Basin (OR/CA), and communal night roosts of up to 300
eagles in Oregon in late winter.
Population dynamics. Not all adults in an area are part of the breeding population.
Some pairs may establish territories and not breed, while others may not even pair. The
percentage of adults breeding and the breeding success of those that do vary with local
food abundance, weather, and habitat conditions (Hansen, 1987; Hansen and Hodges,
1985; McAllister et al., 1986). In past years, bioaccumulation of organochlorine pollutants
reduced the reproductive success of bald eagles. Now, in many areas, these raptors are
reproducing at rates similar to those prior to the widespread use of these pesticides
(Green, 1985). Eagles lay one clutch per year, although replacement clutches may be laid
upon loss of the initial one (Sherrod et al., 1987). Very little is known about mortality rates
of bald eagles; Grier (1980) concluded from population models that adult survival is more
important than reproductive rate to the continued success of bald eagle populations. In
captivity, bald eagles have lived for up to 50 years (Snow, 1973), and one wild eagle,
banded and recaptured in Alaska, was estimated to be almost 22 years old (Cain, 1986).
Upon loss of an initial clutch, bald eagles may lay replacement clutches if sufficient time
remains (Sherrod et al., 1987).
Similar species (from general references)
• The golden eagle (Aquila chrysaetos) is similar in size (81 cm) to the bald
eagle, and its range encompasses all but the southeastern United States.
Small mammals, snakes, birds, and carrion are primary prey items, and
golden eagles prefer mountainous or hilly terrain.
2-93 Bald Eagle
-------
General references
Brown and Amadon (1968); Green (1985); Peterson (1986); Stalmaster and
Gessaman (1982, 1984).
2-94 Bald Eagle
-------
Bald Eagle (Haliaeetus leucocephalus)
Factors
BodyWeight(g)
Metabolic Rate
(kcal/kg-day)
Age/Sex/
Co nd. /Seas.
J F summer
J M summer
AF
AM
egg
egg
at hatching
nestlings:
M 10 days
M 30 days
M 50 days
M 60 days
F 10 days
F 30 days
F 50 days
F 60 days
free-living
A winter
J winter
A F free-living
A M free-living
Mean
5,089
4,014
4,500
3,000
120.6 ± 8.2 SD
102.5 ± 17.9 SD
91.5 ± 5.2 SD
500 (est.)
2,700 (est.)
3,600 (est.)
4,066 ± 35.1 SE
500 (est.)
3,000 (est.)
4,600 (est.)
5,172 ± 46.5 SE
99
111
135
143
Range or
(95% Cl of mean)
4,359 - 5,756
3,524 - 4,568
108-134
71 -125
3,575 - 4,500
4,800 - 5,600
(62 - 290)
(66 - 307)
Location or
subspecies
Alaska
Florida
Wisconsin
Florida
Saskatchewan, Canada
Saskatchewan, Canada
Saskatchewan, Canada
Connecticut
Reference
Imler & Kalmbach, 1955
Wiemeyer, 1991 (pers. comm.)
Krantzetal., 1970
Krantzetal., 1970
Bortolotti, 1984b
Bortolotti, 1984a,b
Bortolotti, 1984a,b
Craig etal., 1988
estimated
Note
No.
1
2
2
3
4
10
CD
Ol
m
0)
(D
-------
Bald Eagle (Haliaeetus leucocephalus)
Factors
Food Ingestion
Rate (g/g-day)
Water Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Co nd. /Seas.
winter:
B B salmon
B B rabbit
B B duck
AB
subadult B
juvenile B
AB
juvenile B
AF
AM
AF
AM
AF
AM
Dietary
Composition
mallard
American widgeon
American coot
other birds
Chinook salmon
sucker
European carp
other fish
unaccounted
Spring
Mean
0.092 ± 0.026 SD
0.075 ± 0.013 SD
0.065 ± 0.012 SD
0.12
0.10
0.091
0.12
0.14
0.035
0.037
1.43
1.19
2,970
2,530
Summer
Range or
(95% Cl of mean)
Fall
Winter
32
9
9
3
21
4
1
1
20
Location or
subspecies
Utah (captive)
Washington (free-flying)
Connecticut (free-flying)
Reference
Stalmaster & Gessaman, 1982
Stalmaster & Gessaman, 1984
Craig etal., 1988
estimated
estimated
estimated
Location/Habitat
(measure)
Washington/river
(% biomass; prey remains
found below communal
roost)
Fitzner& Hanson, 1979
Note
No.
5
6
7
8
9
Note
No.
10
CD
O>
m
0)
(D
-------
Bald Eagle (Haliaeetus leucocephalus)
Dietary
Composition
brown bullhead
white sucker
chain pickerel
smallmouth bass
white perch
other fish
black duck
other birds
mammals
(fish)
channel catfish
Sonora sucker
carp
other fish
(birds)
American coot
great blue heron
(mammals)
desert cottontail
jackrabbit
rock squirrel
(reptiles)
pink salmon
herring
trout
other fish
other animals
Spring
Summer
24.8
19.5
20.1
3.8
3.6
4.9
3.0
13.5
6.8
(57.6)
21.8
8.6
17.3
8.5
(14.1)
8.1
4.4
(28.1)
8.1
14.9
1.1
(0.2)
15.5
32.0
4.5
24.0
24.0
Fall
Winter
Location/Habitat
(measure)
Maine/inland river
(% occurrence in pellets)
samples from all seasons
except winter
central Arizona/desert
scrub, riparian
(% biomass; prey observed
brought to nest or found at
nests)
Alaska/coastal
(% frequency of occurrence;
prey observed brought to
the nest)
Reference
Toddetal., 1982
Haywood & Ohmart, 1986
Ofelt, 1975
Note
No.
10
CD
m
0)
(D
-------
Bald Eagle (Haliaeetus leucocephalus)
Population
Dynamics
Territory Area
(ha)
Territory
Length (km)
Territory
Radius (km)
Winter Home
Range (ha)
Foraging
Distance (km)
Population
Density
(pair/km
shore)
Clutch
Size
Clutches/Yea
r
Days
Incubation
Age at
Fledging
(days)
Number
Fledge per
Active Nest
Age/Sex
Cond./Seas.
pair spring
pair
pair
pair incubat.
pair brooding
J B winter
A B winter
B B winter
summer
summer
M
F
Mean
3,494 ± 2,520 SD
3.5
15.8
0.56 ± 0.18 SE
0.72 ± 0.21 SE
1, 830 ± 1,46050
1,880±900SD
3 to 7
0.38
0.035
0.026
0.045
2
2.3
1
35
79.9±1.08SE
83.0 ± 0.94 SE
1.01
1.28
0.90
1.14
1.00±0.06SE
Range
1,821 -6,392
1.4-7.2
11.1 -26.6
1 -3
1 -4
34-38
0.58-1. 22/1 Oyr
1. 07-1. 58/9 yr
0.76 -1.1 4/7 yr
0-3
Location/Habitat
Arizona/desert, riparian river
Washington/SJ Islands;
Grays Harbor
Minnesota/lake, woods
Missouri/lake
Connecticut/river
se Alaska/riverine
WY, ID, MT/:
Yellowstone
Continental
Snake
NS/NS
PA, DE, MD, NJ
NS/NS
Maryland (captive)
Saskatchewan/lake
California/NS
Montana/NS
Washington/NS
Florida/NS
Alaska/NS
Reference
Haywood & Ohmhart, 1983
Grubb, 1980
Mahaffy & Frenzel, 1987
Griffin & Baskett, 1985
Craig etal., 1988
Hansen, 1987
Swenson etal., 1986
Brown & Amadon, 1968
Schmid, 1966-67
Sherrod etal., 1987
Maestrelli & Wiemeyer, 1975
Bortolotti, 1989
Henny& Anthony, 1989
Henny& Anthony, 1989
Henny& Anthony, 1989
McEwan & Hirth, 1979
Spruntetal., 1973
Note
No.
10
CD
00
m
0)
-------
Bald Eagle (Haliaeetus leucocephalus)
Population
Dynamics
Number
Fledge per
Successful
Nest
Age at
Sexual
Maturity
Annual
Mortality
(percent)
Longevity
Seasonal
Activity
Mating/Layin
g
Fledging
Fall Migration
Spring
Migration
Age/Sex
Cond./Seas.
B
AB
fledging to 1 yr
AB
Begin
late September
December
late October
February
early March
late March
April
early July
early October
late October
November
late March
early March
Mean
1.65±0.26SD
1.35 ±0.11 SD
2.2
1.64
4
5.4
89.3
Peak
late December
late March
late July
late August
June
November
December/January
December
December
April
early April
Range
1. 22-1. 48/6 yr
1 -3
3-5
up to 50 yrs
End
November
late January
March
late April
early April
May
mid-August
mid-December
January
Location/Habitat
Arizona/desert scrub, river
Washington/San Juan Island
PA, DE, MD, NJ/NS
ID, MT, WY/river, lake
United States/NS
Alaska/Amchitka Island
captivity
Location
Florida, Texas
Arizona
se United States
MD, VA, DE
WY, MT, ID
Vancouver BC
s Louisiana
WY, MT, ID
se Alaska
Arizona
Montana
sc Oregon, n California
se Alaska
Arizona
sc Oregon, n California
WY, MT, ID
Illinois
Reference
Grubbetal., 1983
Grubbetal., 1983
Schmid, 1966-67
Swenson et al., 1986
Nye, 1983
Sherrod et al., 1977
Snow, 1973
Reference
Mager, 1977
Grubbetal., 1983
USFWS, 1989
LeFranc & Cline, 1983
Swenson etal., 1986
Brown & Amadon, 1968
Harris etal., 1987
Swenson et al., 1986
Hansen, 1987
Grubbetal., 1983
Crenshaw & McClelland,
1989
Keister etal., 1987
Hodges etal., 1987
Grubbetal., 1983
Keister et al., 1987
Swenson etal., 1986
Sabine, 1981
Note
No.
Note
No.
10
10
CD
m
0)
-------
o
o
M.
Q.
m
0)
CD_
(D
Bald Eagle (Haliaeetus leucocephalus)
1 Cited in Maestrelli and Wiemeyer (1975) and Bortolotti (1984a); juveniles up to 3 years of age.
2 Estimated from Figure 4.
3 Daily energy budget for free-living eagles based on time-activity budgets and metabolic models; assuming 4.5 kg eagle.
4 Estimated using equation 3-37 (Nagy, 1987) and body weights from Imler and Kalmbach (1955).
5 Estimated from observed captures of preweighed salmon provided at feeding stations. Eagle body weight assumed to be 4.5 kg. Some feeding
may have occurred elsewhere.
6 Estimate of food consumed based on observed feeding behaviors and an eagle body weight of 4.5 kg.
7 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Imler and Kalmbach (1955).
8 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Imler and Kalmbach (1955).
9 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Imler and Kalmbach
(1955).
10 Cited in Green, 1985.
-------
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Hodges, J. I.; King, J. G. (1979) Resurvey of the bald eagle breeding population in
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2-107 Bald Eagle
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2.1.8. American Kestrel (falcons)
Order Falconiformes, Family Falconidae. Falcons are the more streamlined of the
raptor species, with long pointed wings bent back at the wrists and large tails that taper at
the tips. They consume many kinds of animals including insects, reptiles, small mammals,
and birds. Falcons are found in a variety of habitats, from cities to the most remote areas.
Strong fliers that achieve high speeds, falcons range in size from the American kestrel (27
cm bill tip to tail tip) to the peregrine falcon (41 to 51 cm).
Selected species
The American kestrel (Falco sparverius), or sparrow hawk, is the most common
falcon in open and semi-open areas throughout North America. There are three recognized
subspecies: F. s. paulus (year-round resident from South Carolina to Florida and southern
Alabama), F. s. peninsularis (year-round resident of southern Baja California), and F. s.
sparverius (widespread and migratory) (Bohall-Wood and Collopy, 1986). Predators of the
kestrel include large raptors such as great horned owls, golden eagles, and red-tailed
hawks (Meyer and Balgooyen, 1987).
Body size. Weighing slightly over one tenth of a kilogram, the kestrel is the
smallest falcon native to the United States (Brown and Amadon, 1968). As for most
raptors, females are 10 to 20 percent larger than males (Bloom, 1973; Craighead and
Craighead, 1956). Kestrel body weights vary seasonally, with maximum weight (and fat
deposits) being achieved in winter and minimum weights in summer (Bloom, 1973;
Gessaman and Haggas, 1987).
Habitat. Kestrels inhabit open deserts, semi-open areas, the edges of groves
(Brown and Amadon, 1968), and even cities (National Geographic Society, 1987). In several
areas, investigators have found that male kestrels tend to use woodland openings and
edges, while females tend to utilize more open areas characterized by short or sparse
ground vegetation, particularly during the winter (Koplin, 1973, cited in Mills, 1976; Meyer
and Balgooyen, 1987; Mills, 1975, 1976; Smallwood, 1987). In other areas, however,
investigators have found no such differentiation (Toland, 1987; Sferra, 1984). In Florida,
kestrels appear to prefer sandhill communities (particularly pine/oak woodlands); these
areas provide high-quality foraging habitat and the majority of available nest sites (Bohall-
Wood and Collopy, 1986). Kestrels are more likely to use habitats close to centers of
human activities than are most other raptors (Fischer et al., 1984).
Food habits. Kestrels prey on a variety of small animals including invertebrates
such as worms, spiders, scorpions, beetles, other large insects, amphibians and reptiles
such as frogs, lizards, and snakes, and a wide variety of small- to medium-sized birds and
mammals (Brown and Amadon, 1968; Mueller, 1987). Large insects, such as grasshoppers,
are the kestrels' primary summer prey, although in their absence kestrels will switch to
small mammals (Collopy, 1973) and birds (Brown and Amadon, 1968). In winter, small
mammals and birds comprise most of the diet (Collopy and Koplin, 1983; Koplin et al.,
1980). Kestrels usually cache their vertebrate prey, often in clumps of grass or in tree
limbs and holes, to be retrieved later (Collopy, 1977; Mueller, 1987; Rudolph, 1982; Toland,
2-109 American Kestrel
-------
1984). Invertebrate prey usually are eaten immediately (Rudolph, 1982). In Florida, where
small mammals are scarce and reptiles are abundant, lizards are an important component
of the diet (Bohall-Wood and Collopy, 1987). Kestrels forage by three different techniques:
using open perches from which to spot and attack ground prey, hovering in the air to spot
ground prey, and catching insects on the wing (Rudolph, 1982, 1983).
Molt. Females begin their molt during incubation and complete it by the end of the
breeding season. Males, who are responsible for capturing most of the prey for the family,
do not begin their molt until near the end of the breeding season (Smallwood, 1988).
Migration. The American kestrel is a year-round resident over most of the United
States, but is migratory over the northern-most portions of its range (National Geographic
Society, 1987). Because of their late molt, males migrate and arrive at the wintering
grounds later than females or immatures (Smallwood, 1988).
Breeding activities and social organization. Adult kestrels are solitary, except
during the breeding season, and maintain territories even in winter (Brown and Amadon,
1968). Kestrels typically build their nests in tree cavities, but have used holes in telephone
poles, buildings, or stream banks when tree cavities are not available (Brown and Amadon,
1968). Both parents participate in incubation, but the female performs most of the
incubation, while the male provides her with food (Brown and Amadon, 1968). Following
hatching, the male brings the majority of the prey to the nestlings (Brown and Amadon,
1968). After fledging, young kestrels remain dependent on their parents for food for at
least 2 to 4 additional weeks (Lett and Bird, 1987). Fledglings often perch and socialize
with their siblings prior to dispersal (Lett and Bird, 1987). In Florida, resident kestrels
(paulus subspecies) maintain year-round pair bonds and joint territories. The resident
pairs have a competitive advantage over winter migrants (sparverius subspecies) in their
territories (Bohall-Wood and Collopy, 1986).
Home range and resources. Although some investigators have not noted territorial
defense (e.g., Craighead and Craighead, 1956), Mills (1975) demonstrated that kestrels
defend territories by introducing captured birds into other birds' territories. Winter
foraging territories range from a few hectares in productive areas (e.g., in California)
(Meyer and Balgooyen, 1987) to hundreds of hectares in less productive areas (e.g., Illinois,
Michigan) (Craighead and Craighead, 1956; Mills, 1975). Summer breeding territories
probably follow the same pattern (Craighead and Craighead, 1956).
Population density. Although much smaller than red-tailed hawks and bald eagles,
reported kestrel breeding population densities can be similarly low (e.g., 0.0003 to 0.004
nests per hectare; see table).
Population dynamics. Kestrels are sexually mature in the first breeding season
after their birth (Carpenter et al., 1987). Scarcity of suitable nesting cavities probably limits
the size of kestrel populations in parts of the United States (Cade, 1982). Three to four
young may fledge per nest per year, but mortality of juveniles in the first year is high (60 to
90 percent) (Craighead and Craighead, 1956; Henny, 1972). Adult mortality can be low
(e.g., 12 percent per year) (Craighead and Craighead, 1956).
2-110 American Kestrel
-------
Similar species (from general references)
• The peregrine falcon (Falco peregrinus), a rare resident of woods,
mountains, and coasts, preys almost exclusively on birds. Though
uncommon, they can be found wintering in most states, but rarely breeding.
These large falcons (38 cm) have been reintroduced in some areas in the
United States and have nested in urban environments.
• The merlin (Falco columbarius), larger (30 cm) than the kestrel, can be found
in a variety of habitats but nests in open woods or wooded prairies.
Wintering along coasts and near cities of the Great Plains, it primarily eats
birds.
• The prairie falcon (Falco mexicanus) also is larger (39 to 50 cm) than the
kestrel and inhabits dry, open country and prairies. A year-round resident of
the western United States, prairie falcons prey chiefly on birds and small
mammals.
General references
Cade (1982); Craighead and Craighead (1956); National Geographic Society (1987);
Brown and Amadon (1968).
2-111 American Kestrel
-------
American Kestrel (Falco sparverius)
Factors
Body Weight
(g)
Metabolic
Rate
(kcal/kg-day)
Food
Ingestion Rate
(g/g-day)
Water
Ingestion
Rate (g/g-day)
Age/Sex/
Cond./Seas.
Ffall
F winter
Mfall
M winter
F laying/inc.
Ffall
F winter
M incubate
Mfall
M winter
F laying/inc.
Ffall
F winter
M incubate
Mfall
M winter
A F basal
A M basal
A F free-living
A M free-living
A B winter
(vert, prey)
(invert, prey)
A M summer
AF
AM
Mean
115±8.6SD
132±13SD
103±6.7SD
114±7.8SD
124
127
138
108
111
119
414.4 ± 9.84 SE
368.7 ± 17.0 SE
327.2 ± 5.72 SE
337.6 ± 16.8 SE
364.9 ± 26.9 SE
386.4 ± 9.41 SE
134
140
333
345
0.29
(0.18)
(0.11)
0.31
0.11
0.12
Range or
(95% Cl of mean)
(157-706)
(162-733)
Location
California, Imperial Valley
California, Imperial Valley
Utah
Utah
Utah (free-living)
Utah (free-living)
nw California (free-living)
Ohio (seminatural
enclosure)
Reference
Bloom, 1973
Bloom, 1973
Gessaman & Haggas, 1987
Gessaman & Haggas, 1987
Gessaman & Haggas, 1987
Gessaman & Haggas, 1987
estimated
estimated
Koplinetal., 1980
Barrett & Mac key, 1975
estimated
Note
No.
1
1
2
3
4
5
10
_1
10
(D
T
o'
0)
3
-------
American Kestrel (Falco sparverius)
Factors
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AF
AM
AF
AM
Dietary
Composition
invertebrates
mammals
birds
reptiles
other
vertebrates
(primarily lizards)
invertebrates
Coleoptera
other invertebrates
frogs (Rana aurora)
other herpetofauna
Microtus californicus
Sorex vagrans
other mammals
Spring
49
51
Mean
0.089
0.079
267
242
Summer
Fall
Range or
(95% Cl of mean)
Winter
32.6
31.7
30.3
1.9
3.5
10.8
14.2
8.0
12.2
30.2
9.4
11.5
Location
Location/Habitat
(measure)
California/open areas, woods
(% wet weight of prey
observed captured)
Florida/dry pine-oak
woodlands (sandhill)
(% wet weight of prey observed
captured)
California/hayfields, pasture
(% wet weight of prey
observed captured)
Reference
estimated
estimated
Meyer & Balgooyen, 1987
Bohall-Wood & Collopy,
1987
Collopy & Koplin, 1983
Note
No.
6
7
Note
No.
10
_1
CO
(D
T
o'
0)
3
-------
American Kestrel (Falco sparverius)
Population
Dynamics
Territory
Size (ha)
Population
Density
Clutch
Size
Clutches/Year
Days
Incubation
Age at
Fledging
Age/Sex
Cond./Seas.
A F winter
A M winter
A B winter
A B summer
A B summer
pairs
summer
pairs
summer
pairs
summer
B B fall
A B winter
A B spring
Mean
31.6 ± 10.7 SD
13.1 ±2.0SD
154
202 ±131 SD
131±100SD
0.0026 nests/ha
0.0004 nests/ha
0.0035 pairs/ha
birds/ha:
0.0007 ± 0.00004 SD
0.0005 ± 0.0001 SD
0.0010 ±0.0002 SD
4.3
4 to 5
1
33.7 ± 0.33 SE
29 to 30
27.4 days
Range
18.7-42.0
9.7-14.8
<452
41 - 500
21 -215
0.0023-0.0031
0.0003 - 0.0006
0.0005-0.0012
0.0005 - 0.0006
0.0008-0.0011
3-7
33-35
26 - 30 days
Location/Habitat
California/open areas,
woods
Illinois/agricultural area
Wyoming/grasslands,
forests
Michigan/wood lots, fields
Missouri/urban
Missouri/rural
Wyoming/grasslands, forest
s Michigan/fields, wood lots
California/juniper,
sagebrush
NS/NS
Quebec, Canada/captive
Maryland/captive
NS/NS
Maryland/captive
Reference
Meyer & Balgooyen,
1987
Mills, 1975
Craighead & Craighead,
1956
Craighead & Craighead,
1956
Toland & Elder, 1987
Toland & Elder, 1987
Craighead & Craighead,
1956
Craighead & Craighead,
1956
Bloom & Hawks, 1983
Brown & Amadon, 1968
Carpenter et al., 1987
Porter & Wiemeyer, 1972
Brown & Amadon, 1968
Porter & Wiemeyer, 1972
Note
No.
10
(D
T
o'
0)
3
-------
American Kestrel (Falco sparverius)
Population
Dynamics
Number
Fledge per
Active Nest
Number
Fledge per
Successful
Nest
Age at Sexual
Maturity
Annual
Mortality
(percent)
Longevity
Seasonal
Activity
Mating/
Laying
Hatching
Molt
Age/Sex
Cond./Seas.
B
AB
JB
AB
JB
early May
mid -April
early April
mid-March
early June
early May
mid-May
Mean
3.1
3.8
3.7
1yr
12
88
46.0 ± 4.6 SE
60.7
Peak
late May
late June
early May
Range
up to 9 yrs
End
late June
early June
mid-May
early June
late July
mid-June
mid-September
Location/Habitat
California/juniper,
sagebrush
Wyoming/grasslands, forest
California/juniper,
sagebrush
Quebec, Canada/captive
s Michigan, Wyoming/
open areas, woods
North America/NS
Quebec, Canada/captive
California
central US
northern Utah
Florida
California
northern Utah
central Missouri
northern Utah
Reference
Bloom & Hawks, 1983
Craighead & Craighead,
1956
Bloom & Hawks, 1983
Carpenter et al., 1987
Craighead & Craighead,
1956
Henny, 1972
Carpenter et al., 1987
Reference
Bloom & Hawks, 1983
Brown & Amadon, 1968
Gessaman & Haggas,
1987
Brown & Amadon, 1968
Bloom & Hawks, 1983
Gessamen & Haggas,
1987
Toland & Elder, 1987
Gessaman & Haggas,
1987
Note
No.
Note
No.
10
_1
Ol
(D
T
o'
0)
3
-------
American Kestrel (Falco sparverius)
Seasonal
Activity
Begin
early
September
early March
mid -April
Peak
End
early November
Location
northern Utah
south Michigan
Wyoming
Reference
Gessaman & Haggas,
1987
Craighead & Craighead,
1956
Craighead & Craighead,
1956
Note
No.
10
_1
o>
1 Investigators estimated values from time-activity budget studies of kestrels in the field and rates of energy expenditure duri ng different activities
measured in the laboratory.
2 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and body weights from winter measurements by Gessaman and Haggas (1987).
3 Estimated using equation 3-37 (Nagy, 1987) and body weights from winter measurements by Gessaman and Haggas (1987).
4 Authors observed prey captured daily, and estimated total wet-weight prey intake using measured or reported weights for identifiable prey and
estimated weights for unidentifiable invertebrate prey (also, assumed kestrel weighed 119 g). Also, see Chapters 3 and 4 for methods by
estimating food ingestion rates.
5 Estimated using equation 3-15 (Calderand Braun, 1983) and body weights from winter measurements by Gessaman and Haggas (1987).
6 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from winter measurements by Gessaman and Haggas (1987).
7 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, cited in Walsberg and King, 1978) and body weights from winter measurements by
Gessaman and Haggas (1987).
(D
T
o'
0)
3
(D
-------
References (including Appendix)
Barrett, G. W.; Mackey, C. V. (1975) Prey selection and caloric ingestion rate of captive
American kestrels. Wilson Bull. 87: 514-519.
Bird, D. M.; Clark, R. G. (1983) Growth of body components in parent- and hand-reared
captive kestrels. Raptor Res. 17: 77-84.
Bloom, P. H. (1973) Seasonal variation in body weight of sparrow hawks in California.
Western Bird Bander 48: 17-19.
Bloom, P. H.; Hawks, S. J. (1983) Nest box use and reproductive biology of the American
kestrel in Lassen County, California. Raptor Res. 17: 9-14.
Bohall-Wood, P.; Collopy, M. W. (1986) Abundance and habitat selection of two American
kestrel subspecies in north-central Florida. Auk 103: 557-563.
Bohall-Wood, P. G.; Collopy, M. W. (1987) Foraging behavior of southeastern American
kestrels in relation to habitat use. Raptor Res. 6: 58-65.
Brown, L.; Amadon, D. (1968) Eagles, hawks, and falcons of the world. New York, NY:
McGraw Hill Book Co.
Cade, T. J. (1982) The falcons of the world. Ithaca, NY: Cornell University Press.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Carpenter, J. W.; Gabel, R. R.; Wiemeyer, S. N.; et al. (1987) Captive breeding. In:
Pendleton, B. A.; Millsap, B. A.; Cline, K. W.; et al., eds. Raptor management
techniques manual. Washington, DC: National Wildlife Federation; pp. 350-355.
Collopy, M. W. (1973) Predatory efficiency of American kestrels wintering in northwestern
Califonia. Raptor Res. 7: 25-31.
Collopy, M. W. (1977) Food caching by female American kestrels in winter. Condor 79:
63-68.
Collopy, M. W.; Koplin, J. R. (1983) Diet, capture success, and mode of hunting by female
American kestrels in winter. Condor 85: 369-371.
Craighead, J. J.; Craighead, F. C. (1956) Hawks, owls and wildlife. Harrisburg, PA: The
Stackpole Co. and Washington, DC: Wildlife Management Institute.
Duke, G. E.; Evanson, O. A.; Jegers, A. A. (1976) Meal to pellet intervals in 14 species of
captive raptors. Comp. Biochem. Physiol. 53A: 1-6.
2-117 American Kestrel
-------
Duke, G. E.; Mauro, L; Bird, D. M. (1987) Physiology. In: Pendleton, B. A.; Millsap, B. A.;
Cline, K. W.; et al., eds. Raptor management techniques manual. Washington, DC:
Institute for Wildlife Research, National Wildlife Federation; Sci. Tech. Ser. No. 10;
pp. 262-267.
Enderson, J. H. (1960) A population study of the sparrow hawk in east-central Illinois.
Wilson Bull. 72:222-231.
Fischer, D. L.; Ellis, K. L.; Meese, R. J. (1984) Winter habitat selection of diurnal raptors in
central Utah. Raptor Res. 18: 98-102.
Gessaman, J. A. (1979) Premigratory fat in the American kestrel. Wilson Bull. 91: 625-262.
Gessaman, J. A.; Haggas, L. (1987) Energetics of the American kestrel in northern Utah.
Raptor Res. 6: 137-144.
Henny, C. J. (1972) An analysis of the population dynamics of selected avian species with
special reference to changes during the modern pesticide era. Washington, DC: Bur.
Sport. Fish. Wildl.; Wildl. Res. Rep. 1.
King, J. R. (1974) Seasonal allocation of time and energy resources in birds. In: Paynter, R.
A., Jr., ed. Avian energetics. Cambridge, MA: Nuttall Ornithol. Club; pp. 4-70.
Koplin, J. R. (1973) Differential habitat use by sexes of American kestrels wintering in
northern California. Raptor Res. 7: 39-42.
Koplin, J. R.; Collopy, M. W.; Bammann, A. R.; et al. (1980) Energetics of two wintering
raptors. Auk 97: 795-806.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
Lasiewski, R. C.; Dawson, W. R. (1967). A reexamination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Lett, D. W.; Bird, D. M. (1987) Postfledging behavior of American kestrels in southwestern
Quebec. Wilson Bull. 99: 77-82.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Meyer, R. L.; Balgooyen, T. G. (1987) A study and implications of habitat separation by sex
of wintering American kestrels (Falco sparverius L.). Raptor Res. 6: 107-123.
Mills, G. S. (1975) A winter population study of the American kestrel in central Ohio. Wilson
Bull. 87: 241-247.
Mills, G. S. (1976) American kestrel sex ratios and habitat separation. Auk 93: 740-748.
2-118 American Kestrel
-------
Mueller, H. C. (1987) Prey selection by kestrels: a review. Raptor Res. 6: 83-106.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Porter, R. D.; Wiemeyer, S. N. (1972) Reproductive patterns in captive American kestrels
(sparrow hawks). Condor 74: 46-53.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Rudolph, S. G. (1982) Foraging strategies of American kestrels during breeding. Ecology
63: 1268-1276.
Rudolph, S. G. (1983) Aerial insect-catching by American kestrels. Condor 85: 368-369.
Sferra, N. J. (1984) Habitat selection by the American kestrel (Falco sparverius) and
red-tailed hawk (Buteo jamaicensis) wintering in Madison County, Kentucky. Raptor
Res. 18: 148-150.
Smallwood, J. A. (1987) Sexual segregation by habitat in American kestrels wintering in
southcentral Florida: vegetative structure and responses to differential prey
availability. Condor 89: 842-849.
Smallwood, J. A. (1988) A mechanism of sexual segregation by habitat by American
kestrels (Falco sparverius) wintering in south-central Florida. Auk 105: 36-46.
Sparrowe, R. D. (1972) Prey-catching behavior in the sparrow hawk. J. Wildl. Manage. 36:
279-308.
Toland, B. R. (1984) Unusual predatory and caching behavior of American kestrels in
central Missouri. Raptor Res. 18: 107-110.
Toland, B. R. (1987) The effect of vegetative cover on foraging strategies, hunting success
and nesting distribution of American kestrels in central Missouri. Raptor Res. 21:
14-20.
Toland, B. R.; Elder, W. H. (1987) Influence of nest-box placement and density on
abundance and productivity of American kestrels in central Missouri. Wilson Bull.
99: 712-717.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Wing, L.; Wing, A. H. (1939) Food consumption of a sparrow hawk. Condor 41: 168-170.
2-119 American Kestrel
-------
Zar, J. H. (1968) Standard metabolism comparisons between orders of birds. Condor 70:
278.
Zar, J. H. (1969) The use of the allometric model for avian standard metabolism - body
weight relationships. Comp. Biochem. Physiol. 29: 227-234.
2-120 American Kestrel
-------
2.1.9. Northern Bobwhite (quail)
Order Galliformes, Family Phasiadinae. Quail are ground-dwelling birds with short,
heavy bills adapted for foraging on the ground for seeds and insects. Most species inhabit
brush, abandoned fields, and open woodlands; some inhabit parklands. Quail and most
other gallinaceous birds are poor flyers that seldom leave the ground and do not migrate.
All species of this family gather in coveys (i.e., flocks of varying size) during some part of
the year. Quail range in size from Montezuma's quail (22 cm bill tip to tail tip) to the
mountain and Gambel's quail (28 cm); sexes are similar in size but differ in appearance.
Selected species
The northern bobwhite (Colinus virginianus) feeds mainly on seeds by gleaning on
the ground and low vegetation. It ranges from southeastern Wyoming, east to southern
Minnesota and across to southern Maine, south through the central and eastern United
States to eastern New Mexico in the west and to Florida in the east (American
Ornithologists' Union, 1983). It is the most widespread of the North American quail and
used to be very common, particularly east of the Rocky Mountains. Over the past three
decades, however, populations have been declining throughout its range (Brennan, 1991).
Body size. Northern bobwhite are average-sized quail (25 cm). Wild bobwhites
typically weigh between 150 and 200 g depending on location and season (see table), while
commercially bred stock usually exceed 200 g and may reach 300 g or more (Brenner and
Reeder, 1985; Koerth and Guthery, 1991). Males and females are similar in size, and
weights tend to increase with latitude and toward the west coast of the United States
(Hamilton, 1957; Rosene, 1969; Roseberry and Klimstra, 1971). Females are heaviest in the
spring and summer when they are laying eggs; males are lightest at this time of year
(Hamilton, 1957; Roseberry and Klimstra, 1971). Juveniles tend to weigh slightly less than
adults through winter (Hamilton, 1957; Roseberry and Klimstra, 1971). Koerth and Guthery
(1987) found both males and females to maintain between 9 and 11 percent body fat (as a
percentage of dry body weight) throughout the year in southern Texas; more northern
populations may maintain higher body fat ratios, particularly just prior to breeding (McRae
and Dimmick, 1982).
Habitat. During the breeding season, grasslands, idle fields, and pastures are the
preferred nesting habitat, and bobwhite often nest in large clumps of grasses (Roseberry
and Klimstra, 1984). Shade, open herbaceous cover, and green and growing vegetation are
required for suitable nest sites (Lehmann, 1984). Bobwhites forage in areas with open
vegetation, some bare ground, and light litter (Stoddard, 1931). Nearby dry powdery soils
are important for dust bathing (Johnsgard, 1988). Shrubby thickets up to 2 m high are
used for cover during midday (Schroeder, 1985). Although their range is extensive,
northern bobwhite reproduce poorly in the arid western portions of their range and during
droughts elsewhere (Schroeder, 1985). During the winter, they require wooded cover with
understory for daytime cover, preferably adjacent to open fields for foraging (Yoho and
Dimmick, 1972). They tend to roost at night in more open habitats with short and sparse
vegetation (Schroeder, 1985). In the more northern latitudes, cover and food can be limited
during the winter (Rosene, 1969). Changes in land use, primarily
2-121 Northern Bobwhite
-------
the distribution of farms and farming methods, have eliminated large areas of bobwhite
habitat in the last three decades (Brennan, 1991).
Food habits. Bobwhites forage during the day, primarily on the ground or in a light
litter layer less than 5 cm deep (Rosene, 1969). Seeds from weeds, woody plants, and
grasses comprise the majority of the adult bobwhite's diet throughout the year (Handley,
1931; Bent, 1932; Lehmann, 1984), although in winter in the south, green vegetation has
been found to dominate the plant materials in their diet (Campbell-Kissock et al., 1985).
Insects and other invertebrates can comprise up to 10 to 25 percent of the adults' diet
during the spring and summer in more northerly areas and year-round in the south
(Campbell-Kissock et al., 1985; Handley, 1931; Lehmann, 1984). Insects comprise the bulk
of the chicks' diet; up to 2 or 3 weeks of age chicks may consume almost 85 percent
insects, the remainder of the diet consisting of berries and seeds (Handley, 1931). Most
insects consumed by bobwhite chicks are very small, less than 8 mm in length and 0.005 g
(Hurst, 1972). Juvenile bobwhite, on the other hand, may consume only 25 percent insects,
the remainder of their diet being fruit and seeds (Handley, 1931). Quail consume little grit.
Korschgen (1948) found grit in only 3.4 percent of over 5,000 crops examined, and agreed
with Nestler (1946) that hard seeds can replace grit as the grinding agent for northern
bobwhite.
In some areas, bobwhites apparently can acquire their daily water needs from dew,
succulent plants, and insects (Stoddard, 1931); in more arid areas or in times of drought,
however, northern bobwhite need surface water for drinking (Johnsgard, 1988; Lehmann,
1984; Prasad and Guthery, 1986). Females need more water than males during the
breeding season, and both sexes may require more water in the winter than in the summer
when their diet is more restricted to seeds with low water content (Koerth and Guthery,
1990). Measurements on captive quail have indicated a daily water requirement of up to 13
percent of their body mass (see table); however, water intake requirements for free-ranging
birds may be higher, perhaps 14 to 21 percent of body mass per day (Koerth and Guthery,
1990). In the absence of adequate water, females may fail to reproduce (Koerth and
Guthery, 1991).
Dustbathing. Quail frequently dustbathe, although the reason for the behavior is
debated.0 They scratch in dry dirt or dust, toss the dust up into their feathers, rub their
head and sides in the dust, and then shake the dust from their plumage (Borchelt and
Duncan, 1974). Experiments by Driver et al. (1991) indicate that ingestion of materials
preened from feathers and direct dermal uptake can be significant exposure pathways for
quail exposed to aerial application of pesticides. Dust bathing might, therefore, provide a
significant exposure route for bobwhites using contaminated soils.
Molt. Juveniles attain adult plumage during their first fall molt at about 3 to 5
months of age (Hamilton, 1957; Stoddard, 1931). Adults undergo a complete prebasic
°Stoddard (1931) and others have suggested that dust bathing helps to control ectoparasites;
Borchelt and Duncan (1974) suggest that dust bathing helps control the amount of oil on the
quails' feathers.
2-122 Northern Bobwhite
-------
molt in the late summer and fall into winter plumage; in spring, a limited renewal of
feathers around the head and throat provides the breeding plumage (Bent, 1932).
Migration. The northern bobwhite is a year-round resident over its entire range but
may disperse locally to a different cover type or altitude with the changing season
(Lehmann, 1984). Most winter in wooded or brushy areas, returning to more open habitats
in spring for the breeding season (Lehmann, 1984; Rosene, 1969). Populations nesting at
higher elevations tend to move to lower ground where the winters are less severe
(Stoddard, 1931). The more southerly populations may be more sedentary; in a study in
Florida, northern bobwhite were found no further than 1 km from where they were banded,
and 86 percent were found within 400 m from their banding site over a 1- to 5-year period
(Smith et al., 1982).
Breeding activities and social organization. Northern bobwhite build nests on the
ground in open woodlands or in or around fields used for foraging. Most nests are
constructed in grassy growth near open ground, often in areas with scattered shrubs and
herbaceous growth (Klimstra and Roseberry, 1975; Stoddard, 1931). Both the male and
female scrape out a saucer-shaped depression in the ground 2 to 6 cm deep and 10 to 12
cm across, lining it with dead grasses from the previous year's growth (Bent, 1932;
Rosene, 1969). They lay large clutches, 12 to 30 eggs, which one or both parents incubate
for approximately 23 days (Lehmann, 1984; Simpson, 1976). As a general rule, clutch size
and nest success both decrease as the season progresses (Roseberry and Klimstra, 1984).
Family units, consisting of both the male and female as well as the offspring, sometimes
remain intact through the summer, but more often, one or both parents are lost to
predation (some females leave their brood to the male and begin another), and other pairs
or individual adults may adopt chicks from other broods (Lehmann, 1984). By fall, northern
bobwhites of all ages gather in larger coveys for the fall and winter. The quail remain in
coveys until the next spring, when they disperse as mating season begins (Lehmann, 1984;
Roseberry and Klimstra, 1984). Coveys of northern bobwhite tend to average 10 to 12 or
15 birds (up to 30) (Johnsgard, 1988; Lehmann, 1984; Rosene, 1969). When roosting in
winter, the birds in a covey form a small circle on the ground under a tree or in thick brush,
with heads facing outward and their bodies closely packed to conserve heat.
Home range and resources. In the breeding season, the bobwhite's home range
includes foraging areas, cover, and the nest site and may encompass several hectares.
Mated males and incubating females have the smallest spring and summer home ranges;
bachelor males and post-nesting males and females have much larger foraging ranges (see
table). Bobwhite tend to use a portion of their home range more intensively than the
remainder of the range (Urban, 1972). In the fall and winter, the range of each bobwhite
covey must include adequate open foraging areas and cover, typically shrubby or woody
thickets (Rosene, 1969). Each covey may utilize an area of several hectares, although as in
summer, there tend to be activity centers where the quail spend most of their time (Yoho
and Dimmick, 1972).
Population density. Bobwhite density depends on food and cover availability and
varies from year to year as well as from one location to another (Roseberry and Klimstra,
1984). Densities are highest at the end of the breeding season in the fall. In the
2-123 Northern Bobwhite
-------
southeast, densities may reach values as high as 7.5 birds (adults and juveniles) per
hectare, although average values of 2 to 3 may be more common in these areas (Guthery,
1988; Lehmann, 1984; Smith et al., 1982). Winter and spring densities between 0.1 and 0.8
birds per hectare have been recorded in the spring further north (Roseberry et al., 1979).
Population dynamics. Bobwhites attempt to rear one or two broods per year (up to
three in the south) (Bent, 1932; CKWRI, 1991; Stanford, 1972b). Bobwhite clutch sizes are
generally smaller in more southerly populations (Roseberry and Klimstra, 1984) and
smaller as the breeding season progresses in any given locale (Lehmann, 1984; Simpson,
1976). Predation is a major cause of nest loss; once hatched, chicks leave the nest
immediately to follow both or one parent (Lehmann, 1984; Roseberry and Klimstra, 1984).
Juveniles can survive without parental care after about 6 weeks of age (Lehmann, 1984).
They reach maturity by 16 weeks of age in the laboratory although they continue to gain
weight through about 20 weeks (Moore and Cain, 1975), and they may require 8 to 9
months to mature in the wild (Johnsgard, 1988; Jones and Hughes, 1978). Adult mortality
as well as juvenile mortality is high, with 70 to 85 percent of birds surviving less than 1
year (Brownie et al., 1985; Lehmann, 1984); thus, the bulk of the population turns over each
year.
Similar species (from general references)
• California quail (Callipepla californica), also known as valley quail, are
similar in size (25 cm) to the bobwhite and also gather in coveys during
autumn and winter. They are common in open woodlands, brushy foothills,
stream valleys, and suburbs, usually near permanent surface waters;
however, their range is restricted largely to the western coastal States and
Baja California.
• Gambel's quail (Callipepla gambelii) is larger (28 cm) than the bobwhite, and
is a resident of the southwestern desert scrublands, usually near permanent
surface waters. It also gathers in coveys in winter.
• The scaled quail (Callipepla squamata), similar in size (25 cm) to the
bobwhite, is restricted to the mesas, plateaus, semidesert scrublands, and
grasslands mixed with scrub, primarily of western Texas, New Mexico, and
Mexico.
• Mountain quail (Oreortyx pictus) are found in the chapparal, brushy ravines,
and mountain slopes of the west up to 3,000 m. These also are large quail
(28 cm). During the fall, they gather in coveys and descend to lower altitudes
for the winter.
• The Montezuma quail (Cyrtonyx montezumae), formerly known as the
harlequin quail, is a small (22 cm), secretive resident of the southwest. This
species is usually found in grassy undergrowth of juniper or oak-pine
woodlands.
2-124 Northern Bobwhite
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General references
Johnsgard (1988); Lehmann (1984); National Geographic Society (1987); Rosene
(1969); Roseberry and Klimstra (1984); Stoddard (1931).
2-125 Northern Bobwhite
-------
Northern Bobwhite (Colinus virginianus)
Factors
Body Weight
(g)
Body Fat
(% dry weight)
Body Fat
(% dry weight)
(continued)
Age/Sex/
Co nd. /Seas.
A B fall
A B winter
A B spring
A M winter
A M summer
A F winter
A F summer
A M winter
A M summer
A F winter
A F summer
at hatching
day 6
day 10
day 19
day 32
day 43
day 55
day 71
day 88
day 106
J B fall
A M winter
A M spring
A F winter
A F spring
A M winter
A M spring
A F winter
A F spring
Mean
189.9 ± 3.28 SE
193.9 ± 4.56 SE
190.0 ± 4.98 SE
181
163
183
180
161
154
157
157
6.3
9 -10
10-13
20-25
35-45
55-65
75-85
110-120
125-150
140-160
174.0 ± 3.49 SE
15.5 ± 2.8 SD
8.8±3.2SD
13.8 ± 2.7 SD
12.7 ± 2.4 SD
10.2 ± 0.6 SE
7.9±0.2SE
10.6 ± 0.8 SE
9.7±0.3SE
Range or
(95% Cl of mean)
(weight gain:)
(0.5 - 0.75 g/day)
(1.5g/day)
(1.75 g/day)
(1.75 -2.0 g/day)
9.0-11.9
6.5-10.0
8.3-19.9
7.7-11.2
Location or
subspecies
Kansas
Illinois
west Rio Grande, Texas
southwest Georgia/both
captive and wild birds
living in farms, woods,
and thickets
Kansas
Tennessee
southern Texas/captive
Reference
Robel, 1969
Roseberry& Klimstra, 1971
Guthery et al., 1988
Stoddard, 1931
Robel, 1969
McRae & Dimmick, 1982
Koerth & Guthery, 1987
Note
No.
10
o>
o
3-
(D
T
CD
O
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Northern Bobwhite (Colinus virginianus)
Factors
Egg Weight
(grams)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
(kcal/kg-day)
Water
Ingestion Rate
(g/g-day)
Inhalation Rate
(m3/day)
Surface Area
(cm2)
Age/Sex/
Co nd. /Seas.
A F non breed
A F laying
A M basal
A F basal
A M free-living
A F free-living
A B winter
A B spring
A B summer
A B fall
A B winter
A B fall
A B spring
A M summer
A F summer
A M summer
A F summer
A M summer
A F summer
A M summer
A F summer
Mean
9.3±0.3SE
8.6
183.3
243.9
129
125
320
311
0.093 ± 0.0032 SE
0.067 ± 0.0021 SE
0.079 ± 0.0061 SE
0.072 ± 0.0017 SE
587
657
519
0.10 ± 0.023 SD
0.13 ± 0.037 SD
0.11
0.10
0.10
0.11
298
320
Range or
(95% Cl of mean)
8.0-10.2
(151 -677)
(147-659)
Location or
subspecies
Texas
southwest Georgia
Nebraska/captive
southern Texas/captive
Kansas
southern Texas/captive
Reference
Koerth & Guthery, 1991
Stoddard, 1931
Case, 1982
estimated
estimated
Koerth & Guthery, 1990
Robel, 1969
Koerth & Guthery, 1990
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
7
8
10
o
3-
(D
T
CD
O
(D
-------
Northern Bobwhite (Colinus virginianus)
Dietary
Composition
adults:
(total plant foods)
misc. seeds
other seeds:
legumes
senna
cultivated plants
grasses
sedges
mast
spurges
fruits
forage plants
(total animal foods)
grasshoppers
bugs
beetles
adults:
seeds of weeds
seeds of woody
plants
seeds of grasses
cultivated grains, etc.
greens
insects
adults:
seeds of forbs
seeds of grasses
seeds/fruits of
woody plants
unidentified seeds
green vegetation
invertebrates
Spring
(87.2)
21.1
15.2
7.2
2.1
3.1
1.1
14.1
0.1
11.1
12
(12.8)
3.2
2.8
4.6
43.64
4.03
13.2
3.7
27.4
8.03
Summer
(78.7)
6.0
3.9
0.4
2.1
11.3
1.2
0.2
1.2
45.8
0.3
(19.6)
7.5
4.4
6.3
33.7
20.5
24.8
1.9
4.9
14.2
3.5
51.7
9.7
4.6
4.8
25.8
Fall
(79.7)
11.1
10.1
0.2
5.3
26.0
2.4
0.5
5.5
11.3
0.3
(20.3)
16.6
0.6
0.8
30.0
39.7
0.7
8.3
3.4
17.9
19.0
42.9
-
-
1.8
36.2
Winter
(96.8)
2.6
31.5
12.8
2.6
2.3
1.1
28.0
0.4
9.5
5.2
(3.2)
2.4
0.1
0.2
34.3
9.5
7.2
15.4
10.3
23.3
12.0
4.9
1.4
2.3
72.4
6.5
Location/Habitat
(measure)
southeastern United
States/NS
(% volume; crop and gizzard
contents)
south Texas/semi-prairie,
brushland
(% dry volume; crop
contents)
southwest
Texas/grasslands
drought conditions
(% wet volume; crop
contents)
Reference
Handley, 1931
Lehmann, 1984
Campbell-Kissocketal., 1985
Note
No.
10
00
o
3-
(D
T
CD
O
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Northern Bobwhite (Colinus virginianus)
Population
Dynamics
Home Range
Size (ha/bird)
(ha/covey)
Population
Density
(IM/ha)
Clutch Size
Clutches/Year
Days
Incubation
Age/Sex/
Cond./Seas.
summer:
AB
A M mated
A M un mated
A F nesting
A F post-nest
winter:
BB
BB
B B fall
B B spring
B B fall
B B spring
B B fall
B B spring
B B winter
B B winter
B B winter
March
August
Mean
3.6
7.6 ± 5.0 SD
16.7 ± 9.5 SD
6.4 ± 4.0 SD
15.6 ±9.1 SD
6.8±2.9SD
15.4
0.21 ±0.0031 SE
0.10 ± 0.0003 SE
0.63 ± 0.24 SD
0.24 ± 0.05 SD
5.0 ± 0.30 SE
2.2 ±0.21 SE
0.63 ± 0.18 SD
2.25±1.16SD
3.65 ± 2.22 SD
12.9
13.7 ± 3.28 SD
25.0
9.4
1
23
Range or
(95% Cl of mean)
4.0-11.7
12.1 -18.6
0.28 - 0.92
0.18-0.33
0.37 - 0.88
0.6-3.9
1.7-7.6
4-33
6-28
0-3
21 -25
Location/Habitat
Iowa/State game area
south Illinois/idle farms
woods, brush, cornfields
Tennessee/woods, old fields
cultivated fields
south lllinois/NS
south Texas/upland
rangeland
south Illinois/agricultural
south Texas/mixed brush
rangeland
South Carolina/farms,
woods
Florida/pine woods
south Texas/prairie, brush
Illinois/agricultural
southwest Georgia/pine
woods, farms
NS/NS
south Texas/prairie, brush
Reference
Grim & Seitz, 1972
Urban, 1972
Yoho & Dimmick, 1972
Bartholomew, 1967
Guthery, 1988
Roseberry et al., 1979
Guthery, 1988
Rosene, 1969
Smith etal., 1982
Lehmann, 1984
Roseberry & Klimstra, 1984
Simpson, 1976
CKWRI, 1991
Lehmann, 1984
Note
No.
10
o
3-
(D
T
CD
O
-------
Northern Bobwhite (Colinus virginianus)
Population
Dynamics
Percent Nests
Successful
Number Hatch
per
Successful
Nest
Age at Sexual
Maturity
Annual
Mortality Rates
(percent)
Longevity
(months)
Seasonal
Activity
Mating/ Laying
Hatching
Age/Sex/
Cond./Seas.
spring/
summer
March
August
B
B
AM
AF
JM
JF
BB
no hunting
BM
BF
starting:
B November
B October
March
mid -April
April
mid-March
late April
early May
mid-May
Mean
17.5
32.6 ±8.1 SD
12.2
20.0
8.4
8-9 months
16 weeks
78.8 ± 2.47 SE
85.3 ± 2.72 SE
81.8 ± 2.46 SE
87.2±1.68SE
81
52
56
10.6
8.5
Range or
(95% Cl of mean)
15.4-19.0
21.0-52.8
64.7 - 94.8
68.4 - 98.6
73.0 - 93.7
67.9-95.8
End
May -June August
mid-August
mid-May - July September
May - June mid-September
May -August October
mid-June October
June -August early October
Location/Habitat
southwest Georgia/pine
woods, farms
south Illinois/agricultural
south Texas/semiprairie,
brush
southwest Georgia/pine
woods, farms
NS/NS (wild)
South Carolina/lab
Florida/open woods
Illinois/agricultural
Florida/pine woods
Texas/semiprairie, brush
central Missouri/NS
Florida
south Texas
south Illinois
south Texas
sw Georgia, northern Florida
Missouri
south Illinois
Reference
Simpson, 1976
Roseberry & Klimstra, 1984
Lehmann, 1984
Simpson, 1976
Johnsgard, 1988
Jones & Hughes, 1978
Brownie etal., 1985
Roseberry & Klimstra, 1984
Pollock et al., 1989
Lehmann, 1984
Marsden & Baskett, 1958
Bent, 1932
Lehmann, 1984
Roseberry & Klimstra, 1984
Lehmann, 1984
Stoddard, 1931
Stanford, 1972a
Roseberry & Klimstra, 1984
Note
No.
9
Note
No.
CO
o
o
3-
(D
T
CD
O
-------
Northern Bobwhite (Colinus virginianus)
Seasonal
Activity
Molt fall
spring
Begin
August
early February
Peak
September
March -April
End
October
early June
Location
NS
sw Georgia, northern Florida
Reference
Bent, 1932
Stoddard, 1931
Note
No.
10
CO
2
3
4
5
6
7
8
Metabolized energy requirements of farm-raised birds in captivity: (1) 7 weeks prior to laying (mean weight of hens = 194 g) and (2) during laying
(mean weight of hens = 215 g).
Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and summer body weights from Roseberry and Klimstra (1971).
Estimated using equation 3-37 (Nagy, 1987) and summer body weights from Roseberry and Klimstra (1971).
Diet of commercial game food with only 5 to 10 percent water content; maintained at temperature, humidity, and light cycle typical for Texas.
Gross energy intake calculated from the average volume of crop contents in shot birds, assuming a 1.5-hour retention period, 2.30 kcal/cm3 for
the contents, and constant foraging throughout the daylight hours, which is likely to overestimate food intake.
Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Roseberry and Klimstra (1971).
Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Roseberry and Klimstra (1971).
Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Roseberry and
Klimstra (1971).
Expected remaining longevity for those juvenile quail that survived to the month indicated.
o
3-
(D
T
CD
O
(D
-------
References (including Appendix)
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2-132 Northern Bobwhite
-------
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2-133 Northern Bobwhite
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2-134 Northern Bobwhite
-------
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Schroeder, R. L. (1985) Habitat suitability models index: northern bobwhite. U.S. Fish Wildl.
Serv. Biol. Rep. 82(10.104).
Sermons, W. O.; Speake, D. W. (1987) Production of second broods by northern bobwhites.
Wilson Bull. 99: 285-286.
2-135 Northern Bobwhite
-------
Simpson, R. C. (1976) Certain aspects of the bobwhite quails life history in southwest
Georgia. Atlanta, GA: Georgia Dept. Nat. Resour.; Tech. Bull. WL1.
Smith, G. F.; Kellogg, F. I.; Doster, G. L; et al. (1982) A 10-year study of bobwhite quail
movement patterns. Proc. Natl. Bobwhite Quail Symp. 2: 35-44.
Stanford, J. A. (1972a) Bobwhite quail population dynamics: relationships of weather,
nesting, production patterns, fall population characteristics, and harvest in Missouri
quail. Proc. Natl. Bobwhite Quail Symp. 1: 115-139.
Stanford, J. A. (1972b) Second broods in bobwhite quail. Proc. Natl. Bobwhite Quail Symp.
1:21-27.
Stempel, M. E. (1960) Quail hatching and primary feather moult in adults. Proc. Iowa Acad.
Sci. 67:616-621.
Stoddard, H. L. (1931) The bobwhite quail: its habits, preservation and increase. New York,
NY: Charles Scribner's Sons.
Tomlinson, R. E. (1975) Weights and wing lengths of wild Sonoran masked bobwhites
during fall and winter. Wilson Bull. 87: 180-186.
Urban, D. (1972) Aspects of bobwhite quail mobility during spring through fall months.
Proc. Natl. Bobwhite Quail Symp. 1: 194-199.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Wiseman, D. S.; Lewis, J. C. (1981) Bobwhite use of habitat in tallgrass rangeland. Wildl.
Soc. Bull. 9: 248-255.
Wood, K. N.; Guthery, F. S.; Koerth, N. E. (1986) Spring-summer nutrition and condition of
northern bobwhites in south Texas. J. Wildl. Manage. 50: 84-88.
Yoho, N. S.; Dimmick, R. W. (1972) Habitat utilization by bobwhite quail during winter. Proc.
Natl. Bobwhite Quail Symp. 1: 90-99.
2-136 Northern Bobwhite
-------
2.1.10. American Woodcock (woodcock and snipe)
Order Charadriformes, Family Scolopacidae. These inland members of the
sandpiper family have a stocky build, long bill, and short legs. However, their habitats and
diet are distinct. Woodcock inhabit primarily woodlands and abandoned fields, whereas
snipe are found in association with bogs and freshwater wetlands. Both species use their
long bills to probe the substrate for invertebrates. The woodcock and snipe are similar in
length, although the female woodcock weighs almost twice as much as the female snipe.
Selected species
The American woodcock (Scolopax minor) breeds from southern Canada to
Louisiana throughout forested regions of the eastern half of North America. The highest
breeding densities are found in the northern portion of this range, especially in the Great
Lakes area of the United States, northern New England, and southern Canada (Gregg,
1984; Owen et al., 1977). Woodcock winter primarily in the southeastern United States and
are year-round residents in some of these areas. Woodcock are important game animals
over much of their range (Owen et al., 1977).
Body size. Woodcock are large for sandpipers (28 cm bill tip to tail tip), and females
weigh more than males (Keppie and Redmond, 1988). Most young are full grown by 5 to 6
weeks after hatching (Gregg, 1984).
Habitat. Woodcock inhabit both woodlands and abandoned fields, particularly those
with rich and moderately to poorly drained loamy soils, which tend to support abundant
earthworm populations (Cade, 1985; Owen and Galbraith, 1989; Rabe et al., 1983a). In the
spring, males use early successional open areas and woods openings, interspersed with
low brush and grassy vegetation, for singing displays at dawn and dusk (Cade, 1985;
Keppie and Redmond, 1985). Females nest in brushy areas of secondary growth
woodlands near their feeding areas, often near the edge of the woodland or near a break in
the forest canopy (Gregg, 1984). During the summer, both sexes use second growth
hardwood or early successional mixed hardwood and conifer woodlands for diurnal cover
(Cade, 1985). At night, they move into open pastures and early successional abandoned
agricultural fields, including former male singing grounds, to roost (Cade, 1985; Dunford
and Owen, 1973; Krohn, 1970). During the winter, woodcock use bottomland hardwood
forests, hardwood thickets, and upland mixed hardwood and conifer forests during the
day. At night, they use open areas to some degree, but also forested habitats (Cade, 1985).
Diurnal habitat and nocturnal roosting fields need to be in close proximity to be useful for
woodcock (Owen et al., 1977).
Food habits. Woodcocks feed primarily on invertebrates found in moist upland
soils by probing the soil with their long prehensile-tipped bill (Owen et al., 1977; Sperry,
1940). Earthworms are the preferred diet, but when earthworms are not available, other
soil invertebrates are consumed (Miller and Causey, 1985; Sperry, 1940; Stribling and
Doerr, 1985). Some seeds and other plant matter may also be consumed (Sperry, 1940).
Krohn (1970) found that during summer most feeding was done in wooded areas prior to
entering fields at night, but other studies have indicated that a significant amount of food
2-137 American Woodcock
-------
is acquired during nocturnal activities (Britt, 1971, as cited in Dunford and Owen, 1973).
Dyer and Hamilton (1974) found that during the winter in southern Louisiana, woodcock
exhibited three feeding periods: early morning (0100 to 0500 hours) in the nocturnal
habitat, midday (1000 to 1300 hours) in the diurnal habitat, and at dusk (1700 to 2100
hours) again in the nocturnal fields; earthworms and millipedes were consumed in both
habitat types. Most of the woodcocks' metabolic water needs are met by their food
(Mendall and Aldous, 1943, as cited in Cade, 1985), but captive birds have been observed
to drink (Sheldon, 1967). The chicks leave the nest soon after hatching, but are dependent
on the female for food for the first week after hatching (Gregg, 1984).
Molt. Woodcock molt twice annually. The prenuptial molt involves body plumage,
some wing coverts, scapulars, and tertials and occurs in late winter or early spring; the
complete postnuptial molt takes place in July or August (Bent, 1927).
Migration. Fall migration begins in late September and continues through
December, often following the first heavy frost (Sheldon, 1967). The migration may take 4
to 6 weeks (Sheldon, 1967). Some woodcock winter in the south Atlantic region, while
those that breed west of the Appalachian Mountains winter in Louisiana and other Gulf
States (Martin et al., 1969, as cited in Owen et al., 1977). Woodcock are early spring
migrants, leaving their wintering grounds in February and arriving on their northern
breeding grounds in late March to early April (Gregg, 1984; Sheldon, 1967; Owen et al.,
1977). Dates of woodcock arrival at their breeding grounds vary from year to year
depending on the timing of snowmelt (Gregg, 1984). Sheldon (1967) summarizes spring
and fall migration dates by States from numerous studies.
Breeding activities and social organization. From their arrival in the spring, male
woodcock perform daily courtship flights at dawn and at dusk, defending a site on the
singing grounds in order to attract females for mating (Owen et al., 1977; Gregg, 1984).
Often several males display on a single singing ground, with each defending his own
section of the area. Females construct their nests on the ground, usually at the base of a
tree or shrub located in a brushy area adjacent to an opening or male singing ground
(Gregg and Hale, 1977; McAuley et al., 1990; Owen et al., 1977). Females are responsible
for all of the incubation and care of their brood (Trippensee, 1948). The young leave the
nest soon after hatching and can sustain flight by approximately 18 days of age (Gregg,
1984).
Home range and resources. The home range of woodcocks encompasses both
diurnal cover areas and nocturnal roosting areas and varies in size depending on season
and the distribution of feeding sites and suitable cover. During the day, movements are
usually limited until dusk, when woodcock fly to nocturnal roost sites. Hudgins et al.
(1985) and Gregg (1984) found spring and summer diurnal ranges to be only 1 to 10
percent of the total home range. Movement on the nocturnal roost sites also is limited;
however, during winter, woodcock are more likely to feed and move around at night
(Bortner, pers. comm.). Singing males generally restrict their movements more than non-
singing males, juveniles, and females (Owen et al., 1977).
Population density. The annual singing-ground survey conducted by the United
States and Canada provides information on the population trends of woodcock in the
2-138 American Woodcock
-------
northern states and Canada during the breeding season (note from B. Bortner, U.S. Fish
and Wildlife Service, Office of Migrating Bird Management, to Susan Norton, January 9,
1992). Gregg (1984) summarized results of several published singing-ground surveys and
found estimates to vary from 1.7 male singing grounds per 100 ha in Minnesota (Godfrey,
1974, cited in Gregg, 1984) to 10.4 male singing grounds per 100 ha in Maine (Mendall and
Aldous, 1943, cited in Gregg, 1984). Although this method is appropriate for assessing
population trends, flushing surveys, telemetry, and mark-recapture are better methods for
estimating woodcock densities because there are variable numbers of females and
nonsinging males associated with active singing grounds (Dilworth, Krohn, Riffenberger,
and Whitcomb pers. comm., cited by Owen et al., 1977). For example, Dwyer et al. (1988)
found 2.2 singing males per 100 ha in a wildlife refuge in Maine, but with mark-recapture
techniques, they found yearly summer densities of 19 to 25 birds per 100 ha in the same
area.
Population dynamics. Woodcocks attempt to raise only a single brood in a given
year but may renest if the initial clutch is destroyed (McAuley et al., 1990; Sheldon, 1967).
In 12 years of study in Wisconsin, Gregg (1984) found 42 percent of all nests to be lost to
predators and another 11 percent lost to other causes. Survival of juveniles in their first
year ranges from 20 to 40 percent, and survival of adults ranges from 35 to 40 percent for
males to approximately 40 to 50 percent for females (Dwyer and Nichols, 1982; Krohn et al.,
1974). Derleth and Sepik (1990) found high adult survival rates (0.88 to 0.90 for both sexes)
between June and October in Maine, indicating that adult mortality may occur primarily in
the winter and early spring. They found lower summer survival rates for young woodcock
between fledging and migration than for adults during the same months, with most losses
of young attributed to predation.
Similar species (from general references)
• The common snipe (Gallinago gallinago) is similar in length (27 cm) to the
woodcock, although lighter in weight. Snipe are primarily found in
association with bogs and freshwater wetlands and feed on the various
invertebrates associated with wetland soils. Snipe breed primarily in boreal
forest regions and thus are found slightly north of the woodcock breeding
range, with some areas of overlap in the eastern half of the continent. The
breeding range of the snipe, however, extends westward to the Pacific coast
and throughout most of Alaska, thus occupying a more extensive east-west
range than the woodcock.
General references
Cade (1985); Dwyer et al. (1979); Dwyer and Storm (1982); Gregg (1984); National
Geographic Society (1987); Owen et al. (1977); Sheldon (1967); Trippensee (1948).
2-139 American Woodcock
-------
American Woodcock (Scolopax mi not)
Factors
Body Weight
(g)
Egg Weight (g)
Chick Growth
Rate (g/day)
Metabolic Rate
(kcal/kg-day)
Age/Sex/
Cond./Seas.
AM
AF
A M April
A M May
A M June
A M summer
J M summer
A F summer
J F summer
A M fall
J M fall
A F fall
J F fall
at hatching
at laying
near hatching
M
F
A F basal
A M basal
A F basal
A F free-living
A F nesting
A M free-living
A F free-living
Mean
176
218
134.6 ± 2.9 SE
133.8 ± 5.8 SE
151.2 ± 9.5 SE
145.9
140.4
182.9
168.8
169
164
213
212
13.0
18-19
14-16
5.1
6.2
115
126
118
315
553
313
296
Range or
(95% Cl of
mean)
127-165
117-152
162-216
151 -192
9-16
(148-662)
(140-627)
Location
throughout range
Maine
central Massachusetts
Minnesota
Wisconsin
Wisconsin
Maine
s Michigan
s Michigan
Reference
Nelson & Martin, 1953
Dwyeretal., 1988
Sheldon, 1967
Marshall (unpubl.)
Gregg, 1984
Gregg, 1984
Dwyeretal., 1982
Rabeetal., 1983b
estimated
Rabeetal., 1983b
estimated
Note
No.
1
2
3
4
5
10
*».
O
(D
T
o'
0)
3
O
O
Q.
O
O
O
-------
American Woodcock (Scolopax mi not)
Factors
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
A B winter
(earthworm
diet)
AM
AF
AM
AF
AM
AF
Dietary
Composition
earthworms
Diptera
Coleoptera
Lepidoptera
other animals
plants
earthworms
beetle larvae
grit (inorganic)
other organic
earthworms
other invertebrates
earthworms
Coleoptera
Hymenoptera
Mean
0.77
0.10
0.10
0.11
0.13
314
362
Summer
67.8
6.9
6.2
3.3
5.3
10.5
58
10
31
1
Range or
(95% Cl of
mean)
0.11 -1.43
Fall
Winter
99+
<1
87
11
2
Location
Louisiana (captive)
Location/Habitat
(measure)
North America/NS
(% volume; stomach
contents)
Maine/fields
(% wet weight; mouth
esophagus, stomach, &
proventriculus contents)
N Carolina/soybean fields
(% wet weight; digestive
tract)
Alabama/NS
(% volume; esophagus
contents)
Reference
Stickel et al., 1965
estimated
estimated
estimated
Reference
Sperry, 1940
Krohn, 1970
Stribling & Doerr, 1985
Miller & Causey, 1985
Note
No.
6
7
8
Note
No.
9
10
10
(D
T
o'
0)
3
O
O
Q.
O
O
O
-------
American Woodcock (Scolopax mi not)
Population
Dynamics
Home Range
Size (ha)
Population
Density
(birds/ha)
Clutch
Size
Clutches/
Year
Percent Nests
Hatching
Days
Incubation
Age at
Fledging
Age/Sex
Cond./Seas.
A M inactive
A M active
A M singing
B B summer
A F with
brood
B B winter
B B winter
B B winter
nests in
spring
A M summer
A F summer
J B summer
B B summer
1st clutch
2nd clutch
Mean
3.1 (median)
73.6 (median)
10.5 (median)
32.4 ± 27.6 SD
4.5
3.38
0.20
0.034
0.21 (nests/ha)
0.035
0.056
0.125
0.223
4
3.8 ± 0.42 SD
3.0 ± 0.67 SD
1 but renest if 1st
lost
about 50
19-21
18 -19 days
Range
0.3-6.0
38.2-171.2
4.6 - 24.1
7-98
0.026 - 0.046
0.037 - 0.074
0.108-0.143
0.190-0.250
3-5
Location/Habitat
Pennsylvania/mixed forests
with shrubs and fields
Wisconsin/woods, open
areas, brush
North Carolina/agricultural:
unfilled soy stubble
unfilled corn stubble
rebedded corn fields
Pennsylvania/mixed pine
and
hardwoods, open fields
Maine/second growth forest,
meadows, and ponds
throughout range and
habitats
Maine/mixed forests,
agricultural fields
throughout range and
habitats
Maine/mixed forests, fields
NS/NS
Wisconsin/woods, open
areas, brush
Reference
Hudgins etal., 1985
Gregg, 1984
Connors & Doerr, 1982
Coon etal., 1982
Dwyeretal., 1988
Bent, 1927
McAuley etal., 1990
McAuley etal., 1990
McAuley etal., 1990
Mendall & Aldous, 1943;
Pettingill, 1936
Gregg, 1984
Note
No.
11
10
*».
10
(D
T
o'
0)
3
O
O
Q.
O
O
O
-------
American Woodcock (Scolopax mi not)
Population
Dynamics
Age at
Sexual
Maturity
Annual
Mortality
Rates
Seasonal
Activity
Mating/Laying
Hatching
Molt
Migration
spring
fall
Age/Sex
Cond./Seas.
M
F
A M east
A M central
J M east
J M central
A F east
A F central
J F east
J F central
early February
early April
early February
late February
late March
mid-April
mid-February
March
October
late
September
Mean
< 1 year
1 year
65 ± 5.2 SD
60±15SD
80 ± 4.8 SD
64±12SD
51 ±7.3SD
47 ± 9.6 SD
64 ± 7.7 SD
69 ± 9.4 SD
early May
mid-May
August to
early
September
April
Range
End
mid-March
early June
early March
December
mid-December
Location/Habitat
throughout range and
habitats
eastern and central United
States/NS
Texas
Maine
Louisiana
Virginia
Connecticut
Massachusetts
Maine
NS/NS
leaving North Carolina
arriving in northern range
arriving North Carolina
leaving Canada
Reference
Sheldon, 1967
Dwyer& Nichols, 1982
Reference
Whiting & Boggus, 1982
Dwyeretal., 1982
Pettingill, 1936
Pettingill, 1936
Pettingill, 1936
Sheldon, 1967
Dwyeretal., 1982
Owen & Krohn, 1973
Connors & Doerr, 1982
Gregg, 1984
Sheldon, 1967
Owen etal., 1977
Note
No.
Note
No.
1
1
1
12
10
*».
CO
(D
T
o'
0)
3
O
O
Q.
O
O
O
-------
American Woodcock (Scolopax mi not)
1 As cited in Sheldon (1967).
2 Metabolic rate estimated by authors from equation of Aschoff and Pohl (1970).
3 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and summer body weights from Nelson and Martin (1953).
4 Estimate of free-living metabolism based on energy budget model. Metabolism during nesting estimated for peak needs during egg-laying.
5 Estimated using equation 3-37 (Nagy, 1987) and summer body weights from Nelson and Martin (1953).
6 Estimated using equation 3-15 (Calder and Braun, 1983) and summer body weights from Nelson and Martin (1953).
7 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and summer body weights from Nelson and Martin (1953).
8 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and summer body weights from Nelson and
Martin (1953).
9 Grit comprised only 14 percent of total digestive tract contents volume.
10 Should provide a more accurate estimate of proportion of soft-bodied earthworms consumed than would including other portions of the digestive
tract.
11 Cited in Trippensee (1948).
12 Cited in Owen et al. (1977).
10
I
(D
T
o'
0)
3
O
O
Q.
O
O
O
-------
References (including Appendix)
Aldous, C. M. (1938) Woodcock management studies in Maine 1937. Trans. North Am.
Wildl. Nat. Resour. Conf. 3: 839-846.
Aschoff, J.; Pohl, H. (1970) Rhythmic variations in energy metabolism. Fed. Proc. 29:
1541-1552.
Bent, A. C. (1927) Life histories of North American shore birds. Part 1. Washington, DC:
U.S. Government Printing Office; Smithsonian Inst. U.S. Nat. Mus., Bull. 142.
Britt, T. L. (1971) Studies of woodcock on the Louisiana wintering ground [master's thesis].
Shreveport, LA: Louisiana State University.
Cade, B. S. (1985) Habitat suitability index models: American woodcock (wintering). U.S.
Fish Wildl. Serv. Biol. Rep. 82(10.105).
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Connors, J. I.; Doerr, P. D. (1982) Woodcock use of agricultural fields in coastal North
Carolina. In: Dwyer, T. J.; Storm, G. W., tech. coords. Woodcock ecology and
management. U.S. Fish Wildl. Serv., Wildl. Res. Rep. 14; pp. 139-147.
Coon, R. A.; Williams, B. K.; Lindzey, J. S.; et al. (1982) Examination of woodcock nest sites
in central Pennsylvania. U.S. Fish Wildl. Serv., Wildl. Res. Rep. 14; pp. 55-62.
Derleth, E. L.; Sepik, G. F. (1990) Summer-fall survival of the American woodcock in Maine.
J. Wildl. Manage. 54: 97-106.
Dunford, R. D.; Owen, R. B. (1973) Summer behavior of immature radio-equipped woodcock
in central Maine. J. Wildl. Manage. 37: 462-469.
Dwyer, T. J.; Nichols, J. D. (1982) Regional population inferences for the American
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management. U.S. Fish Wildl. Serv., Wildl. Res. Rep. 14; pp. 12-21.
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-------
Dwyer, T. J.; Sepik, G. F.; Derleth, E. L.; et al. (1988) Demographic characteristics of Maine
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2-146 American Woodcock
-------
Martin, F. W.; Williams, S. O.; Newsom, J. D.; et al. (1969) Analysis of records of
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Mendall, H. L.; Aldous, C. M. (1943) The ecology and management of the American
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woodcock. Wilson Bull. 85: 31-41.
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Owen, R. B.; Anderson, J. M.; Artmann, J. W.; et al. (1977) American woodcock. In:
Sanderson, G. C., ed. Management of migratory shore and upland game birds in
North America. Washington, DC: Int. Assoc. Fish Wildl. Agencies; pp. 147-175.
Pettingill, O. S., Jr. (1936) The American woodcock. Boston Soc. Nat. Hist. Mem. 9(2).
Rabe, D. L.; Prince, H. H.; Beaver, D. L. (1983a) Feeding-site selection and foraging
strategies of American woodcock. Auk 100: 711-716.
Rabe, D. L.; Prince, H. H.; Goodman, E. D. (1983b) The effect of weather on bioenergetics of
breeding American woodcock. J. Wildl. Manage. 47: 762-771.
2-147 American Woodcock
-------
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Sheldon, W. G. (1967) The book of the American woodcock. Amherst, MA: University of
Massachusetts Press.
Sperry, C. (1940) Food habits of a group of shore birds; woodcock, snipe, knot, and
dowitcher. U.S. Dept. Int., Bur. Biol. Survey, Wildl. Res. Bull. 1; 37 pp.
Stickel, W. H.; Hayne, D. W.; Stickel, L. F. (1965) Effects of heptachlor-contaminated
earthworms on woodcocks. J. Wildl. Manage. 29: 132-146.
Stribling, H. L.; Doerr, P. D. (1985) Nocturnal use of fields by American woodcock. J. Wildl.
Manage. 49: 485-491.
Trippensee, R. E. (1948) American woodcock. Wildlife management. New York, NY:
McGraw-Hill; pp. 323-332.
Tufts, R. W. (1940) Some studies in bill measurements and body weights of American
woodcock (Philohela minor). Can. Field-Nat. 54: 132-134.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Wetherbee, D. K.; Wetherbee, N. S. (1961) Artificial incubation of eggs of various bird
species and some attributes of neonates. Bird Banding 32: 141-159.
Whiting, R. M.; Boggus, T. G. (1982) Breeding biology of American woodcock in east Texas.
In: Dwyer, T. J.; Storm, G. W., tech. coords. Woodcock ecology and management.
U.S. Fish Wildl. Serv., Wildl. Res. Rep. 14; pp. 132-138.
2-148 American Woodcock
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2.1.11. Spotted Sandpiper (sandpipers)
Order Charadriiformes, Family Scolopacidae. The family Scolopacidae includes
numerous species of shorebirds, e.g., sandpipers, tattlers, knots, godwits, curlews,
yellowlegs, willets, and dowitchers. Those known as sandpipers tend to be small with
moderately long legs and bills. Most sandpipers forage on sandy beaches and mudflats; a
few utilize upland areas. They feed almost exclusively on small invertebrates, either by
probing into or gleaning from the substrate. Most species are highly migratory, breeding in
arctic and subarctic regions and either wintering along the coasts or in southern latitudes
and the southern hemisphere; therefore, many are only passage migrants throughout most
of the United States. Scolapids range in size from the least sandpiper (11.5 cm bill tip to
tail tip) to the long-billed curlew (48 cm).
Selected species
The spotted sandpiper (Actitis macularia) (19 cm) is a very common summer
resident of freshwater and saltwater bodies throughout most of the United States. These
sandpipers are most often encountered singly but may form small flocks. Most winter in
the neotropics.
Body size. Females (approximately 50 g) are significantly larger than males
(approximately 40 g) (Oring and Lank, 1986).
Habitat. Spotted sandpipers breed along the edges of bodies of water, usually in
open habitats, from the northern border of the boreal forest across North America, south to
the central United States (Oring and Lank, 1986). They require open water for bathing and
drinking, semi-open habitat for nesting, and dense vegetation for breeding (Bent, 1929;
Oring et al., 1983).
Food habits. In coastal areas, spotted sandpipers search the beach and muddy
edges of inlets and creeks, wading less frequently than most sandpipers; inland they feed
along the shores of sandy ponds and all types of streams, sometimes straying into
meadows, fields, and gardens in agricultural areas (Bent, 1929). Their diet is composed
primarily of terrestrial and marine insects (Bent, 1929). While adult flying insects comprise
the bulk of the diet, crustaceans, leeches, molluscs, small fish, and carrion also are eaten
(Oring et al., 1983). Young feed themselves immediately after hatching, concentrating on
small invertebrates (Oring and Lank, 1986). During insect outbreaks, sandpipers will
forage in wooded areas near water, and they have been observed eating eggs and fish on
occasion (Oring, pers. obs.).
Molt. Partial prenuptial molt of body plumage occurs in March and April, while the
postnuptial molt begins by August with the body feathers and ends anywhere from October
to April with the loss of the primary flight feathers (Bent, 1929).
Migration. Spotted sandpipers generally migrate in small flocks or solitarily
(National Geographic Society, 1987). They winter from southern United States to northern
Chile, Argentina, and Uraguay (Oring and Lank, 1986), and breed across North
2-149 Spotted Sandpiper
-------
America, north from Virginia and southern California (National Geographic Society, 1987).
In the spring, females arrive at the breeding grounds earlier than males (in one study, by
about 2 weeks; Oring and Lank, 1982).
Breeding activities and social organization. The primary consideration for nesting
sites is proximity to water, and spotted sandpipers have been known to build their ground
nests in such diverse conditions as depressions in volcanic rock and strawberry patches
(Bent, 1929). Spotted sandpipers are polyandrous (i.e., a single female lays eggs for
multiple males), with males supplying most of the incubation and parental care (Oring,
1982). Thus reproduction is limited by the number of males present (Lank et al., 1985).
Spotted sandpipers lay a determinate clutch of four eggs. Females may lay several
clutches in a year, often a dozen eggs per season (Maxson and Oring, 1980). Egg laying
begins between late May and early June in Minnesota (Lank et al., 1985), and males
incubate after the third egg is laid (Oring et al., 1986). Females sometimes incubate and
brood when another male is not available (Maxson and Oring, 1980). Parents brood small
chicks and protect them with warning calls or by distracting or attacking predators (Oring
and Lank, 1986).
Home range and resources. Although a variety of vegetation types are used, nests
usually are placed in semi-open vegetation near the edge of a lake, river, or ocean (Oring et
al., unpubl., as cited in Oring et al., 1983; McVey, pers. obs.). The suitability of nesting
habitat varies from year to year in some locations due to levels of precipitation and
predators (Oring et al., 1983).
Population density. Spotted sandpiper nesting densities have been studied well at
only one location, on Little Pelican Island, Leech Lake, Minnesota. At this location,
densities ranged from 4 to 13 females per hectare and 7 to 20 males per hectare over a 10-
year period, depending on weather and other conditions (Oring et al., 1983).
Population dynamics. Females may lay one to six clutches for different males over
one season (Oring et al., 1984), averaging 1.3 to 2.7 mates per year (Oring et al., 1991b).
Female mating and reproductive success increase with age, but male success does not
(Oring et al., 1991b). Lifetime reproductive success is most affected by fledging success
and longevity for both males and females (Oring et al., 1991a).
Similar species (from general references)
• The solitary sandpiper (Tringa solitaria) is usually seen singly in freshwater
swamps or rivers. Present over much of the United States during annual
migrations, this average-sized sandpiper (18 cm) winters along the southeast
and Gulf coasts.
• The western sandpiper (Calidris mauri) is a small sandpiper (13 cm),
common on mudflats and sandbars, that winters on both the Atlantic and
Pacific shores of the United States.
2-150 Spotted Sandpiper
-------
• The least sandpiper (Calidris minutilla), the smallest of this group (11 cm), is
common in winter on salt marshes and muddy shores of rivers and estuaries
in coastal areas across the United States.
• The semipalmated sandpipers (Calidris pusilla) are small birds (13 cm) seen
in the United States primarily during migration and rarely wintering on
Florida coasts.
• Most other members of the family Scolopacidae forage by gleaning.
General references
Oring and Lank (1986); Lank et al. (1985); National Geographic Society (1987); Oring
etal. (1991a, 1991b).
2-151 Spotted Sandpiper
-------
Spotted Sandpiper (Actitis macularia)
Factors
Body Weight
(g)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
A F spring
A M spring
A F pre-breed
A F laying
AF
incubating
A M pre-breed
AM
incubating
A M brooding
A F free-living
A M free-living
AF
AM
AF
AM
AF
AM
Mean
47.1
37.9
404 - 787
383 - 745
368
440
303
425
436
460
0.16
0.17
0.039
0.033
131
113
Dietary
Composition Spring Summer
mayflies /
midges /
Population
Dynamics
Territory
Size (ha)
Age/Sex
Cond./Seas.
Range or
(95% Cl of mean)
43-50
34-41
(202 - 937)
(213-994)
Fall Winter
Mean Range
approx. 0.25
Location
Minnesota island
Minnesota
Location/Habitat
(measure)
Minnesota/island in lake
Reference
Maxson & Oring, 1980
Maxson & Oring, 1980
estimated
estimated
estimated
estimated
Reference
Maxson & Oring, 1980
Location/Habitat Reference
NS/NS Maxson & Oring, 1980
Note
No.
1
2
3
4
5
6
Note
No.
Note
No.
tJl
10
CO
TS
o
CO
0)
3
Q.
•o
•5'
(D
-------
Spotted Sandpiper (Actitis macularia)
Population
Dynamics
Population
Density (N/ha)
Clutch Size
Clutches/Year
Days
Incubation
Age at
Fledging
Number
Fledge per
Nest That
Hatches
Number
Fledge per
Successful
Nest
Age at
Sexual
Maturity
Annual
Mortality
Rates (percent)
Longevity
Seasonal
Activity
Mating
Hatching
Age/Sex
Cond./Seas.
A F summer
A M summer
F
M
F
M
AF
early May
early June
Mean
10
13.9
4
18 to 24
approximately
18 days
1.83
2.58
1 year
1 year
approx. 31
approx. 30
3.7 years
late May - early
June
late June
Range
3.8-12.5
7.5-20.0
3-5
1 -6
0.58 - 2.76
1.67-2.91
End
Location/Habitat
Minnesota/island in lake
NS/NS
Minnesota/NS
NS/NS
NS/NS
Minnesota/island in lake
Minnesota/island in lake
Minnesota/island in lake
Minnesota/island in lake
Minnesota/island in lake
Reference
Oring etal., 1983
Bent, 1929; Oring etal., 1983
Oring etal., 1983
Oring, unpublished
Oring etal., 1991a
Oring etal., 1984
Oring etal., 1984
Oring etal., 1983
Oring et al., 1983; Oring &
Lank, 1982; Oring,
unpublished
Oring etal., 1983
Minnesota Lank et al., 1985
Minnesota Lank et al., 1985
Note
No.
7
Note
No.
tJl
CO
CO
-o
o
CO
0)
3
Q.
•o
•5'
(D
-------
Spotted Sandpiper (Actitis macularia)
Seasonal
Activity
Molt fall
spring
Begin
August
late June
early July
Peak
March -April
early - mid-July
mid-July
End
October
Location
NS
Minnesota
Reference
Bent, 1929
Bent, 1929
Lank etal., 1985
Note
No.
10
1 Estimated by authors; allometric model not specified.
2 Estimated using equation 3-37 (Nagy, 1987) and body weights from Maxson and Oring (1980).
3 See Chapters 3 and 4 for methods of estimating food ingestion rates; also see Section 4.1.3 and Table 4-4 for sediment ingestion rates for
sandpipers.
4 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Maxson and Oring (1980).
5 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Maxson and Oring (1980).
6 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Maxson and Oring
(1980).
7 Spotted sandpipers are determinate layers, with a clutch size of four eggs. Clutches with fewer eggs are not complete or have lost eggs; larger
clutches are the result of more than one female laying in a nest.
CO
-o
o
CO
0)
3
Q.
•
(D
-------
References (including Appendix)
Bent, A. C. (1929) Life histories of North American shore birds. Part 2. Washington, DC:
U.S. Government Printing Office; Smithsonian Inst. U.S. Nat. Mus., Bull. 146.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Dunning, J. B., Jr. (1984) Body weights of 686 species of North American birds. Western
Bird Banding Association, Monograph No. 1. Cave Creek, AZ: Eldon Publishing.
Kuenzel, W. J.; Wiegert, R. G. (1973) Energetics of a spotted sandpiper feeding on brine fly
larvae (Paracoenia; Diptera: Ephydridae) in a thermal spring community. Wilson
Bull. 85: 473-476.
Lank, D. B.; Oring, L. W.; Maxson, S. J. (1985) Mate and nutrient limitation of egg-laying in a
polyandrous shorebird. Ecology 66: 1513-1524.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
Maxson, S. J.; Oring, L. W. (1980) Breeding season time and energy budgets of the
polyandrous spotted sandpiper. Behaviour 74: 200-263.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Oring, L. W. (1982) Avian mating systems. In: Farner, D. S.; King, J. R., eds. Avian biology,
v. 6. New York, NY: Academic Press; pp. 1-92.
Oring, L. W.; Lank, D. B. (1982) Sexual selection, arrival times, philopatry and site fidelity in
the polyandrous spotted sandpiper. Behav. Ecol. Sociobiol. 10: 185-191.
Oring, L. W.; Lank, D. B. (1986) Polyandry in spotted sandpipers: the impact of environment
and experience. In: Rubenstein, D. I.; Wrangham, R. W., eds. Ecological aspects of
social evolution - birds and mammals; pp. 21-42.
Oring, L. W.; Lank, D. B.; Maxson, S. J. (1983) Population studies of the polyandrous
spotted sandpiper. Auk 100: 272-285.
Oring, L. W.; Lank, D. B.; Maxson, S. J. (1984) Mate and nutrient limitation of breeding in
the polyandrous spotted sandpiper (abstract only). Am. Zool. 24: 60A.
2-155 Spotted Sandpiper
-------
Oring, L. W.; Fivizzani, A. J.; Halawani, M. E. (1986) Changes in plasma prolactin associated
with laying and hatch in the spotted sandpiper. Auk 103: 820-822.
Oring, L.W.; Colwell, M.A.; Reed, J.M. (1991a) Lifetime reproductive success in the spotted
sandpiper (Actitis macularia): sex differences and variance components. Behav.
Ecol. Sociobiol. 28: 425-432.
Oring, L.W.; Reed, J.M.; Colwell, M.A.; et al. (1991b) Factors regulating annual mating
success and reproductive success in spotted sandpipers (Actitis macularia). Behav.
Ecol. Sociobiol. 28: 433-442.
Palmer, R. S. (1949) Maine birds. Bull. Mus. Comp. Zool. Harvard No. 102.
Poole, E. L. (1938) Weights and wing areas in North American birds. Auk 55: 511-517.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Walsberg, G. E.; King, J.R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Zar, J. H. (1968) Standard metabolism comparisons between orders of birds. Condor 10:
278.
2-156 Spotted Sandpiper
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2.1.12. Herring Gull (gulls)
Order Charadriiformes, Family Laridae. Gulls are medium- to large-sized sea birds
with long pointed wings, a stout, slightly hooked bill, and webbed feet. They are abundant
in temperate coastal areas and throughout the Great Lakes. Although gulls may feed from
garbage dumps and landfills, most take natural prey. Gulls nest primarily in colonies,
although some of the larger species also nest solitarily. Many populations migrate
annually between breeding and wintering areas. North American gull species range in size
from Bonaparte's gull (33 cm bill tip to tail tip) to the great black-backed gull (76 cm).
Selected species
The herring gull (Larus argentatus) (64 cm) has the largest range of any North
American gull, from Newfoundland south to the Chesapeake Bay along the north Atlantic
and west throughout the Great Lakes into Alaska. Along the Pacific coast, the similar-sized
western gull (L. occidentalis) is the ecological equivalent of the herring gull. Both species
take primarily natural foods, especially fish, although some individuals of both species
forage around fishing operations and landfills (Pierotti, 1981, 1987; Pierotti and Annett,
1987). The increase in number of herring gulls in this century has been attributed to the
increasing abundance of year-round food supplies found in landfills (Drury, 1965; Harris,
1970); however, birds specializing on garbage have such low reproductive success that
they cannot replace themselves in the population (Pierotti and Annett, 1987, 1991). An
alternative explanation of the species' expansion is that cessation of taking of gulls by the
feather industry in the late 1800's has allowed gull numbers to return to pre-exploitation
levels (Graham, 1975).
Body size. Adult females (800 to 1,000 g) are significantly smaller than males (1,000
to 1,300 g) in both the herring gull (Greig et al., 1985) and the western gull (Pierotti, 1981).
Chicks grow from their hatching weight of about 60 to 70 g to 800 to 900 g within 30 to 40
days, after which time their weight stabilizes (Dunn and Brisbin, 1980; Norstrom et al.,
1986; Pierotti, 1982). Norstrom et al. (1986) fitted chick growth rates to the Gompertz
equation as follows:
BW = 997 e-e(-°088(t'14 8)) for females, and
BW = 1193 e-e(-°075(t -16-3)) for males,
where BW equals body weight in grams and t equals days after hatching. Adults show
seasonal variation in body weight (Coulson et al., 1983; Norstrom et al., 1986).
Habitat. Nesting colonies of herring gulls along the northeastern coast of the United
States are found primarily on sandy or rocky offshore or barrier beach islands (Kadlec and
Drury, 1968). In the Great Lakes, they are found on the more remote, secluded, and
protected islands and shorelines of the lakes and their connecting rivers (Weseloh, 1989).
Smaller colonies or isolated pairs also can be found in coastal marshes (Burger, 1980a),
peninsulas, or cliffs along seacoasts, lakes, and rivers (Weseloh, 1989), and occasionally in
inland areas or on buildings or piers (Harris, 1964). Gulls are the most abundant seabirds
2-157 Herring Gull
-------
offshore from fall through spring, and are only found predominantly inshore during the
breeding season in late spring and summer (Powers, 1983; Pierotti, 1988). Gulls forage
predominantly offshore, within 1 to 5 km of the coast (Pierotti, 1988). In all seasons the
number of birds feeding at sea outnumber those feeding inshore (data from Powers, 1983;
Pierotti, pers. comm.). Inshore, herring gulls forage primarily in intertidal zones but also
search for food in wet fields, around lakes, bays, and rock jetties, and at landfills in some
areas (Burger, 1988). In Florida, herring gull presence at landfills is restricted to the winter
months (December through April) and may consist primarily of first-year birds that
migrated from more northerly populations (e.g., from the Great Lakes) (Patton, 1988).
Food habits. Gulls feed on a variety of foods depending on availability, including
fish, squid, Crustacea, molluscs, worms, insects, small mammals and birds, duck and gull
eggs and chicks, and garbage (Bourget, 1973; Burger, 1979a; Fox et al., 1990; Pierotti and
Annett, 1987). Gulls forage on open water by aerial dipping and shallow diving around
concentrations of prey. At sea, such concentrations often are associated with whales or
dolphins, other seabirds, or fishing boats (McCleery and Sibly, 1986; Pierotti, 1988). In the
Great Lakes, concentrations of species such as alewife occur seasonally (e.g., when
spawning) (Fox et al., 1990). Gulls also forage by stealing food from other birds and by
scavenging around human refuse sites (e.g., garbage dumps, fish plants, docks, and
seaside parks) (Burger and Gochfeld, 1981; 1983; Chapman and Parker, 1985). Individual
pairs of gulls may specialize predominantly on a single type of food; for example, three
quarters of a population of herring gulls in Newfoundland were found to specialize either
on blue mussels, garbage, or adults of Leach's storm-petrel, with 60 percent of the
specialists concentrating on mussels between 0.5 and 3 cm in length (Pierotti and Annett,
1987; 1991). Diet choices may change with the age and experience of adult birds as well as
with availability of prey (Pierotti and Annett, 1987; 1991). Females take smaller prey and
feed less on garbage than do males (Pierotti, 1981; Greig et al., 1985). For example, Fox et
al. (1990) found females to feed more on smelt (100 to 250 mm) and males more on alewife
(250 to 300 mm) in the Great Lakes region. Adult gulls sometimes attack and eat chicks of
neighboring gulls or other species of seabird (Brown, 1967; Schoen and Morris, 1984).
Juveniles up to 3 years of age forage less efficiently than adults (Greig et al., 1983;
MacLean, 1986; Verbeek, 1977). In the Great Lakes, herring gulls' high consumption of
alewife during their spawn may result in high exposures of the gulls to lipophilic
contaminants that biomagnify (Fox et al., 1990).
Metabolism. Norstrom et al. (1986) have estimated an annual energy budget for
free-living female herring gulls that breed in the Great Lakes and an annual energy budget
for free-living juvenile herring gulls in the Great Lakes in their first year. Between
September and March, the nonbreeding season, they estimate that adult females require
250 to 260 kcal/day. Following a dip in energy requirements to 210 kcal/day when the male
feeds the female during courtship, the female's needs increase to peak at 280 kcal/day for
egg production, then fall to approximately 210 kcal/day during incubation. The energy
required to forage for food for the chicks is substantial, rising through July to peak in
August at 310 to 320 kcal/day, then declining again until September when feeding chicks
has ceased. These estimates compare well with those derived from Nagy's (1987) equation
to estimate free-living metabolic rates for seabirds, except that the energy peaks required
to produce eggs and to feed chicks are not included in Nagy's model. Readers interested
in the metabolic rates of first-year herring gulls are referred to Norstrom et al. (1986). Ellis
2-158 Herring Gull
-------
(1984) provides an overview of seabird energetics and additional discussion of approaches
and models for estimating metabolic rates of free-ranging seabirds.
Molt. Gull chicks are downy gray with dark brown spotting and molt into a dark-
gray or brown mottled juvenile plumage. At the end of the first year, portions of the
plumage have paled, and by the second year, gray plumage develops along the back and
top of wings. By their third year, young gulls resemble dirty adults, and they acquire their
full adult plumage by 4 years (Harrison, 1983; Kadlec and Drury, 1968). Adult gulls, at least
in some populations, begin their primary feather molt during incubation and complete the
molt by mid- to late fall (Coulson et al., 1983). They molt and replace the large body
feathers from mid-summer to early fall (Coulson et al., 1983).
Migration. Herring gull populations along the northeast coast of North America tend
to be migratory, while adult herring gulls of the Great Lakes are year-round residents.
Along the western North Atlantic, most herring gulls arrive on their breeding grounds
between late February and late April. They remain until late August or early September
when they leave for their wintering grounds along the Atlantic and Gulf coasts or well
offshore (Burger, 1982; Pierotti, 1988). Adult and older subadult herring gulls in the Great
Lakes area are essentially nonmigratory (Mineau et al., 1984; Weseloh et al., 1990). Thus,
in contrast to other fish-eating birds in the Great Lakes system that migrate south in the
winter, herring gulls are exposed to any contaminants that may be in Great Lakes' fish
throughout the year (Mineau et al., 1984). Postbreeding dispersal away from breeding
colonies begins in late July and ends in August, with all ages traveling short distances.
Great Lakes herring gulls less than a year old usually migrate to the Gulf or Atlantic coast
(Smith, 1959; Mineau et al., 1984), traveling along river systems and the coast (Moore,
1976).
Breeding activities and social organization. Gulls nest primarily in colonies on
offshore islands, and nest density is strongly affected by population size (Pierotti, 1981;
1982; 1987). Typically, males arrive at the breeding grounds first and establish territories.
Both sexes build the nest of vegetation on the ground in areas that are sheltered from wind
but may be exposed to the sun (Pierotti, 1981; 1982). Males feed females for 10 to 15 days
prior to the start of egg laying (Pierotti, 1981). From the laying of the first egg until the
chicks are 3 to 4 weeks old, one or both parents will be present at all times (Tinbergen,
1960). Males perform most territorial defense, females perform most incubation, and both
parents feed the chicks until they are at least 6 to 7 weeks old (Burger, 1981; Pierotti, 1981;
Tinbergen, 1960). All gulls are strongly monogamous; pair bonds can persist for 10 or
more years and usually only are terminated by the death of a mate or failure to reproduce
successfully (Tinbergen, 1960). Males may be promiscuous in populations with more
females than males (Pierotti, 1981). Herring gull colonies often are found in association
with colonies of other species, including other gulls (Bourget, 1973; Brown, 1967). In some
nesting colonies, gulls attack chicks of neighboring gulls and other species (Brown, 1967;
Schoen and Morris, 1984).
Home range and resources. During the breeding season, herring gulls defend a
territory of several tens of square meters around the immediate vicinity of the nest (Burger,
1980b). Their daily foraging range depends on the availability of prey and on the foraging
strategy, age, and sex of the gull. Using radiotelemetry on gulls in the Great Lakes, Morris
2-159 Herring Gull
-------
and Black (1980) demonstrated that some parents with chicks forage at specific locations
within 1 km of the colony whereas other parents make extended flights to destinations
across a lake more than 30 km away. Similarly, gulls that feed at sea may range tens of
kilometers from their nest whereas gulls from the same colony feeding in the intertidal
zone may travel less than 1 km (Pierotti and Annett, 1987; 1991). Males typically range
farther than females and take larger prey items (Pierotti and Annett, 1987; 1991). At sea
during the nonbreeding season, gulls may range hundreds of kilometers during a day
(Pierotti, pers. comm.).
Population density. As described above, population density is determined by
available nesting space, size of the breeding population, and quality of habitat. Small
islands with good feeding areas nearby can have several hundred nests per hectare
(Kadlec, 1971; Parsons, 1976b; Pierotti, 1982). In poor quality habitat, some pairs nest
solitarily without another nest for several kilometers (Weseloh, 1989).
Population dynamics. Herring gulls and western gulls usually do not begin
breeding until at least 4 years of age for males and 5 years of age for females (Burger,
1988; Pierotti, 1981; Pierotti, pers. comm.). Kadlec and Drury (1968) suggest that in a given
year, 15 to 30 percent of adults of breeding age do not breed. Most breeding females
produce three-egg clutches, but individuals in poor condition may lay only one or two eggs
(Parsons, 1976a; Pierotti, 1982; Pierotti and Annett, 1987; 1991). Herring gulls will lay
replacement eggs if all or a portion of their original clutch is destroyed (Parsons, 1976a).
Hatching success appears to be influenced by female diet, with garbage specialists
hatching a smaller percentage of eggs than fish or intertidal (mussel) specialists (Pierotti
and Annett, 1987, 1990, 1991). Predation, often by gulls of the same or other species, also
contributes to egg losses (Paynter, 1949; Harris, 1964; Davis, 1975). Many herring gull
chicks that hatch die before fledging, most within the first 5 days after hatching (Harris,
1964; Kadlec et al., 1969; Brown, 1967). Adult mortality is low (around 10 percent per year),
and some birds may live up to 20 years (Brown, 1967; Kadlec and Drury, 1968). Subadult
birds exhibit higher mortality (20 to 30 percent per year) (Kadlec and Drury, 1968; Chabrzyk
and Coulson, 1976).
Similar species (from general references)
• The western gull (Larus occidentalis) (64 cm), found on the Pacific coast of
the United States, is the ecological equivalent of the herring gull and is
similar in size (53 cm); males range from 1,000 to 1,300 g and females from
800 to 1,000 g (Pierotti, 1981).
• The glaucous gull (Larus hyperboreus) is larger (69 cm) than the herring gull
and is the predominant gull breeding in the high arctic. Birds from Alaska
are slightly smaller than birds from eastern Canada.
• The glaucous-winged gull (Larus glaucescens) is similar in size to the
herring gull (66 cm) and is the primary breeding species north of the
Columbia River. This species hybridizes extensively with the herring gull in
Alaska.
2-160 Herring Gull
-------
• The California gull (Larus californicus) is smaller (53 cm) than the herring
gull. This species breeds primarily in the Great Basin Desert and winters
along the Pacific coast.
• The great black-backed gull (Larus marinus) is the largest species of gull (76
cm) in North America and breeds from Labrador to Long Island.
• The ring-billed gull (Larus delawarensis) is of average size (45 cm) and is the
most common breeding gull in the Great Lakes and northern prairies.
• Franklin's gull (Larus pipixcan) is a small (37 cm), summer resident of the
Great Plains.
General references
For general information: Harrison (1983); National Geographic Society (1987);
Tinbergen (1960); Graham (1975). For discussion of diet: Burger (1988); Fox et al. (1990);
Pierotti (1981); Pierotti and Annett (1987).
2-161 Herring Gull
-------
Herring Gull (Larus argentatus)
Factors
Body Weight
(g)
Chick Growth
Rate (g/day)
Egg Weight (g)
Metabolic Rate
(kcal/kg-day)
Age/Sex
Cond./Seas.
A F spring
A M spring
A F summer
A M summer
at hatching
10 days old
20 days old
30 days old
30 days old
30 days old
< 5 days
5-30 days
5-30 days
5-25 days
3 egg clutch
2 egg clutch
in 1983
in 1984
A M basal
A F basal
A standard
A M free-
living
A F free-
living
Mean
951 ±88SD
1,184±116SD
999 ± 90 SD
1,232 ± 107 SD
65
230
590
810
964 ± 77 SD
818±99SD
8.8-13.1
26.3 ± 6.5 SD
33.4 ± 4.7 SD
30.2 ± 1.75 SD
87.2
85.7
92.0 ± 5.9 SD
98.0 ± 8.0 SD
86
91
99
233
248
Range or
(95% Cl of mean)
832-1,274
1,014-1,618
50-80
120-380
420 - 800
610-1,000
26.7-31.4
(84 - 646)
(92 - 669)
Location
Lake Huron
Newfoundland
Maine
Newfoundland/rocky island
Newfoundland/grassy island
Newfoundland/island
Newfoundland/island
meadow
Newfoundland/rocky island
Maine/coastal island
New Brunswick
Lake Superior, Canada
laboratory
Reference
Norstrom etal., 1986
Threlfall & Jewer, 1978
Dunn & Brisbin, 1980
Pierotti, 1982
Pierotti, 1982
Pierotti, 1982
Pierotti, 1982
Hunt, 1972
Herbert & Barclay, 1988
Meathrel etal., 1987
estimated
Lustick etal., 1978
estimated
Also see text for a discussion of annual variation in free-living metabolic rate in herring gulls.
Note
No.
1
2
3
o>
10
I
(D
3
CD
0
c
-------
Herring Gull (Larus argentatus)
Factors
Food Ingestion
Rate (g/g-day)
Water
Ingestion Rate
(g/g-day)
Inhalation Rate
(m3/day)
Surface Area
(cm2)
Age/Sex
Cond./Seas.
A M breeding
A F breeding
A M breeding
A F breeding
AM
AF
AM
AF
AM
AF
Dietary
Composition
months:
Mytilus edulis
sea urchin
fish
Oceanodroma
leuchorhoa
Fratercula arctica
adults
Fratercula, Uria
chicks
Larus sp. eggs
Vaccinum
angustifolium
Gadus morhua
offal
assorted refuse
Mean
0.20
0.21
0.19
0.18
0.055
0.059
0.48
0.41
1,150
1,001
Summer
Mid-May/
Mid-June
30.9
5.8
11.4
22.4
5.8
0.0
3.1
-
12.4
5.8
Summer
Mid-June/
Mid-July
0.9
0.0
71.1
7.0
0.0
3.5
0.9
-
1.7
0.9
Range or
(95% Cl of mean)
Summer
Mid -July/
Mid-Aug.
9.1
4.5
18.9
15.9
1.5
9.1
0.8
9.9
14.4
6.8
Summer
Location
Newfoundland -
diet of mussels
Newfoundland -
diet of garbage
Location/Habitat
(measure)
Newfoundland/island
(% occurrence in
regurgitations and
pellets)
Reference
Pierotti & Annett, 1991
Pierotti&Annett, 1991
estimated
estimated
estimated
Reference
Haycock &Threlfall, 1975
Note
No.
4
5
6
7
8
Note
No.
o>
CO
I
(D
3
CD
0
c
-------
Herring Gull (Larus argentatus)
Dietary
Composition
year:
American smelt
alewife
other fish
birds
voles
insects & refuse
lake:
fish
insects
offal, garbage
gull chicks
adult birds
amphibians
earthworms
crayfish
snails
crabs
garbage
offal
worms
other inverts.
fish
Population
Dynamics
Foraging
Radius (km)
Population
Density
(nests/ha)
Summer
1978
46.1
23.1
20.5
2.6
2.6
12.8
Ontario
91.8
5.5
0.5
2.2
1.6
0.5
2.2
0
Summer
1979
18.4
73.7
0
2.6
2.6
0
Erie
94.1
5.9
2.9
0
0
0
0
0
3
14
27
5
23
28
unknown
Summer
61
1980
.2
16.7
3.4
13.8
3.4
3.4
Huron
75.8
5.6
13.6
1
1
.0
.0
0
11
.6
0.5
AM 10 to 15
A F 5 to 10
summer 227
summer 217
75
Summer
1981
57.8
23.4
3.1
6.2
9.4
0
Superior
38.6
42.1
21.0
0
3.5
0
1.7
0
3-50
3-25
138-350
Location/Habitat
(measure)
Lake Ontario
(% occurrence in
regurgitations from and
stomach contents of
incubating adults)
Great Lakes
(% occurrence in boli
regurgitated by chicks)
CA,FL,NY,NJ,TX/
coastal
(% of gulls feeding on items)
offshore feeding on fish was
not included in observations
NS/coastal
Massachusetts/coastal
islands
Newfoundland/island - rocky
Newfoundland/island -
grassy slope
Reference
Fox etal., 1990
Foxetal., 1990
Burger, 1988
Reference
Pierotti, pers. comm.
Kadlec, 1971
Pierotti, 1982
Pierotti, 1982
Note
No.
Note
No.
10
o>
I
(D
3
CD
0
c
-------
Herring Gull (Larus argentatus)
Population
Dynamics
Clutch
Size
Clutches/Year
Days
Incubation
Age at
Fledging
(days)
Number
Fledge
per
Active Nest
Number
Fledge per
Successful
Nest
Age at
Sexual
Maturity
Annual
Mortality Rates
(percent)
Age/Sex/
Cond./Seas.
3 colonies
6 colony-yrs
3 colony-yrs
6 colony-yrs
3 colonies
F
M
B
AB
JB
AB
Mean
2.78
2.54
2.38
2.84 ± 0.44 SD
1
30.5
29
51
43
1.42
1.65
1.78
2.19
1.80
5 years
4 - 5 years
4.3 to 5.8
8
22
7.3
Range
2.51 -2.90
(over 8 sites)
1 -6
(per nest)
2.3-2.8
(over 1 1 years)
1 -2*
28-33
35 - 44 to 56 - 61
31 to 52
1.40-1.44
1.40-2.13
1.62-2.10
2.16-2.25
1.79-1.80
3-8
17-33
Location/Habitat
New Jersey/salt marsh
islands
NE United States/coastal
Maine/coastal islands
Lake Superior, Canada/
islands
(* if first eggs lost)
Holland/NS
Newfoundland/island
Massach usetts/coastal
island
New Brunswick/island
New Jersey/coastal
Lake Ontario/lakeshore
Lake Erie/lakeshore
Lake Huron/lakeshore
New Jersey/coastal
throughout range/NS
Scotland/coastal
New England/coastal
Scotland/coastal
Reference
Burger, 1979b
Nisbet&Drury, 1984
Hunt, 1972
Meathreletal., 1987
Burger, 1979a; Bourget, 1973
Tinbergen, 1960
Pierotti, 1982
Kadlec etal., 1969
Paynter, 1949
Burger & Shisler, 1980
Mineau etal., 1984
(minimum and maximum are
yearly means)
Burger & Shisler, 1980
Greig etal., 1983; Pierotti,
pers. comm.
Coulson etal., 1982
Kadlec & Drury, 1968
Chabryzk & Coulson, 1976
Note
No.
9
o>
Ol
I
(D
3
CD
0
c
-------
Herring Gull (Larus argentatus)
Population
Dynamics
Longevity
Seasonal
Activity
Mating/
Laying
Hatching
Migration
spring
fall
Molt
Age/Sex/
Cond./Seas.
AB
late April
early May
early May
early May
May
early June
late June
February
August
June
Mean
10
Range
up to 30 years
early May
mid-May
mid-May
late May
mid - late May
June
mid-June
late June
July
End
early June
early June
mid-June
end May
July
end June
mid-July
late April
September
August
Location/Habitat
NS/NS
Location
ne shore Lake Superior
Maine
New Jersey
Newfoundland
Great Lakes
Massachusetts
Newfoundland
New Brunswick
northwestern Atlantic
populations
Newfoundland
Reference
Pierotti, pers. comm.
Reference
Morris & Haymes, 1977
Bourget, 1973
Burger, 1977, 1979b
Pierotti, 1982
Foxetal., 1990
Kadlec, 1971
Pierotti, 1982, 1987
Paynter, 1949
Burger, 1982
Pierotti, pers. comm.
Note
No.
Note
No.
o>
o>
I
(D
3
CD
0
c
1 Weight of chicks from first egg laid in 1978 for the rocky island and in 1977 for the grassy area. In some years and some locations, chicks from
the first egg were heavier than the rest, and at other times and locations, the first chick was lighter.
2 Estimated using equation 3-29 (Lasiewski and Dawson, 1967) and body weights from Threlfall and Jewer (1978).
3 Estimated using equation 3-38 (Nagy, 1987) and body weights from Threlfall and Jewer (1978).
4 Estimated using 11.2 meals of mussel consumed per day per pair, weight of 80 g per mussel meal of which half is shell and not included in
ingestion rate, assuming that the female accounts for 46 percent of pair's energy requirement and the male accounts for 54 percent, and using
the body weights of Threlfall and Jewer (1978).
5 Estimated using 4.2 meals of garbage consumed per day per pair, weight of 100 g per garbage meal, assuming that the female accounts for 46
percent of pair's energy requirement and the male accounts for 54 percent, and using the body weights of Threlfall and Jewer (1978).
6 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Threlfall and Jewer (1978).
7 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Threlfall and Jewer (1978).
8 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Threlfall and Jewer
(1978).
9 Beginning with first egg.
-------
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2-169 Herring Gull
-------
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2-170 Herring Gull
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Pierotti, R.; Annett, C. (1987) Reproductive consequences of dietary specialization and
switching in an ecological generalist. In: Kamil, A. C.; Krebs, J.; Pulliam, H. R., eds.
Foraging behavior. New York, NY: Plenum Press; pp. 417-442.
Pierotti, R.; Annett, C. A. (1990) Diet and reproductive output in seabirds: food choices by
individual, free-living animals can affect survival of offspring. BioSci. 40: 568-574.
Pierotti, R.; Annett, C. A. (1991) Diet choice in the herring gull: constraints imposed by
reproductive and ecological factors. Ecology 72: 319-328.
Poole, E. L. (1938) Weights and wing areas in North American birds. Auk 55: 511-517.
2-171 Herring Gull
-------
Powers, K. D. (1983) Pelagic distributions of marine birds off the northeastern U.S. NOAA,
Tech. Mem. NMFS-F/NED-27: 1-201.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Schoen, R. B.; Morris, R. D. (1984) Nest spacing, colony location, and breeding success in
herring gulls. Wilson Bull. 96: 483-488.
Sibly, R. M.; McCleery, R. H. (1983) Increase in weight of herring gulls while feeding. J.
Anim. Ecol. 52: 35-50.
Smith, W. J. (1959) Movements of Michigan herring gulls. Bird-Banding 30: 69-104.
Threlfall, W.; Jewer, D. D. (1978) Notes on the standard body measurements of two
populations of herring gulls (Larus argentatus). Auk 95: 749-753.
Tinbergen, N. (1960) The herring gull's world. New York, NY: Harper and Row, Publishers.
Verbeek, N. A. (1977) Comparative feeding behavior of immature and adult herring gulls.
Wilson Bull. 89:415-421.
Vermeer, K. (1973) Food habits and breeding range of herring gulls in the Canadian prairie
provinces. Condor 75: 478-480.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Weseloh, D. H. (1989) Herring gull. In: Cadman, M. D.; Eagles, P. F.; Helleiner, F. M., eds.
Atlas of the breeding birds of Ontario. Waterloo, University of Waterloo Press; pp.
182-183.
Weseloh, D. V.; Mineau, P.; Struger, J. (1990) Geographical distribution of contaminants
and productivity measures of herring gulls in the Great Lakes: Lake Erie and
connecting channels 1978/79. Sci. Tot. Environ. 91: 141-159.
2-172 Herring Gull
-------
2.1.13. Belted Kingfisher (kingfishers)
Order Coraciiformes, Family Alcedinidae. Kingfishers are stocky, short-legged
birds with large heads and bills. They exist on a diet mostly of fish, which they catch by
diving, from a perch or the air, head first into the water. They nest in burrows in earthen
banks that they dig using their bills and feet.
Selected species
The belted kingfisher (Ceryle alcyon, formerly Megaceryle alcyon) is a medium-
sized bird (33 cm bill tip to tail tip) that eats primarily fish. It is one of the few species of
fish-eating birds found throughout inland areas as well as coastal areas. The belted
kingfisher's range includes most of the North American continent; it breeds from northern
Alaska and central Labrador southward to the southern border of the United States (Bent,
1940). Two subspecies sometimes are recognized: the eastern belted kingfisher (Ceryle
alcyon alcyon), which occupies the range east of the Rocky Mountains and north to
Quebec, and the western belted kingfisher (Cercyle alcyon caurina), which occupies the
remaining range to the west (Bent, 1940).
Body size. The sexes are similar in size and appearance, although the female tends
to be slightly larger (Salyer and Lagler, 1946). Bent (1940) reported that western
populations are somewhat larger than eastern ones. Nestlings reach adult body weight by
about 16 days after hatching, but then may lose some weight before fledging (Hamas,
1981).
Habitat. Belted kingfishers are typically found along rivers and streams and along
lake and pond edges (Hamas, 1974). They are also common on seacoasts and estuaries
(Bent, 1940). They prefer waters that are free of thick vegetation that obscures the view of
the water and water that is not completely overshadowed by trees (Bent, 1940; White,
1953). Kingfishers also require relatively clear water in order to see their prey and are
noticeably absent in areas when waters become turbid (Bent, 1940; Davis, 1982; Salyer and
Lagler, 1946). White (1953) suggested that water less than 60 cm deep is preferred. They
prefer stream riffles for foraging sites even when pools are more plentiful because of the
concentration offish at riffle edges (Davis, 1982). Belted kingfishers nest in burrows within
steep earthen banks devoid of vegetation beside rivers, streams, ponds, and lakes; they
also have been found to nest in slopes created by human excavations such as roadcuts
and landfills (Hamas, 1974). Sandy soil banks, which are easy to excavate and provide
good drainage, are preferred (Brooks and Davis, 1987; Cornwell, 1963; White, 1953). In
general, kingfishers nest near suitable fishing areas when possible but will nest away from
water and feed in bodies of water other than the one closest to home (Cornwell, 1963).
Food habits. Belted kingfishers generally feed on fish that swim near the surface or
in shallow water (Salyer and Lagler, 1946; White, 1953; Cornwell, 1963). Davis (pers.
comm. in Prose, 1985) believes that these kingfishers generally catch fish only in the upper
12 to 15 cm of the water column. Belted kingfishers capture fish by diving either from a
perch overhanging the water or after hovering above the water (Bent, 1940). Fish
2-173 Belted Kingfisher
-------
are swallowed whole, head first, after being beaten on a perch (Bent, 1940). The average
length offish caught in a Michigan study was less than 7.6 cm but ranged from 2.5 to 17.8
cm (Salyer and Lagler, 1946); Davis (1982) found fish caught in Ohio streams to range from
4 to 14 cm in length. Several studies indicate that belted kingfishers usually catch the prey
that are most available (White, 1937, 1953; Salyer and Lagler, 1946; Davis, 1982). Diet
therefore varies considerably among different water bodies and with season (see examples
in Appendix). Although kingfishers feed predominantly on fish, they also sometimes
consume large numbers of crayfish (Davis, 1982; Saylerand Lagler, 1946), and in
shortages of their preferred foods, have been known to consume crabs, mussels, lizards,
frogs, toads, small snakes, turtles, insects, salamanders, newts, young birds, mice, and
berries (Bent, 1940). Parents bring surprisingly large fish to their young. White (1953)
found that nestlings only 7 to 10 days old were provided fish up to 10 cm long, and
nestlings only 2 weeks old were provided with fish up to 13 cm in length. After fledging,
young belted kingfishers fed on flying insects for their first 4 days after leaving the nest,
crayfish for the next week, and by the 18th day post-fledging, could catch fish (Salyer and
Lagler, 1946).
Molt. The juvenile plumage is maintained through the winter, and young birds
undergo their first prenuptial molt in the spring (between February and April) involving
most of the body plumage (Bent, 1940). Adults have a complete postnuptial molt in the fall
(August to October) (Bent, 1940).
Migration. This kingfisher breeds over most of the area of North America and
winters in most regions of the continental United States (National Geographic Society,
1987). Although most northern kingfishers migrate to southern regions during the coldest
months, some may stay in areas that remain ice-free where fishing is possible (Bent, 1940).
Breeding activities and social organization. During the breeding season, pairs
establish territories for nesting and fishing (Davis, 1982); otherwise, belted kingfishers are
solitary. They are not colonial nesters and will defend an unused bank if it lies within their
territory (Davis, 1982). In migrating populations, the males arrive before the females to find
suitable nesting territories (Davis, 1982). Kingfishers excavate their burrows in earthen
banks, forming a tunnel that averages 1 to 2 m in length, although some burrows may be
as long as 3 to 4 m (Hamas, 1981; Prose, 1985). The burrow entrance is usually 30 to 90
cm from the top of the bank (Bent, 1940; White, 1953) and at least 1.5 m from the base
(Cornwell, 1963). Burrows closer to the top may collapse, and burrows too low may flood
(Brooks and Davis, 1987). Burrows may be used for more than one season (Bent, 1940).
Five to seven eggs are laid on bare substrate or on fish bones within the burrow (Hamas,
1981; White, 1953). Only one adult, usually the female, spends the night in the nest cavity;
males usually roost in nearby forested areas or heavy cover (Cornwell, 1963). Both
parents incubate eggs and feed the young (Bent, 1940). After fledging, the young remain
with their parents for 10 to 15 days (Sayler and Lagler, 1946).
Home range and resources. During the breeding season, belted kingfishers require
suitable nesting sites with adequate nearby fishing. During spring and early summer, both
male and female belted kingfishers defend a territory that includes both their nest site and
their foraging area (Davis, 1982). By autumn, each bird (including the young of the year)
2-174 Belted Kingfisher
-------
defends an individual feeding territory only (Davis, 1982). The breeding territories (length
of waterline protected) can be more than twice as long as the fall and winter feeding
territories, and stream territories tend to be longer than those on lakes (Davis, 1982; Salyer
and Lagler, 1946). Foraging territory size is inversely related to prey abundance (Davis,
1982).
Population density. Breeding densities of between two and six pairs per 10 km of
river shoreline have been recorded, with density increasing with food availability (Brooks
and Davis, 1987; White, 1936).
Population dynamics. Kingfishers are sensitive to disturbance and usually do not
nest in areas near human activity (White, 1953; Cornwell, 1963). Kingfishers typically
breed in the first season after they are born (Bent, 1940). Fledging success depends on
food availability, storms, floods, predation, and the integrity of the nest burrow but can be
as high as 97 percent (M. J. Hamas, pers. comm.). Dispersal of young occurs within a
month of fledging (White, 1953). No data concerning annual survivorship rates were found.
Similar species (from general references)
• The green kingfisher (Chloroceryle americana) is smaller (22 cm) than the
belted kingfisher and is only common in the lower Rio Grande Valley. It also
is found in southeastern Arizona and along the Texas coast, usually during
fall and winter.
• The ringed kingfisher (Ceryle torquata) is larger (41 cm) and resides in the
lower Rio Grande Valley in Texas and Mexico.
General references
Bent (1940); Fry (1980); National Geographic Society (1987); Prose (1985); White
(1953).
2-175 Belted Kingfisher
-------
Belted Kingfisher (Ceryle alcyon)
Factors
Body Weight
(g)
Nestling
Growth Rate
(g/day)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion Rate
(g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Co nd. /Seas.
AB
AB
AB
at hatching
at fledging
at fledging
A B basal
A B free-living
AB
nestlings
AB
AB
AB
Mean
148 ± 20.8 SD
136 ± 15.6 SE
158±11.5SE
10-12
148 ± 13.3 SE
169 ± 11.9 SE
5 to 6
132
327
0.50
0.11
0.094
280
Range or
(95% Cl of mean)
125-215
(154-693)
1.0-1.75
Location or
subspecies
Pennsylvania
Pennsylvania
Ohio
Minnesota
Pennsylvania
Ohio
Pennsylvania, Ohio/streams
northcentral lower Michigan
Nova Scotia
Reference
Powdermill Nature Center
(unpubl.)
B rooks & Davis, 1987
Brooks & Davis, 1987
Hamas, 1981
Brooks & Davis, 1987
Brooks & Davis, 1987
Brooks & Davis, 1987
estimated
estimated
Alexander, 1977
White, 1936
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
7
8
o>
Q.
5
3
(Q
(D
-------
Belted Kingfisher (Ceryle alcyon)
Dietary Composition
trout
non-trout fish
Crustacea
insects
amphibians
birds and mammals
unidentified
trout
other game & pan fish
(e.g., perch,
centrarchids)
forage fish (e.g.,
minnow, stickleback,
sculpins)
unidentified fish
crayfish
insects
salmon fry
salmon (1-yr-old)
salmon (2-yr-old)
trout
sticklebacks
killifish
suckers
crayfish
cyprinids
(minnows)
(stonerollers)
(unidentified)
other fish
Spring
Summer
17*
29
5
19
27
1
2
30
13
15
1
41
<1
11
42
1
15
30
<1
<1
13
76
(13)
(38)
(26)
10
Fall
Winter
Location/Habitat (measure)
lower Michigan/lake
(% wet weight; stomach
contents)
*data from spring and fall
also
Michigan/trout streams
(% wet volume; stomach
contents)
Nova Scotia/riparian -
streams
(% of total number of prey;
fecal pellets)
southwest Ohio/creek
(% of total number of prey
brought to nestlings)
Reference
Alexander, 1977
Salyer & Lagler, 1946
White, 1936
Davis, 1982
Note
No.
Q.
5
3
(Q
(D
-------
Belted Kingfisher (Ceryle alcyon)
Population
Dynamics
Territory Size
(km shoreline)
Population
Density
(pair/km shore)
Clutch Size
Clutches/Year
Days
Incubation
Age at
Fledging
Number
Fledge per
Active Nest
Age at Sexual
Maturity
Age/Sex/
Cond./Seas.
early summer -
breeding pairs:
late summer -
nonbreeding
individuals:
A B summer
A B summer
Mean
2.19 ± 0.56 SE
1.03±0.28SE
1.03±0.22SE
0.39 ± 0.093 SE
0.11 -0.19
0.6
5.8±0.7SE
6.8±0.4SE
1
1
22
28 days
4.5±1.9SE
5.3 ± 2.2 SE
1 year
Range
Location/Habitat
Pen nsylvan ia/streams
Ohio/streams
southwest Ohio/streams
southwest Ohio/streams
Pennsylvania/streams
Nova Scotia/streams
Pen nsylvan ia/streams
Ohio/streams
Pennsylvania, Ohio/streams
Minnesota/lake
Minnesota/lake
NS/NS
Pennsylvania/streams
Ohio/streams
throughout range
Reference
Brooks & Davis, 1987
Brooks & Davis, 1987
Davis, 1980
Davis, 1980
Brooks & Davis, 1987
White, 1936
Brooks & Davis, 1987
Brooks & Davis, 1987
Brooks & Davis, 1987
Hamas, 1975
Hamas, 1975
Bent, 1940
Brooks & Davis, 1987
Brooks & Davis, 1987
Bent, 1940
Note
No.
9
oo
Q.
5
3
(Q
(D
-------
Belted Kingfisher (Ceryle alcyon)
Seasonal
Activity
Mating
Begin
April
May
August
February
late February
mid-March
early April
Peak
April to May
June
early June
End
early July
late July
October
April
mid-October
mid-November
mid-December
Location
Minnesota
Minnesota
Nova Scotia
NS
NS
Maine
NY, SD, Wl, NE
Massachusetts, New Jersey
PA, Rl, MO
NY, CT, IL, Wl
Maine, Nova Scotia
Reference
Hamas, 1975
Hamas, 1975
White, 1936
Bent, 1940
Bent, 1940
Bent, 1940
Bent, 1940
Bent, 1940
Bent, 1940
Bent, 1940
Bent, 1940
Note
No.
Q.
5
3
(Q
1 Cited in Dunning (1984).
2 Brooks and Davis (1987) reported fledging weights of 149 and 169 g for two populations. Given a hatching weight of about 10 g and 28 days
required to fledge, on average, chicks must gain 5 to 6 g per day. Hamas (1981) found gains of approximately 8.5 g per day until day 18, and a
loss of approximately 4.5 g per day until fledging.
3 Estimated using equation 3-28 (Lasiewski and Dawson, 1967) and body weights from Powdermill Nature Center (unpubl.).
4 Estimated using equation 3-37 (Nagy, 1987) and body weights from Powdermill Nature Center (unpubl.).
5 Estimated by author.
6 Estimated using equation 3-15 (Calderand Braun, 1983) and body weights from Powdermill Nature Center (unpubl.).
7 Estimated using equation 3-19 (Lasiewski and Calder, 1971) and body weights from Powdermill Nature Center (unpubl.).
8 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Powdermill Nature
Center (unpubl.).
9 They are known to renest up to three times if clutches are lost early (Bent, 1940).
(D
-------
References (including Appendix)
Alexander, G. R. (1974) The consumption of trout by bird and mammal predators on the
North Branch Au Sable River. Michigan Dept. Nat. Resources, Dingell - Johnson
Proj.; F-30-R, Final Report.
Alexander, G. R. (1977) Food of vertebrate predators on trout waters in north central lower
Michigan. Michigan Academician 10: 181-195.
Bent, A. C. (1940) Life histories of North American cuckoos, goat suckers, hummingbirds,
and their allies. Washington, DC: U.S. Government Printing Office; Smithsonian Inst.
US Nat. Mus., Bull. 176.
Brooks, R. P.; Davis, W. J. (1987) Habitat selection by breeding belted kingfishers (Ceryle
alcyon). Am. Midi. Nat. 117: 63-70.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Cornwell, G. W. (1963) Observations on the breeding biology and behavior of a nesting
population of belted kingfishers. Condor 65: 426-431.
Davis, W. J. (1980) The belted kingfisher, Megaceryle alcyon: its ecology and territoriality
[master's thesis]. Cincinnati, OH: University of Cincinnati.
Davis, W. J. (1982) Territory size in Megaceryle alcyon along a stream habitat. Auk 99:
353-362.
Dunning, J. B., Jr. (1984) Body weights of 686 species of North American birds. Western
Bird Banding Association, Monograph No. 1. Cave Creek, AZ: Eldon Publishing.
Fry, C. (1980) The evolutionary biology of kingfishers (Alcedinidae). In: The living bird,
1979-80. Ithaca, NY: The Laboratory of Ornithology, Cornell University; pp. 113-160.
Hamas, M. J. (1974) Human incursion and nesting sites of the belted kingfisher. Auk 91:
835-836.
Hamas, M. J. (1975) Ecological and physiological adaptations for breeding in the belted
kingfisher (Megaceryle alcyon) [Ph.D. dissertation]. Duluth, MN: University of
Minnesota.
Hamas, M. J. (1981) Thermoregulatory development in the belted kingfisher. Comp.
Biochem. Physiol. A: Comp. Physiol. 69: 149-152.
Lasiewski, R. C.; Calder, W. A. (1971) A preliminary allometric analysis of respiratory
variables in resting birds. Resp. Phys. 11: 152-166.
2-180 Belted Kingfisher
-------
Lasiewski, R. C.; Dawson, W. R. (1967). A reexamination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Poole, E. L. (1938) Weights and wing areas in North American birds. Auk 55: 511-517.
Prose, B. L. (1985) Habitat suitability index models: belted kingfisher. U.S. Fish Wildl. Serv.
Biol. Rep. 82(10.87).
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Salyer, J. C.; Lagler, K. F. (1946) The eastern belted kingfisher, Megaceryle alcyon alcyon
(Linnaeus), in relation to fish management. Trans. Am. Fish. Soc. 76: 97-117.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
White, H. C. (1936) The food of kingfishers and mergansers on the Margaree River, Nova
Scotia. J. Biol. Board Can. 2: 299-309.
White, H. C. (1937) Local feeding of kingfishers and mergansers. J. Biol. Board Can. 3:
323-338.
White, H. C. (1938) The feeding of kingfishers: food of nestlings and effect of water height.
J. Biol. Board 4: 48-52.
White, H. C. (1953) The eastern belted kingfisher in the maritime provinces. Fish. Res.
Board Can. Bull. 97.
2-181 Belted Kingfisher
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2.1.14. Marsh Wren (wrens)
Order Passer/formes. Family Troqlodytidae. Wrens are small insectivorous birds
that live in a variety of habitats throughout the United States. They have long, slender bills
adapted for gleaning insects from the ground and vegetation. Most species are migratory,
although some populations are year-round residents.
Selected species
The marsh wren (Cistothorus palustris) is a common bird inhabiting freshwater
cattail marshes and salt marshes. Marsh wrens breed throughout most of the northern half
of the United States and in coastal areas as far south as Florida; they winter in the
southern United States and into Mexico, particularly in coastal areas. Marsh wrens eat
mostly insects, and occasionally snails, which they glean from the surface of vegetation.
This species was formerly known as the long-billed marsh wren (Telmatodytes palustris).
Body size. Although wrens are small (13 cm bill tip to tail tip; about 10 g body
weight), males tend to be about 10 percent heavier than females (see table). Body weight
varies seasonally; in Georgia, where marsh wrens are resident throughout the year, they
tend to be heavier in the spring and summer than in the fall and winter (Kale, 1965).
Habitat. Marsh wrens inhabit freshwater and saltwater marshes, usually nesting in
association with bulrushes, cattails, and sedges or on occasion in mangroves (Welter,
1935; Bent, 1948; Kale, 1965; Verner, 1965). Standing water from several centimeters to
nearly a meter is typical of the areas selected (Bent, 1948). Permanent water is necessary
to provide a food supply of insects necessary to maintain the birds and as a defense
against predation (Verner and Engelsen, 1970). Deeper water and denser vegetation are
associated with reduced predation rates (Leonard and Pieman, 1987).
Food habits. Marsh wrens consume aquatic invertebrates, other insects, and
spiders, which they glean from the water surface, on stems and leaves of emergent
vegetation, and the marsh floor (Kale, 1965; Welter, 1935). They sometimes also feed by
flycatching (Welter, 1935). The insect orders most commonly taken include Coleoptera
(both adults and larvae), Diptera (adults and larvae), Hemiptera (juveniles and adults),
Lepidoptera (larvae most commonly fed to nestlings); and Odonata (newly emerged) (Bent,
1948; Kale, 1964). When feeding the young, at first the parents bring mosquito adults and
larvae, midges, larval tipulids, and other small insects (Welter, 1935). As the young
mature, the parents bring larger insects such as ground beetles, diving beetles, long-
horned beetles, caterpillars, dragonflies, and sawflies to the nestlings (Welter, 1935). In a
population in Georgia, spiders (usually 1 to 3 mm in size, sometimes 12 to 15 mm), small
crabs (5 to 7 mm), small snails (1 to 3 mm), and insect eggs also were consumed and fed
to nestlings (Kale, 1965). Thus, organisms that are aquatic for all or part of their lives are
an important component of the diet of marsh wren adults and nestlings.
Migration. Marsh wrens are year-round residents in some southern and coastal
maritime regions where marshes do not freeze. Most migratory wrens breed throughout
the northern half of the United States through southern Canada and winter in Mexico and
2-183 Marsh Wren
-------
the southern half of the United States (Bent, 1948; Verner, 1965; American Ornthologists'
Union, 1983; National Geographic Society, 1987).
Breeding activities and social organization. Many populations of marsh wren are
polygynous, with some males mating with two, occasionally three, females in a season,
while the remaining males have one mate or remain bachelors. For example, Leonard and
Pieman (1987) found 5 to 11 percent bachelor males, 41 to 48 percent monogamous males,
37 to 43 percent bigamous males, and 5 to 12 percent trigamous males in two marshes in
Manitoba, Canada. Similarly, Verner and Engelsen (1970) found 16 percent bachelors, 57
percent monogamous, and 25 percent bigamous males in eastern Washington state. In
contrast, Kale (1965) found most males to be monogamous through 4 years of study in
Georgia.
Males arrive at the breeding marshes before the females to establish territories that
include both nest sites and foraging areas (Kale, 1965; Verner, 1965; Welter, 1935). Males
build several nests in their territories throughout the breeding season (Kale, 1965; Verner,
1965). The female usually only adds lining material to a nest of her choice, although some
may help construct the breeding nest (Kale, 1965). Breeding nests are oblong in shape,
with a side opening, and are woven of cattails, reeds, and grasses and lashed to standing
vegetation, generally 30 cm to 1 m above standing water or high tide (Bent, 1948; Verner,
1965). Incubation lasts approximately 2 weeks, as does the nestling period (Kale, 1965;
Verner, 1965). After fledging, one or both parents continue to feed the young for about 12
days (Verner, 1965). Many populations typically rear two broods per year, although some
may rear three (Kale, 1965; Verner, 1965). In the more monogamous populations, both
parents regularly feed young, but in the more polygynous ones, the females may provide
most of the food, with males assisting only toward the end of the nestling period (Leonard
and Pieman, 1988; Verner, 1965).
Home range and resources. Marshes smaller than 0.40 ha usually are not used by
breeding marsh wrens (Bent, 1948). Average male territory size for a given year and
location can range from 0.006 to 0.17 ha, depending on the habitat and conditions of the
year (see table). Also, there is a trend in polygynous populations for polygynous males to
defend larger territories than monogamous males or males that end up as bachelors
(Verner and Engelson, 1970; Verner, 1964; Kale, 1965).
Population density. Because the species is polygynous, there may be more females
than males inhabiting breeding marshes. Population density varies with the suitability and
patchiness of the habitat. Densities as high as 120 adult birds per hectare have been
recorded (Kale, 1965).
Population dynamics. Clutch size and number of clutches per year vary with
latitude and climate (see table). In some populations, marsh wrens commonly destroy
eggs and kill the nestlings of other pairs of their own species and other marsh-nesting
passerines (Orians and Wilson, 1964; Pieman, 1977; Welter, 1935). Fledging success
depends strongly on nest location; nests over deeper water are less vulnerable to
predation (Leonard and Pieman, 1987). Of nests lost to all causes, Leonard and Pieman
(1987) found 44 percent due to mammalian predators, 27 percent due to other wrens, 11
percent due to weather, 8 percent due to nest abandonment, and 13 percent unknown. The
2-184 Marsh Wren
-------
annual mortality of adults is lower than that of first-year birds. Both sexes of this species
usually commence breeding in the first year following hatching (Kale, 1965).
Similar species
• The sedge wren (Cistothorus platensis, formerly known as the short-billed
marsh wren) nests locally in wet meadows or shallow sedge marshes and
hayfields in the northeastern United States, wintering primarily in the
southeastern United States. It is slightly smaller (11 cm) than the marsh
wren.
Note: None of the other wren species inhabit marshes, although all forage
by gleaning insects from vegetation and other surfaces. Wrens that inhabit
moist woodlands and open areas are listed below.
• The house wren (Troglodytes aedon) (12 cm) breeds throughout most of the
United States, into southern Canada. It inhabits open habitats with brush
and shrubs and is found in orchards, farmyards, and urban gardens and
parks.
• The winter wren (Troglodytes troglodytes) (10 cm) breeds in southern
Canada, where it nests in dense brush, especially along moist coniferous
woodlands. It winters primarily in the southeastern United States, where it
inhabits many types of woodlands.
• The Carolina wren (Thryothorus ludovicianus) (14 cm) is nonmigratory and
can be found in both summer and winter in the eastern United States as far
north as northern Delaware and as far west as Oklahoma. It inhabits moist
woodlands and swamps and wooded suburban areas.
• Bewick's wren (Thryomanes bewickii) (13 cm) is more common in western
States than the house wren and is declining east of the Mississippi. It is
found in brushland, stream edges, and open woods.
General references
Kale (1965); Gutzwiller and Anderson (1987); Leonard and Pieman (1987); Verner
(1965), National Geographic Society (1987).
2-185 Marsh Wren
-------
Marsh Wren (Cistothorus palustris)
Factors
Body Weight
(g)
Egg Weight (g)
Metabolic Rate
(I02/kg-day)
Metabolic Rate
(kcal/kg-day)
Age/Sex/
Co nd. /Seas.
F breeding
M breeding
AF
AM
JB
nestling:
dayl
day3
dayS
day?
day 9
day 11
day 13
at fledging
A B basal
A B near
basal
A Blight
activity
A B basal
A B near
basal
A Blight
activity
A B free-living
A F free-living
A M free-
living
Mean
10.6 ± 0.99 SD
11.9 ± 0.72 SD
9.4 ±1.1 SD
10.6 ± 0.7 SD
9.4±1.6SD
1.1
2.1
4.7
6.8
10.0
10.6
11.3
8.84 ± 0.70 SD
1.14±0.10SD
91.2
113
169
444
557±115SD
788±115SD
880 ± 90 SD
1,209
1,174
Range or
(95% Cl of mean)
9.0-13.5
10.5-13.5
(571 - 2,563)
(554 - 2,486)
Location or
subspecies
New York
Georgia
New York, Minnesota/fresh
marshes
Georgia
Georgia
Georgia (captive)
Georgia (captive)
Reference
Tintle (unpubl.)
Kale, 1965
Welter, 1935
Kale, 1965
Kale, 1965
Kale, 1965
Kale, 1965
Kale, 1965
Kale, 1965
Kale, 1965
estimated
Note
No.
1
2
3
4
5
6
7
8
9
10
11
00
o>
0)
55
-------
Marsh Wren (Cistothorus palustris)
Factors
Food Ingestion
Rate
Water
Ingestion Rate
(g/g-day)
Surface Area
(cm2)
Age/Sex/
Co nd. /Seas.
A B free-living
A B free-living
A F free-living
A M free-
living
AF
AM
AF
AM
Dietary Composition
Hymenoptera
Homoptera
Coleoptera
Lepidoptera
Diptera
Hemiptera
Orthoptera
spiders
other arthropods
(crabs, amphipods)
molluscs (snails)
other (insect eggs,
undetermined, etc.)
Mean
1,155±130SD
kcal/kg-day
0.67 g/g-day
0.99 g/g-day
0.96 g/g-day
0.28
0.26
45
48
17.3
13.0
11.6
14.6
8.9
5.4
5.6
15.1
1.8
3.5
4.5
Range or
(95% Cl of mean)
Winter
12.4
40.1
12.6
2.9
7.7
10.0
0.8
6.2
0.9
4.0
3.3
Location or
subspecies
Georgia (captive)
Georgia (captive)
Location/Habitat (measure)
Georgia/salt marsh
(% wet volume;
stomach contents)
Reference
Kale, 1965
estimated from Kale, 1965
estimated
estimated
estimated
Kale, 1965
Note
No.
12
13
14
15
16
Note
No.
17
00
0)
55
-------
Marsh Wren (Cistothorus palustris)
Population
Dynamics
Territory
Size (ha)
Population
Density
Clutch Size
Clutches/Year
Days
Incubation
Age/Sex/
Cond./Seas.
A M spring
A M spring
A M spring
spring:
pairs/ha
males/ha
males/ha
Mean
0.0060 ± 0.0014 SD
0.01 56 ± 0.0050 SD
0.0085 ± 0.0042 SD
0.17 ±0.021 SE
0.07 ± 0.06 SD
48.3 ± 5.3 SD
8.5
16.9
3.7±0.5SD
4.5
6.0 ± 0.19 SD
5.8 ± 0.8 SD
1 -2
2
2-3
13.1
15.1
Range
0.0242 - 0.360
45.1 - 56.2
3.4-4.3
3-5
4-8
0-3
0-2
0-3
12-14
13-16
Location/Habitat
Georgia/salt marsh 1, 1958
Georgia/salt marsh 2, 1958
Georgia/salt marsh 2, 1959
west Washington/fresh
mixed-species marsh
Manitoba/fresh cattail marsh
Georgia/salt marsh (4 years)
west Washington/fresh
mixed-species marsh
(2 areas)
Manitoba/fresh mixed-
species marsh (3 years)
Georgia/salt marsh
east Washington/fresh
pond-margin marsh
Manitoba/fresh cattail marsh
Georgia/salt marsh
east Washington/fresh
pond- margin marsh
west Washington/fresh
mixed-species marsh
Georgia/salt marsh
west Washington/fresh
marsh
Reference
Kale, 1965
Verner, 1965
Leonard & Pieman, 1986
Kale, 1965
Verner, 1965
Leonard & Pieman, 1987
Kale, 1965
Verner, 1965
Leonard & Pieman, 1987
Kale, 1965
Verner, 1965
Verner, 1965
Kale, 1965
Verner, 1965
Note
No.
00
00
0)
55
-------
Marsh Wren (Cistothorus palustris)
Population
Dynamics
Age at
Fledging
Number
Fledge per
Active Nest
Number
Fledge per
Successful
Nest
Age at Sexual
Maturity
Annual
Mortality
Rates (percent)
Seasonal
Activity
Mating/Laying
Hatching
Migration fall
spring
Age/Sex/
Cond./Seas.
B
B
B
B
AB
JB
April
mid -April
late March
late May
early May
mid-April
September
April
Mean
12-13
14
3.4±3.4SD
4.5±1.3SD
5.1 ±1.2SD
1 year
1 year
32
70
May - June
April - May
May
mid-March
(non migratory)
Range
10-15
11 -16
End
mid-August
early July
mid-July
early August
mid-July
early August
late October
June
Location/Habitat
Georgia/salt marsh
Washington/fresh marshes
Manitoba/fresh mixed marsh
Manitoba/fresh mixed-
species marsh
Manitoba/fresh cattail marsh
Manitoba/fresh marsh
Washington/fresh marsh
Georgia/salt marsh
Georgia
eastern Washington
(Turnbull)
western Washington (Seattle)
New York
eastern Washington
(Turnbull)
western Washington (Seattle)
New York, Minnesota
New York, Minnesota
eastern Washington
(Turnbull)
western Washington (Seattle)
Reference
Kale, 1965
Verner, 1965
Leonard & Pieman, 1987
Leonard & Pieman, 1987
Leonard & Pieman, 1987
Leonard & Pieman, 1987
Verner, 1971
Kale, 1965
Reference
Kale, 1965
Verner, 1965
Verner, 1965
Welter, 1935
Verner, 1965
Verner, 1965
Welter, 1935
Welter, 1935
Verner, 1965
Verner, 1965
Note
No.
Note
No.
00
0)
55
-------
Marsh Wren (Cistothorus palustris)
1 As cited in Dunning (1984).
2 Collection dates not specified. Resident population; presumably averaged from birds captured throughout the year.
3 Estimated from Welter's (1935) growth curve based on 50 nestlings.
4 Measured by oxygen respirometry; lowest value of metabolism of postabsorptive wrens resting in the dark (but not at night) at temperatures
within the thermoneutral zone.
5 Measured by oxygen respirometry; birds not postabsorptive, but resting in a dark box at temperatures within the thermoneutral zone.
6 Measured by oxygen respirometry; birds somewhat active in their cage.
7 Estimated from oxygen consumption, for conditions, see note 3.
8 Estimated from oxygen consumption, for conditions, see note 4.
9 Estimated from oxygen consumption, for conditions, see note 5.
10 Estimated from measured daily food intake, excretory losses, assimilation, and respiration for active birds in small cages (173 weekly
determinations total). Because of the birds' high activity levels, Kale (1965) considered the measure representative of free-living birds.
11 Estimated using allometric equation 3-36 (Nagy, 1987) and body weights from Kale (1965).
12 Measured daily food intake of birds in cages and measured caloric content of diet provided. Because of the birds' high activity levels, Kale (1965)
considered the measure representative of free-living birds.
13 Estimated from Kale's (1965) measured daily food intake (see note 11) assuming 5.62 kcal/gram (dry weight) insects, a 70 percent assimilation
efficiency, and a 67 percent water content for insects.
14 Estimated from free-living metabolic rate estimated from Nagy's (1987) equation 3-36 (see note 10) assuming the same parameters described in
note 12. These predicted food ingestion rates (>0.95 g/g-day) for free-living birds exceed the value estimated for Kale's (1965) caged birds (0.67
g/g-day); however, the latter does not include metabolic requirements of searching for food, reproduction, or unusual thermoregulatory demands.
15 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Kale (1965).
16 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Kale (1965).
17 Summer column represents combination of spring and summer data; winter column represents combination of fall and winter data.
0)
55
-------
References (including Appendix)
American Ornithologists' Union. (1983) Check-list of North American birds. Lawrence, KS:
Allen Press, Inc.
Bent, A. C. (1948) Life histories of North American nuthatches, wrens, thrashers, and their
allies. Washington, DC: U.S. Government Printing Office; Smithsonian Inst. U.S. Nat.
Mus., Bull. 195.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Dunning, J. B., Jr. (1984) Body weights of 686 species of North American birds. Western
Bird Banding Association, Monograph No. 1. Cave Creek, AZ: Eldon Publishing.
Gutzwiller, K. J.; Anderson, S. H. (1987) Habitat suitability index models: marsh wren. U.S.
Fish Wildl. Serv. Biol. Rep. 82(10.139).
Kale, H. W., II (1964) Food of the long-billed marsh wren, Telmatodytes palustris griseus, in
the salt marshes of Sapelo Island, Georgia. Oriole 29: 47-61.
Kale, H. W., II. (1965) Ecology and bioenergetics of the long-billed marsh wren
Telmatoidytes palustris griseus (Brewster) in Georgia salt marshes. Publ. Nuttall
Ornith. Club No. 5.
Leonard, M. L.; Pieman, J. (1986) Why are nesting marsh wrens and yellow-headed
blackbirds spatially segregated? Auk 103: 135-140.
Leonard, M. L.; Pieman, J. (1987) Nesting mortality and habitat selection by marsh wrens.
Auk 104: 491-495.
Leonard, M. L.; Pieman, J. (1988) Mate choice by marsh wrens: the influence of male and
territory quality. Anim. Behav. 36: 517-528.
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Orians, G. H.; Wilson, M. F. (1964) Interspecific territories of birds. Ecology 45: 736-745.
Pieman, J. (1977) Intraspecific nest destruction in the long-billed marsh wren,
Telmatodytes palustris plustris. Can. J. Zool. 55: 1997-2003.
2-191 Marsh Wren
-------
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Verner, J. (1964) Evolution of polygamy in the long-billed marsh wren. Evolution 18:
252-261.
Verner, J. (1965) Breeding biology of the long-billed marsh wren. Condor 67: 6-30.
Verner, J. (1971) Survival and dispersal of male long-billed marsh wrens. Bird-Banding 42:
92-98.
Verner, J.; Engelsen, G. H. (1970) Territories, multiple nest building, and polygamy in the
long-billed marsh wren. Auk 87: 557-567.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Welter, W. A. (1935) The natural history of the long-billed marsh wren. Wilson Bull. 47: 3-34.
2-192 Marsh Wren
-------
2.1.15. American Robin (thrushes)
Order Passer/formes. Family Muscicapidae, Subfamily Turdinae. Thrushes are
common, medium-sized birds that eat worms, insects, and fruit. They live in a variety of
habitats, including woodlands, swamps, suburbs, and parks. Most thrushes build nests of
mud and vegetation on the ground or in the crotches of trees or shrubs; bluebirds nest in
holes in trees and posts or in nest boxes. This group forages primarily on the ground and
in low vegetation by probing and gleaning. Some thrushes are neotropical migrants while
others reside year-round in North America. Thrushes range in size from the eastern and
western bluebirds (18 cm from bill tip to tail tip) to the American robin (25 cm). Male and
female plumages are similar in most thrushes, although in some species, such as the
bluebirds, the males are more brightly colored.
Selected species
The American robin (Turdus migratorius) occurs throughout most of the continental
United States and Canada during the breeding season and winters in the southern half of
the United States and in Mexico and Central America. The breeding range of the robin has
expanded in recent times with the increasing area covered by lawns and other open
habitats (Howell, 1942; Martin et al., 1951; James and Shugart, 1974).
Body size. The sexes are similar in size and appearance. Their size varies slightly
geographically; the smallest robins are found in the eastern United States and along the
Pacific coast, and the largest ones occur in the Rocky Mountains, northern Great Plains,
and northern deserts (Aldrich and James, 1991).d The size of robins tends to increase with
latitude in eastern North America but does not in western North America (Aldrich and
James, 1991). Fledglings attain adult size at approximately 6 weeks of age (Howell, 1942).
Habitat. Access to fresh water, protected nesting sites, and productive foraging
areas are important requirements for breeding robins (Speirs, 1953). Breeding habitats
include moist forests, swamps, open woodlands, orchards, parks, and lawns. Robins
forage on the ground in open areas, along habitat edges, or the edges of streams; they
also forage above ground in shrubs and within the lower branches of trees (Paszkowski,
1982; Malmborg and Willson, 1988). Nests in wooded areas are usually near some type of
opening such as the forest edge or a treefall gap (Young, 1955; Knupp et. al., 1977). During
the nonbreeding season, robins prefer moist woods or fruit-bearing trees and shrubs
(Robbins et al., 1983). In the fall, flocks of migratory robins are often found along forest
edges or clearings where fruits are most plentiful (Baird, 1980).
Food habits. Robins forage by hopping along the ground in search of ground-
dwelling invertebrates and by searching for fruit and foliage-dwelling insects in shrubs and
low tree branches (Malmborg and Willson, 1988; Paszkowski, 1982). In the months
preceding and during the breeding season, robins feed mainly (greater than 90 percent
volume) on invertebrates and on some fruits; during the remainder of the year, their diet
"Based on linear measurements of museum study skins.
2-193 American Robin
-------
consists primarily (over 80 to 99 percent by volume) of fruits (Martin et al., 1951; Gochfeld
and Burger, 1984; Wheelwright, 1986). Robins eat a wide variety of both plant and animal
foods; in a compilation of diet records collected throughout the United States and southern
Canada, Wheelwright (1986) found that robins consumed fruits from 51 genera and
invertebrates from 107 families. Commonly eaten fruits include plums, dogwood, summac,
hackberries, blackberries, cherries, greenbriers, raspberries, and juniper (Martin et al.,
1951; Wheelwright, 1986); common invertebrates include beetles, caterpillars, moths,
grasshoppers, spiders, millipedes, and earthworms (Martin et al., 1951; Wheelwright, 1986;
Paszkowski, 1982). Wheelwright (1986) has compiled seasonal changes in the proportion
of plants and invertebrates consumed by robins in three different sections of the United
States (see table). Wheelwright (1986) also has summarized the average occurrence of
fruits of various plant families in the stomachs of robins by month for these sections.
Martin et al. (1951) have summarized the occurrence of fruits of various plant families in
more specific areas of the United States (see Appendix).
Wheelwright (1986) found no differences between the sexes in the proportion or
types of invertebrates and fruits eaten. Very young robins (up to at least 35 days of age)
feed almost entirely on insects and other invertebrates (Howell, 1940). Older juveniles tend
to eat a higher proportion of fruit and easy-to-capture prey than adults (Gochfeld and
Burger, 1984; Wheelwright, 1986). In a given area, robins often show food preferences: a
population in central New York seemed to prefer northern arrowwood and spice bush fruits
over most other plants (Wheelwright, 1988); in Illinois, a group ate predominantly frost
grapes and Virginia creeper in the late summer and fall (Malmborg and Willson, 1988).
During seasons when fruits dominate the diet, robins may need to consume
quantities in excess of their body weight to meet their metabolic needs each day (see
table). Robins as well as other fruit-eating birds exhibit a low digestive efficiency for fruits;
Karasov and Levey (1990) estimated the metabolizable energy coefficient (MEC) (i.e., the
proportion of food energy that actually is assimilated) for robins eating a mixed fruit diet to
be only 55 percent, perhaps because of the low retention time of the digested matter in the
gut (Levey and Karasov, 1992). The short retention time might actually be an adaptation to
eating fruit because large quantities of fruit must be processed to obtain an adequate
protein intake. In contrast, when eating insects, robins (as well as other bird species)
exhibit a higher digestive efficiency of approximately 70 percent (Levey and Karasov,
1989). Moreover, the energy content of insects tends to be higher than that of most fruits,
particularly on a wet-weight basis (see Chapter 4). Thus, during the spring when robins
are consuming insects, they should consume a smaller amount relative to their body
weight than when eating fruits (Chapter 4 provides approaches that can be used to
estimate insect ingestion rates for robins).
Molt. Postjuvenile and postbreeding (prebasic) molts occur from late July to
October (Wheelwright, 1986; Sharp, 1990). During this molt, robins are consuming largely
fruits and other plant materials, which contain limited proteins. This may contribute to
larger fruit consumption rates at this time. During the prebreeding (prealternate) molt,
robins are feeding primarily on insects and other invertebrates (letter
2-194 American Robin
-------
from N.T. Wheelright, Department of Biology, Bowdoin College, Brunswick, ME, to Sue
Norton, March 18, 1992).
Migration. Most robins nesting in the northern United States and Canada winter in
the Gulf Coast States and the Carolinas (Speirs, 1953; Dorst, 1962, as cited in Henny,
1972). Wintering robins are most abundant between 30 and 35 degrees N latitude (Speirs,
1953). Robin flocks migrate during the day (Robbins et al., 1983); most northern robins
leave their breeding grounds from September to November and return between February
and April (Howell, 1942; Young, 1951; Fuller, 1977).
Breeding activities and social organization. The onset of the breeding season is
later at higher latitudes (approximately 3 days for each additional degree in the east) and
altitudes, but mating and egg laying generally occur in April or May (James and Shugart,
1974; Knupp et al., 1977). Males arrive on the breeding grounds before females to
establish territories; females pair with established males, usually for the duration of the
breeding season (Young, 1951). The female primarily builds the nest out of mud, dried
grass, weedy stems, and other materials, constructing it on horizontal limbs, tree-branch
crotches, within shrubs, or on any one of a number of man-made structures with horizontal
surfaces (Howell, 1942; Klimstra and Stieglitz, 1957). First clutches usually contain three
or four eggs; later clutches tend to contain fewer eggs (Young, 1955). The female does all
of the incubating, which continues for 10 to 14 days following the laying of the second egg
(Klimstra and Stieglitz, 1957; Young, 1955). Both males and females feed the nestlings
(Young, 1955). Following fledging, the brood often divides, with the male and female each
feeding half of the fledglings for another 2 weeks (Weatherhead and McRae, 1990).
Females may start another brood before the current one is independent, leaving the male
to feed all of the fledglings (Young, 1955). After reaching independence, juveniles often
form foraging flocks in areas of high food availability (Hirth et al., 1969).
Early in the breeding season, robins often roost communally. Males can continue to
use these roosts throughout the breeding season, whereas females stop once they begin
incubating eggs (Howell, 1940; Pitts, 1984). As fall approaches and their diet turns more
toward fruits, robins in many areas begin to roost communally again and may join other
species, such as common grackles and European starlings, in large roosts (Morrison and
Caccamise, 1990).
Home range and resources. During the breeding season, male robins establish
breeding territories, which the female helps to defend against other robins. Nonetheless,
the territories of different pairs often overlap where neither pair can establish dominance
(Young, 1951). Most foraging during the breeding season is confined to the territory, but
adults sometimes leave to forage in more productive areas that are shared with other
individuals (Howell, 1942; Young, 1951; Pitts, 1984). In some prime nesting areas (e.g.,
dense coniferous forest), where robin densities are high, territories are small and the birds
might often forage elsewhere (Howell, 1942). Adult robins often return to the same territory
in succeeding years (Young, 1951). During the nonbreeding roosting period, robins are
likely to return to the same foraging sites for many weeks and to join roosts within 1 to 3
km of these foraging areas (Morrison and Caccamise, 1990).
2-195 American Robin
-------
Population density. Nesting population density varies with habitat quality. Densely
forested areas that provide well-protected nest sites have been found to support high
densities of nesting robins; however, the relatively small territories found in these areas
might not be used as much for foraging as those containing open areas (Howell, 1942). In
the nonbreeding season, robins often join single- or mixed-species roosts that can include
tens of thousands of birds (Morrison and Caccamise, 1990). Wintering robins are most
common in pine or oak pine communities of the southeastern and southcentral United
States, and decrease in abundance in drier, less forested areas westward (Speirs, 1953).
Population dynamics. Robins first attempt to breed the year after they hatch
(Henny, 1972) and will raise multiple broods in a season (Howell, 1942). Predation is often
a major source of mortality for both eggs and nestlings (Knupp et al., 1977; Klimstra and
Stieglitz, 1957). Approximately half of the adult birds survive from year to year (Farner,
1949; Henny, 1972); the average longevity of a robin that survives to its first January is
from 1.3 to 1.4 years (Farner, 1949).
Similar species (from general references)
• The wood thrush (Hylocichla mustelina), which is smaller than the robin (18
cm), co-occurs with the robin in some woodland habitats but is only present
in the eastern United States. This species nests primarily in the interiors of
mature forests and has been decreasing in abundance over the past decade
as forested habitats in North America become increasingly fragmented
(Robbins et al., 1989; Terborgh, 1989). This species is also primarily a
summer resident, wintering in Florida and the neotropics.
• The hermit thrush (Catharus guttatus) is found in coniferous and mixed
woodlands at northerly latitudes or high elevations and winters primarily in
the southern half of the United States. This species is also significantly
smaller (15 cm) than the robin.
• Swainson's thrush (Catharus ustulatus) is present in the western and
northeastern United States during the summer months, wintering in the
neotropics. It is also smaller than the robin (16 cm).
• The varied thrush (Ixoreus naevius) occurs in moist coniferous forests of the
Pacific Northwest. This bird is similar in size (21 cm) to the robin.
General references
Howell (1942); Young (1955); National Geographic Society (1987); Robbins et al.
(1983); Sharp (1990).
2-196 American Robin
-------
American Robin (Turdus migratorius)
Factors
Body Weight
(g)
Egg Weight (g)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (kcal/kg-
day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Age/Sex/
Cond./Seas.
A B all seas.
A M nonbreed.
A F nonbreed.
A M breeding
A F breeding
nestlings:
at hatching
day 2
day 4
day 6
dayS
day 10
day 14
A B basal
- B existence
A B free-living
A B free-living
B B free-living
- B free-living
AB
Mean
77.3 ± 0.36 SE
86.2 ±6.1 SD
83.6 ± 6.4 SD
77.4
80.6
5.5
12.6
24.3
39.4
50.9
55.2
55.0
6.26
259
344
713
1,070±220SD
0.89 ± 0.73 SD
1.52±0.25SD
0.14
Range or
(95% Cl of mean)
63.5-103
4.1 -6.7
8.4-17.5
17.9-32.3
32.5-45.9
42.0 - 59.3
49.0 - 63.2
51.8-58.2
4.6-8.4
(336-1,513)
760-1,330
1.22-1.96
Location or
subspecies
Pennsylvania
New York
New York
New York/forest
New York
Kansas
Kansas
California
Kansas
Reference
Clench & Leberman, 1978
Wheelwright, 1986
Wheelwright, 1986
Howell, 1942
Howell, 1942
estimated
Hazeltonetal., 1984
(estimate)
estimated
Hazeltonetal., 1984
Skorupa & Hothem, 1985
Hazeltonetal., 1984
estimated
Note
No.
1
2
3
4
5
6
7
8
3
(D
?.
O
0)
3
o
o;
5'
-------
American Robin (Turdus migratorius)
Factors
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
AB
Dietary Composition
nestlings/fledglings:
earthworms
sowbugs
spiders
millipedes
short-horned grass-
hoppers
beetles
lepidopteran larvae
ants
unidentified animal
grass (all parts)
mulberries
honeysuckle seeds
unidentified plants
adults:
fruit
invertebrates
adults:
fruit
invertebrates
adults:
fruit
invertebrates
Mean
198
182
7
93
8
92
17
83
Summer
15.0
1.7
2.3
3.1
4.9
11.6
24.7
3.2
5.2
19.5
3.2
2.4
4.2
68
32
41
59
29
71
Range or Location or
(95% Cl of mean) subspecies
Fall
92
8
76
24
63
37
Winter
83
17
73
27
70
30
Location/Habitat
(measure)
south central New
York/forest
(% wet weight; stomach
contents)
(age of robins ranged from 3
to 35 days after hatching;
presence of grass is likely to
be accidental - carried along
with prey)
eastern United States
(% volume;
stomach contents)
central United States
(% volume;
stomach contents)
western United States
(% volume;
stomach contents)
Reference
Walsberg & King, 1978
estimated
Reference
Howell, 1942
Wheelwright, 1986
Wheelwright, 1986
Wheelwright, 1986
Note
No.
9
10
Note
No.
11
11
11
00
3
(D
?.
O
0)
3
o
o;
5'
-------
American Robin (Turdus migratorius)
Population
Dynamics
Territory
Size (ha)
Foraging
Home Range
(ha)
Population
Density
(pairs/ha)
Clutch Size
Clutches/Year
Days
Incubation
Age at
Fledging
(days)
Number
Fledge per
Breeding Pair
Number
Fledge per
Successful
Nest
Age/Sex
Cond./Seas.
spring
AB
AB
AB
summer,
adults
feeding:
nestlings
fledglings
spring
AB
AB
AB
B
five areas
Mean
0.42
0.11
0.21
0.15 ±0.021 SE
0.81 ±0.13SE
1.98±0.48SD
8.6
4.9
3.17
3.45 ± 0.59 SD
2
12.5 ± 0.14 SE
13.4 ± 0.13 SE
5.6
3.9
1.5 ± 0.45 SE
2.9
2.5 ± 0.15 SD
Range
0.12-0.84
1.39-2.54
1 -5
1 -5
1 -3
10-14
2.4 - 3.4
(over 5 areas)
Location/Habitat
Tennessee/campus
New York/dense conifers
/unspecified forest
Ontario/deciduous forest
Tennessee/campus
New York/dense conifers
/unspecified forest
Illinois/suburban
Wisconsin/park
New York/forest
Wisconsin/park
Wisconsin/park
Wisconsin/park
New York/forest
Ontario/deciduous forest
Wisconsin/park
Maine/forest
Reference
Pitts, 1984
Howell, 1942
Weatherhead & McRae, 1990
Pitts, 1984
Howell, 1942
Klimstra & Stieglitz, 1957
Young, 1955
Howell, 1942
Young, 1955
Young, 1955
Young, 1955
Howell, 1942
Weatherhead & McRae, 1990
Young, 1955
Knuppetal., 1977
Note
No.
12
13
3
(D
?.
O
0)
3
o
o;
5'
-------
American Robin (Turdus migratorius)
Population
Dynamics
Age at
Sexual
Maturity
Annual
Mortality Rates
(percent)
Longevity
(years)
Age/Sex
Cond./Seas.
B
AB
JB
after Jan. 1 of
first year
early April
late April
early May
early May
early May
mid-May
mid-April
early June
mid-Sept.
February
mid -March
Mean
1 year
51±0.5SE
78-82
1.3-1.4
mid-April
late May
July & August
mid-October
Range
up to 9
late April
mid-July
early July
early November
early November
March
mid-April
Location/Habitat
NS
North America
North America
Location
Illinois
south central New York
n Maine
west: California, New
Mexico
east: VA, WV, DC, NY
northeast: VT, NH, CT
Kentucky
Colorado
North America
migrating through
Minnesota
leaving New York
arriving New York
arriving Wisconsin
Reference
Henny, 1972
Henny, 1972
Farner, 1949
Klimstra & Stieglitz, 1957
Howell, 1942
Knuppetal., 1977
James & Shugart, 1974
James & Shugart, 1974
James & Shugart, 1974
James & Shugart, 1974
James & Shugart, 1974
Wheelwright, 1986
Fuller, 1977
Howell, 1942
Howell, 1942
Young, 1951
Note
No.
Note
No.
10
ISJ
o
o
3
(D
?.
O
0)
3
o
o;
5'
1 As cited in Dunning (1984).
2 Estimated using equation 3-27 (Lasiewski and Dawson, 1967) and body weights from Clench and Leberman (1978).
3 Hazelton et al. (1984) estimate using Kendeigh's (1969) equations for a 55-g bird.
4 Estimated using equation 3-36 (Nagy, 1987) and body weights from Clench and Leberman (1978).
-------
American Robin (Turdus migratorius)
5 Estimated kcal consumed in feeding trials. Diet consisted of paired offerings of fruit (to test preferences) over a 2-day period, 12 trials per pairing.
Fruit included strawberries (2.29 kcal/g), cherries (4.34 kcal/g), green grapes (2.59 kcal/g), and purple grapes (5.85 kcal/g). Mean weight of the
birds = 55 g.
6 Based on gizzard contents of robins caught foraging in vineyards; diet 85 percent (wet weight) grapes, 11.5 percent invertebrates, and 4.5 percent
other plants. Mean weight of the birds = 82.3 g.
7 Based on same study described in note 5 and estimated weights of fruits consumed.
8 Estimated using equation 3-15 (Calder and Braun, 1983) and body weights from Clench and Leberman (1978).
9 Beak surface area 3.1 cm2; leg surface area 14.0 cm2.
10 Estimated using equation 3-21 (Meeh, 1879 and Rubner, 1883, as cited in Walsberg and King, 1978) and body weights from Clench and Leberman
(1978).
11 The U.S. Biological Survey and U.S. Fish and Wildlife Service records on which this study is based have several limitations: more birds were
collected in agricultural and suburban than natural areas; seasons and time of day of collection were convenient to the collectors; quickly
digested foods such as earthworms and other soft-bodied insects are underrepresented.
12 Birds nesting in high densities in dense coniferous forest probably foraged elsewhere more of the time than did birds with larger territories in
less dense forests.
13 Also included data from Howell (1942) (Ithaca, New York) in calculations.
10
o
3
(D
?.
O
0)
3
o
o;
5'
-------
References (including Appendix)
Aldrich, J. W.; James, F. C. (1991) Ecogeographic variation in the American robin (Turdus
migratorius). Auk 108: 230-249.
Armstrong, J. T. (1965) Breeding home range in the nighthawk and other birds: its
evolutionary and ecological significance. Ecology 46: 619-629.
Baird, J. W. (1980) The selection and use of fruit by birds in an eastern forest. Wilson Bull.
92: 63-73.
Bovitz, P. (1990) Relationships of foraging substrate selection and roosting in American
robins and European starlings [master's thesis]. New Brunswick, NJ: Rutgers
University.
Brackbill, H. (1952) Three-brooded American robin. Bird-Banding 23: 29.
Butts, W. K. (1927) The feeding range of certain birds. Auk 44: 329-350.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Clench, M. H.; Leberman, R. C. (1978) Weights of 151 species of Pennsylvania birds
analyzed by month, age, and sex. Bull. Carnegie Mus. Nat. Hist.
Dorst, J. (1962) The migration of birds. Boston: Houghton Mifflin Co.
Dunning, J. B., Jr. (1984) Body weights of 686 species of North American birds. Western
Bird Banding Association, Monograph No. 1. Cave Creek, AZ: Eldon Publishing.
Farner, D. S. (1945) Age groups and longevity in the American robin. Wilson Bull. 57: 56-74.
Farner, D. S. (1949) Age groups and longevity in the American robin: comments, further
discussion, and certain revisions. Wilson Bull. 61: 68-81.
Fuller, P. (1977) Fall robin migration. Loon 49: 239-240.
Gochfeld, M.; Burger, J. (1984) Age differences in foraging behavior of the American robin
(Turdus migratorius). Behaviour 88: 227-239.
Hamilton, W. J., Jr. (1940) Summer food of the robin determined by fecal analyses. Wilson
Bull. 52: 79-82.
Hamilton, W. J., Jr. (1943) Spring food of the robin in central New York. Auk 60: 273.
2-202 American Robin
-------
Hazelton, P. K., Robel, R. J.; Dayton, A. D. (1984) Preferences and influences of paired food
items on energy intake of American robins (Turdus migratorius) and gray catbirds
(Dumetella carolinensis). J. Wildl. Manage 48: 198-202.
Henny, C. J. (1972) An analysis of the population dynamics of selected avian species with
special reference to changes during the modern pesticide era. Washington, DC: Bur.
Sport. Fish. Wildl., Wildl. Res. Rep. 1.
Hirth, D. H.; Hester, A. E.; Greeley, F. (1969) Dispersal and flocking of marked young robins
(Turdus m. migratorius) after fledging. Bird-Banding 40: 208-215.
Howell, J. C. (1940) Spring roosts of the robin. Wilson Bull. 52: 19-23.
Howell, J. C. (1942) Notes on the nesting habits of the American robin (Turdus migratorius
L.). Am. Midi. Nat. 28: 529-603.
James, F. C.; Shugart, H. H. (1974) The phenology of the nesting season of the American
robin (Turdus migratorius) in the United States. Condor 76: 159-168.
Jung, R. E. (1992) Individual variation in fruit choice by American robins Turdus
migratorius. Auk 109: 98-111.
Karasov, W. H.; Levey, D. J. (1990) Digestive system trade-offs and adaptations of
frugivorous passerine birds. Physiol. Zool. 63: 1248-1270.
Kendeigh, S. C. (1969) Tolerance of cold and Bergmann's rule. Auk 86: 13-25.
Klimstra, W. D.; Stieglitz, W. O. (1957) Notes on reproductive activities of robins in Iowa
and Illinois. Wilson Bull. 69: 333-337.
Knupp, D. M.; Owen, R. B.; Dimond, J. B. (1977) Reproductive biology of American robins in
northern Maine. Auk 94: 80-85.
Lasiewski, R. C.; Dawson, W. R. (1967). A reexamination of the relation between standard
metabolic rate and body weight in birds. Condor 69: 12-23.
Levey, D. J.; Karasov, W. H. (1989) Digestive responses of temperate birds switched to fruit
or insect diets. Auk 106: 675-686.
Levey, D. J.; Karasov, W. H. (1992) Digestive modulation in a seasonal frugivore: the
American robin Turdus migratorius. Am. J. Physiol. 262: G711-G718.
Malmborg, P. K.; Willson, M. F. (1988) Foraging ecology of avian frugivores and some
consequences for seed dispersal in an Illinois woodlot. Condor 90: 173-186.
Martin, A. C.; Zim, H. S.; Nelson, A. L. (1951) American wildlife and plants. New York, NY:
McGraw-Hill Book Company, Inc.
2-203 American Robin
-------
Meeh, K. (1879) Oberflachenmessungen des mensclichen Korpers. Z. Biol. 15: 426-458.
Morrison, D. W.; Caccamise, D. F. (1990) Comparison of roost use by three species of
communal roostmates. Condor 92: 405-412.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Geographic Society. (1987) Field guide to the birds of North America. Washington,
DC: National Geographic Society.
Paszkowski, C. A. (1982) Vegetation, ground, and frugivorous foraging of the American
robin Turdus migratorius. Auk 99: 701-709.
Pitts, T. D. (1984) Description of American robin territories in northwest Tennessee.
Migrant 55: 1-6.
Robbins, C. S.; Bruun, B.; Zim, H. S. (1983) A guide to field identification: birds of North
America. New York, NY: Golden Press.
Robbins, C. S.; Sauer, J. R.; Greenberg, R. S.; et al. (1989) Population declines in North
American birds that migrate to the neotropics. Proc. Natl. Acad. Sci. USA 86: 7658-
7662.
Rubner, M. (1883) Uber den Einfluss der Korpergrosse auf Stoff- und Kraftweschsel. Z.
Biol. 19: 535-562.
Sharp, M. H. (1990) America's songbird-species profile: American robin (Turdus
migratorius). Wild Bird 4: 22-27.
Skorupa, J. P.; Hothem, R. L. (1985) Consumption of commercially-grown grapes by
American robins (Turdus migratorius): a field evaluation of laboratory estimates. J.
Field Ornithol. 56: 369-378.
Speirs, J. M. (1953) Winter distribution of robins east of the Rocky Mountains. Wilson Bull.
65: 175-183.
Terborgh, J. (1989). Where have all the birds gone? Princeton, NJ: Princeton University
Press.
Walsberg, G. E.; King, J. R. (1978) The relationship of the external surface area of birds to
skin surface area and body mass. J. Exp. Biol. 76: 185-189.
Weatherhead, P. J.; McRae, S. B. (1990) Brood care in American robins: implications for
mixed reproductive strategies by females. Anim. Behav. 39: 1179-1188.
Wheelwright, N. T. (1986) The diet of American robins: an analysis of U.S. Biological
Survey records. Auk 103: 710-725.
2-204 American Robin
-------
Wheelwright, N. T. (1988) Seasonal changes in food preferences of American robins in
captivity. Auk 105: 374-378.
Young, H. (1951) Territorial behavior of the eastern robin. Proc. Linnean Soc. N.Y. 58-62:
1-37.
Young, H. (1955) Breeding behavior and nesting of the eastern robin. Am. Midi. Nat. 53:
329-352.
2-205 American Robin
Page 2-206 was left blank.
-------
2.2. MAMMALS
Table 2-2 lists the mammalian species described in this section. For range maps,
refer to the general references identified in the individual species profiles. The remainder
of this section is organized by species in the order presented in Table 2-2. The availability
of information in the published literature varies substantially among species, as is reflected
in the profiles. Some of the selected species include two or more subspecies; these are
indicated in the profiles when reported by the investigators. Body lengths of the mammals
are reported for the length of the outstretched animal from the tip of the nose to the base
of the tail. The tail measurements do not include the hairs at the tip, but only the tail
vertebrae. Body weight is reported as fresh wet weight with pelage, unless otherwise
noted.
2-207
-------
Table 2-2. Mammals Included in the Handbook
Order
Subfamily
Soricidae
Canidae
Procyonidae
Mustelidae
Mustelinae
Lutrinae
Phocidae
Cricetidae
Sigmodontinae
Arvicolinae
Leporidae
Common name
short-tailed shrew
red fox Vulpes
raccoon
mink
river otter
harbor seal
deer mouse
prairie vole
meadow vole
muskrat
eastern cottontail
Scientific name
Blarina brevicauda
vulpes 2.2.2
Procyon lotor
Mu stela vison
Lutra canadensis
Phoca vitulina
Peromyscus maniculatus
Microtus ochrogaster
Microtus pennsylvanicus
Ondatra zibethicus
Sylvilagus floridanus
Section
2.2.1
2.2.3
2.2.4
2.2.5
2.2.6
2.2.7
2.2.8
2.2.9
2.2.10
2.2.11
2-208
-------
2.2.1. Short-Tailed Shrew (shrews)
Order Insectivora, Family Soricidae. Shrews are small insectivorous mammals that
inhabit most regions of the United States. They have high metabolic rates and can eat
approximately their body weight in food each day. Most species are primarily vermivorous
and insectivorous, but some also eat small birds and mammals.
Selected species
The northern short-tailed shrew (Blarina brevicauda) ranges throughout the north-
central and northeastern United States and into southern Canada (George et al., 1986). It
eats insects, worms, snails, and other invertebrates and also may eat mice, voles, frogs,
and other vertebrates (Robinson and Brodie, 1982). Because they prey on other
vertebrates, shrews can concentrate DDT (and presumably other bioaccumulative
chemicals) to levels 10 times higher than either Peromyscus and Clethrionomys (Dimond
and Sherburne, 1969). Shrews are an important component of the diet of many owls
(Palmer and Fowler, 1975; Burt and Grossenheider, 1980) and are also prey for other
raptors, fox, weasels, and other carnivorous mammals (Buckner, 1966).
Body size. Short-tailed shrews are 8 to 10 cm in length with a 1.9 to 3.0 cm tail
(Burt and Grossenheider, 1980). The short-tailed shrew is the largest member of the
genus, with some weighing over 22 g (George et al., 1986; see table). Some studies have
found little or no sexual dimorphism in size (Choate, 1972), while other reports show that
males are slightly larger than females (George et al., 1986; Guilday, 1957).
Metabolism. Short-tailed shrews are active for about 16 percent of each 24-hour
period (Martinsen, 1969), in periods of around 4.5 minutes at a time (Buckner, 1964). The
shrew's metabolism is inversely proportional to the ambient temperature, within the range
of 0 to 25 C (Randolph, 1973). Sleeping metabolism is half that associated with normal,
exploring activity (Randolph, 1973). Randolph (1973) developed a regression equation for
metabolism (cc O2/g-hour) during (1) interrupted sleep:6
(Winter) Y = 4.754 - 0.0869 (X -16.4305)
(Summer) Y = 5.3448 - 0.1732 (X -16.2310)
and (2) normal exploring activity:
(Winter) Y = 6.5425 - 0.0516 (X -12.0600)
(Summer) Y = 7.949 - 0.2364 (X -16.9554) where X= ambient temperature
in °C.
Randolph (1973) also developed a regression equation for overall metabolism (cal/animal-
hour) for shrews spending equal amounts of time sleeping and exploring (cal/animal-hour)
as a function of ambient temperature:
"Randolph's (1973) equations could be simplified to match that of Deavers and Hudson (1981;
next page) in form; however, we report the equations as Randolph reported them.
2-209 Short-Tailed Shrew
-------
(Winter) Y = 583.83 - 7.53 (X -13.68)
(Summer) Y = 544.86 - 20.37 (X -16.33), where X= ambient temperature in °C.
Deavers and Hudson (1981) found a linear increase in standard (near basal)
metabolism with decreasing temperature that is similar to that for interrupted sleep
described above (Y = standard metabolism in cc O2/g-hour):
Y = 8.84 - 0.22 (X) where X= ambient temperature.
Deavers and Hudson (1981) found that within the thermoneutral zone, the standard
metabolic rate of the short-tailed shrew is approximately 190 percent the metabolic rate
predicted from body weight.
Habitat. Short-tailed shrews inhabit a wide variety of habitats and are common in
areas with abundant vegetative cover (Miller and Getz, 1977). Short-tailed shrews need
cool, moist habitats because of their high metabolic and water-loss rates (Randolph, 1973).
Food habits. The short-tailed shrew is primarily carnivorous. Stomach analyses
indicate that insects, earthworms, slugs, and snails can make up most of the shrew's food,
while plants, fungi, millipedes, centipedes, arachnids, and small mammals also are
consumed (Hamilton, 1941; Whitaker and Ferraro, 1963). Small mammals are consumed
more when invertebrates are less available (Allen, 1938; Platt and Blakeley, 1973, cited in
George et al., 1986). Shrews are able to prey on small vertebrates because they produce a
poison secretion in their salivary glands that is transmitted during biting (Pearson, 1942,
cited in Eadie, 1952). The short-tailed shrew stores food, especially in the autumn and
winter (Hamilton, 1930; Martin, 1984). Robinson and Brodie (1982) found that short-tailed
shrews cached most (86.6 percent) of the prey captured; only 9.4 percent was consumed
immediately. Short-tailed shrews consume approximately 40 percent more food in winter
than in summer (Randolph, 1973). The shrew must consume water to compensate for its
high evaporative water loss, despite the fact that it obtains water from both food and
metabolic oxidation (Chew, 1951). Deavers and Hudson (1981) indicated that the short-
tailed shrew's evaporative water loss increases with increasing ambient temperature even
within its thermoneutral zone. Short-tailed shrews' digestive efficiency is about 90 percent
(Randolph, 1973).
Temperature regulation and molt. The short-tailed shrew does not undergo torpor
but uses nonshivering thermogenesis (NST) to compensate for heat loss during cold
stress in winter (Zegers and Merritt, 1987). The short-tailed shrew exhibits three molts.
Two are seasonal molts, the first in October/November replaces summer with winter
pelage and occurs in first- and second-year shrews. The spring molt can occur any time
from February to October. The third molt occurs in postjuveniles that have reached adult
size (Findley and Jones, 1956).
Breeding activities and social organization. The short-tailed shrew probably breeds
all year, including limited breeding in winter even in the northern portions of its range
(Blus, 1971). In Illinois, males were found to be most active from January to July, females
from March to September (Getz, 1989). There are two peak breeding periods, in
2-210 Short-Tailed Shrew
-------
the spring and in late summer or early fall (Blair, 1940). The home ranges of short-tailed
shrews in summer overlap both within and between sexes (Blair, 1940), although females
with young do exhibit some territoriality (Platt, 1976). Nomadic shrews are either young of
the year or adults moving to areas with more abundant prey (Platt, 1976).
Home range and resources. Short-tailed shrews inhabit round, underground nests
and maintain underground runaways, usually in the top 10 cm of soil, but sometimes as
deep as 50 cm (Hamilton, 1931; and Jameson, 1943, cited in George et al., 1986). Winter,
nonbreeding home ranges can vary from 0.03 to 0.07 ha at high prey densities to 1 to 2.2
ha during low prey densities with a minimum of territory overlap. In the summer, ranges of
opposite sex animals overlap, but same sex individuals do not; females with young exclude
all others from their area (Platt, 1976).
Population density. Population densities vary by habitat and season (Getz, 1989;
Jackson, 1961; Platt, 1968). In east-central Illinois, population density was higher in
bluegrass than in tallgrass or alfalfa (Getz, 1989). In all three of these habitats, the short-
tailed shrew exhibited annual abundance cycles, with peak densities ranging from 2.5 to 45
shrews per hectare, depending on the habitat (Getz, 1989). The peaks occurred from July
to October (12.9/ha average for all three habitats), apparently just following peak
precipitation levels (Getz, 1989).
Population dynamics. Winter mortality up to 90 percent has been reported for the
short-tailed shrew (Barbehenn, 1958; Gottschang, 1965; Jackson, 1961, cited in George et
al., 1986); however, Buckner (1966) suggests that mortality rates in winter may be closer to
70 percent, which is similar to the average monthly mortality rate he found for subadult
animals. Several litters, averaging four to five pups, are born each year (George et al.,
1986).
Similar species (from general references)
• The masked shrew (Sorex cinereus) (length 5.1 to 6.4 cm; weight 3 to 6 g) is
smaller than the short-tailed shrew and is the most common shrew in moist
forests, open country, and brush of the northern United States and
throughout Canada and Alaska. It feeds primarily on insects.
• Merriam's shrew (Sorex merriami) (5.7 to 6.4 cm) is found in arid areas and
sagebrush or bunchgrass of the western United States and is smaller than
the short-tailed shrew.
• The smokey shrew (Sorex fumeus) (6.4 to 7.6 cm; 6 to 9 g), smaller than the
short-tailed, prefers birch and hemlock forests with a thick leaf mold on the
ground to burrow in. It uses burrows made by small mammals or nests in
stumps, logs, and among rocks. Range is limited to the northeast United
States and east of the Great Lakes in Canada.
• The southeastern shrew (Sorex longirostris) (5.1 to 6.4 cm; 3 to 6 g) prefers
moist areas. Found mostly in open fields and woodlots, its range is limited
2-211 Short-Tailed Shrew
-------
to the southeastern United States. It nests in dry grass or leaves in a
shallow depression.
• The long-tailed shrew (Sorex dispar) (7.0 cm; 5 to 6 g) inhabits cool, moist,
rocky areas in deciduous or deciduous-coniferous forests of the northeast,
extending south to the North Carolina and Tennessee border.
• The vagrant shrew (Sorex vagrans) (5.9 to 7.3 cm; 7 ± g) inhabits marshy
wetlands and forest streams. Its range is confined to the western United
States, excluding most of California and Nevada. In addition to insects, it
also eats plant material.
• The Pacific shrew (Sorex pacificus) (8.9 cm) is slightly larger than the short-
tailed shrew. It is limited to redwood and spruce forests, marshes, and
swamps of the northern California and southern Oregon coasts.
• The dwarf shrew (Sorex nanus) (6.4 cm) is rare throughout its limited range
in the western United States.
• The least shrew (Cryptotis parva) (5.6 to 6.4 cm; 4 to 7 g) is easily
distinguished from other shrews by its cinnamon color. It inhabits grassland
and marsh; its range is similar to the short-tailed shrew but does not extend
as far north.
• The desert shrew (Notiosorex crawfordi) (Gray shrew) (5.1 to 6.6 cm) is
rarely seen and is found only in the arid conditions, chaparral slopes, alluvial
fans, and around low desert shrubs of the extreme southwest. It nests
beneath plants, boards, or debris.
General references
Burt and Grossenheider (1980); George et al. (1986).
2-212 Short-Tailed Shrew
-------
Short-Tailed Shrew (Blarina brevicauda)
Factors
Body Weight
(g)
Metabolic
Rate
(I02/kg-day)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
M summer
F summer
Mfall
Mfall
neon ate
basal
average daily
average daily
+ 20°C
-20°C
basal
average daily
average daily
AB:22-23°C
AB:25°C
AB
AB
AB
AB
Mean
1 5.0 ± 0.78 SD
19.21 ±0.42SD
17.40 ± 0.48 SD
16.87 ±0.21 SD
1 5.58 ± 0.23 SD
82
125
127 ± 15.3 SD
126.5
207.1
390
600
680
7.95 ±0.17 g/dSD
0.49 g/g-day
0.62 g/g-day
0.223
0.026
54
84
Range
or (95% Cl)
17.0-22.0
14.0-21.0
13.0-22.0
12.5-22.5
0.67-1.29
80-84
106-150
94-218
Location
New Hampshire
w Pennsylvania
Maryland/lab
Pennsylvania/lab
NS/lab
Ontario, CAN/lab
Pennsylvania/lab
Wisconsin/lab
Ohio/lab
Wisconsin/lab
Illinois/lab
Pennsylvania/lab
Reference
Schlesinger & Potter, 1974
Guilday, 1957
Blus, 1971
Pearson, 1947
Morrison, 1948
Randolph, 1973
Pearson, 1947
Morrison etal., 1957
Barrett & Stuek, 1976
Morrison etal., 1957
Chew, 1951
estimated
Pearson, 1947
estimated
Note
No.
1
2
3
4
5
6
7
8
9
10
ISJ
_1
CO
CO
3-
o
3-
i!
(D
Q.
CO
-------
Short-Tailed Shrew (Blarina brevicauda)
Dietary
Composition
earthworms
slugs & snails
misc. animals
Endegon (fungi)
beetles
vegetation
lepidopteran
larvae
chilopoda
other
insects
annelids
vegetable matter
centipedes
arachnids
snails
small mammals
Crustacea
undetermined
Population
Dynamics
Home Range
Size (ha)
Spring
Age/Sex/
Cond./Seas.
A F summer
A M summer
BBall
B B winter (a)
B B winter (b)
Summer
31.4
27.1
8.1
7.7
5.9
5.4
4.3
1.8
8.6
77.6
41.8
17.1
7.4
6.1
5.4
5.2
3.7
2.4
Fall
Mean
0.39 ± 0.036 SD
Winter
Location/Habitat
(measure)
New York/NS
(% volume; stomach
contents)
(June through October
collections combined)
eastern United States
(primarily New York)/NS
(% frequency of
occurrence; stomach
contents)
(all seasons combined)
Range
<0.1 -0.36
<0.1 -1.8
0.03 - 0.07
0.10-0.22
Reference
Whitaker&Ferraro, 1963
Hamilton, 1941
Location/Habitat
s Michigan/bluegrass
s Manitoba/tamarack bog
c New York/old field
Reference
Blair, 1940
Buckner, 1966
Platt, 1976
Note
No.
Note
No.
10
10
ISJ
CO
3"
O
3-
i!
(D
Q.
CO
-------
Short-Tailed Shrew (Blarina brevicauda)
Population
Dynamics
Population
Density (N/ha)
Litter
Size
Litters
/Year
Days
Gestation
Age at
Weaning
(days)
Age at
Sexual
Maturity
Annual
Mortality
Longevity
Age/Sex/
Cond./Seas.
winter
spring
summer
fall
BB
M
M
F
BB
M
F
B
Mean
2.3
5.9
11.4
10.0
5.4
4.7 ± 0.2 SE
several
21 -22
25-30
< 1 year
93%
4.6 months
4.4 months
Range
1.6-121
0.06-0.16
2-8
1 -8
> 65 days
> 83 days
< 20 months
Location/Habitat
ec Illinois/alfalfa
Wisconsin/beech-maple
Manitoba, Canada/
tamarack bog
Indiana/NS
Maryland/lab
NS/NS
Maryland/lab
Maryland/lab
Maryland/lab
NS/NS
Indiana/NS
MD, PA, NY, MA/NS
Maryland/lab
c New York/woods, field
Reference
Getz, 1989
Jackson, 1961; Williams,
1936
Buckner, 1966
French, 1984
Blus, 1971
George etal., 1986
Blus, 1971
Blus, 1971
Blus, 1971
Pearson, 1944
French, 1984
Pearson, 1945
Blus, 1971
Dapson, 1968
Note
No.
11
12
11
13
10
ISJ
_1
Ol
CO
3"
o
3-
i!
(D
Q.
CO
-------
Short-Tailed Shrew (Blarina brevicauda)
Seasonal
Activity
Mating
Begin
late February
October
February
Peak
April - May
May - June
End
mid-September
November
July
Location
Indiana
c New York
NS
NS
Reference
French, 1984
Dapson, 1968
Findley& Jones, 1956
Findley & Jones, 1956
Note
No.
11
11
10
ISJ
_1
o>
1 Ambient temperatures 25 to 30°C; mean weight of shrews = 21.2 g.
2 Ambient temperatures 15to25°C; mean weight of shrews = 21 g.
3 Calculated from oxygen consumption rate; mean weight of shrews = 21.2 g. Basal metabolism is 186 percent higher than predicted from
equations 3-42 or 3-43, in agreement with the finding of Deavers and Hudson (1981). Average daily metabolism was estimated over 24-hour
period at 25 to 30 C and is 146 percent higher than the free-living metabolic rate predicted on the basis of equation 3-47 (Nagy, 1987).
4 Calculated from average food consumption rate (liver; 1.22 kcal/g wet weight) at 25 C. This value is 167 percent higher than the free-living
metabolic rate predicted on the basis of equation 3-47 (Nagy, 1987).
5 Diet of mealworms estimated to provide 2.33 kcal/g live weight. Assimilation efficiency for shrews consuming mealworms = 89.5 ±1.9 SD.
6 Diet of beef liver; mean weight of shrews = 21 g.
7 Estimated using equation 3-20 (Stahl, 1967) and adult male summer body weights from Guilday (1957).
8 Estimate for 21.2-g shrew.
9 Estimated using equation 3-22 (Stahl, 1967) and adult male summer body weights from Guilday (1957).
10 (a) At high prey density; (b) at low prey density.
11 Cited in George et al. (1986).
12 From pairing to parturition.
13 Mean longevity of animals that survived to weaning.
CO
3-
o
3-
(D
Q.
CO
-------
References (including Appendix)
Allen, D. L. (1938) Ecological studies on the vertebrate fauna of a 500-acre farm in
Kalamazoo County, Michigan. Ecol. Monogr. 8: 347-436.
Barbehenn, K. R. (1958) Spatial and population relationships between Microtus and Blarina.
Ecology 39: 293-304.
Barrett, G. W.; Stueck, K. L. (1976) Caloric ingestion rate and assimilation efficiency of the
short-tailed shrew, Blarina brevicauda. Ohio J. Sci. 76: 25-26.
Blair, W. F. (1940) Notes on home ranges and populations of the short-tailed shrew.
Ecology 21: 284-288.
Blair, W. F. (1941) Some data on the home ranges and general life history of short-tailed
shrews, red-backed voles and woodland jumping mice in northern Michigan. Am.
Midi. Nat. 25: 681-685.
Blus, L. J. (1971) Reproduction and survival of short-tailed shrews (Blarina brevicauda) in
captivity. Lab. Anim. Sci. 21: 884-891.
Buckner, C. H. (1964) Metabolism, food capacity, and feeding behavior in four species of
shrews. Can. J. Zool. 42: 259-279.
Buckner, C. H. (1966) Populations and ecological relationships of shrews in tamarack bogs
of southeastern Manitoba. J. Mammal. 47: 181-194.
Burt, W. H.; Grossenheider, R. P. (1980) A field guide to the mammals of North America
north of Mexico. Boston, MA: Houghton Mifflin Co.
Chew, R. M. (1951) The water exchanges of some small mammals. Ecol. Monogr. 21:
215-225.
Choate, J. R. (1972) Variation within and among populations of short-tailed shrews, Blarina
brevicauda. J. Mammal. 53: 116-128.
Dapson, R. W. (1968) Reproduction and age structure in a population of short-tailed
shrews, Blarina brevicauda. J. Mammal. 49: 205-214.
Deavers, D. R.; Hudson, J. W. (1981) Temperature regulation in two rodents (Clethrionomys
gapperi and Peromyscus leucopus) and a shrew (Blarina brevicauda) inhabiting the
same environment. Physiol. Zool. 54: 94-108.
Dimond, J. B.; Sherburne, J. A. (1969) Persistence of DDT in wild populations of small
mammals. Nature 221: 486-487.
2-217 Short-Tailed Shrew
-------
Eadie, R. W. (1952) Shrew predation and vole populations on a localized area. J. Mammal.
33: 185-189.
Findley, J. S.; Jones, J. K., Jr. (1956) Molt of the short-tailed shrew, Blarina brevicauda.
Am. Midi. Nat. 56: 246-249.
French, T. W. (1984) Reproduction and age structure of three Indiana shrews. Proc. Indiana
Acad. Sci. 94: 641-644.
George, S. B.; Choate, J. R.; Genoways, H. H. (1986) Blarina brevicauda. American Society
of Mammalogists; Mammalian Species 261.
Getz, L. L. (1989) A 14-year study of Blarina brevicauda populations in east-central Illinois.
J. Mammal. 70: 58-66.
Gottschang, J. L. (1965) Winter populations of small mammals in old fields of southwestern
Ohio. J. Mammal. 46: 44-52.
Guilday, J. E. (1957) Individual and geographic variation in Blarina brevicauda from
Pennsylvania. Ann. Carnegie Mus. 35: 41-68.
Hamilton, W. J., Jr. (1929) Breeding habits of the short-tailed shrew, Blarina brevicauda. J.
Mammal. 10: 125-134.
Hamilton, W. J., Jr. (1930) The food of the Soricidae. J. Mammal. 11: 26-39.
Hamilton, W. J., Jr. (1931) Habits of the short-tailed shrew, Blarina brevicauda (Say). Ohio
J. Sci. 31:97-106.
Hamilton, W. J., Jr. (1941) The foods of small forest mammals in eastern United States. J.
Mammal. 22: 250-263.
Jackson, H. H. T. (1961) Mammals of Wisconsin. Madison, Wl: University of Wisconsin
Press.
Jameson, E. W., Jr. (1943) Notes on the habits and siphanapterous parasites of the
mammals of Welland County, Ontario. J. Mammal. 24: 194-197.
Lomolino, M. V. (1984) Immigrant selection, predation, and the distribution of Microtus
pennsylvanicus and Blarina brevicauda on islands. Am. Nat. 123: 468-483.
Martin, I. G. (1984) Factors affecting food hoarding in the short-tailed shrew Blarina
brevicauda. Mammalia 48: 65-71.
Martinsen, D. L. (1969) Energetics and activity patterns of short-tailed shrews (Blarina) on
restricted diets. Ecology 50: 505-510.
2-218 Short-Tailed Shrew
-------
Miller, H.; Getz, L. L. (1977) Factors influencing local distribution and species diversity of
forest small mammals in new England. Can. J. Zool. 55: 806-814.
Morrison, P. R. (1948) Oxygen consumption in several small wild mammals. J. Cell. Comp.
Physiol. 31:69-96.
Morrison, P. R.; Pierce, M.; Ryser, F. A. (1957) Food consumption and body weight in the
masked and short-tailed shrews (genus Blarina) in Kansas, Iowa, and Missouri. Ann.
Carnegie Mus. 51: 157-180.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Mono. 57: 111-128.
Neal, C. M.; Lustick, S. I. (1973) Energetics and evaporative water loss in the short-tailed
shrew Blarina brevicauda. Physiol. Zool. 46: 180-185.
Palmer, E. L.; Fowler, H. S. (1975) Fieldbook of natural history. New York, NY: McGraw-Hill
Book Co.
Pearson, O. P. (1942) The cause and nature of a poisonous action produced by the bite of a
shrew (Blarina brevicauda). J. Mammal. 23: 159-166.
Pearson, O. P. (1944) Reproduction in the shrew (Blarina brevicauda Say). Am. J. Anat. 75:
39-93.
Pearson, O. P. (1945) Longevity of the short-tailed shrew. Am. Midi. Nat. 34: 531-546.
Pearson, O. P. (1947) The rate of metabolism of some small mammals. Ecology 29:
127-145.
Platt, A. P. (1968) Differential trap mortality as a measure of stress during times of
population increase and decrease. J. Mammal. 49: 331-335.
Platt, W. J. (1974) Metabolic rates of short-tailed shrews. Physiol. Zool. 47: 75-90.
Platt, W. J. (1976) The social organization and territoriality of short-tailed shrew (Blarina
brevicauda) populations in old-field habitats. Anim. Behav. 24: 305-318.
Platt, W. J.; Blakeley, N. R. (1973) Short-term effects of shrew predation upon invertebrate
prey sets in prairie ecosystems. Proc. Iowa Acad. Sci. 80: 60-66.
Randolph, J. C. (1973) Ecological energetics of a homeothermic predator, the short-tailed
shrew. Ecology 54: 1166-1187.
Richardson, J. H. (1973) Locomotory and feeding activity of the shrews, Blarina brevicauda
and Suncus murinus. Am. Midi. Nat. 90: 224-227.
2-219 Short-Tailed Shrew
-------
Robinson, D. E.; Brodie, E. D. (1982) Food hoarding behavior in the short-tailed shrew
Blarina brevicauda. Am. Midi. Nat. 108: 369-375.
Schlesinger, W. H.; Potter, G. L. (1974) Lead, copper, and cadmium concentrations in small
mammals in the Hubbard Brook Experimental Forest. Oikos 25:148-152.
Stahl, W. R. (1967) Scaling of respiratory variables in mammals. J. Appl. Physiol. 22:
453-460.
Whitaker, J. O., Jr.; Ferraro, M. G. (1963) Summer food of 220 short-tailed shrews from
Ithaca, New York. J. Mammal. 44: 419.
Williams, A. B. (1936) The composition and dynamics of a beech-maple climax community.
Ecol. Monogr. 6: 317-408.
Zegers, D. A.; Merritt, J. F. (1987) Adaptations of Peromyscus for winter survival in an
Appalachian montane forest. J. Mammal. 69: 516-523.
2-220 Short-Tailed Shrew
-------
2.2.2. Red Fox (foxes and coyotes)
Order Carnivora, Family Canidae. Unlike the more social wolves, foxes and coyotes
tend to hunt alone, although coyotes may hunt larger prey in pairs. Foxes and coyotes are
primarily carnivorous, preying predominantly on small mammals, but they also may eat
insects, fruits, berries, seeds, and nuts. Foxes are found throughout most of the United
States and Canada, including the arctic, as are coyotes with the exception of the
southeastern United States. Foxes and coyotes are active primarily at night.
Selected species
Red foxes (Vulpes vulpes) are present throughout the United States and Canada
except in the southeast, extreme southwest, and parts of the central states. Red fox prey
extensively on mice and voles but also feed on other small mammals, insects, hares, game
birds, poultry, and occasionally seeds, berries, and fruits (Palmer and Fowler, 1975).
Twelve subspecies are recognized in North America (Abies, 1974).
Body size. The dog-sized red fox has a body about 56 to 63 cm in length, with a 35
to 41 cm tail (Burt and Grossenheider, 1980). They weigh from 3 to 7 kg, with the males
usually outweighing the females by about 1 kg (Voigt, 1987; see table).
Habitat. As the most widely distributed carnivore in the world, the red fox can live
in habitats ranging from arctic areas to temperate deserts (Voigt, 1987). Red foxes utilize
many types of habitat—cropland, rolling farmland, brush, pastures, hardwood stands, and
coniferous forests (MacGregor, 1942; Eadie, 1943; Cook and Hamilton, 1944; Abies, 1974).
They prefer areas with broken and diverse upland habitats such as occur in most
agricultural areas (Abies, 1974; Samuel and Nelson, 1982; Voigt, 1987). They are rare or
absent from continuous stands of pine forests in the southeast, moist conifer forests along
the Pacific coast, and semiarid grasslands and deserts (Abies, 1974).
Food habits. The red fox feeds on both animal and plant material, mostly small
mammals, birds, insects, and fruit (Korschgen, 1959; Samuel and Nelson, 1982). Meadow
voles are a major food in most areas of North America; other common prey include mice
and rabbits (Korschgen, 1959; Voigt, 1987). Game birds (e.g., ring-necked pheasant and
ruffed grouse) and waterfowl are seasonally important prey in some areas (Pils and Martin,
1978; Sargeant, 1972; Voigt and Broadfoot, 1983). Plant material is most common in red
fox diets in summer and fall when fruits, berries, and nuts become available (Johnson,
1970; Major and Sherburne, 1987). Red foxes often cache food in a hole for future use
(Samuel and Nelson, 1982). They also are noted scavengers on carcasses or other refuse
(Voigt, 1987). Most activity is nocturnal and at twilight (Nowak and Paradiso, 1983).
Temperature regulation and molt. In winter, foxes do not undergo hibernation or
torpor; instead, they are active year-round. They undergo one molt per year, which usually
begins in April and is finished by June. The winter coat is regrown by October or
November in northern latitudes (Voigt, 1987).
2-221 Red Fox
-------
Breeding activities and social organization. Breeding occurs earlier in the south
than in the red fox's northern ranges (Samuel and Nelson, 1982) (see table). A mated pair
maintains a territory throughout the year, with the male contributing more to its defense
than the female (Preston, 1975). Pups are born and reared in an underground den, and the
male assists the female in rearing young, bringing food to the den for the pups (Samuel
and Nelson, 1982). Pups first emerge from the den when 4 to 5 weeks old (Samuel and
Nelson, 1982). Once considered solitary, red foxes now are reported to exhibit more
complex social habits (MacDonald and Voigt, 1985). A fox family, the basic social unit,
generally consists of a mated pair or one male and several related females (MacDonald,
1980; Voigt, 1987). The additional females are usually nonbreeders that often help the
breeding female (Voigt, 1987).
Home range and resources. The home ranges of individuals from the same family
overlap considerably, constituting a family territory (Sargeant, 1972; Voigt and MacDonald,
1984). Territories of neighboring red fox families are largely nonoverlapping and
contiguous, usually resulting in all parts of a landscape being occupied by foxes. Territory
sizes range from less than 50 to over 3,000 ha (see table). Territories in urban areas tend
to be smaller than those in rural areas (Abies, 1969). Adults visit most parts of their
territory on a regular basis; however, they tend to concentrate their activities near to their
dens, preferred hunting areas, abundant food supplies, and resting areas (Abies, 1974;
Keenan, 1981). Territory boundaries often conform to physical landscape features such as
well-traveled roads and streams (Abies, 1974). Territory defense is primarily by
nonaggressive mechanisms involving urine scent-marking and avoidance behaviors.
Scent marking occurs throughout the territory; there is little patrolling of territory
boundaries. Each fox or family usually has a main underground den and one or more other
burrows within the home range (Nowak and Paradiso, 1983). Most dens are abandoned
burrows of other species (e.g., woodchucks, badgers) (Samuel and Nelson, 1982). Tunnels
are up to 10 m in length and lead to a chamber 1 to 3 m below the surface (Nowak and
Paradiso, 1983). Pup-rearing dens are the focal point of fox activity during spring and early
summer. Foxes have some rest sites and usually forage away from the den (Voigt, 1987).
Population density. One red fox family per 100 to 1,000 ha is typical (Voigt, 1987;
see table). Red foxes have larger home ranges where population densities are low and in
poorer habitats (Voigt, 1987). Most young foxes, especially males, disperse before the age
of 1 (Voigt, 1987), usually during September to March, with peaks in dispersal in October
and November (Phillips et al., 1972; Storm et al., 1976).
Population dynamics. Foxes usually produce pups their first year, except in
extremely high density areas and in some years in northern portions of their range where
they may delay breeding until the next season (Allen, 1984; Harris, 1979; Storm et al., 1976;
Voigt and MacDonald, 1984). Litter size generally averages four to six pups (see table).
The pups leave the den about 1 month after birth, and they are weaned by about 8 to 10
weeks of age (Abies, 1974). Red foxes incur high mortality rates as a result of shooting,
trapping, disease, and accidents (e.g., roadkills) (Storm et al., 1976). Two factors that tend
to limit red fox abundance are competition with other canids, especially coyotes, and
seasonal limits on food availability (Voigt, 1987). Fecundity is higher in areas of high
mortality and low population densities (Voigt, 1987).
2-222 Red Fox
-------
Similar species (from general references)
• The arctic fox (Alopex lagopus) is smaller than the red fox (body length
approximately 51 cm; weight 3.2 to 6.7 kg) and is restricted in its distribution
to the arctic, found in the United States only in Alaska. This species
primarily scavenges for food but also eats lemmings, hares, birds, and eggs
as well as berries in season.
• The swift fox (Vulpes velox) is smaller than the red fox (body length 38 to 51
cm; weight 1.8 to 2.7 kg) and inhabits the deserts and plains of the southwest
and central United States. It dens in ground burrows and feeds on small
mammals and insects.
• The kit fox (Vulpes mac rot is) is similar in size to the swift fox and is
considered by some to be the same species, although it has noticeably
larger ears. It inhabits the southwestern United States and prefers open,
level, sandy areas and low desert vegetation. It feeds on small mammals and
insects.
• The gray fox (Urocyon cinereoargenteus) is similar in size (body length 53 to
74 cm; weight 3.2 to 5.8 kg) to the red fox and ranges over most of the United
States except the northwest and northern prairies, inhabiting chaparral, open
forests, and rimrock regions. Secretive and nocturnal, gray foxes will climb
trees to evade enemies. They feed primarily on small mammals but also eat
insects, fruits, acorns, birds, and eggs.
• The coyote (Cam's latrans) is much larger (body length 81 to 94 cm; weight 9
to 22 kg) than the red fox and is found throughout most of the United States
(except possibly eastern), western Canada, and Alaska. It inhabits prairies,
open woodlands, brushy and boulder-strewn areas, and dens in the ground.
Coyotes share some feeding habits with the red fox but also scavenge and
hunt larger prey in pairs.
General references
Abies (1974); Burt and Grossenheider (1980); Palmer and Fowler (1975); Voigt
(1987).
2-223 Red Fox
-------
Red Fox (Vulpes vulpes)
Factors
Body Weight
(kg)
Pup Growth
Rate (g/day)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Age/Sex/
Cond./Seas.
A M spring
A F spring
A M fall
A F fall
neonate B
at weaning B
birth to
weaning
J summer
A M basal
A F basal
A M free-living
A F free-living
J 5-8 wks
J 9-1 2 wks
J 13-24 wks
A before
whelp
F after whelp
A
nonbreeding
AM
AF
AM
AF
Mean
5.25 ± 0.18 SE
4.13 ±0.11 SE
4.82 ± 0.081 SE
3.94 ± 0.079 SE
0.102 ± 0.12 SD
0.70
15.9
193±56SD
47.9
51.1
161
168
0.16
0.12
0.11
0.075
0.14
0.069
0.084
0.086
2.0
1.7
Range or
(95% Cl of mean)
4.54 - 7.04
3.27 - 4.72
4.13-5.68
2.95 - 4.59
0.071 -0.109
(68 - 383)
(71 - 400)
Location
Illinois
Iowa
Wisconsin
North Dakota
North Dakota/lab
Ohio/lab
North Dakota/lab
North Dakota/captive
North Dakota/captive
Reference
Storm etal., 1976
Storm etal., 1976
Storm & Abies, 1966
Sargeant, 1978
Sargeant, 1978
Vogtsberger& Barrett, 1973
estimated
estimated
Sargeant, 1978
Sargeant, 1978
Sargeant, 1978
estimated
estimated
Note
No.
1
2
3
4
5
10
ISJ
10
o
X
-------
Red Fox (Vulpes vulpes)
Age/Sex/
Factors Cond./Seas.
Surface Area A M
(cm2) A F
Dietary
Composition
rabbits
small mammals
pheasant
other birds
misc.
not accounted for
mammals
birds
arthropods
plants
unspecified/other
rabbits
mice/rats
other mammals
poultry
carrion
livestock
birds
invertebrates
plant foods
mammals
birds
arthropods
plants
u ns pecif led/other
Spring
92.2
2.4
0.2
4.6
0.6
24.8
24.2
4.0
21.0
12.9
9.8
0.6
trace
2.7
Range or
Mean (95% Cl of mean)
3,220
2,760
37.1
43.2
11.6
6.3
1.8
10.7
6.2
1.4
45.0
13.0
0.3
1.2
15.3
6.9
61.7
0.2
4.2
31.1
2.8
36.5
21.3
8.1
16.3
6.5
2.0
1.1
1.6
6.6
44.4
33.0
8.4
11.2
2.0
1.0
65.0
8.6
<0.1
26.1
0.3
38.7
22.5
8.2
11.6
7.4
5.4
3.8
trace
2.1
81.4
4.8
2.8
7.0
4.0
Location
Location/Habitat
(measure)
Nebraska/statewide
(% wet volume; stomach
contents)
Illinois/farm and woods
(% wet weight; stomach
contents)
Missouri
(% wet volume; stomach
contents)
Maryland/Appalachian
Province (fall & winter)
(% wet weight; stomach
contents)
Reference
estimated
Powell & Case, 1982
Knable, 1974
Korschgen, 1959
Hockman & Chapman, 1983
Note
No.
6
Note
No.
10
ISJ
10
Ol
O
X
-------
Red Fox (Vulpes vulpes)
Population
Dynamics
Territory size
(ha)
Population
Density (N/ha)
Litter
Size
Litters/Year
Days
Gestation
Age at
Weaning
Age at
Sexual
Maturity
Age/Sex/
Cond./Seas.
A B summer
A M summer
A F summer
A F spring
A M all year
A F all year
B B spring
B B spring
BB
F
Mean
1,611
1,967
1,137
699±137SD
717
96
0.001
0.01
5.5
6.8
6.7
4.2
4.1
1
51 -54
8 -10 weeks
10 months
Range
277 - 3,420
514-3,420
277-1,870
596 - 855
57-170
0.046 - 0.077
2- 9
3-12
Location/Habitat
nw British Columbia/
alpine and subalpine
ec Minnesota/woods, fields,
swamp
Wisconsin/diverse
Canada/northern boreal
forests/arctic tundra
s Ontario, Canada/southern
habitats
"good fox range" in
North America
s Wisconsin/farm, marsh,
pasture
Illinois/farm and woods
Iowa/farm and woods
upper Michigan/NS
North Dakota/prairie
potholes
NS/NS
New York/NS
NS/NS
Illinois, Iowa/farm woods
Reference
Jones & Theberge, 1982
Sargeant, 1972
Abies, 1969
Voigt, 1987
Voigt, 1987
Abies, 1974
Pils& Martin, 1978
Storm etal., 1976
Storm etal., 1976
Switzenberg, 1950
Allen, 1984
Samuel & Nelson, 1982
Sheldon, 1949
Abies, 1974
Storm etal., 1976
Note
No.
7
8
7
8
7
9
10
ISJ
10
o>
O
X
-------
Red Fox (Vulpes vulpes)
Population
Dynamics
Annual
Mortality
Rates (percent)
Longevity
Seasonal
Activity
Mating
Parturition
Molt
Disperal
Age/Sex/
Cond./Seas.
BB
JM
JF
AF
AB
Begin
early Dec.
late December
late January
February
April
late
September
Mean
79.4
83
81
74
77
< 1.5yrs
Peak
late January
Jan. - Feb.
March
late March, April
Range
up to 6 yrs
End
late February
March
early February
March
June
March
Location/Habitat
s Wisconsin/various
Illinois/Iowa/
farms and woods
NS/NS
Iowa
New York
southern Ontario, Canada
northern Ontario, Canada
southern CAN
e North Dakota
NS/NS
Illinois, Iowa
Reference
Pils& Martin, 1978
Storm etal., 1976
Storm etal., 1976
Reference
Storm etal., 1976
Layne & McKeon, 1956;
Sheldon, 1949
Voigt, 1987
Voigt, 1987
Voigt, 1987
Sargeant, 1972
Voigt, 1987
Storm etal., 1976
Note
No.
Note
No.
9
10
ISJ
10
o
X
1 Estimated using extrapolation equation 3-45 (Boddington, 1978) and body weights from Storm et al. (1976) (Illinois).
2 Estimated using extrapolation equation 3-47 (Nagy, 1987) and body weights from Storm et al. (1976) (Illinois).
3 Food consumption of an adult pair for 11 days prior to whelping (i.e., parturition) and of the adult female for the first 4 weeks after whelping.
4 Estimated using extrapolation equation 3-17 (Calder and Braun, 1983) and body weights from Storm et al. (1976) (Illinois).
5 Estimated using extrapolation equation 3-20 (Stahl, 1967) and body weights from Storm et al. (1976) (Illinois).
6 Estimated using extrapolation equation 3-22 (Stahl, 1967) and body weights from Storm et al. (1976) (Illinois).
7 Litter size determined from embryo count. Using placenta! scars generally overestimates litter size, and counting live pups often underestimates
litter size (Allen, 1983; Lindstrom, 1981).
8 Method of determining litter size not specified.
9 Cited in Samuel and Nelson (1982).
-------
References (including Appendix)
Abies, E. D. (1969) Home range studies of red foxes (Vulpes vulpes). J. Mammal. 50:
108-120.
Abies, E. D. (1974) Ecology of the red fox in North America. In: Fox, M. W., ed. The wild
canids. New York, NY: Van Nostrand Reinhold; pp. 148-163.
Allen, S. H. (1983) Comparison of red fox litter sizes determined from counts of embryos
and placenta! scars. J. Wildl. Manage. 47: 860-863.
Allen, S. H. (1984) Some aspects of reproductive performance in the red fox in North
Dakota. J. Mammal. 65: 246-255.
Allen, S. H.; Gulke, J. (1981) The effect of age on adult red fox body weights. Prairie Nat.
13: 97-98.
Asdell, S. A. (1946) Patterns of mammalian reproduction. Ithaca, NY: Comstock Publ. Co.
Boddington, M. J. (1978) An absolute metabolic scope for activity. J. Theor. Biol. 75: 443-
449.
Burt, W. H.; Grossenheider, R. P. (1980) A field guide to the mammals of North America
north of Mexico. Boston, MA: Houghton Mifflin Co.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Cook, D. B.; Hamilton, W. J., Jr. (1944) The ecological relationship of red fox food in
eastern New York. Ecology 24: 94-104.
Dalke, P. D.; Sime, P. R. (1938) Home and seasonal ranges of the eastern cottontail in
Connecticut. Trans. N. Amer. Wildl. Conf. 3: 659-669.
Dekker, D. (1983) Denning and foraging habits of red foxes, Vulpes vulpes, and their
interaction with coyotes, Cam's latrans, in central Alberta. Can. Field-Nat. 97:
303-306.
Eadie, W. R. (1943) Food of the red fox in southern New Hampshire. J. Wildl. Manage. 7:
74-77.
Green, J. S.; Flinders, J. T. (1981) Diets of sympatric red foxes and coyotes in southeastern
Idaho. Great Basin Nat. 41: 251-254.
Halpin, M. A.; Bissonette, J. A. (1983) Winter resource use by red fox (Vulpes vulpes)
(abstract only). Trans. Northeast Sect. Wildl. Soc. 40: 158.
2-228 Red Fox
-------
Hamilton, W. J., Jr. (1935) Notes on food of red foxes in New York and New England. J.
Mammal. 16: 16-21.
Harris, S. (1979) Age-related fertility and productivity in red foxes, Vulpes vulpes, in
suburban London. J. Zool. (London) 187: 195-199.
Harris, S.; Smith, G. C. (1987) Demography of two urban fox (Vulpes vulpes) populations. J.
Appl. Ecol. 24: 75-86.
Hockman, J. G.; Chapman, J. A. (1983) Comparative feeding habits of red foxes (Vulpes
vulpes) and gray foxes (Urocyon cinereoargentus) in Maryland. Am. Midi. Nat. 110:
276-285.
Hoffman, R. A.; Kirkpatrick, C. M. (1954) Red fox weights and reproduction in Tippecanoe
County, Indiana. J. Mammal. 55: 504-509.
Johnson, W. J. (1970) Food habits of the red fox in Isle Royale National Park, Lake
Superior. Am. Midi. Nat. 84: 568-572.
Johnson, D. H.; Sargeant, A. B. (1977) Impact of red fox predation on the sex ratio of prairie
mallards. Washington, DC: U.S. Fish Wildl. Serv.; Wildl. Res. Rep. 6.
Jones, D. M.; Theberge, J. B. (1982) Summer home range and habitat utilization of the red
fox (Vulpes vulpes) and gray foxes (Urocyon cinereoargentus) in Maryland. Am.
Midi. Nat. 110:276-285.
Keenan, R. J. (1981) Spatial use of home range among red foxes (Vulpes vulpes) in south-
central Ontario. In: Chapman, J. A.; Pursley, D., eds. Worldwide furbearer
conference proceedings, August, 1980; Frostburg, Maryland; pp. 1041-1063.
Knable, A. E. (1970) Food habits of the red fox (Vulpes fulva) in Union County, Illinois.
Trans. III. State Acad. Sci. 63: 359-365.
Knable, A. E. (1974) Seasonal trends in the utilization of major food groups by the red fox
(Vulpes fulva) in Union County, Illinois. Trans. III. State Acad. Sci. 66: 113-115.
Korschgen, L. J. (1959) Food habits of the red fox in Missouri. J. Wildl. Manage. 23:
168-176.
Kuehn, D. W.; Berg, W. E. (1981) Notes on movements, population statistics, and foods of
the red fox in north-central Minnesota. Minn. Wildl. Res. Q. 41: 1-10.
Layne, J. N.; McKeon, W. H. (1956) Some aspects of red fox and gray fox reproduction in
New York. N.Y. Fish and Game J. 3: 44-74.
Lindstrom, E. (1981) Reliability of placenta! scar counts in the red fox (Vulpes vulpes L.)
with special reference to fading of the scars. Mammal Rev. 11: 137-49.
2-229 Red Fox
-------
Llewellyn, L. M.; Uhler, F. M. (1952) The foods of fur animals of the Patuxent Research
Refuge, Maryland. Am. Midi. Nat. 48: 193-203.
MacDonald, D. W. (1980) Social factors affecting reproduction amongst red foxes (Vulpes
vulpes L. 1758). In: Zimen, E., ed. The red fox, biogeographica: v. 18. The
Netherlands: W. Junk, The Hague; pp. 123-175.
MacDonald, D. W.; Voigt, D. R. (1985) The biological basis of rabies models. In: Bacon, P.
J., ed. Population dynamics of rabies in wildlife. London, UK: Academic Press; pp.
71-107.
MacGregor, A. E. (1942) Late fall and winter foods of foxes in central Massachusetts. J.
Wildl. Manage. 6: 221-224.
Major, J. T.; Sherburne, J. A. (1987) Interspecific relationships of coyotes, bobcats, and red
foxes in western Maine. J. Wildl. Manage. 51: 606-616.
Maurel, D. (1980) Home range and activity rhythm of adult male foxes during the breeding
season. In: Amlaner, C. J.; MacDonald, D. W., eds. A handbook on biotelemetry and
radio tracking. Edmonds, WA: The Franklin Press; pp. 697-702.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Mono. 57: 111-128.
Nowak, R. M.; Paradiso, J. L. (1983) Foxes. In: Walker's mammals of the world. 4th ed.
Baltimore, MD: Johns Hopkins University Press; pp. 932-980.
Palmer, E. L.; Fowler, H. S. (1975) Fieldbook of natural history. New York, NY: McGraw-Hill
Book Co.
Phillips, R. L.; Andrews, R. D.; Storm, G. L.; et al. (1972) Dispersal and mortality of red
foxes. J. Wildl. Manage. 36: 237-248.
Pils, C. M.; Martin, M. A. (1978) Population dynamics, predator-prey relationships and
management of the red foxes in Wisconsin. Madison, Wl: Wise. Dept. Nat. Resour.
Tech. Bull. No. 105; 56 pp.
Pils, C. M.; Martin, M. A.; Lange, E. (1981) Harvest, age structure, survivorship, productivity
of red foxes in Wisconsin. Madison, Wl: Wise. Dept. Nat. Resour. Tech. Bull. No.
125; 19 pp.
Powell, D. G.; Case, R. M. (1982) Food habits of the red fox in Nebraska. Trans. Nebr. Acad.
Sci. and Affil. Soc. 10: 13-16.
Preston, E. M. (1975) Home range defense in the red fox, Vulpes vulpes L. J. Mammal. 56:
645-652.
2-230 Red Fox
-------
Richards, S. H.; Mine, R. L. (1953) Wisconsin fox populations. Madison, Wl: Wise. Cons.
Dept. Tech. Wildl. Bull. No. 6; 78 pp.
Samuel, D. E.; Nelson, B. B. (1982) Foxes. In: Chapman, J. A.; Feldhammer, G. A., eds. Wild
mammals of North America. Baltimore, MD: Johns Hopkins University Press; pp.
475-490.
Sargeant, A. B. (1972) Red fox spatial characteristics in relation to waterfowl predation. J.
Wildl. Manage. 36: 225-236.
Sargeant, A. B. (1978) Red fox prey demands and implications to prairie duck production.
J. Wildl. Manage. 42: 520-527.
Sargeant, A. B.; Pfeifer, W. K.; Allen, S. H. (1975) A spring aerial census of red foxes in
North Dakota. J. Wildl. Manage. 39: 30-39.
Sargeant, A. B.; Allen, S. H.; Fleskes, J. P. (1986) Commercial sunflowers: food for red
foxes in North Dakota. Prairie Nat. 18: 91-94.
Sargeant, A. B.; Allen, S. H.; Hastings, J. O. (1987) Spatial relations between sympatric
coyotes and red foxes in North Dakota. J. Wildl. Manage. 51: 285-293.
Sargeant, A. B.; Allen, S. H.; Johnson, D. H. (1981) Determination of age and whelping dates
of live red fox pups. J. Wildl. Manage. 45: 760-765.
Schoonmaker, W. J. (1938) Notes on mating and breeding habits of foxes in New York
state. J. Mammal. 19: 375-376.
Scott, T. G. (1943) Some food coactions of the northern plains red fox. Ecol. Monogr. 13:
427-480.
Sheldon, W. G. (1949) Reproductive behavior of foxes in New York state. J. Mammal. 30:
236-246.
Stahl, W. R. (1967) Scaling of respiratory variables in mammals. J. Appl. Physiol. 22:
453-460.
Stanley, W. C. (1963) Habits of the red fox in northeastern Kansas. Univ. Kansas Mus. Nat.
Hist. Misc. Pub. 34: 1-31.
Storm, G. L.; Abies, E. D. (1966) Notes on newborn and fullterm wild red foxes. J. Mammal.
47: 116-118.
Storm, G. L.; Andrews, R. D.; Phillips, R. L.; et al. (1976) Morphology, reproduction,
dispersal and mortality of midwestern red fox populations. Wildl. Monogr. 49: 1-82.
Switzenberg, D. F. (1950) Breeding productivity in Michigan red foxes. J. Mammal. 31:
194-195.
2-231 Red Fox
-------
Tullar, B. J. (1983) An unusually long-lived red fox. N.Y. Fish Game J. 30: 227.
Tullar, B. J., Jr.; Berchielli, L. T. (1980) Movement of the red fox in central New York. N.Y.
Fish Game J. 27: 197-204.
Vogtsberger, L. M.; Barrett, G. W. (1973) Bioenergetics of captive red foxes. J. Wildl.
Manage. 37: 495-500.
Voigt, D. R.; MacDonald, D. W. (1984) Variation in the spatial and social behaviour of the
red fox, Vulpes vulpes. Acta Zool. Fenn. 171: 261-265.
Voigt, D. R.; Tinline, R. L. (1980) Strategies for analyzing radio tracking data. In: Amlaner,
C. J., Jr.; MacDonald, D. W., eds. A handbook on biotelemetry and radio tracking.
Oxford, United Kingdom: Pergamon Press; pp. 387-404.
Voigt, D. (1987) Red fox. In: Novak, M.; Baker, J. A.; Obbarel, M. E.; et al., eds. Wild
furbearer management and conservation. Pittsburgh, PA: University of Pittsburgh
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Voigt, D. R.; Broadfoot, J. (1983) Locating pup-rearing dens of red foxes with
radio-equipped woodchucks. J. Wildl. Manage. 47: 858-859.
2-232 Red Fox
-------
2.2.3. Raccoon (raccoons, coatis, ringtails)
Order Carnivora, Family Procyonidae. Procyonids are medium-sized omnivores
that range throughout much of North America. Raccoons, coatis, and ringtails feed on
insects, small mammals, birds, lizards, and fruits. Ringtails are much smaller and more
slender than raccoons and consume a higher proportion of animal matter (Kaufmann,
1982). Coatis are slightly smaller than racoons and are limited in their distribution in the
United States to just north of the Mexican border.
Selected species
The raccoon (Procyon lotoi) is the most abundant and widespread medium-sized
omnivore in the North America. They are found throughout Mexico, Central America, the
United States, except at the higher elevations of the Rocky Mountains, and into southern
Canada (Kaufmann, 1982). During the last 50 years, raccoon populations in the United
States have increased greatly (Sanderson, 1987). In suburban areas, they frequently raid
garbage cans and dumps. Raccoons are preyed on by bobcats, coyotes, foxes, and great
horned owls (Kaufmann, 1982). Twenty-five subspecies are recognized in the United
States and Canada; however, most researchers do not identify the subspecies studied
because different subspecies inhabit essentially nonoverlapping geographic ranges.
Body size. Raccoons measure from 46 to 71 cm with a 20 to 30 cm tail. Body
weights vary by location, age, and sex from 3 to 9 kg (Kaufmann, 1982; Sanderson, 1987).
The largest raccoons recorded are from Idaho and nearby states, while the smallest reside
in the Florida Keys (Lotze and Anderson, 1979). Juveniles do not reach adult size until at
least the end of their second year (Stuewer, 1943b). In the autumn, fat reserves account
for 20 to 30 percent or more of the raccoon's weight (Whitney and Underwood, 1952, cited
in Kaufmann, 1982). In Minnesota, Mech et al. (1968) found that juveniles gained weight
almost linearly until mid-November, after which they began to lose weight until April.
Weight loss in adults and yearlings can reach 50 percent during the 4 months of winter
dormancy (e.g., 4.3-kg loss fora 9.1-kg raccoon) (Thorkelson and Maxwell, 1974; Mech et
al., 1968). In Alabama, where raccoons are active all year, winter weight losses are less, 16
to 17 percent on average (Johnson, 1970).
Habitat. Raccoons are found near virtually every aquatic habitat, particularly in
hardwood swamps, mangroves, floodplain forests, and freshwater and saltwater marshes
(Kaufmann, 1982). They are also common in suburban residential areas and cultivated and
abandoned farmlands (Kaufmann, 1982) and may forage in farmyards (Greenwood, 1982).
Stuewer (1943a) stated that a permanent water supply, tree dens, and available food are
essential. Raccoons use surface waters for both drinking and foraging (Stuewer, 1943a).
Food habits. The raccoon is an omnivorous and opportunistic feeder. Although
primarily active from sunset to sunrise (Kaufmann, 1982; Stuewer, 1943a), raccoons will
change their activity period to accommodate the availability of food and water (Sanderson,
1987). For example, salt marsh raccoons may become active during the day to take
advantage of low tide (Ivey, 1948, cited in Sanderson, 1987). Raccoons feed primarily on
fleshy fruits, nuts, acorns, and corn (Kaufmann, 1982) but also eat grains, insects, frogs,
2-233 Raccoon
-------
crayfish, eggs, and virtually any animal and vegetable matter (Palmer and Fowler, 1975).
The proportion of different foods in their diet depends on location and season, although
plants are usually a more important component of the diet. They may focus on a preferred
food, such as turtle eggs, when it is available (Stuewer, 1943a). They also will feed on
garbage and carrion. Typically, it is only in the spring and early summer that raccoons eat
more animal than plant material. Their late summer and fall diets consist primarily of
fruits. In winter, acorns tend to be the most important food, although raccoons will take
any corn or fruits that are still available (Kaufmann, 1982; Stuewer, 1943a).
Temperature regulation and molt. From the central United States into Canada,
raccoons undergo a winter dormancy lasting up to 4 months (Stuewer, 1943a). It is not a
true hibernation, however, and they can be easily awakened (Kaufmann, 1982). Animals in
the south are active year-round (Goldman, 1950). Snow cover, more than low
temperatures, triggers winter dormancy (Stuewer, 1943a; Mech et al., 1966; Kaufmann,
1982). The raccoon's annual molt begins early in spring and lasts about 3 months
(Kaufmann, 1982).
Breeding activities and social organization. Although solitary, adult raccoons come
together for a short time during the mating period (Kaufmann, 1982), which begins earlier
(January to March) in their northern range than in their southern range (March to June)
(Johnson, 1970; Sanderson, 1987). Male and female home ranges overlap freely and each
male may mate with several females during the breeding season (Mech et al., 1966;
Johnson, 1970; Kaufmann, 1982; Stuewer, 1943a). The most common group of raccoons is
a mother and her young of that year. Further north in their range, a family will den together
for the winter and break up the following spring (Kaufmann, 1982). Males are territorial
toward one another but not toward females; females are not territorial (Fritzell, 1978).
Home range and resources. The size of a raccoon's home range depends on its sex
and age, habitat, food sources, and the season (Sanderson, 1987). Values from a few
hectares to more than a few thousand hectares have been reported, although home ranges
of a few hundred hectares appear to be most common (see Appendix). In general, home
ranges of males are larger than those of females, the home range of females with young is
restricted, and winter ranges are smaller than ranges at other times of the year for both
sexes (Sanderson, 1987). During the winter, raccoons commonly den in hollow trees; they
also use the burrows of other animals such as foxes, groundhogs, skunks, and badgers.
These sites are used for sleeping during warmer periods. After wintering in one den, the
female will choose a new den in which to bear her young (Kaufmann, 1982). Schneider et
al. (1971) found that once the cubs leave the den, the family will not use it again that year.
Population density. Population density depends on the quality and quantity of food
resources and den sites. Values between 0.005 and 1.5 raccoons per hectare have been
reported, although 0.1 to 0.2 per hectare is more common (see Appendix). Populations
exceeding one raccoon per hectare have been reported in residential areas (Hoffman and
Gottschang, 1977). Although raccoons may prefer tree dens over ground dens, particularly
for raising young (Stuewer, 1943a), Butterfield (1954) found high raccoon densities in an
area with few tree dens but numerous ground dens.
2-234 Raccoon
-------
Population dynamics. Males generally are not sexually mature by the time of the
first regular breeding season following their birth, but they may mature later that summer
or fall (Johnson, 1970; Sanderson, 1951). Females may become pregnant in their first year
(Johnson, 1970). In a review of several studies, Kaufmann (1982) found that up to 60
percent of both wild and captive females mate and produce litters in their first year. In
Illinois and Missouri, Fritzell et al. (1985) found pregnancy rates of yearlings from 38 to 77
percent. After their first year, almost all females breed annually (Fritzell et al., 1985).
Females produce only one litter each year, and the female alone cares for the young
(Sanderson, 1987; Stuewer, 1943a, 1943b). With some exceptions (Bissonnette and Csech,
1937), larger litter sizes usually occur in the raccoon's northern range (Lotze and
Anderson, 1979). Some juveniles of both sexes disperse from the areas where they were
born during the fall or winter of their first year, while others stay and raise young within
their parents' home range (Stuewer, 1943a). The highest mortality rates occur within the
first 2 years; the age structure of populations in Alabama suggests that mortality is higher
for subadults than for juveniles (Johnson, 1970).
Similar species (from general references)
• The coati (Nasua nasua) is slightly smaller than the raccoon (4 to 6 kg) but
with a much longer tail (51 to 64 cm). Ranging throughout Central America
from Panama to Mexico (Kaufmann, 1982), the coati is rare in the United
States where it inhabits open forests of the southwest, near the Mexican
border. It forages primarily for grubs and tubers but also feeds on fruits,
nuts, bird eggs, lizards, scorpions, and tarantulas. Coatis roll arthropods on
the ground to remove wings and scales.
• The ringtail (Bassariscus astutus) is smaller (36 to 41 cm; 0.9 to 1.13 kg) than
the raccoon, with a tail equal to its body length. It ranges throughout the
southwestern United States into northern California and Oregon, inhabiting
chaparral, rocky ridges, and cliffs near water. Ringtails are omnivorous like
the raccoon but consume a higher proportion of animal matter, feeding
mainly on small mammals, insects, birds, and lizards as well as fruits. They
den in caves or crevices along cliffs, hollow trees, under rocks, and in
unused buildings. Although ringtails sometimes live in colonies, mated pairs
are more common. More nocturnal than the raccoon, the ringtail is only
active at dawn and dusk (Kaufmann, 1982).
General references
Burt and Grossenheider (1980); Goldman (1950); Johnson (1970); Kaufmann (1982);
Palmer and Fowler (1975); Sanderson (1987).
2-235 Raccoon
-------
Raccoon (Procyon lotot)
Factors
Body Weight
(kg)
Pup Growth
Rate (g/day)
Metabolic
Rate
(I02/kg-day)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Age/Sex/
Cond./Seas.
AM
A F parous
A F nulliparous
JM
JF
AM
AF
AM
AF
neonate
birth to 7 days
8 to 19 days
20 to 30 days
31 to 40 days
41 to 50 days
birth to 6 wks
6 to 9 wks
10 to 16 wks
Winter
15-35°C
JB
A M basal
A F basal
A M free-living
A F free-living
Mean
7.6
6.4
6.0
5.1
4.8
6.76
5.74
4.31
3.67
0.075
17
21
11
12
23
17.8
3.9
29.5
9.36±1.68SD
304
44.8
46.8
183
187
Range
or (95% Cl)
7.0-8.3
5.6 - 7.1
5.1 -7.1
4.6 - 5.7
4.2 - 5.3
up to 8.8
up to 5.9
(83 - 400)
(85 - 408)
Location
we Illinois
Missouri
Alabama
w New York/captive
w New York
NS/lab
Washington, DC/National
Zoo
Ohio/lab
Reference
Sanderson, 1984
Nagel, 1943
Johnson, 1970
Hamilton, 1936
Hamilton, 1936
Montgomery, 1969
Mugaas etal., 1984
Teubner & Barrett, 1983
estimated
estimated
Note
No.
1
2
3
10
ISJ
CO
o>
o
o
o
o
3
-------
Raccoon (Procyon lotot)
Factors
Water
Ingestion Rate
(g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AM
AF
AM
AF
AM
AF
Dietary
Composition
crayfish
snails
insects
reptiles/amphibians
fish
rodents
corn
Smilax
acorns
pokeberry
wild cherry
blackberries
grapes
persimmon
Mean
0.082
0.083
2.47
2.17
3,796
3,414
Spring
37
5
40
6
3
7
0
0
0
0
0
0
0
0
Summer
8
5
39
5
2
2
1
trace
trace
trace
17
16
trace
0
Range
or (95% Cl)
Fall
3
3
18
3
trace
trace
2
trace
5
17
2
trace
23
11
Winter
9
6
12
7
2
8
19
6
17
2
0
0
8
7
Location
Location/Habitat
(measure)
Maryland/forested
bottomland
(% wet volume; digestive
tract)
Reference
estimated
estimated
estimated
Reference
Llewellyn hler, 1952
&U
Note
No.
4
5
6
Note
No.
10
ISJ
CO
o
o
o
o
3
-------
Raccoon (Procyon lotot)
Dietary
Composition
frogs
fish
birds
mammals
other/unspecified
persimmon
corn
grapes
pokeberry
acorns
sugar hackberry
cherry
insects
crayfish
Mollusca
(mussels and oysters)
Crustacea (shrimp &
crabs)
Pisces (goby
& cabezon)
Annelida
(marine worms)
Echiurida (worm)
fruits
insects
mammals
grains (e.g. corn)
earthworms
amphibians
vegetation
reptiles
molluscs
birds
carrion
unspecified
Spring
8.1
1.2
trace
1.7
7.8
0
57.6
0
0
0
0
0
22.0
1.6
Summer
trace
0
0
0
6.7
35.8
0
trace
20.5
0
0
29.5
3.5
4.0
44
25
9
20
1
37.9
8.2
14.3
14.7
7.2
4.4
6.1
3.0
1.9
1.5
1.5
0.2
Fall
0
0
trace
1.4
1.8
57.3
10.0
10.2
4.5
5.4
5.5
0
2.4
1.5
Winter
0
0
8.4
0
7.2
27.4
25.9
0
0
4.2
18.4
0
trace
1.4
Location/Habitat
(measure)
Tennessee/NS
(% wet volume; digestive
tract)
sw Washington/tidewater
mudflats
(% wet volume; stomach
contents)
New York/NS
(% wet volume; stomach
contents)
Reference
Tabatabai & Kennedy, 1988
Tyson, 1950
Hamilton, 1951
Note
No.
7
10
ISJ
CO
00
o
o
o
o
3
-------
Raccoon (Procyon lotot)
Population
Dynamics
Home
Range
Size
(ha)
Population
Density (N/ha)
Litter
Size
Litters
/Year
Days
Gestation
Age at
Weaning
(days)
Age at
Sexual
Maturity
Annual
Mortality
Rates
(percent)
Age/Sex/
Cond./Seas.
A M spr./sum.
A F spr./sum.
A M May - Dec
A F May - Dec
A M all year
A F all year
NS
spring
spring
1 to 3 yrs
4yrs +
M
F
AB
AB
JB
Mean
2,560
806
204
108
65±18SE
39±16SE
1.46
0.17
0.022
3.4
3.8
2.43
1
63
84
15 months
1 year
56
38
42
Range
670 - 4,946
229-1,632
18.2-814
5.3 - 376
63-112
Location/Habitat
North Dakota/prairie
potholes
Michigan/riparian
Georgia/coastal island
Ohio/residential woods
Lake Erie, Ohio/
Sandusky Bay, marsh
Wisconsin/marsh
n lllinois/NS
Alabama/bottomlands,
marsh
most of range/NS
North America/NS
NS/lab
Alabama/NS
IL, MO/NS
Missouri/NS
sw Iowa/agricultural
Reference
Fritzell, 1978
Stuewer, 1943a
Lotze, 1979
Hoffman & Gottschang, 1977
Urban, 1970
Dorney, 1954
Fritzell et al., 1985
Johnson, 1970
Sanderson, 1987
Hamilton, 1936; Sanderson,
1987; Stuewer, 1943b
Montgomery, 1969
Johnson, 1970
Fritzell etal., 1985
Sanderson, 1951
Clark etal., 1989
Note
No.
8
9
10
11
10
ISJ
CO
o
o
o
o
3
-------
Raccoon (Procyon lotot)
Population
Dynamics
Longevity
Age/Sex/
Cond./Seas. Mean
A B 3.1 years
A B 1.8 years
February
January
April
April
late
November
March
February
early April
May
summer
Range
August
March
May
October
March/April
Location/Habitat
Alabama/NS
Missouri/NS
sw Georgia, nw Florida
n United States
Michigan
sw Georgia, nw Florida
northern latitudes
ec Minnesota
Reference
Johnson, 1970
Sanderson, 1951
McKeever, 1958
Johnson, 1970
Stuewer, 1943b
McKeever, 1958
Goldman, 1950
Whitney & Underwood, 1952
Note
No.
11
Note
No.
12
10
ISJ
1 Estimated using equation 3-43 (Boddington, 1978) and body weights from Nagel (1943).
2 Estimated using equation 3-45 (Nagy, 1987) and body weights from Nagel (1943).
3 See Chapters 3 and 4 for methods for calculating food ingestion rates from free-living metabolic rate and diet.
4 Estimated using equation 3-17 (Calder and Braun, 1983) and body weights from Nagel (1943).
5 Estimated using equation 3-20 (Stahl, 1967) and body weights from Nagel (1943).
6 Estimated using equation 3-22 (Stahl, 1967) and body weights from Nagel (1943).
7 Collections from April through October.
8 Measured from April through July.
9 Based on radiotracking.
10 Average of three methods of estimating density.
11 Hunted population.
12 Cited in Schneider etal. (1971).
o
o
o
o
3
-------
References (including Appendix)
Alexander, G. (1977) Food of vertebrate predators on trout waters in north central lower
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Asdell, S. A. (1964) Patterns of mammalian reproduction. Ithaca, NY: Comstock Publ. Co.
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Bissonnette, T. H.; Csech, A. G. (1937) Modification of mammalian sexual cycles. Part 7,
fertile matings of raccoons in December instead of February induced by increasing
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Brown, C. E. (1936) Rearing wild animals in captivity, and gestation periods. J. Mammal. 17:
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Burt, W. H.; Grossenheider, R. P. (1980) A field guide to the mammals of North America
north of Mexico. Boston, MA: Houghton Mifflin Co.
Butterfield, R. T. (1944) Populations, hunting pressure, and movement of Ohio raccoons.
Trans. North Am. Wildl. Conf. 9: 337-344.
Butterfield, R. T. (1954) Some raccoon and groundhog relationships. J. Wildl. Manage. 18:
433-437.
Cagle, F. R. (1949) Notes on the raccoon, Procyon lotor megalodous Lowery. J. Mammal.
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Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
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Cauley, D. L.; Schinner, J. R. (1973) The Cincinnati raccoons. Nat. Hist. 82: 58-60.
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Iowa raccoon population. J. Wildl. Manage. 53: 982-990.
Cowan, W. F. (1973) Ecology and life history of the raccoon (Procyon lotor hirtus Nelson
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2-241 Raccoon
-------
Cunningham, E. R. (1962) A study of the eastern raccoon, Procyon lotor(L.), on the Atomic
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Dew, R. D. (1978) Biology of the raccoon, Procyon lotor, I. Genie variation. II. Population
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Dorney, R. S. (1954) Ecology of marsh raccoons. J. Wildl. Manage. 18: 217-225.
Eisenberg, J. F. (1981) The mammalian radiations; an analysis of trends in evolution,
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Ewer, R. F. (1973) The carnivores. Ithaca, NY: Cornell University Press.
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Greenwood, R. J. (1982) Nocturnal activity and foraging of prairie raccoons (Procyon lotor)
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Hamilton, W. J., Jr. (1940) The summer food of minks and raccoons on the Montezuma
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Hamilton, W. J., Jr. (1951) Warm weather foods of the raccoon in New York state. J.
Mammal. 32: 341-344.
Hoffman, C. O.; Gottschang, J. L. (1977) Numbers, distribution, and movements of a
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Ivey, R. D. (1948) The raccoon in the salt marshes of northeastern Florida. J. Mammal. 29:
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Johnson, A. S. (1970) Biology of the raccoon (Procyon lotor varius Nelson and Goldman) in
Alabama. Alabama Cooperative Wildlilfe Research Unit; Auburn Univ. Agric. Exp.
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2-242 Raccoon
-------
Kaufmann, J. H. (1982) Raccoon and allies. In: Chapman, J. A.; Feldhamer, G. A., eds. Wild
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Lowery, G. H., Jr. (1936) A preliminary report on the distribution of the mammals of
Louisiana. Louisiana Acad. Sci. Proc. 3: 1-39.
McComb, W. C. (1981) Effects of land use upon food habits, productivity, and
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McKeever, S. (1958) Reproduction in the raccoon in the southeastern United States. J.
Wildl. Manage. 22:211.
Mech, L. D.; Tester, J. R.; Warner, D. W. (1966) Fall daytime resting habits of raccoons as
determined by telemetry. J. Mammal. 47: 450-466.
Mech, L. D.; Barnes, D. M.; Tester, J. R. (1968) Seasonal weight changes, mortality, and
population structure of raccoons in Minnesota. J. Mammal. 49: 63-73.
Montgomery, G. G. (1969) Weaning of captive raccoons. J. Wildl. Manage. 33: 154-159.
Moore, D. W.; Kennedy, M. L. (1985) Weight changes and population structure of raccoons
in western Tennessee. J. Wildl. Manage. 49: 906-909.
Mugaas, J. N.; Mahlke, K. P.; Broudy, E.; et al. (1984) Metabolism of raccoons, Procyon
lotor, in winter and summer (abstract only). Am. Zool. 24: 89A.
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Palmer, E. L.; Fowler, H. S. (1975) Fieldbook of natural history. New York, NY: McGraw-Hill
Book Co.
2-243 Raccoon
-------
Sanderson, G. C. (1951) Breeding habits and a history of the Missouri raccoon population
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2-244 Raccoon
-------
Tabatabai, F. R.; Kennedy, M. L. (1988) Food habits of the raccoon (Procyon lotor) in
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2-245 Raccoon
Page 2-246 was left blank.
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2.2.4. Mink (mink, weasels, ermine)
Order Carnivora, Family Mustelidae. Although varied in size, most members of this
family have long, slender bodies and short legs. Throughout the family, the male is usually
larger than the female. The more terrestrial species feed primarily on small mammals and
birds. Mustelids that live around lakes and streams feed on aquatic prey such as fish,
frogs, and invertebrates (Burt and Grossenheider, 1980).
Selected species
The mink (Mustela vison) is the most abundant and widespread carnivorous
mammal in North America. Mink are distributed throughout North America, except in the
extreme north of Canada, Mexico, and arid areas of the southwestern United States. It is
common throughout its range but often overlooked because of its solitary nature and
nocturnal activity. Mink are particularly sensitive to PCBs and similar chemicals, and have
been found to accumulate PCBs in subcutaneous fat to 38 to 200 times dietary
concentrations, depending on the PCB congener (Hornshaw et al., 1983).
Body size. Body size varies greatly throughout the species' range, with males
weighing markedly more than females (in some populations, almost twice as much, see
table). Males measure from 33 to 43 cm with a 18 to 23 cm tail. Females measure from 30
to 36 cm with a 13 to 20 cm tail (Burt and Grossenheider, 1980). Farm-raised mink tend to
be larger than wild mink (letter from R.J. Aulerich, Department of Animal Science, Michigan
State University, East Lansing, Ml, to Susan Norton, January 7, 1992).
Metabolism. Harper et al. (1978) evaluated the energy requirements of growing
farm-raised male mink during a 21-day period when about 20 percent of their total growth
would occur. They expressed food intake on the basis of metabolic body size (MBS)
instead of body weight (BW) where MBS = BW(kg)073. Metabolizable energy (ME)
requirements were 147.8 ± 6.06 (kcal/kgMBS-day). Accounting for assimilation efficiency,
this corresponded to a gross energy (GE) intake of approximately 203 (kcal/kgMBS-day).
Iversen (1972) found that basal metabolic rate for mink and other mustelids
weighing 1 kg or more could be expressed by the equation:
BMR = 84.6Wt°78(±0.15),
where BMR = basal metabolic rate in kcal/day and Wt = body weight in kilograms. This
model reflects the finding that the larger mustelids have a slightly (10 to 15 percent) higher
basal metabolic rate than expected for mammals in general/ Free-living metabolic rates
would be expected to be three to five times higher (see table).
Habitat. Mink are found associated with aquatic habitats of all kinds, including
waterways such as rivers, streams, lakes, and ditches, as well as swamps, marshes, and
'Mustelid species much smaller than 1 kg (i.e., the stoat and weasel) have much higher basal
metabolic rates than predicted for mammals in general.
2-247 Mink
-------
backwater areas (Linscombe et al., 1982). Mink prefer irregular shorelines to more open,
exposed banks (Allen, 1986). They also tend to use brushy or wooded cover adjacent to
the water, where cover for prey is abundant and where downfall and debris provide den
sites (Allen, 1986).
Food habits. Mink are predominantly nocturnal hunters, although they are
sometimes active during the day. Shorelines and emergent vegetation are the mink's
principal hunting areas (Arnold, 1986, cited in Eagle and Whitman, 1987). Mink are
opportunistic feeders, taking whatever prey is abundant (Hamilton, 1936, 1940; Errington,
1954; Sargeant et al., 1973). Mammals are the mink's most important prey year-round in
many parts of their range (Eagle and Whitman, 1987), but mink also hunt aquatic prey such
as fish, amphibians, and crustaceans and other terrestrial prey such as bird, reptiles, and
insects, depending on the season (Linscombe et al., 1982). In marsh habitats in summer,
muskrats can be an important food source depending on their population density and
vulnerability (e.g., health) (Hamilton, 1940; Sealander, 1943; Errington, 1954). Mink diet
also can depend on marsh water level; Proulx et al. (1987) found that with high water
levels, mink captured predominantly crayfish and meadow voles, but during periods of low
water, the mink preyed on aquatic birds and muskrats deeper in the marsh. Similarly,
Errington (1939) found that mink predation on muskrats in the prairie pothole region can
increase dramatically in times of drought as the muskrat burrows become more exposed.
Also in this region, ducklings and molting adult ducks that frequent shorelines are
particularly vulnerable to mink predation (Arnold and Fritzell, 1987; Sargeant et al., 1973).
In winter, mink often supplement their diet with fish (Eagle and Whitman, 1987). Females
tend to be limited to smaller prey than males, who are able to hunt larger prey such as
rabbits and muskrats more successfully (Birks and Dunstone, 1985; Sealander, 1943).
Temperature regulation and molt. In winter, mink do not undergo hibernation or
torpor; instead, they are active year-round. Mink replace their summer coat in mid to late
fall with a darker more dense coat and molt again in the spring (Eagle and Whitman, 1987;
Linscombe et al., 1982).
Breeding activities and social organization. Mating occurs in late winter to early
spring (Eagle and Whitman, 1987). Variation in the length of mating season with different
subspecies reflects adaptations to different climates (Linscombe et al., 1982). Ovulation is
induced by mating, and implantation is delayed (Eagle and Whitman, 1987). Parturition
generally occurs in the late spring, and the mink kits are altricial (helpless) at birth
(Linscombe et al., 1982). Mink are generally solitary, with females only associating with
their young of the year. Female home ranges generally do not overlap with the home
ranges of other females, nor do the home ranges of males overlap with each other (Eagle
and Whitman, 1987). The home range of a male may overlap the home range of several
females, however, particularly during the breeding season (Eagle and Whitman, 1987).
Home range and resources. The home range of mink encompasses both their
foraging areas around waterways and their dens. When denning, mink use bank burrows
of other animals, particularly muskrats, as well as cavities in tree roots, rock or brush
piles, logjams, and beaver lodges (Melquist et al., 1981; Birks and Linn, 1982; Eagle and
Whitman, 1987). Individual mink may use several different dens within their home range,
males more so than females (Birks and Linn, 1982). Melquist et al. (1981) found that den
2-248 Mink
-------
sites in Idaho were 5 to 100 m from the water, and they never observed mink more than 200
m from water. The shape of mink home ranges depends on habitat type; riverine home
ranges are basically linear, whereas those in marsh habitats tend to be more circular (Birks
and Linn, 1982; Eagle and Whitman, 1987). Home range size depends mostly on food
abundance, but also on the age and sex of the mink, season, and social stability (Arnold,
1986; Birks and Linn, 1982; Eagle and Whitman, 1987; Linn and Birks, 1981; Mitchell, 1961).
In winter, mink spend more time near dens and use a smaller portion of their home range
than in summer (Gerell, 1970, cited in Linscombe et al., 1982). Adult male home ranges are
generally larger than adult female home ranges (Eagle and Whitman, 1987), particularly
during the mating season when males may range over 1,000 ha (Arnold, 1986).
Population density. Population density depends on available cover and prey.
Population densities typically range from 0.01 to 0.10 mink per hectare (see table). In
riverine environments, it can be more meaningful to measure densities in terms of number
of mink per unit length of shoreline covered rather than in terms of number per hectare.
Population dynamics. Mink reach sexual maturity at 10 months to a year and may
reproduce for 7 years, possibly more (Enders, 1952; Ewer, 1973). Female mink can
reproduce once per year and usually give birth to their first litters at the age of 1 year
(Eagle and Whitman, 1987). Females often live to the age of 7 years in captivity (Enders,
1952).
Similar species (from general references)
• The long-tailed weasel (Mustela frenata) is smaller (males 23 to 27 cm, 200 to
340 g; females 20 to 23 cm, 85 to 200 g) than the mink. It is considered
beneficial in agriculture because it kills small rodents, but it does not harm
poultry. Although it does not range as far north as the mink, the long-tailed
weasel does inhabit parts of the southwest.
• The least weasel (Mustela nivalis) is smaller than the mink (males 15 to 17
cm, 39 to 63 g; females 14 to 15 cm, 38 to 40 g) and inhabits meadows, fields,
and wooded areas. The least weasel feeds extensively on mice and insects.
Its habitat is limited to the north central United States and Canada.
• The ermine (Mustela erminea), or shortfall weasel, is smaller (males 15 to 17
cm, 71 to 170 g; females 13 to 19 cm, 28 to 85 g) than the mink. The ermine
inhabits woody areas near water and feeds primarily on small mammals.
The ermine's range is limited to the northern and western United States and
Canada.
• The black-footed ferret (Mustela nigripes) is larger (36 to 46 cm; up to 1.1 kg)
than the mink and inhabits western prairies in the United States, although it
now is an endangered species. It feeds on prairie dogs and other small
animals.
2-249 Mink
-------
General references
Burt and Grossenheider (1980); Eagle and Whitman (1987); Hall (1981); Linscombe
et al. (1982); Palmer and Fowler (1975).
2-250 Mink
-------
Mink (Mustela vison)
Factors
Weight
(g)
Pup Growth
Rate (g/day)
Age/Sex/
Cond./Seas.
AM
AM
A M spring
A F spring
A M summer
J M summer
A M fall
J M fall
A F summer
J F summer
A F fall
J F fall
neonate
neon ate
0-30 days; M
31-90d; M
91-120 d; M
121-150 d; M
151-180 d; M
0-30 days; F
31-90 d; F
91-120 d; F
121-150 d; F
151-180 d; F
Mean
1,734±350SD
974 ± 202 SD
1,040
777
1,233
952
550
533
586
582
8.3±1.54SD
7.0
21
15
9.0
4.3
6.5
13
6.7
1.7
0.6
Range or
(95% Cl of mean)
< 2,300
< 1,400
6-10
Location
western races
eastern races
Michigan (farm-raised)
Montana
Montana
NS
Michigan (farm-raised)
NS/(farm-raised)
Reference
Harding, 1934
Harding, 1934
Hornshaw et al., 1983
Mitchell, 1961
Mitchell, 1961
Eagle & Whitman, 1987
Hornshaw et al., 1983
Wehr et al. (unpublished)
Note
No.
1
1
2
10
Ol
-------
Mink (Mustela vison)
Factors
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
A F basal
A M basal
A F ranch cage
A F free-living
A M free-living
A M summer
A M winter
A F winter
A M yr-round
AF
AM
AF
AF
AM
AF
AM
Dietary
Composition
ducks
other birds
eggs
muskrats
ground squirrels
other mammals
insects
Mean
96
84
258
258
236
0
0
0
0
0
.13
.12 ± 0.0048 SE
.16 ± 0.0075 SE
.22
.11
0.099
0.028
0
0
.33
.55
743
1,120
Spring
5.2
18.8
3.3
42.0
14.2
15.5
1.0
Summer
32.5
21.6
14.5
2.1
0.5
25.3
3.5
Range or
(95% Cl of mean)
(110-507)
(121 -550)
Fall Winter
Location
(farm-raised)
(captive)
Michigan (farm-raised)
(farm-raised)
Location/Habitat
(measure)
Manitoba, Can/aspen
parklands of prairie
potholes
(% dry weight in scats;
male mink only)
Reference
estimated
Farrell & Wood, 1968b
estimated
Arnold & Fritzell, 1987
Bleavins & Aulerich, 1981
estimated
estimated
Farrell & Wood, 1968c
estimated
estimated
Arnold & Fritzell, 1987
Note
No.
3
4
5
6
7
8
9
10
11
Note
No.
10
ISJ
Ol
10
-------
Mink (Mustela vison)
Dietary
Composition
(habitat/season)
trout
non-trout fish
unidentified fish
crustaceans
amphibians
birds/mammals
vegetation
unidentified
(sex of mink)
muskrat
cottontail
small mammals
large birds
small birds
snakes
frogs
fish
crayfish
frogs
mice & rats
fish
rabbits
crayfish
birds
fox squirrels
muskrats
other
Spring
Summer
(stream; year-round)
52
6
3
11
2
5
17
4
Fall
Winter
(river; year-round)
56
26
3
4
3
6
1
1
(M) (F)
43 14
16 12
5 17
18 11
trace
2 2
10 37
5 4
1 3
24.9
23.9
19.9
10.2
9.3
5.6
2.2
1.3
2.7
Location/Habitat
(measure)
Michigan/stream, river
(% wet weight; stomach
contents)
Michigan/NS
(% volume; stomach
contents)
M issou ri/statewide
(% dry volume; stomach
contents)
Reference
Alexander, 1977
Sealander, 1943
Korschgen, 1958
Note
No.
12
10
ISJ
Ol
CO
-------
Mink (Mustela vison)
Population
Dynamics
Home Range
Size
Population
Density
Litter
Size
Litters
/Year
Days
Gestation
Age at
Weaning
Age at
Sexual
Maturity
Longevity
Age/Sex/
Cond./Seas.
AM
AF
AF
AM
JM
AF
A F winter
A F winter
eat meat
fully
homeothermic
B
B
F
Mean
770 ha
2.63 km
1.23km
1.85km
0.03 - 0.085 N/ha
0.006 N/ha
0.6 N/km river
4.2
4
1
51
37 days
7 weeks
10 months
1 year
7
Range
259 - 380 ha
7.8 ha
20.4 ha
1.8 -5.0 km
1.1 -1.4km
1.0 -2.8 km
2-8
4-10
39-76
40-75
maximum 10 years
maximum 11 years
Location/Habitat
North Dakota/prairie
potholes
Manitoba, Canada/prairie
potholes
Montana/riverine:
heavy vegetation
sparse vegetation
Sweden/stream
Montana/river
Michigan/river
Michigan/(farm-raised)
Montana/river
North America/NS
North America/NS
North America/NS
United States/(farm-raised)
Louisiana/NS
NS/NS
United States/(farm-raised)
NS/NS
NS/zoo
NS/(farm-raised)
Reference
Eagle (unpublished)
Arnold & Fritzell, 1987
Mitchell, 1961
Gerell, 1970
Mitchell, 1961
Marshall, 1936
Hornshaw et al., 1983
Mitchell, 1961
Hall & Kelson, 1959
Hall & Kelson, 1959
Hall & Kelson, 1959
Enders, 1952
Svilha, 1931
Kostron & Kukla, 1970
Enders, 1952
Ewer, 1973
Eisenberg, 1981
Enders, 1952
Note
No.
13
1
14
14
14
15
10
ISJ
Ol
-------
Mink (Mustela vison)
Seasonal
Activity
Begin
April
Peak
April
March
fall
mid- to late fall
End
June
Location
Alaska
Montana
Florida, Cypress Swamp
most areas (except south)
NS
Reference
Burns, 1964
Mitchell, 1961
Humphrey & Zinn, 1982
Eagle & Whitman, 1987
Eagle & Whitman, 1987
Note
No.
14
10
ISJ
Ol
01
1 Cited in Linscombe et al. (1982).
2 Cited in NRC (1982).
3 Estimated using Iversen's (1972) model and summer body weights from Mitchell (1961); equation 3-43 (Boddington, 1978) and body weights from
Mitchell (1961) yield slightly lower estimates (see text).
4 Estimated using equation 3-47 (Nagy 1987) and body weights from Mitchell (1961).
5 Arnold and Fritzell (1987) estimated that mink require 180 g of prey per day by assuming a male body mass of 1,420 g and using the model of
Cowan et al. (1957) derived from measures of prey requirements for captive mink.
6 Diet of whole chicken (20 percent), commercial mink cereal (17 percent), ocean fish scraps (13 percent), and beef parts, cooked eggs, and
powdered milk. Moisture content of feed = 66.2 percent.
7 Estimated using equation 3-47 (Nagy, 1987), summer body weights from Mitchell (1961), and dietary composition of Alexander (1977). See
Chapter 4, Figure 4-7 for the calculations.
8 Estimated using equation 3-17 (Calder and Braun, 1983) and body weights from Mitchell (1961).
9 Diet contained 65 percent water.
10 Estimated using equation 3-20 (Stahl, 1967) and body weights from Mitchell (1961).
11 Estimated using equation 3-22 (Stahl, 1967) and body weights from Mitchell (1961).
12 Collected from fur buyers.
13 Cited in Allen (1986).
14 Cited in Eagle and Whitman (1987).
15 Cited in Eisenberg (1981).
-------
References (including Appendix)
Alexander, G. (1977) Food of vertebrate predators on trout waters in north central lower
Michigan. Michigan Academician 10: 181-195.
Allen, A. W. (1986) Habitat suitability index models: mink. U.S. Fish Wildl. Serv. Biol. Rep.
82(10.127).
Arnold, T. W. (1986) The ecology of prairie mink during the waterfowl breeding season
[master's thesis]. Columbia, MO: University of Missouri.
Arnold, T. W.; Fritzell, E. K. (1987) Food habits of prairie mink during the waterfowl
breeding season. Can. J. Zool. 65: 2322-2324.
Birks, J. D.; Dunstone, N. (1985) Sex-related differences in the diet of the mink Mustela
vison. Holarctic Ecol. 8: 245-252.
Birks, J. D.; Linn, I. J. (1982) Studies of home range of the feral mink, Mustela vison. Symp.
Zool. Soc. Lond. 49: 231-257.
Bleavins, M. R.; Aulerich, R. J. (1981) Feed consumption and food passage in mink
(Mustela vison) and European ferrets (Mustela putorius furo). Lab. Anim. Sci. 31:
268-269.
Boddington, M. J. (1978) An absolute metabolic scope for activity. J. Theor. Biol. 75: 443-
449.
Burgess, S. A.; Bider, J. R. (1980) Effects of stream habitat improvements on invertebrates,
trout populations, and mink activity. J. Wildl. Manage. 44: 871-880.
Burns, J. J. (1964) The ecology, economics, and management of mink in the
Yukon-Kuskokwim Delta, Alaska [master's thesis]. Anchorage, AK: University of
Alaska.
Burt, W. H.; Grossenheider, R. P. (1980) A field guide to the mammals of North America
north of Mexico. Boston, MA: Houghton Mifflin Co.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Chanin, P. R.; Linn, I. (1980) The diet of the feral mink (Mustela vison) in southwest Britain.
J. Zool. (London) 192: 205-223.
Cowan, I. M.; Wood, A. J.; Kitts, W. D. (1957) Feed requirements of deer, beaver, bear, and
mink for growth and maintenance. Trans. North Am. Wildl. Conf. 22: 179-188.
2-256 Mink
-------
Cowan, W. F.; Reilly, J. R. (1973) Summer and fall foods of mink on the J. Clark Salyer
National Wildlife Refuge. Prairie Nat. 5: 20-24.
Eagle, T. C.; Whitman, J. S. (1987) Mink. In: Novak, M.; Baker, J. A.; Obbarel, M. E.; et al.,
eds. Wild furbearer management and conservation. Pittsburgh, PA: University of
Pittsburgh Press; pp. 615-624.
Eberhardt, L. E. (1974) Food habits of prairie mink (Mustela vison) during the waterfowl
breeding season [master's thesis]. St. Paul, MN: University of Minnesota.
Eisenberg, J. F. (1981) The mammalian radiations. Chicago, IL: University of Chicago
Press.
Enders, R. K. (1952) Reproduction of the mink (Mustela vison). Proc. Am. Philos. Soc. 96:
691-755.
Errington, P. L. (1939) Reactions of muskrat populations to drought. Ecology 20: 168-186.
Errington, P. L. (1954) The special responsiveness of minks to epizootics in muskrat
populations. Ecol. Monogr. 24: 377-393.
Ewer, R. F. (1973) The carnivores. Ithaca, NY: Cornell University Press.
Farrell, D. J.; Wood, A. J. (1968a) The nutrition of the female mink (Mustela vison). I. The
metabolic rate of the mink. Can. J. Zool. 46: 41-46.
Farrell, D. J.; Wood, A. J. (1968b) The nutrition of the female mink (Mustela vison). II. The
energy requirement for maintenance. Can. J. Zool. 46: 47-52.
Farrell, D. J.; Wood, A. J. (1968c) The nutrition of the female mink (Mustela vison). III. The
water requirement for maintenance. Can. J. Zool. 46: 53-56.
Gerell, R. (1970) Home ranges and movements of the mink Mustela vison Schreber in
southern Sweden. Oikos 20: 451-460.
Gilbert, F. F.; Nancekivell, E. G. (1982) Food habits of mink (Mustela vison) and otter (Lutra
canadensis) in northeastern Alberta. Can. J. Zool. 60: 1282-1288.
Guilday, J. E. (1949) Winter food of Pennsylvania mink. Pennsylvania Game News 20:
12-32.
Hall, E. R. (1981) The mammals of North America. 2nd ed. New York, NY: John Wiley and
Sons.
Hall, E. R.; Kelson, K. R. (1959) The mammals of North America. 1st ed. New York, NY: The
Ronald Press Co.
Hamilton, W. J., Jr. (1936) Food habits of the mink in New York. J. Mammal. 17: 169.
2-257 Mink
-------
Hamilton, W. J., Jr. (1940) The summer food of minks and raccoons on the Montezuma
Marsh, New York. J. Wildl. Manage. 4: 80-84.
Hamilton, W. J., Jr. (1959) Foods of mink in New York. N.Y. Fish and Game J. 6: 77-85.
Harding, A. R. (1934) Mink trapping. Columbus, OH: A. R. Harding.
Harper, R. H.; Travis, H. F.; Glinsky; M. S. (1978) Metabolizable energy requirement for
maintenance and body composition of growing farm raised male mink (Mustela
vison). J. Nutr. 108: 1937-1943.
Hornshaw, T. C.; Aulerich, R. J.; Johnson, H. E. (1983) Feeding Great Lakes fish to mink:
effects on mink and accumulation and elimination of PCBs by mink. J. Toxicol.
Environ. Health 11: 933-946.
Humphrey, S. R.; Zinn, T. L. (1982) Seasonal habitat use by river otters and everglades
mink. J. Wildl. Manage. 46: 375-381.
Iversen, J. A. (1972) Basal energy metabolism of mustelids. J. Comp. Physiol. 81: 341-344.
Korschgen, L. J. (1958) December food habits of mink in Missouri. J. Mammal. 39: 521-527.
Kostron, K.; Kukla, F. (1970) Changes in thermoregulation in mink kits within the 45 days of
ontogenesis. Acta Univ. Agric., Facultas Agronomica, Sbornik Vysoke Skoly
Zemedelske (Brunn) (rada A) 18: 461-469.
Linn, I. J.; Birks, J. D. (1981) Observations on the home ranges of feral American mink
(Mustela vison) in Devon, England, as revealed by radio-tracking. In: Chapman,
J. A.; Pursley, D., eds. Proceedings worldwide furbearer conference: v. 1. August
1980; Frostburg, MD; pp. 1088-1102.
Linscombe, G.; Kinler, N.; Aulerich, R. J. (1982) Mink. In: Chapman, J. A.; Feldhammer, G.
A., eds. Wild mammals of North America. Baltimore, MD: Johns Hopkins University
Press; pp. 329-643.
Marshall, W. H. (1936) A study of the winter activities of the mink. J. Mammal. 17: 382-392.
McCabe, R. A. (1949) Notes on live-trapping mink. J. Mammal. 30: 416-423.
McDonnell, J. A.; Gilbert, F. F. (1981) The responses of muskrats (Ondatra zibethicus) to
water level fluctuations at Luther Marsh, Ontario. In: Chapman, J. A.; Pursley, D.,
eds. Proceedings worldwide furbearer conference: v. 1. August 1980; Frostburg,
MD; pp. 1027-1040.
Melquist, W. E.; Whitman, J. S.; Hornocker, M. G. (1981) Resource partitioning and
coexistence of sympatric mink and river otter populations. In: Chapman, J. A.;
Pursley, D., eds. Proceedings worldwide furbearer conference: v. 1. August 1980;
Frostburg, MD; pp. 187-220.
2-258 Mink
-------
Mitchell, J. L. (1961) Mink movements and populations on a Montana river. J. Wildl.
Manage. 25: 48-54.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
National Research Council (NRC) (1982) Nutrient requirements of mink and foxes. In:
Nutrient requirements of domestic animals series, No. 7. Washington, DC: National
Academy of Sciences, National Academy Press.
Palmer, E. L.; Fowler, H. S. (1975) Fieldbook of natural history. New York, NY: McGraw-Hill
Book Co.
Pendleton, G. W. (1982) A selected annotated bibliography of mink behavior and ecology.
Brookings, SD: South Dakota State University; Tech. Bull. No. 3.
Perel'dik, N. S.; Milovanov, L. V.; Erin, A. T. (1972) Feeding fur bearing animals.
Washington, DC: Translated from Russian by the Agricultural Research Service,
U.S. Department of Agriculture and the National Science Foundation.
Proulx, G.; McDonnell, J. A.; Gilbert, F. F. (1987) The effect of water level fluctuations on
muskrat, Ondatra zibethicus, predation by mink, Mustela vison. Can. Field-Nat. 101:
89-92.
Sargeant, A. B.; Swanson, G. A.; Doty, H. (1973) Selective predation by mink, Mustela
vison, on waterfowl. Am. Midi. Nat. 89: 208-214.
Sealander, J. A. (1943) Winter food habits of mink in southern Michigan. J. Wildl. Manage.
7:411-417.
Stahl, W. R. (1967) Scaling of respiratory variables in mammals. J. Appl. Physiol. 22:
453-460.
Svilha, A. (1931) Habits of the Louisiana mink (Mustela vison vulgivagus). J. Mammal. 12:
366-368.
Williams, T. M. (1980) A comparison of running and swimming energetics in the mink
(abstract). Am. Zool. 20: 909.
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2-259 Mink
Page 2-260 was left blank.
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2.2.5. River Otter
Order Carnivora, Family Mustelidae. Mustelids have long, slender bodies, short
legs, and anal scent glands. Throughout the family, the male is usually larger than the
female. The more terrestrial species of this family occupy various habitats and feed
primarily on small mammals and birds. Mustelids that live around lakes and streams feed
primarily on aquatic species such as fish, frogs, and invertebrates (Palmer and Fowler,
1975; Burt and Grossenheider, 1980).
Selected species
The northern river otter (Lutra canadensis) historically lived in or near lakes,
marshes, streams, and seashores throughout much of the North American continent (Hall,
1981). Currently, many populations along the coastal United States and Canada are stable
or increasing, but this species is rare or extirpated throughout much of the midwestern
United States (Toweill and Tabor, 1982). The river otter dens in banks and hollow logs.
Individuals range over large areas daily, feeding primarily on fish. Although otters have
few natural predators, while on land, they may be taken by coyotes, fox, or dogs (Melquist
and Hornocker, 1983). Otters clean themselves frequently by rubbing and rolling in any dry
surface (Toweill and Tabor, 1982). Otters appear to undergo bradycardia while submerged
and can stay underwater for up to 4 minutes (Melquist and Dronkert, 1987). Because of its
piscivorous diet and high trophic level, the river otter is a noteworthy indicator of
bioaccumulative pollution in aquatic ecosystems (Melquist and Dronkert, 1987).
Body size. River otters measure 66 to 76 cm with a 30 to 43 cm tail. Sexual
dimorphism in size is seen among all subspecies (Harris, 1968; van Zyll de Jong, 1972,
cited in Toweill and Tabor, 1982), and adult males (5 to 10 kg) outweigh females (4 to 7 kg)
by approximately 17 percent (Melquist and Hornocker, 1983; see Table). Full adult weight
generally is not attained until sexual maturity after 2 years of age (Melquist and Hornocker,
1983). Along the Pacific Coast, there is some evidence that size decreases from north to
south (Toweill and Tabor, 1982).
Metabolism. Iversen (1972) found that basal metabolic rate of otters and other
mustelids weighing 1 kg or more could be expressed by the equation:
BMR = 84.6Wt°78(±0.15),
where BMR = basal metabolic rate in kcal/day and Wt = body weight in kilograms. Free-
living metabolic rates would be expected to be three to five times higher (see table).
Habitat. Almost exclusively aquatic, the river otter is found in freshwater, estuarine,
and some marine environments all the way from coastal areas to mountain lakes (Toweill
and Tabor, 1982). They are found primarily in food-rich coastal areas, such as the lower
portions of streams and rivers, estuaries, nonpolluted waterways, the lakes and tributaries
that feed rivers, and areas showing little human impact (Mowbray et al., 1979; Tabor and
Wight, 1977).
2-261 River Otter
-------
Food habits. Otters usually are active in the evening and from dawn to midmorning,
although they can be active any time of day (Melquist and Hornocker, 1983). The bulk of
the river otter's diet is fish; however, otters are opportunistic and will feed on a variety of
prey depending on availability and ease of capture. River otters take different fish species
according to their availability and how well the fish can escape capture (Loranger, 1981).
Depending on availability, otters also may consume crustaceans (especially crayfish),
aquatic insects (e.g., stonefly nymphs, aquatic beetles), amphibians, insects, birds (e.g.,
ducks), mammals (e.g., young beavers), and turtles (Burt and Grossenheider, 1980; Lagler
and Ostenson, 1942; Liers, 1951b; Melquist and Hornocker, 1983; Palmer and Fowler, 1975;
Toweill and Tabor, 1982). Gilbert and Nancekivell (1982) observed that otters consume
more waterfowl in the northerly latitudes than in the south, probably because of the ease of
capturing the waterfowl during their molt in the north. Otters probe the bottoms of ponds
or streams for invertebrates and may ingest mud or other debris in the process (Liers,
1951b). Otters in captivity required 700-900 g of food daily (Harris, 1968, cited in Toweill
and Tabor, 1982).
Temperature regulation and molt. Seasonal patterns in otters are not well
understood. Otters are active throughout the year (Toweill and Tabor, 1982), with the most
intense activity levels during the winter (Larsen, 1983; Melquist and Hornocker, 1983).
They undergo a gradual molt in spring and fall (Melquist and Dronkert, 1987).
Breeding activities and social organization. Adult males are usually solitary; an
adult female and two or three pups make up a typical family group (Melquist and Dronkert,
1987). River otters breed in late winter or early spring over a period of 3 months or more.
Birth of a litter follows mating by about 1 year; however, implantation is delayed for
approximately 10 months, and active gestation lasts only 2 months (Pearson and Enders,
1944, cited in Toweill and Tabor, 1982; Melquist and Dronkert, 1987). Newborn otters are
born blind but fully furred and depend on their mother for milk until 3 to 5 months of age
(Johnstone, 1978; Liers, 1951b). Family groups disperse about 3 months after the pups are
weaned (Melquist and Hornocker, 1983).
Home range and resources. The river otter's home range encompasses the area
needed for foraging and reproduction (Melquist and Dronkert, 1987). The shape of the
home range varies by habitat type; for example, near rivers or coastal areas, it may be a
long strip along the shoreline (measured in kilometers), but in marshes or areas with many
small streams, the home range may resemble a polygon (measured in hectares; Melquist
and Dronkert, 1987). All parts of a home range are not used equally; instead, several
activity centers may be interconnected by a stream or coast (Melquist and Hornocker,
1983). Food has the greatest influence on habitat use, but adequate shelter in the form of
temporary dens and resting sites also plays a role (Anderson and Woolf, 1987a; Melquist
and Hornocker, 1983). River otters use dens dug by other animals or natural shelters such
as hollow logs, logjams, or drift piles (Toweill and Tabor, 1982; Melquist and Dronkert,
1987). Beaver bank dens and lodges accounted for 38 percent of resting sites used by
radio-tracked otters in Idaho (Melquist and Hornocker, 1983). River otters appear to prefer
flowing water habitats (e.g., streams) over more stationary water (e.g., lakes, ponds) (Idaho
study; Melquist and Hornocker, 1983).
2-262 River Otter
-------
River otters maintain distinct territories within their home ranges: females maintain
a feeding area for their families, males for breeding purposes (Toweill and Tabor, 1982).
Individuals tend to avoid confrontation through mutual avoidance (Melquist and Hornocker,
1983). Home ranges are most restricted for lactating females (Melquist and Dronkert,
1987). Adult and subadult males have larger, more variable home ranges than females.
Population density. River otter populations show variable spacing in relation to
prey density and habitat (Hornocker et al., 1983). This characteristic, along with their
secretive habits and use of several den sites, makes it difficult to estimate river otter
populations (Melquist and Dronkert, 1987). Population density of otters often is expressed
in terms of number per kilometer of waterway or coastline because of their dependence on
aquatic habitats. Densities between one otter every kilometer to one otter every 10 km of
river or shoreline are typical (see table).
Population parameters. Otters generally are not sexually mature until 2 years of
age (Liers, 1951b; Hamilton and Eadie, 1964; Tabor and Wight, 1977; Lauhachinda, 1978).
Adult females appear to reproduce yearly in Oregon (based on a pregnancy rate of almost
100 percent; Tabor and Wight, 1977), but Lauhachinda (1978) concluded that they breed
every other year in Alabama and Georgia. Litters usually consist of two to three pups,
although litters as large as six pups occur (see table). As adults, river otter mortality rates
are low, between 15 and 30 percent per year (Lauhachinda, 1978; Tabor and Wight, 1977).
Similar species (from general references)
• The sea otter (Enhydra lutris) (76 to 91 cm body and 28 to 33 cm tail; weight
13 to 38 kg) inhabits kelp beds and rocky shores from the Aleutian Islands to
California. Its diet includes fish, abalones, sea urchins, and other marine
animals.
General references
Burt and Grossenheider (1980); Melquist and Dronkert (1987); Palmer and Fowler
(1975); Toweill and Tabor (1982).
2-263 River Otter
-------
River Otter (Lutra canadensis)
Factors
Weight
(kg)
Pup Growth
Rate (g/day)
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
AM
AF
YM
YF
AM
AF
YM
YF
neon ate
neonate
10 to 20 days
A F basal
A M basal
A F free-living
A M free-living
AF
AM
AF
AM
AF
AM
Mean
8.13±1.15SD
6.73±1.00SD
6.36 ± 0.98 SD
5.83±1.82SD
9.20 ± 0.6 SE
7.90 ± 0.2 SE
7.90 ± 0.4 SE
7.20 ±0.1 SE
0.132
0.140 to 0.145
26.7
44.8
42.6
183
178
0.082
0.080
2.5
2.9
3,785
4,280
Range or
(95% Cl of
mean)
5.0-15
5.84 - 10.4
4.74 - 8.72
4.41 -8.31
3.75-7.01
(83 - 400)
(81 -391)
Location
throughout range
Alabama, Georgia
we Idaho
New York
Alabama, Georgia
NS
Reference
Melquist& Dronkert, 1987
Lauhachinda, 1978
Melquist& Hornocker, 1983
Hamilton & Eadie, 1964
Hill & Lauhachinda, 1981
Liers, 1951 a
estimated
estimated
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
7
8
10
ISJ
o>
(D
-------
River Otter (Lutra canadensis)
Dietary
Composition
fish
(sucker)
(sculpins)
(squawfish)
(perch)
(whitefish)
invertebrates
birds
mammals
reptiles
invertebrates
(aquatic insects)
(fr water shrimp)
fishes
(trout)
(sculpin)
(sunfish)
frog
salamander
snake
birds
mammals
fish
(sunfish)
(minnow/carp)
(herring)
(bass)
frogs
crayfish
dragonfly nymphs
birds
Spring
100
(52)
(40)
(5)
(22)
(21)
2
<1
1
0
41.6
19.6
14.3
91.4
23.7
20.5
47.1
19.6
0.3
0.2
6.7
8.1
97
(31)
(52)
(49)
(26)
3
12
2
4
Summer
93
(47)
(31)
(4)
(3)
(10)
7
12
4
1
44.2
19.2
8.9
92.9
9.8
20.9
72.8
19.2
0.7
0.7
4.1
5.3
69
(31)
(0)
(38)
(0)
6
50
0
13
Fall
97
(17)
(38)
(D
(7)
(24)
10
1
3
0
33.3
10.7
10.7
100
33.3
21.3
60.0
10.7
1.3
—
1.3
2.7
98
(80)
(17)
(10)
(5)
11
8
6
3
Winter
99
(30)
(42)
(6)
(9)
(66)
12
<1
1
0
26.3
4.0
4.0
100
29.3
25.3
33.3
9.1
—
—
1
4.0
99
(52)
(44)
(40)
(14)
16
7
2
1
Location/Habitat
(measure)
we Idaho/mountain streams
and lakes
(percent frequency of
occurrence in scats)
(most of the fish were longer
than 30 cm)
nw Montana/
lakes and streams
(percent frequency of
occurrence in scats)
nw Illinois/Mississippi River
(percent frequency of
occurrence in scats)
Reference
Melquist& Hornocker, 1983
Greer, 1955
Anderson & Woolf, 1987b
Note
No.
10
ISJ
o>
Ol
(0
-------
River Otter (Lutra canadensis)
Dietary
Composition
game & pan fish
forage fish
fish remains
amphibians
other invertebrates
Population
Dynamics
Home Range
Size (ha or km
river)
Population
Density
(IM/ha or N/km
shoreline)
Spring
32
17.6
3.0
16.1
25.8
AB
AB
AM
AF
yearling M
yearling F
adult F
BB
BB
A F breeding
A M breeding
yearling B
BB
BB
AB
Summer
Fall Winter
400
295
ha
ha
43 ± 20 SD km
32±6.2SDkm
31 ±9.2SDkm
28±7.5SDkm
0.26/km
0.05/km
0.01 9/km
0.071/km
0.85/km
0.0025/ha
Range
400 -1,900 ha
2,900 - 5,700 ha
10 -78 km
25 - 40 km
23 - 50 km
15 -39 km
0.17-0.37/km
0.0094 -0.014 /ha
Location/Habitat
(measure)
Michigan/habitat NS
(% volume; stomach
contents)
Missouri/marsh, streams
Colorado (fall-spr)/NS
se Texas/coastal marsh
we Idaho/river drainage
(no trends seen with
season)
we Idaho/river drainage
se Alaska/coastal - island
se Texas/coastal marsh
Missouri/marsh, streams
Reference
Lagler & Ostenson, 1942
Reference
Erickson etal., 1984
Mack, 1985
Foy, 1984
Melquist& Hornocker, 1983
Melquist& Hornocker, 1983
Woolington, 1984
Foy, 1984
Erickson etal., 1984
Note
No.
Note
No.
9
9
9
9
9
9
10
ISJ
o>
o>
(D
-------
River Otter (Lutra canadensis)
Population
Dynamics
Litter
Size
Litters
/Year
Days
Gestation
Age at
Weaning
Age at
Sexual
Maturity
Annual
Mortality
Rates (percent)
Longevity
Age/Sex/
Cond./Seas.
1 yr old
2 yr old
3 yr old
4 yr old
5 to 12yrsold
total
active
F
M
birth - 1 yr
1 - 2 yrs
2-11 yrs
AM
AF
AB
Mean
2.73 ± 0.77 SD
2.68 ±0.71 SD
2.1 ±0.7SD
0.53 ±0.91 SD
0.87 ± 0.96 SD
1.60±1.42SD
2.29 ± 1.25 SD
2.67±1.40SD
1
60-63
2 yrs
2 yrs
32
54
27
17.8
20.3
Range
1 -4
1 -4
0-3
0-3
0-4
1 -5
0-6
290 - 380
> 90 days
< 1 5 yrs
Location/Habitat
Maryland/wetlands
Alabama, Georgia/NS
New York/NS
Maine/NS
NS
Wisconsin/captive
NS
NS
New York/NS
Oregon/NS
Alabama, Georgia/riverine
Alabama, Georgia/riverine
Reference
Mowbray et al., 1979
Hill & Lauhachinda, 1981
Hamilton & Eadie, 1964
Docktor et al., 1987
Trippensee, 1953
Liers, 1951b
Lancia & Hair, 1983
Harris, 1968
Hamilton & Eadie, 1964
Tabor & Wight, 1977
Lauhachinda, 1978
Lauhachinda, 1978
Note
No.
10
11
12
13
10
ISJ
o>
(D
-------
River Otter (Lutra canadensis)
Seasonal
Activity
Mating
Parturition
Dispersal
Begin
January
March
winter
mid-March
late March
late January
Peak
March to April
late winter
April to May
End
May
April
spring
mid-May
early April
May
Location
Michigan
New York
AL, FL, GA
Maryland, Chesapeake Bay
we Idaho
Alabama
we Idaho
Reference
Hooper & Ostenson, 1949
Hamilton & Eadie, 1964
Lauhachinda, 1978
Mowbray et al., 1979
Melquist& Hornocker, 1983
Lauhachinda, 1978
Melquist& Hornocker, 1983
Note
No.
14
15
10
ISJ
o>
00
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Summary of studies discussed by Hall (1981) and Woolington (1984).
Cited in Toweill and Tabor (1982).
Estimated using equation 3-43 (Boddington, 1978) and adult body weights from Lauhachinda (1978).
Estimated using equation 3-47 (Nagy, 1987) and adult body weights from Lauhachinda (1978).
See Chapters 3 and 4 for methods of estimating food ingestion rates.
Estimated using equation 3-17 (Calder and Braun, 1983) and adult body weights from Lauhachinda (1978).
Estimated using equation 3-20 (Stahl, 1967) and adult body weights from Lauhachinda (1978).
Estimated using equation 3-22 (Stahl, 1967) and adult body weights from Lauhachinda (1978).
Cited in Melquistand Dronkert (1987).
Determined from implanted embryo counts.
Determined from corpora lutea counts.
Total gestation period (including preimplantation).
Active gestation period (postim plantation), cited in Melquistand Dronkert (1987).
Cited in Toweill and Tabor (1982).
Dispersal at age 12 to 13 months.
(D
-------
References (including Appendix)
Alexander, G. (1977) Food of vertebrate predators on trout waters in north central lower
Michigan. Michigan Academician 10: 181-195.
Anderson, K. L. (1981) Population and reproduction characteristics of the river otter in
Virginia and tissue concentrations of environmental contaminants [master's thesis].
Blacksburg, VA: Virginia Polytechnic Institute.
Anderson, K. L.; Scanlon, P. F. (1981) Reproduction and population characteristics of river
otters in Virginia. Virginia J. Sci. 32: 87.
Anderson, E. A.; Woolf, A. (1987a) River otter habitat use in northwestern Illinois. Trans.
Illinois Acad. Sci. 80: 107-114.
Anderson, E. A.; Woolf, A. (1987b) River otter food habits in northwestern Illinois. Trans.
Illinois Acad. Sci. 80: 115-118.
Boddington, M. J. (1978) An absolute metabolic scope for activity. J. Theor. Biol. 75: 443-
449.
Burt, W. H.; Grossenheider, R. P. (1980) A field guide to the mammals of North America
north of Mexico. Boston, MA: Houghton Mifflin Co.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Chabreck, R. H.; Holcombe, J. E.; Linscombe, R. G.; et al. (1982) Winter foods of river
otters from saline and fresh environments in Louisiana. Proc. Annu. Conf.
Southeast Assoc. Fish Wildl. Agencies 36: 473-483.
Docktor, C. M.; Bowyer, T. R.; Clark, A. G. (1987) Number of corpora lutea as related to age
and distribution of river otter in Maine. J. Mammal. 68: 182-185.
Eisenberg, J. F. (1981) The mammalian radiations; an analysis of trends in evolution,
adaptation, and behavior. Chicago, IL: University of Chicago Press.
Erickson, D. W.; McCullough, C. R.; Porath, W. R. (1984) River otter investigations in
Missouri. Missouri Dept. Conserv.; Pittman-Robertson Proj. W-13-R-38, Final Report.
Foy, M. K. (1984) Seasonal movement, home range, and habitat use of river otter in
southeastern Texas [master's thesis]. College Station, TX: Texas A&M University.
Gilbert, F. F.; Nancekivell, E. G. (1982) Food habits of mink (Mustela vison) and otter (Lutra
canadensis) in northeastern Alberta. Can. J. Zool. 60: 1282-1288.
2-269 River Otter
-------
Greer, K. R. (1955) Yearly food habits of the river otter in the Thompson Lakes region,
Northwestern Montana, as indicated by scat analyses. Am. Midi. Nat. 54: 299-313.
Greer, K. R. (1956) Fur resources and investigations: study of the otter food habits along a
segment of the Gallatin River. Montana Fish and Game Dept.; Job Comp. Rep.
W-049-R-06:35-59.
Grenfell, W. E., Jr. (1974) Food habits of the river otter in Suisin Marsh, central California
[master's thesis]. Sacramento, CA: California State University.
Grinnell, J.; Dixon, J. S.; Linsdale, J. M. (1937) Fur-bearing mammals of California.
Berkeley, CA: University of California Press.
Hall, E. R. (1981) The mammals of North America. 2nd ed. New York, NY: John Wiley and
Sons.
Hall, E. R.; Kelson, K. R. (1959) The mammals of North America. 1st ed. New York, NY: The
Ronald Press Co.
Hamilton, W. J., Jr. (1961) Late fall, winter and early spring foods of 141 otters from New
York. N. Y. Fish and Game J. 8: 106-109.
Hamilton, W. J., Jr.; Eadie, W. R. (1964) Reproduction in the otter, Lutra canadensis. J.
Mammal. 45: 242-252.
Harris, C. J. (1968) Otters: a study of the recent Lutrinae. London, U.K.: Weidenfield &
Nicolson.
Harris, J. (1969) Breeding the Canadian otter Lutra c. canadensis in a private collection. Int.
Zoo Yearbook 9: 90-91.
Hill, E. P.; Lauhachinda, V. (1981) Reproduction in river otters from Alabama and Georgia.
In: Chapman, J. A.; Pursley, D., eds. Proceedings worldwide furbearer conference:
v. 1. August 1980; Frostburg, MD.
Hooper, E. T.; Ostenson, B. T. (1949) Age groups in Michigan otter. Ann Arbor, Ml:
University of Michigan; Mus. Zool. Occas. Pap. 518.
Hornocker, M. G.; Messick, J. P.; Melquist, W. E. (1983) Spacial strategies in three species
of Mustelidae. Acta Zool. Fenn. 174: 185-188.
Humphrey, S. R.; Zinn, T. L. (1982) Seasonal habitat use by river otters and Everglades
mink. J. Wildl. Manage. 46: 375-381.
Iversen, J. A. (1972) Basal energy metabolism of Mustelids. J. Comp. Physiol. 81: 341-344.
Johnstone, P. (1978) Breeding and rearing the Canadian otter (Lutra canadensis) at Mole
Hall Wildlife Park, 1966-1977. Int. Zoo Yearbook 18: 143-147.
2-270 River Otter
-------
Knudsen, G. J.; Hale, J. B. (1968) Food habits of otters in the Great Lakes region. J. Wildl.
Manage. 32: 89-93.
Lagler, K. F.; Ostenson, B. T. (1942) Early spring food of the otter in Michigan. J. Wildl.
Manage. 6: 244-254.
Lancia, R. A.; Hair, J. D. (1983) Population status of bobcat (Felis rufus) and river otter
(Lutra canadensis) in North Carolina. Raleigh, NC: North Carolina State Univ., Proj.
E-1;65pp.
Larsen, D. N. (1983) Habitats, movements, and foods of river otters in coastal southeastern
Alaska [master's thesis]. Fairbanks, AL: University of Alaska.
Larsen, D. (1984) Feeding habits of river otters in coastal southeastern Alaska. J. Wildl.
Manage. 48: 1446-1452.
Lauhachinda, V. (1978) Life history of the river otter in Alabama with emphasis on food
habits [Ph.D. dissertation]. Auburn, AL: University of Alabama.
Liers, E. E. (1951 a) My friends the land otters. Nat. Hist. 60: 320-326.
Liers, E. E. (1951b) Notes on the river otter (Lutra canadensis). J. Mammal. 32: 1-9.
Liers, E. E. (1966) Notes on breeding the Canadian otter Lutra canadensis in captivity and
longevity records of beavers Castor canadensis. Int. Zoo Yearbook 6: 171-172.
Loranger, A. J. (1981) Late fall and early winter foods of the river otter (Lutra canadensis)
in Massachusetts, 1976 -1978. In: Chapman, J. A.; Pursley, D., eds. Worldwide
furbearer conference proceedings, v 1; August 3-11, 1980; Frostburg, MD; pp. 599-
605.
MacFarlane, R. (1905) Notes on mammals collected and observed in the northern
Mackenzie River District. Proc. U.S. Natl. Mus. 23: 716-717.
Mack, C. M. (1985) River otter restoration in Grand County, Colorado [master's thesis]. Fort
Collins, CO: Colorado State University.
McDaniel, J. C. (1963) Otter population study. Proc. Annu. Conf. Southeast. Assoc. Game
and Fish Comm. 17: 163-168.
Melquist, W. E.; Dronkert, A. E. (1987) River otter. In: Novak, M.; Baker, J. A.; Obbarel, M.
E.; et al., eds. Wild furbearer management and conservation. Pittsburgh, PA:
University of Pittsburgh Press; pp. 627-641.
Melquist, W. E.; Hornocker, M. G. (1983) Ecology of river otters in west central Idaho. In:
Kirkpatrick, R. L., ed. Wildlife monographs: v. 83. Bethesda, MD: The Wildlife
Society; 60 pp.
2-271 River Otter
-------
Melquist, W. E.; Whitman, J. S.; Hornocker, M. G. (1981) Resource partitioning and
coexistence of sympatric mink and river otter populations. In: Chapman, J. A.;
Pursley, D., eds. Worldwide furbearer conference proceedings, v 1; August 3-11,
1980; Frostburg, MD; pp. 187-220.
Modafferi, R.; Yocom, C. F. (1980) Summer food of river otter in north coastal California
lakes. Murrelet 61: 38-41.
Mowbray, E. E.; Pursley, D.; Chapman, J. A. (1979) The status, population characteristics
and harvest of the river otter in Maryland. Waverly Press; Maryland Wildl. Admin.,
Publ. Wildl. Ecol. 2; 16pp.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Mono. 57: 111-128.
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Zool. 95: 21-35.
Pierce, R. M. (1979) Seasonal feeding habits of the river otter (Lutra canadensis) in ditches
of the Great Dismal Swamp [master's thesis]. Norfolk, VA: Old Dominion University.
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Sheldon, W. G.; Toll, W. G. (1964) Feeding habits of the river otter in a reservoir in central
Massachusetts. J. Mammal. 45: 449-455.
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only). Proc. La. Acad. Sci. 48: 138.
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453-460.
Stenson, G. B.; Badgero, G. A.; Fisher, H. D. (1984) Food habits of the river otter Lutra
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Tabor, J. E.; Wight, H. M. (1977) Population status of river otter in western Oregon. J. Wildl.
Manage. 41: 692-699.
2-272 River Otter
-------
Toll, W. G. (1961) The ecology of the river otter (Lutra canadensis) in the Quabbin
Reservation of central Massachusetts [master's thesis]. Amherst, MA: University of
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Toweill, D. E. (1974) Winter food habits of river otters in western Oregon. J. Wildl. Manage.
38: 107-111.
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2-273 River Otter
Page 2-274 was left blank.
-------
2.2.6. Harbor Seal (hair seals)
Order Carnivora, Family Phocidae. Seals, sea lions, and walruses are collectively
referred to as pinnipeds (Latin for wing-footed). Pinnipeds are divided into three families:
otarids (sea lions and fur seals); phocids (hair seals, also called true seals or earless
seals); and walruses. Most pinnipeds feed on marine species such as fish, squid, and
other invertebrates (Burt and Grossenheider, 1980). Unlike fur seals, which are protected
from the cold marine environment by a dense layer of underfur, phocids rely only on a
thick blubber layer for insulation (Pierotti and Pierotti, 1980). Phocids include both the
smallest (ring seals) and the largest (elephant seals) of the pinnipeds. The geographic
range of most phocid species is from the arctic Atlantic and Pacific south to the coasts of
Canada and Alaska, although some do inhabit warmer water (Burt and Grossenheider,
1980). Most phocids, with the exception of the elephant seal, do not exhibit the large
disparity in size between the sexes, which is characteristic of otarids (sea lions and fur
seals) (Burt and Grossenheider, 1980).
Selected species
In North America, harbor seals (Phoca vitulina) range from Alaska to Baja California,
Mexico, along the Pacific coast (subspecies richardsi; Hoover, 1988), and from
Newfoundland to eastern Long Island along the Atlantic coast (subspecies concolor, Payne
and Selzer, 1989). They are one of the most commonly seen pinniped species, in part due
to their tendency to inhabit coastal areas (Hoover, 1988). Harbor seals can be found along
the Pacific coast on a year-round basis (except during stormy periods in winter), but
Atlantic populations winter offshore when coastal ice has formed in their usual haul-out
areas (Boulva and McLaren, 1979). The recent increases in harbor seal populations in New
England waters appear to be due to a southward dispersal of seals from rookeries in Maine
following the termination of a Massachusetts bounty on harbor seals (1962) and the
passage of the Marine Mammal Protection Act (1972) (Payne and Schneider, 1984).
The spotted or largha seal (Phoca largha) is a closely related species that until
recently was considered a subspecies of the harbor seal. It is similar in size, appearance,
and feeding habits to the Pacific harbor seal, but it tends to inhabit colder waters along the
Pacific coasts (Ashwell-Erickson and Eisner, 1981). In North America, it seldom ventures
further south than the northern coast of Alaska (Ashwell-Erickson and Eisner, 1981). The
spotted seal requires ice for breeding haul-outs and gives birth about 2 months earlier than
the Pacific harbor seal (Ashwell-Erickson and Eisner, 1981; Boulva and McLaren, 1979).
The harbor seal, in contrast, breeds on land (Boulva and McLaren, 1979).
Body size. The length and weight of harbor seals vary geographically, but sexually
mature adults tend to be about 1.5 m in length and weigh from 65 to 90 kg (Ashwell-
Erickson and Eisner, 1981; Pitcher and Calkins, 1979). Harbor seals exhibit some sexual
dimorphism, the male being larger (Pitcher and Calkins, 1979). Body length usually is used
to measure size because weight can vary substantially with factors such as season, food
availability, and molting (Ronald et al., 1982). Newborn pups are around 80 cm long and
weigh from 8.6 to almost 15 kg, with females often weighing less than males (Newby, 1973;
Pitcher and Calkins, 1979; Rosen, 1989). Harbor seal pups are highly precocial and are
2-275 Harbor Seal
-------
able to swim within hours of birth (Boulva and McLaren, 1979; Lawson and Renouf, 1987).
Seal milk consists of about half fat, and the pups more than double their weight before they
are weaned at approximately 30 days (Bigg, 1969a, as cited in Pitcher and Calkins, 1979).
Harbor seals continue to grow with age for several years beyond the age of sexual maturity
(Boulva and McLaren, 1979; Pitcher and Calkins, 1979). Body fat varies seasonally with
food intake, while total body weight and lean body mass increase with age (Ashwell-
Erickson and Eisner, 1981). Harbor seals, unlike many other pinnipeds, do not fast for
extended periods during the molting period or breeding season (Boulva and McLaren,
1979; Pierotti and Pierotti, 1980).
Habitat. Harbor seals inhabit a variety of environments and are able to tolerate a
wide range of temperatures and water salinities (Boulva and McLaren, 1979; Hoover, 1988).
In its eastern range, the harbor seal inhabits inlets, islets, reefs, and sandbars (Boulva and
McLaren, 1979). In western North America, the harbor seal inhabits tidal mud flats, sand
bars, shoals, river deltas, estuaries, bays, coastal rocks, and offshore islets (Johnson and
Jeffries, 1977), even ranging up rivers into freshwater areas in search of food (Roffe and
Mate, 1984). Harbor seals also inhabit some freshwater lakes (Power and Gregoire, 1978).
Habitats used for haul-outs include cobble and sand beaches, tidal mud flats, offshore
rocks and reefs, glacial and sea ice, and man-made objects such as piers and log booms
(Hoover, 1988).
Food habits. Harbor seals' diet varies seasonally and includes bottom-dwelling
fishes (e.g., flounder, sole, eelpout), invertebrates (e.g., octopus), and species that can be
caught in periodic spawning aggregations (e.g., herring, lance, squid) (Everitt et al., 1981;
Lowry and Frost, 1981; Pitcher and Calkins, 1979; Roffe and Mate, 1984).9 Harbor seals are
opportunistic, consuming different prey in relation to their availability and ease of capture
(Pitcher and Calkins, 1979; Pitcher, 1980; Shaffer, 1989). They may move into rivers on a
seasonal basis in pursuit of prey (e.g., eulachon in the Columbia River during winter;
Brown et al., 1989). They hunt alone or in small groups (Hoover, 1988). Fish species
consumed range between 40 and 280 mm, with mean values of between 60 and 180 mm
(Brown and Mate, 1983). Recently weaned pups tend to feed on prey that are more easily
captured than fish, such as shrimp or other crustaceans (Hoover, 1988; Pitcher and
Calkins, 1979). During the breeding and molting seasons, when harbor seals spend more
time on land, adults rely on their blubber layer as an additional source of energy (Ashwell-
Erickson and Eisner, 1981). During this time, they may be more susceptible to lipophilic
contaminants (e.g., PCBs) that may have accumulated in their blubber (Hoover, 1988).
9Studies of harbor seal diet often rely on counts of fish sagittal otoliths found in scats or stomach
contents. These otoliths can be identified to the level of species, annuli on the otoliths counted to
determine age, and fish weights and lengths estimated from otolith dimensions. However, partial
or complete digestion of otoliths, particularly of small fish species, may result in significant
underestimates of the proportion of these prey in seal diets, particularly from scat analysis (da
Silva and Neilson, 1985; Harvey, 1989). Studies of stomach contents of stranded seals also may
present a biased picture of dietary composition due to extended periods of fasting prior to
stranding (Selzeret al., 1986).
2-276 Harbor Seal
-------
In general, food consumption by adult seals is highest in winter and lowest in the
summer (Ashwell-Erickson and Eisner, 1981; Ashwell-Erickson et al., 1979). Innes et al.
(1987) estimated allometric equations for maintenance food ingestion rates (IR; wet-weight
biomass) with body weight (BW, kg) for phocids:
IRmaint(kg/day) = 0.079 BW(kg)°71 adult (N = 11; r2 = 0.84);
IRmaint(kg/day) = 0.032 BW(kg)1 °° juveniles (N = 19; r2 = 0.68); and
IRmaint(kg/day) = 0.068 BW(kg)°78 both adults and juveniles (N = 30; r2 = 0.68).
Allometric equations for food ingestion rates of growing animals (IR; wet-weight
biomass) with body weight (BW, kg) for phocids also have been estimated (Innes et al.,
1987):
IRgrowth(kg/day) = 0.0919 BW(kg)084 adult (N = 11; r2 = 0.84); and
IRgrowth(kg/day) = 0.0547 BW(kg)084 juveniles (N = 19; r2 = 0.68).
Innes et al. (1987) found that growing juvenile phocid seals ingested 1.7 times more
biomass per day than a similar-sized growing adult and 1.4 times more than juvenile
phocids that were not growing.
Boulva and McLaren (1979) estimated a relationship between body weight and daily
food ingestion for harbor seals from eastern Canada:
IRfree-,iving(k9'day) = 0.089 BW(kg)076 adults (N = 26).
Perez (1990) estimated the average energy value of the harbor seal's diet to be 1.4 kcal/g
wet weight. Ashwell-Erickson and Eisner (1981) provide age-specific estimates of food
ingestion rates for the closely related spotted seal (see Appendix) and summarize studies
in which food ingestion rates for harbor and spotted seals have been estimated.
Temperature regulation and molt. Harbor seals can maintain their heat balance
while diving in water as low as 13 C without increased muscle activity or metabolic rate
(Ronald et al., 1982). For seals in general, molting is simply part of an ongoing pelage
cycle that is influenced by the seal's environment, physiology, and behavior (Ling, 1974).
Phocids get an entirely new coat with each annual molt (Ling, 1970), a process that takes
about 5 weeks (Scheffer and Slipp, 1944, as cited in Ashwell-Erickson and Eisner, 1981).
During their molt, they spend more time hauled and exhibit a slower metabolic rate (e.g., 83
percent of premolt levels), which decreases their food requirements (Ashwell-Erickson and
Eisner, 1981). After molting, harbor seals increase their fat reserves (and weight) for the
winter and early spring; metabolic rates also might be lowered during this time to conserve
energy (Renouf, 1989).
Breeding activities and social organization. The timing of reproduction in harbor
seals varies with location. Mating and pupping are initiated earlier in the year in more
2-277 Harbor Seal
-------
southern latitudes, but within populations, breeding is synchronized (Hoover, 1988; Slater
and Markowitz, 1983). Harbor seals may form large breeding aggregations on land in areas
where food resources are plentiful (Slater and Markowitz, 1983); however, pupping
activities are not restricted to large, discrete rookeries (Pitcher and Calkins, 1979). Mating
occurs soon after weaning, which is 3 to 6 weeks after birth (Ashwell-Erickson and Eisner,
1981). It is likely that harbor seals are promiscuous (Pierotti and Pierotti, 1980), although
there is some evidence that they are mildly polygynous, with males defending territories at
the haul-out sites (Boulva and McLaren, 1979; Perry, 1989; Slater and Markowitz, 1983).
Following mating, implantation is delayed for 1.5 to 3 months, during which time the female
molts (Bigg, 1969a; Hoover, 1988; Pitcher and Calkins, 1979). At other times of the year,
harbor seals also can be found in groups of 30 to 80 in some haul-out areas (Hoover, 1988).
Home range and resources. Harbor seals generally inhabit highly productive
coastal areas, with upwelling ocean currents that bring nutrients to the surface supporting
abundant marine life (e.g., the California current system, the Gulf of Alaska, and the Gulf of
Maine; Ronald et al., 1982). Harbor seals also require adequate places to haul out, and
their distribution is influenced by the availability of suitable sites (Boulva and McLaren,
1979). In general, seals stay near particular haul-out sites with only local movements
(Brown and Mate, 1983; Pitcher and Calkins, 1979; Slater and Markowitz, 1983). Haul-out
patterns are determined by several factors, including weather, tidal pattern, time of day,
season, and human proximity (Slater and Markowitz, 1983). Harbor seals are considered
fairly sedentary, with individuals showing year-round site fidelity, although some seasonal
movement associated with pupping and long-distance movements are recorded (Pitcher
and Calkins, 1979; Slater and Markowitz, 1983). Data on likely daily or monthly foraging
distances are lacking.
Population density. Harbor seals are found principally in coastal areas within 20 km
of shore; they tend to concentrate in estuaries and protected waters (Hoover, 1988). Their
distribution is highly patchy, and local population densities in haul-out areas with favorable
food resources nearby can be quite high (Pitcher and Calkins, 1979).
Population dynamics. Females are sexually mature by 3 to 5 years of age, whereas
males are sexually mature later, at 4 to 6 years of age (Boulva and McLaren, 1979; Pitcher
and Calkins, 1979). Females only produce one pup per year (Hoover, 1988). Three major
causes of preweaning pup mortality are stillbirth, desertion by the mother, and shark kills
(Boulva and McLaren, 1979). Mortality from birth to 4 years of age was estimated to be 74
percent for females and 79 percent for males in one study, after which it remained at about
10 percent per year (Pitcher and Calkins, 1979). Life expectancy for harbor seals is about
30 years (Newby, 1978).
Similar species (from general references)
• The ringed seal (Phoca hispida) is smaller (1.4 m length; weight to 90 kg)
than the harbor seal and inhabits colder waters. It feeds mainly on marine
invertebrates.
2-278 Harbor Seal
-------
• The harp seal (Phoca groenlandicus) (1.8 m; weight to 180 kg) inhabits deep,
icy water. It ranges from the Arctic Atlantic south to Hudson Bay; it is only
rarely found further south. It feeds on macroplankton and fish.
• The largha or spotted seal (Phoca largha) (1.5 m) is a closely related species
that until recently was considered a subspecies of the harbor seal. Its
characteristics are compared with those of the harbor seal under Selected
species.
• The ribbon seal (Phoca fasciata) (1.6 m; males to 90 kg, females to 76 kg)
lives near pack ice in the Bering Sea and feeds on bottom invertebrates, fish,
and octopus and squid.
General references
Ashwell-Erickson and Eisner (1981); Burt and Grossenheider (1980); Hoover (1988);
Pitcher and Calkins (1979); Ronald et al. (1982).
2-279 Harbor Seal
-------
Harbor Seal (Phoca vitulina)
Factors
Body Weight
(kg)
Pup Growth
Rate (g/day)
Metabolic
Rate
(I02/kg-day)
Age/Sex/
Cond./Seas.
A M (> 7 yrs)
A F (> 7 yrs)
J M 2 yrs
J M 4 yrs
J M 6 yrs
A M 8 yrs
AM 12 yrs
A M 16 yrs
A M 24 yrs
J F 2 yrs
J F 4 yrs
J F 6 yrs
A F 8 yrs
A F 12 yrs
A F 16 yrs
A F 24 yrs
neonate M
neonate F
at weaning B
birth to
weaning
M
F
J B resting
A F resting
Mean
84.6 ±11. 3 SD
76.5 ± 17.7 SD
49
70
84
95
110
120
124
40
56
67
76
90
101
112
12.0 ±0.51 SE
11.5 ±0.31 SE
24.0
520
790
7.3
6.6
Range or
(95% Cl of mean)
Location
Gulf of Alaska
Aleutian Ridge and Pribilof
Islands, Bering Sea, Alaska
Alaska
British Columbia, Canada
Gulf of St. Lawrence/island
marine
California/lab
Reference
Pitcher & Calkins, 1979
Ashwell-Erickson & Eisner,
1981
Pitcher & Calkins, 1979
Bigg, 1969a
Rosen, 1989
Davis etal., 1985
Note
No.
1
2
3
10
ISJ
00
o
I
0)
3-
O
T
CO
(D
0)
-------
Harbor Seal (Phoca vitulina)
Factors
Metabolic Rate
(kcal/kg-day)
Food Ingestion
Rate (g/g-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (rtWday)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
1 to 4 yrs old/
basal
A F basal
A M basal
A F free-living
A M free-living
AB
AB
A F lact./gest.
J B 1st year
AB
AB
AM
AF
AM
AF
Mean
57.5
24.3
22.4
131
129
0.05
0.06 to 0.08
0.10
0.13
0.0048
0.064
18.6
17.2
19,620
18,380
Range or
(95% Cl of mean)
(57 - 300)
(56 - 296)
0.0028 - 0.0091
Location
Bering Sea, Alaska
e Canada/marine
review of several studies
Bering Sea (1 harbor &
1 spotted seal)
seawater ingestion (most
water obtained from food)
Reference
Ashwell-Erickson & Eisner,
1981
estimated
estimated
Boulvaand McLaren, 1979
Ashwell-Erickson & Eisner,
1981
Ashwell-Erickson & Eisner,
1981
Depocas etal., 1971
estimated
estimated
estimated
Note
No.
4
5
6
7
8
10
00
I
0)
3-
O
T
CO
(D
0)
-------
Harbor Seal (Phoca vitulina)
Dietary
Composition
walleye pollock
English sole
shiner perch
Pacific herring
Pacific cod
rex sole
Pacific tomcod
rockfish
Dover sole
Petrale sole
other fish
octopus
salmon
capelin
Pacific cod
walleye pollock
Pacific sandlance
squid & octopus
shrimp, crabs
herring
salmonids
osmerids
cod, tomcod,
walleye, pollock
other
Spring
3.7
37.0
0.0
0
0
37
3.7
3.7
3.7
7.4
3.8
Summer
27.3
0.0
0.0
54.6
0
9.1
0
0
0
0
9.0
17.6
5.4
20.3
6.8
12.2
4.1
20
3.7
6.4
4.4
22.5
26.0
14.1
Fall
32.2
27.0
0.5
3.9
10.1
2.9
4.7
4.7
3.4
1.8
8.8
17.7
0.0
4.8
8.1
9.7
21.0
Winter
1.3
0
63.6
28.6
0
0
0
0
2.6
0
3.9
30.4
0.0
5.4
10.7
14.3
0.0
Location/Habitat
(measure)
Washington/
coastal island
(% of total otoliths
recovered from scat
samples)
Kodiak Island, Alaska/
coastal marine
(% frequency of occurrence;
stomach contents)
Gulf of Alaska/
coastal marine
(% wet volume; stomach
contents)
all seasons combined
Reference
Everittetal., 1981
Pitcher & Calkins, 1979
Pitcher, 1980
Note
No.
10
ISJ
00
10
I
0)
3-
O
T
CO
(D
0)
-------
Harbor Seal (Phoca vitulina)
Population
Dynamics
Foraging
Radius (km)
Population
Density (N/ha)
Litter
Size
Litters
/Year
Months
Gestation
Age at
Weaning
Age at
Sexual
Maturity
(years)
Annual
Mortality
Rates (percent)
Longevity
Age/Sex/
Cond./Seas.
AB
AB
summer
B
B
F
M
F
M
AB
birth to 4 yrs
4 to 5 yrs old
7 to 14 yrs old
> 20 yrs old
AB
AM
AF
Mean
5km
30 to 55 km
0.0305
1
1
10.5 to 11
30 days
35 days
5.5 ± 0.23 SE
3 to 4
6
17.5
77/4 yrs
11/yr
8 to 9/yr
14/yr
Range
unknown
unknown
0.00394-0.0611
highly clumped
distrib.
4-9
5-7
<30
<26
<31
Location/Habitat
California/Bay
Washington/Columbia River
Maine/coastal marine
throughout range and
habitats
throughout range and
habitats
throughout range and
habitats
NS/NS
e Canada/marine
c California/coastal marine
Gulf of Alaska/coastal
marine
e Canada/marine
e Canada/marine
Gulf of Alaska/coastal
marine
e Pacific/NS
Gulf of Alaska/coastal
marine
Reference
Stewart etal., 1989
Beach etal., 1985
Richardson, 1981
Pitcher and Calkins, 1979
Hoover, 1988
Hoover, 1988
FAO Adv. Comm., 1976
Boulva & McLaren, 1979
Slater & Markowitz, 1983
Pitcher & Calkins, 1979
Boulva & McLaren, 1979
Boulva & McLaren, 1979
Pitcher & Calkins, 1979
Newby, 1978
Pitcher & Calkins, 1979
Note
No.
9
10
11
12
10
ISJ
00
CO
I
0)
3-
O
T
CO
(D
0)
-------
Harbor Seal (Phoca vitulina)
Seasonal
Activity
Mating
Parturition
Molt
Begin
early April
mid-May
late April
early February
late June
May
August
early June
late June
Peak
February
July
mid-June
early June
late July
End
July
late June
early May
September
June
September
early September
September/October
Location
Nova Scotia, Canada
Mexico
Bering Sea
Tugidak Island, Alaska
c California
Mexico
Canada
Washington
Washington, Puget Sound
Scotland
Gulf of Alaska
Reference
Boulva & McLaren, 1979
Bigg, 1969b
Bigg, 1969b
Pitcher & Calkins, 1979
Riedman, 1990
Johnson & Jeffries, 1983
Thompson & Rothery, 1987
Pitcher & Calkins, 1979
Note
No.
13
13
14
10
ISJ
00
I
0)
3-
o
T
CO
(D
0)
1 Estimated from graph of growth curve.
2 Cited in Boulva and McLaren (1979). Weight doubled from birth.
3 Juvenile is a yearling; weight 33 kg. Adult female weight 63 kg.
4 Estimated using equation 3-43 (Boddington, 1978) and body weights from Pitcher and Calkins (1979). Caution must be used, however, because
pinnipeds were not included in the data set from which the allometric model was derived.
5 Estimated using equation 3-47 (Nagy, 1987) and body weights from Pitcher and Calkins (1979). Caution must be used, however, because
pinnipeds were not included in the data set from which the allometric model was derived. Mean values are somewhat higher than is consistent
with food ingestion rate estimates and data from the spotted seal (see Appendix).
6 Estimated using equation 3-17 (Calder and Braun, 1983) and body weights from Pitcher and Calkins (1979). Caution must be used, however,
because pinnipeds were not included in the data set from which the allometric model was derived.
7 Estimated using equation 3-20 (Stahl, 1967) and body weights from Pitcher and Calkins (1979). Caution must be used, however, because
pinnipeds were not included in the data set from which the allometric model was derived.
8 Estimated using equation 3-22 (Stahl, 1967) and body weights from Pitcher and Calkins (1979). Caution must be used, however, because
pinnipeds were not included in the data set from which the allometric model was derived.
9 Satellite telemetry of one seal. Foraging radius depends on distribution and abundance of prey.
10 Seventy-five percent of 58 seals radio-tagged in the Columbia River were relocated at haul-out sites 30 to 55 km away. Cited in Hoover (1988).
11 Cited in Ronald etal. (1982).
12 Postweaning mortality.
13 Cited in Hoover (1988).
14 Nineteen to 33 days to complete molt.
-------
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Riedman, M. (1990) The pinnipeds: seals, sea lions, and walruses. Berkeley, CA: University
of California Press.
Roffe, T. J.; Mate, B. R. (1984) Abundances and feeding habits of pinnipeds in the Rogue
River, Oregon. J. Wildl. Manage. 48: 1262-1274.
Ronald, K.; Selley, J.; Healey, P. (1982) Seals. In: Chapman, J. A.; Feldhammer, G. A., eds.
Wild mammals of North America. Baltimore, MD: Johns Hopkins University Press;
pp. 769-827.
Rosen, D. A. (1989) Neonatal growth rates and behaviour in the Atlantic harbour seal,
Phoca vitulina (abstract). In: 8th Biennial Conference on the Biology of Marine
Mammals; December 7-11, 1989; Pacific Grove, CA; p. 57.
Scheffer, V. B.; Slipp, J. W. (1944) The harbor seal in Washington state. Am. Midi. Nat. 32:
373-416.
Schneider, D. C.; Payne, P. M. (1983) Factors affecting haul-out of harbor seals at a site in
southeastern Massachusetts. J. Mammal. 64: 518-520.
Selzer, L. A.; Early, G.; Fiorelli, P. M.; et al. (1986) Stranded animals as indicators of prey
utilization by harbor seals, Phoca vitulina concolor, in southern New England. Fish.
Bull. 84: 217-220.
Shaffer, K. E. (1989) Seasonal and size variations in diets of harbor seals, Phoca vitulina
(abstract). In: 8th Biennial Conference on the Biology of Marine Mammals;
December 7-11, 1989; Pacific Grove, CA; p. 62.
2-288 Harbor Seal
-------
Slater, L. M.; Markowitz, H. (1983) Spring population trends in Phoca vitulina richardi'm two
central California coastal areas. Calif. Fish Game 69: 217-226.
Stahl, W. R. (1967) Scaling of respiratory variables in mammals. J. Appl. Physiol. 22:
453-460.
Stewart, B. S.; Leatherwood, S.; Yochem, P. K.; et al. (1989) Harbor seal tracking and
telemetry by satellite. Mar. Mamm. Sci. 5: 361-375.
Stutz, S. S. (1966) Moult and pelage patterns in the Pacific harbor seal, Phoca vitulina
[master's thesis]. Vancouver, Canada: University of British Columbia.
Thompson, P; Rothery, P. (1987) Age and sex differences in the timing of moult in the
common seal, Phoca vitulina. J. Zool. (London) 212: 597-603.
Wilson, S. C. (1978) Social organization and behavior of harbor seals Phoca vitulina
concolor'm Maine. Final report to Marine Mammal Commission, Contract No. GPO
PB 280-3188. NTIS PB 280 188.
2-289 Harbor Seal
Page 2-290 was left blank.
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2.2.7. Deer Mouse (deer and white-footed mice)
Order Rodentia, Family Muridae (Genus Peromyscus).^ New world mice (family
Muridae) are small, ground-dwelling rodents that live in a large variety of habitats including
woodlands, prairies, rocky habitats, tundra, and deserts. All are nocturnal and are preyed
on by owls, hawks, snakes, and carnivorous mammals. Most species eat primarily seeds,
but some also regularly eat small invertebrates. Many species store food. The genus
Peromyscus is the most widespread and geographically variable of North American
rodents (MacMillen and Garland, 1989).
Selected species
The deer mouse (Peromyscus maniculatus) is primarily granivorous and has the
widest geographic distribution of any Peromyscus species (Millar, 1989; Brown and Zeng,
1989). It is resident and common in nearly every dry-land habitat within its range, including
alpine tundra, coniferous and deciduous forest, and grasslands as well as deserts. There
are many recognized subspecies or races of the deer mouse associated with different
locations or insular habitats, including artemisiae, austerus, bairdii, balaclavae, blandus,
borealis, carli, cooledgei, gambelii, gracilis, labecula, maniculatus, oreas, nebrascensis,
nubiterrae, rufinus, and sonoriensis (MacMillen and Garland, 1989; Millar, 1982)
Body size. Deer mice range from 7.1 to 10.2 cm in length, with a 5.1 to 13 cm tail,
and adults weigh from 15 to 35 g (Burt and Grossenheider, 1980; see table). Body size
varies somewhat among populations and subspecies throughout the species' range. Body
weight also varies seasonally, being lower in autumn and winter and a few grams higher in
spring and summer (Zegers and Merritt, 1988). There may (Fleharty et al., 1973) or may not
(Millar and Schieck, 1986) be seasonal differences in fat content.
Habitat. Deer mice inhabit nearly all types of dry-land habitats within their range:
short-grass prairies, grass-sage communities, coastal sage scrub, sand dunes, wet
prairies, upland mixed and cedar forests, deciduous forests, ponderosa pine forests, other
coniferous forests, mixed deciduous-evergreen forests, juniper/pinon forests, and other
habitats (Holbrook, 1979; Kaufman and Kaufman, 1989; Ribble and Samson, 1987; Wolff
and Hurlbutt, 1982). Few studies have found microhabitat features that distinguish the
deer mouse, and some studies have come to different conclusions regarding habitat
structure preferences (Ribble and Samson, 1987). For example, Vickery (1981) found that
deer mice appeared to prefer areas with moderate to heavy ground and mid-story cover to
more open ground areas, whereas others have found more deer mice in more open than in
more vegetated areas (see Kaufman and Kaufman, 1989).
Food habits. Deer mice are omnivorous and highly opportunistic, which leads to
substantial regional and seasonal variation in their diet. They eat principally seeds,
arthropods, some green vegetation, roots, fruits, and fungi as available (Johnson, 1961;
Menhusen, 1963; Whitaker, 1966). The nonseed plant materials provide a significant
hPeromyscus is considered a member of the family Cricetidae by some mammalogists.
2-291 Deer Mouse
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proportion of the deer mouse's daily water requirements (MacMillen and Garland, 1989).
Food digestibility and assimilation for most of their diet have been estimated to be as high
as 88 percent (Montgomery, 1989). Deer mice may cache food during the fall and winter in
the more northern parts of their range (Barry, 1976; Wolff, 1989). They are nocturnal and
emerge shortly after dark to forage for several hours (Marten, 1973).
Temperature regulation. The deer mouse has a metabolic rate about 1.3 times
higher than the other species in the genus (MacMillen and Garland, 1989; Morris and
Kendeigh, 1981; see table). Its metabolic rate is substantially higher in winter than in
summer (Morris and Kendeigh, 1981; Stebbins, 1978; Zegers and Merritt, 1988). Outside
the thermoneutral zone (25 to 35 C), metabolic rate varies according to the following
equation:
V02 = 0.116 - 0.003(Ta) + 0.0304 (V05)
where V02 = volume oxygen consumed (ml/g-min); Ta = ambient temperature; and V = wind
speed (Chappell and Holsclaw, 1984). Deer mice can enter torpor (body temperature, 19 to
30 C) to reduce metabolic demands in the winter and also in response to brief food
shortages (Tannenbaum and Pivorun, 1988, 1989). The deer mouse uses nonshivering
thermogenesis (NST) to quickly awaken from torpor and to maintain body temperature
during the winter (Zegers and Merritt, 1987). The deer mouse may burrow in soils to assist
thermoregulation; one study measured the burrow dimensions to be 24 cm deep (range 13
to 50 cm) and 132 cm long (range 30 to 470 cm) (Reynolds and Wakkinen, 1987).
Breeding activities and social organization. The duration of the reproductive
season varies with latitude and longitude according to the regression equation:
Y = -33.0 + 2.79 X + 0.0748 Z - 0.0370 X2
where Y = duration of the breeding season in weeks, X = latitude, and Z = longitude (r =
0.58; Millar, 1989). Lactating females have longer gestation periods than nonlactating
females. Newborn deer mice are highly altricial (Layne, 1968). Several studies have
indicated that daily food consumption increases over 15 percent during early pregnancy
and more than doubles during lactation (Glazier, 1979; Millar, 1975, 1978, 1979, 1982, 1985;
Millar and Innes, 1983; Stebbins, 1977). Deer mice are promiscuous; in one study, 19 to 43
percent of litters resulted from multiple inseminations (Birdsall and Nash, 1973, as cited in
Millar, 1989).
Home range and resources. Deer mice tend to occupy more than one nest site,
most frequently in tree hollows up to 8 m from the ground (Wolff and Durr, 1986) but also
among tree roots and under rocks and logs (Wolff and Hurlbutt, 1982; Wolff, 1989). At low
densities, home ranges are maintained by mutual avoidance, but at higher densities,
females may defend a core area or territory (Wolff, 1989). The home range of female deer
mice encompasses both their foraging areas and their nests. Male home ranges are larger
and overlap the home ranges of many females (Cranford, 1984; Taitt, 1981; Wolff, 1985a,
1986; Wolff etal., 1983).
2-292 Deer Mouse
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Population density. Population density varies considerably over space and time
and is often positively correlated with food abundance (Taitt, 1981; Wolff, 1989), moisture
content of plants (Bowers and Smith, 1979), and vegetative cover (van Home, 1982) as well
as season (Montgomery, 1989; Taitt, 1985). Interspecific competition also can play a role in
determining population densities (Kaufman and Kaufman, 1989).
Population dynamics. Although laboratory and field studies have demonstrated that
females can produce their first litter by 3 months of age, females of the more northern
populations do not mature under natural conditions until the spring after the year of their
birth. First litters are consistently smaller than subsequent litters (Millar, 1989), and
latitude and elevation explain a significant amount of the variation in litter size among P.
maniculatus populations (Smith and McGinnis, 1968, as cited in Millar, 1989). Millar (1989)
estimated the relationship between litter size and latitude and longitude to be
Y = -1.62 + 0.0103X + 0.106Z + 0.0004X2 - 0.0005Z2
where Y is the mean litter size; X, the latitude; and Z, the longitude. The largest litters are
produced in northwestern North America. Pups wean within about 3 weeks, and females
may have up to four litters per year in the more southern parts of the species' range (Millar,
1989). Mortality rates are high, and most deer mice live for less than 1 year (Millar and
Innes, 1983).
Similar species (from general references)
• The cactus mouse (Peromyscus eremicus), almost the same size as the deer
mouse (8.1 to 9.1 cm; 17 to 40 g), is found only in low deserts of the extreme
southwest and Mexico. It may feed on green vegetation, seeds, and berries
and can climb trees for food.
• The California mouse (Peromyscus californicus) (9.6 to 11.7 cm; 42 to 50 g)
is found in southwestern California and lives among oaks and dense
chaparral. It stores acorns in nests made of twigs and sticks.
• The canyon mouse (Peromyscus crinitus) (7.6 to 8.6 cm) is limited to the
western United States. It lives in rocky canyons and on lava-covered slopes,
nesting among rocks.
• The oldfield mouse (Peromyscus polionotus), smaller than the deer mouse
(4.1 to 6.1 cm), is limited to the extreme southeastern United States, where it
inhabits sandy beaches and fields and feeds on seeds and berries. Females
may be territorial during the breeding season.
• The white-footed mouse (Peromyscus leucopus) is approximately the same
size as the deer mouse (9.1 to 10.7 cm; 14 to 31 g). Its range extends north
into Canada and west to Arizona but does not extend as far north and west
as the deer mouse's range. Like the deer mouse, the white-footed mouse's
diet consists mainly of arthropods, seeds, and other vegetation, and it
usually nests off the ground. It is most abundant in habitat that includes a
2-293 Deer Mouse
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canopy, such as brushy fields and deciduous woodlots in northern regions
and riparian areas and ravines in prairie and semidesert regions.
• The cotton mouse (Peromyscus gossypinus) (9.1 to 11.7 cm; 28 to 51 g) is
found in the southeastern United States where it inhabits wooded areas,
swampland, stream banks, and field edges. This tree climber nests in trees,
under logs, and in buildings.
• The brush mouse (Peromyscus boylii) (9.7 to 10.7 cm; 22 to 36 g) is limited
to chaparral and rocky areas of the arid and semiarid west and southwest
United States. A good climber, it lives under rocks and debris and in
crevices. It feeds on pine nuts, acorns, seeds, and berries.
General references
Burt and Grossenheider (1980); Kirkland and Lane (1989); Millar (1985, 1989);
Wolff (1989).
2-294 Deer Mouse
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Deer Mouse (Peromyscus maniculatus)
Factors
Body Weight
(g)
Pup Growth
Rate (g/day)
Metabolic
Rate
(I02/kg-day)
Age/Sex
Cond./Seas.
AM
AF
AM
AF
AM
AF
AB
A F nonbreed.
A F gestat.
A F lactat.
neon ate
neonate
at weaning
at weaning
B
M
F
F resting
M avg daily:
winter
spring
summer
Mean
22
20
15.7
14.8
22.3
21.1
19.6 ±0.71 SE
20.3 ± 0.42 SE
31.5 ± 0.43 SE
24.5 ± 0.37 SE
1.8
1.7±0.02SE
8.8
9.3 ± 0.10 SE
0.38 ±0.01 SE
0.27 ± 0.06 SE
0.22 ± 0.05 SE
50
138±5.3SE
102±7.2SE
75±3.4SE
Range or
(95% Cl of
mean)
1.6-2.8
7.7-11.2
0.30-0.95
40-61
Location (subspecies)
North America
NS (austerus)
NS (blandus)
New Hampshire
NS (borealis) lab
North America
Alberta, Canada
North America
Northwest Territories, Canada
Alberta, Canada
(nebrascensis)
Alberta, Canada (borealis)
North America
Alberta, Canada lab
Reference
Millar, 1989
Fordham, 1971
Dewsbury etal., 1980
Schlesinger& Potter, 1974
Millar & Innes, 1983
Millar, 1989
Millar, 1989
Millar, 1989
Millar, 1979
Millar, 1985
Millar & Innes, 1983
MacMillen & Garland, 1989
Stebbins et al., 1980
Note
No.
1
1
2
3
10
ISJ
u>
01
D
(D
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Deer Mouse (Peromyscus maniculatus)
Factors
Metabolic Rate
(kcal/kg-day)
Food
Ingestion
Rate
(gig-day)
Water
Ingestion
Rate (g/g-day)
Inhalation
Rate (m3/day)
Surface Area
(cm2)
Age/Sex
Cond./Seas.
M avg daily:
winter
spring
summer
B free-living:
winter
summer
A M free-living
A F free-living
A F nonbreed.
A F nonbreed.
A F lactating
A F lactating
A F nonbreed.
A M nonbreed.
JM
AB
AB
JM
AM
AF
AM
AF
Mean
668 ± 25 SE
623 ± 35 SE
360±17SE
790
592
547
574
0.19
0.18
0.45
0.38
0.19
0.22
0.21 ±0.01 SE
0.19
0.19
0.34 ± 0.02 SE
0.15
0.025
0.023
91
86
Range or
(95% Cl of
mean)
(259-1,153)
(271 -1,212)
0.123-0.287
Location (subspecies)
Alberta, Canada lab
Illinois lab
Manitoba, Canada
(maniculatus) lab
Alberta, Canada
(borealis) lab
Manitoba, Canada
(maniculatus) lab
Alberta, Canada
(borealis) lab
Virginia lab
South Dakota lab
(sonoriensis) lab
Illinois (bairdii) lab
South Dakota lab
Reference
Stebbinsetal., 1980
Morris & Kendeigh, 1981
estimated
Millar, 1979
Millar & Innes, 1983
Millar, 1979
Millar & Innes, 1983
Cronin & Bradley, 1988
Nelson & Desjardins, 1987
Ross, 1930
Dice, 1922
Nelson & Desjardins, 1987
estimated
estimated
estimated
Note
No.
3
4
5
6
7
6
7
8
9
10
11
12
13
14
15
10
ISJ
u>
o>
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Deer Mouse (Peromyscus maniculatus)
Dietary
Composition
nuts/seeds
arthropods
Lepidopt. larvae
Lepidopt. adults
green veg.
fungus
fruit
unknown
Lepidopt. larvae
corn
misc. veg.
wheat seeds
unident. seeds
green veg.
Echinochloa
seeds
Coleoptera
soybeans
Hemiptera
beetles
grasshoppers
leafhoppers
Lepidopterans
spiders
seeds
forbs
grasses &
sedges
shrubs
Spring
20.6
4.1
15.8
6.5
5.4
7.6
0
3.9
13.4
1.3
14.6
6.4
13.3
21.7
2.6
22.5
4.7
4.0
3.8
Summer
0
56
4
3
5
7
25
1
34.5
4.2
3.1
1.6
5
0
1.2
5.3
3.1
2.7
23.8
4.2
1.8
12.7
2.7
25.9
10.0
2.6
1.4
Fall
24
30
trace
26
12
trace
4
4
16.7
3.2
8.0
3.2
8.8
4.3
6.4
5.1
6.9
4.2
9.4
6.4
1.9
1.5
2.5
56.8
5.6
2.8
0.8
Winter
23
46
2
7
18
1
1
3
4.8
8.7
13.4
23.7
8.3
3.7
0
1.4
10.7
0.9
4.9
2.5
2.5
1.8
0.3
65.4
4.3
4.8
2.6
Location (subspecies)/Habitat
(measure)
Virginia (nubiterrae)!
oak-maple-hickory forest
(% frequency of occurrence;
stomach contents)
Indiana/several habitats
(% volume; stomach
contents)
Colorado/short grass prairie
(% volume by a ranking
method; stomach contents)
Reference
Wolff etal., 1985
Whitaker, 1966
Flake, 1973
Note
No.
10
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Deer Mouse (Peromyscus maniculatus)
Population
Dynamics
Home Range
Size (ha)
Population
Density
(N/ha)
Litter
Size
Litters/Year
Age/Sex/
Cond./Seas.
A M summer
A F summer
A M winter
A F winter
BM
BF
AM
AF
AM
AF
BB
A B summer
B B summer
B B winter
AB
BB
Mean
0.039 ±0.0054 SD
0.027 ±0.0047 SD
0.019 ±0.0065 SD
0.014 ±0.0050 SD
0.058 ± 0.006 SE
0.061 ± 0.005 SE
0.10 ± 0.0063 SE
0.075 ±0.0063 SE
0.128 ± 0.012 SE
0.094 ±0.0013 SE
0.19
2.8
12±6.7SD
3.4
4.4
5.1 ±0.14SE
2.4
1.9 ±0.1 SE
Range
0.054 - 0.065
0.054 - 0.072
12.8-22.4
3.4 - 8.4
12.7-45.5
3.9 - 28
3.0 - 6.4
1 -8
Location (subspecies)IHabitat
Utah/subalpine meadow
snowfree
Utah/subalpine meadow
snowbound
Virginia/mixed deciduous
forest
Oregon/ponderosa pines
\dabol(artemisiae-sarcobatus)
desert
Arizona/desert
Colorado/subalpine meadows
Utah/subalpine meadow
British Columbia,
Canada/burnt
slash
Montana/understory near river
Virginia (nubiterrae)INS
average for North America/NS
Alberta, Canada
(nebrascensis)INS
average for North America/NS
Alberta, Canada
(dorea//s)/various alpine
Reference
Cranford, 1984
Cranford, 1984
Wolff, 1985a
Bowers & Smith, 1979
Bowers & Smith, 1979
Brown & Zeng, 1989
Vaughn, 1974
Cranford, 1984
Sullivan, 1979
Metzgar, 1979
Wolff, 1985b
Millar, 1989
Millar, 1985
Millar, 1989
Millar & Innes, 1983
Note
No.
10
ISJ
u>
00
D
(D
(D
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C
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Deer Mouse (Peromyscus maniculatus)
Population
Dynamics
Days
Gestation
Age at
Weaning
(days)
Age at
Sexual
Maturity
Mortality
Rates
Longevity
Seasonal
Activity
Mating
Dispersal
Age/Sex/
Cond./Seas.
F non-lact.
F lactating
F non-lact.
F lactating
F non-lact.
F lactating
B
B
B
M
F
A F winter
A M winter
J F winter
J M winter
A B summer
J B summer
BB
Begin
April
November
March
May
Mean
23.6
26.9
22.4 ±0.1 SE
24.1 ±0.3SE
25.5 ± 0.3 SE
29.5 ± 1.4 SE
20.2
24.9
17.5
35 days
60 days
100%/winter
33%/winter
56%/winter
70%/winter
20%/2 weeks
19%/2 weeks
< 1 yr
Peak
spring
(males)
Range
22-23
22-27
23-26
24-35
16-25
End
August
April
October
August
Location (subspecies)IHabitat
average for United States/NS
Kansas/NS
Alberta, Canada
( nebrascensis)l\ab
average for North America/NS
Alberta, Canada
(dorea//s)/various alpine
Colorado/NS
Alberta, Canada
(nebrascensis)l\ab
Alberta, Canada (borealis)l
various alpine
Alberta, Canada (borealis)!
various alpine
Alberta, Canada (borealis)!
various alpine
Reference
Millar, 1989
Svendsen, 1964
Millar, 1985
Millar, 1989
Millar & Innes, 1983
Halfpenny, 1980
Millar, 1985
Millar & Innes, 1983
Millar & Innes, 1983
Miller & Innes, 1983
Location (subspecies) Reference
Massachusetts Drickamer, 1978
Texas Blair, 1958
Virginia (nubiterrae) Wolff, 1985b
California Dunmire, 1960
Vancouver, Canada Fairbairn, 1977
Note
No.
16
16
Note
No.
16
16
16
16
10
ISJ
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Deer Mouse (Peromyscus maniculatus)
10
CO
o
o
Seasonal
Activity
Torpor
Begin
Peak
winter
End
Location (subspecies)
northern parts of range
Reference
Tannenbaum & Pivorun, 1989
Note
No.
1 Cited in Montgomery (1989).
2 Growth rate of "newly emerged" pups, soon after leaving the nest.
3 Temperatures during winter averaged -17.7°C (-6 to -22°C); during spring averaged 14.5°C (8 to 22°C); during summer 20.6°C (14 to 32°C).
4 Estimated by authors from laboratory-derived model assuming no reproduction, molt, or weight change and assuming summer temperatures
averaged 17.5 C above ground and 20.2 C in burrows and winter temperatures averaged -3 C above ground and 10.7 C in burrows.
5 Estimated using equation 3-48 (Nagy, 1987) and body weights from Millar (1989).
6 Diet of rat chow with 3 percent water content and 4.5 kcal/g dry weight.
7 Diet of Purina lab chow no. 5001; composition not specified.
8 Diet of lab chow; composition not specified.
9 Diet of lab chow with 8 to 10 percent water content.
10 Mean varied by subspecies; sonoriensis, eremicus, gambelii, and fraterculus tested. Dry diet prepared in lab, probably less than 10 percent water
content; air temperature 21 to 24 C.
11 Dry air at 32 to 34 C; diet of wheat and peanuts, about 10 percent water content.
12 Temperature 20°C ± 2°C; diet of lab chow with 8 to 10 percent water content.
13 Estimated using equation 3-17 (Calder and Braun, 1983) and body weights from Millar (1989).
14 Estimated using equation 3-20 (Stahl, 1967) and body weights from Millar (1989).
15 Estimated using equation 3-22 (Stahl, 1967) and body weights from Millar (1989).
16 Cited in Millar (1989).
D
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References (including Appendix)
Abbott, K. D. (1974) Ecotypic and racial variation in the water and energy metabolism of
Peromyscus maniculatus from the western United States and Baja California,
Mexico [Ph.D. dissertation]. Irvine, CA: University of California.
Agnew, W. J.; Uresk, D. W.; Hansen, R. M.; et al. (1988) Arthropod consumption by small
mammals on prairie dog colonies and adjacent ungrazed mixed grass prairie in
western South Dakota. In: Uresk, D. W.; Schenbeck, G. L.; Cefkin, R., tech. coords.
Eighth Great Plains wildlife damage control workshop proceedings; April 28-30,
1987; Rapid City, South Dakota. Fort Collins, CO: U.S. Dept. Agr., Forest Serv.,
Rocky Mountain Forest and Range Experiment Station; pp. 81-87.
Barry, W. J. (1976) Environmental effects on food hoarding in deermice (Peromyscus). J.
Mammal. 57: 731-746.
Birdsall, D. A.; Nash, D. (1973) Occurrence of successful multiple insemination of females
in natural populations of deer mice (Peromyscus maniculatus). Evolution 27:
106-110.
Blair, W. F. (1940) A study of prairie deer mouse populations in southern Michigan. Am.
Midi. Nat. 24: 273-305.
Blair, W. F. (1958) Effects of x-irradiation of a natural population of deer-mouse
(Peromyscus maniculatus). Ecology 39: 113-118.
Bowers, M. A.; Smith, H. D. (1979) Differential habitat utilization by sexes of the deermouse,
Peromyscus maniculatus. Ecology 60: 869-875.
Brower, J. E.; Cade, T. J. (1966) Ecology and physiology of Napaeozapus insignis (Miller)
and other woodland mice. Ecology 47: 46-63.
Brown, J. H.; Zeng, Z. (1989) Comparative population ecology of eleven species of rodents
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2.2.8. Prairie Vole (voles)
Order Rodentia Family Muridae (subfamily Arvicolinae). New world voles are small,
herbivorous rodents that reside in all areas of the United States where good grass cover
exists. Their presence is characterized by narrow runways through matted grasses.
Microtus species are adapted to underground, terrestrial, and sometimes semiamphibious
habitats (Johnson and Johnson, 1982). They are active by day and night and feed mainly
on shoots, grasses, and bark (Johnson and Johnson, 1982). Voles are prey for snakes,
raptors, and mammalian predators such as short-tailed shrews, badgers, raccoons,
coyotes, and foxes (Eadie, 1952; Johnson and Johnson, 1982; Martin, 1956).
Selected species
The prairie vole (Microtus ochrogaster) represents the ground-burrowing members
of this group. This vole is found in the north and central plains of the United States and in
southern Canada, usually in dry places such as prairies and along fencerows and
railroads. Its range has expanded eastward to West Virginia as a result of clear-cutting of
forests (Jones et al., 1983). Voles are active by day or night (Johnson and Johnson, 1982).
Although prairie and meadow voles usually occupy different habitats, where they coexist
their population densities tend to be negatively correlated (Klatt, 1985; Krebs, 1977).
Body size. The prairie vole measures from 8.9 to 13 cm in length and has a 3.0- to
4.1-cm tail (Burt and Grossenheider, 1980). After reaching sexual maturity, voles continue
to grow for several months (Johnson and Johnson, 1982). Adults weigh from 30 to 45 g
(see table). Prairie voles maintain a relatively constant proportion of their body weight as
fat (15 to 16 percent on a dry-weight basis) throughout the year (Fleharty et al., 1973).
Habitat. The prairie vole inhabits a wide variety of prairie plant communities and
moisture regimes, including riparian, short-grass, or tall-grass communities (Kaufman and
Fleharty, 1974). Prairie voles prefer areas of dense vegetation, such as grass, alfalfa, or
clover (Carroll and Getz, 1976); their presence in a habitat depends on suitable cover for
runways (Kaufman and Fleharty, 1974). They will tolerate sparser plant cover than the
meadow vole because the prairie vole usually nests in burrows at least 50 mm
underground or in grass nests under logs or boards (Klatt and Getz, 1987).
Food Habits. Meadow voles, as other voles, are largely herbivorous, consuming
primarily green succulent vegetation but also roots, bark, seeds, fungi, arthropods, and
animal matter (Johnson and Johnson, 1982; Lomolino, 1984; Stalling, 1990). Voles have
masticatory and digestive systems that allow them to digest fibrous grasses such as
cereals (Johnson and Johnson, 1982). Diet varies by season and habitat according to plant
availability, although meadow and other voles show a preference for young, tender
vegetation (Johnson and Johnson, 1982; Martin, 1956). Voles can damage pastures,
grasslands, crops such as hay and grain, and fruit trees (by eating bark and roots)
(Johnson and Johnson, 1982).
2-311 Prairie Vole
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Temperature regulation and molt. Unlike some other mammals, prairie voles do not
hibernate or exhibit torpor (Johnson and Johnson, 1982). They overwinter without using
their lipid reserves, finding food to meet their metabolic requirements year-round (Fleharty
et al., 1973). Prairie voles use burrows, runways, nests, and snow cover to help maintain
their body temperature. They also modify when they are active to avoid excessively hot or
cold temperatures (Johnson and Johnson, 1982). Voles undergo three molts (juvenile,
subadult, and adult), and molting may occur at any time during the year (Jameson, 1947, as
cited in Stalling, 1990). The subadult-to-adult molt occurs between 8 and 12 weeks of age
(Martin, 1956).
Breeding activities and social organization. Prairie voles are monogamous; a
mated pair occupies the same home range (Thomas and Birney, 1979). Reproduction
occurs throughout the year, and gestation lasts approximately 3 wk (Martin, 1956; Keller,
1985; Nadeau, 1985). Both sexes care for the young; paternal activities include runway
construction, food caching, grooming, retrieving, and brooding the young (Thomas and
Birney, 1979). The young are weaned by about 3 weeks of age (Thomas and Birney, 1979).
Reproductive activity peaks from May to October, coinciding with high moisture availability
(Martin, 1956; Keller, 1985). Monogamous family units apparently defend territories against
other family groups (Ostfeld et al., 1988; Johnson and Johnson, 1982; Thomas and Birney,
1979).
Home range and resources. Prairie voles excavate underground nests that are
used as nurseries, resting areas, and as shelter from severe weather (Klatt and Getz,
1987). They spend very little time away from this nest (Barbour, 1963). In thick vegetation,
prairie voles move about in surface runways, and the number of runways is proportional to
population density (Carroll and Getz, 1976). Female home range size decreases with
increasing prairie vole density according to the following regression equation (Gaines and
Johnson, 1982):
Y= -0.23X + 20.16 where Y= home range length in meters and X= minimum
number alive per 0.8 ha grid.
Abramsky and Tracy (1980) found a similar correlation using both sexes according to the
equation:
Y= -0.20X + 27.12 where Y= home range length in meters and X=number of
individuals per hectare.
Population dynamics. Female prairie voles can reach sexual maturity in about 35 d,
males in 42 to 45 d (Gier and Cooksey, 1967, as cited in Stalling, 1990). Martin (1956) found
in Kansas that females mature within about 6 wk in the summer, but may require 15 wk or
more to mature if born in the fall. Male prairie voles tend to disperse from their natal site;
approximately twice as many females as males mature near their birthplace (Boonstra et
al., 1987). Populations tend to fluctuate with available moisture (Gier, 1967, as cited in
Stalling, 1990). Mortality rates in prairie vole postnestling juveniles and young adults are
similar and higher than adult mortality rates; nestlings have the lowest mortality rate
(Golley, 1961). Average life expectancy in the field is about 1 yr (Martin, 1956).
2-312 Prairie Vole
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Similar species (from general references)
• The pine vole (Microtus pinetorum) (7 to 11 cm), despite its name, usually
inhabits deciduous forest floors, among a thick layer of duff, where it tunnels
through loose soil near the surface. It is found in the eastern half of the
United States, except Florida; in the south, it inhabits pine forests. In
addition to feeding on bark, it burrows for bulbs, tubers, and corms.
• See also similar species listed for the meadow vole in this chapter.
General references
Burt and Grossenheider (1980); Johnson and Johnson (1982); Stalling (1990);
Tamarin (1985).
2-313 Prairie Vole
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Prairie Vole (Microtus ochrogastet)
Factors
Body Weight
(g)
Metabolic Rate
(I02/kg-d)
Metabolic Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Water
Ingestion Rate
(g/g-d)
Inhalation
Rate (m3/d)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
A B summer
A B fall
A B winter
A B spring
AM
AF
neonate B
A winter
A summer
A B basal
A B free-living
A Bat 21 °C
ABat28°C
AB
AB
AB
AB
AB
AB
Mean
41.6
41.9
44.2
39.0
41.3
31.3 ± 0.35 SE
33.3 ± 0.30 SE
2.8±0.4SD
51.8 ± 8.2 SD
41.8±4.8SD
177
399
0.13-0.14
0.09-0.10
0.37
0.29 ± 0.02 SE
0.21
0.14
0.043
139
Range or
(95% Cl of mean)
(190-833)
0.1 5 to 0.26
Location
ne Colorado
ne Colorado
s Indiana
ne Kansas
NS/lab
Illinois/lab
NS/lab
Kansas/lab
Illinois/lab
Reference
Abramsky & Tracy, 1980
Abramsky & Tracy, 1980
Myers & Krebs, 1971
Martin, 1956
Wunderetal., 1977
estimated
estimated
Dice, 1922
Chew, 1951
Dupre, 1983
Dice, 1922
estimated
estimated
estimated
Note
No.
1
2
3
4
5
6
7
8
9
10
CO
TJ
(D
-------
Prairie Vole (Microtus ochrogastet)
Dietary
Composition
Sporobolus asper
Kochia scoparia
Bouteloua gracilis
Bromus japonicus
Rumex crispus
Triticum aestivum
Carexsp.
other
(grasses)
(forbs)
Festuca arundinacea
Dactylis glomerata
Phleum pratense
Tridens flavus
Setaria viridis
Taraxacum officinale
Lamium amplexicaule
Bromus tectorum
Setaria faberi
Capsella bursa-past.
Trifolium stolonifera
arthropods
animal material
other
Population
Dynamics
Home
Range
Size (ha)
Spring
20.5
6.7
8.3
17.1
6.7
5.8
3.9
2.8
5.6
2.7
2.4
0.2
0
3.9
A B all yr
A M all yr
A F all yr
AM
AF
Summer
19.5
22.5
6.5
8.5
9.2
3.4
2.0
28.3
(53.5)
\W.Vj
(46.5)
25.0
1.7
2.0
11.1
6.2
4.8
2.9
4.7
3.9
1.2
0.8
0.3
0.2
1.4
Fall
10.6
1.1
2.1
1.9
1.7
3.9
5.2
2.5
0.7
0.5
0.5
0.0
0.2
1.5
0.098 ± 0.012 SE
0.037 ± 0.0029 SE
0.024 ± 0.0018 SE
0.011
0.0073
Winter
28.9
4.2
5.3
11.0
6.2
1.5
3.4
4.8
21.0
0.6
1.4
0.1
0.0
0.9
Range
Location/Habitat
(measure)
Kansas/forb and grass field
(% volume; stomach
contents)
(Items less than 2% of
volume were combined as
"other")
Missouri/old field
(mean number of food
items; stomach contents)
(Plant parts consumed: leaf,
stem, and seeds of Festuca
and Bromus', leaf and stem
of Tridens and Setaria
faberi', leaf and seeds of
Dactylis and Seteria viridis',
and leaves only of all other
plant species)
Reference
Fleharty& Olson, 1969
Cook etal., 1982
Illinois/bluegrass Jikeetal., 1988
Kansas/NS Swihart & Slade, 1989
ne Colorado/short-grass Abramsky & Tracy, 1980
prairie
Note
No.
Note
No.
10
CO
_1
Ul
TJ
(D
-------
Prairie Vole (Microtus ochrogastet)
Population
Dynamics
Population
Density
(N/ha)
Litter
Size
Litters/Year
Days
Gestation
Pup Growth
Rate (g/d)
Age at
Weaning
Age at
Sexual
Maturity
Annual
Mortality
Longevity
Age/Sex/
Cond./Seas.
summer
winter
spring
summer
summer
winter
spring
fall
days 1 to 10
days 1 1 to 30
> 30 d until
growth stops
F
M
B
B
Mean
25-35
12
78-118
81 -104
168-234
160-197
203 - 247
94-123
3.18 ± 0.24 SD
3.4
4.25
several
21
21
0.6
1.0
0.5
(highly variable)
21 days
35 days
93%
1yr
Range
1 -7
42 to 45 d
up to 1.8 yr
Location/Habitat
w Nebraska/xeric prairie
Illinois/alfalfa field
ne Kansas/grassland
ne Kansas/grassland
Kansas/NS
lllinois/NS
NS/NS
ne Kansas/grassland
NS/NS
ne Kansas/grassland
NS/lab
NS/NS
ne Colorado/short-grass
prairie
ne Kansas/grassland
Reference
Meserve, 1971
Carroll & Getz, 1976
Martin, 1956
Martin, 1956
Jameson, 1947
Cole &Batzli, 1978
Johnson & Johnson, 1982
Martin, 1956
Keller, 1985
Martin, 1956
Thomas & Birney, 1979
Gier& Cooksey, 1967
Abramsky & Tracy, 1980
Martin, 1956
Note
No.
10
11
12
13
10
CO
_1
o>
TJ
(D
-------
Prairie Vole (Microtus ochrogastet)
Seasonal
Activity
Mating
Parturition
Molt
Begin
Peak
May to Oct
May to Oct
anytime
End
Location
NS
NS
NS
Reference
Keller, 1985; Martin, 1956
Keller, 1985; Martin, 1956
Jameson, 1947
Note
No.
13
10
CO
1 Estimated using equation 3-43 (Boddington, 1978) and body weights (summer) from Abramsky and Tracy (1980).
2 Estimated using equation 3-48 (Nagy, 1987) and body weights (summer) from Abramsky and Tracy (1980).
3 Estimated from ingestion rate for diet of oats (74 to 78 percent of total weight of diet) and dry grass, assuming 31 to 34 g body weight. Diet was low
in water (probably less than 10 percent).
4 Measured water drunk from water bottles; diet consisted of rolled oats with sunflower seeds; temperature 28 C.
5 Measured water drunk; diet of dry food.
6 Temperature 21 °C; dry air.
7 Estimated using equation 3-17 (Calder and Braun, 1983) and body weights (summer) from Abramsky and Tracy (1980).
8 Estimated using equation 3-20 (Stahl, 1967) and body weights (summer) from Abramsky and Tracy (1980).
9 Estimated using equation 3-22 (Stahl, 1967) and body weights (summer) from Abramsky and Tracy (1980).
10 Determined from pup count, which may underestimate litter size at birth.
11 Cited in Keller (1985); embryo or pup count.
12 Cited in Keller (1985); embryo or placenta! scar count.
13 Cited in Stalling (1990).
TJ
(D
-------
References (including Appendix)
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population size in Microtus ochrogaster. Oikos 34: 347-355.
Agnew, W. J.; Uresk, D. W.; Hansen; et al. (1988) Arthropod consumption by small
mammals on prairie dog colonies and adjacent ungrazed mixed grass prairie in
western South Dakota. In: Uresk, D. W.; Schenbeck, G. L.; Cefkin, R., tech. coord.
Eighth Great Plains wildlife damage control workshop proceedings; April 28-30,
1987; Rapid City, South Dakota. Fort Collins, CO: U.S. Department of Agriculture,
Forest Service, Rocky Mountain Forest and Range Experiment Station; pp. 81-87.
Barbour, R. W. (1963) Microtus: a simple method of recording time spent in the nest.
Science 141: 41.
Boddington, M. J. (1978) An absolute metabolic scope for activity. J. Theor. Biol. 75: 443-
449.
Boonstra, R.; Krebs, C. J.; Gaines, M. S.; et al. (1987) Natal philopatry and breeding
systems in voles (Microtus spp.). J. Anim. Ecol. 56: 655-673.
Bradley, S. R. (1976) Temperature regulation and bioenergetics of some microtine rodents
[Ph.D. dissertation]. Ithaca, NY: Cornell University.
Burt, W. H.; Grossenheider, R. P. (1980) A field guide to the mammals of North America
north of Mexico. Boston, MA: Houghton Mifflin Co.
Calder, W. A.; Braun, E. J. (1983) Scaling of osmotic regulation in mammals and birds. Am.
J. Physiol. 244: R601-R606.
Carroll, D.; Getz, L. L. (1976) Runway use and population density in Microtus ochrogaster.
J. Mammal. 57: 772-776.
Chew, R. M. (1951) The water exchanges of some small mammals. Ecol. Monogr. 21:
215-225.
Cole, F. R.; Batzli, G. O. (1978) Influence of supplemental feeding on a vole population. J.
Mammal. 59: 809-819.
Colvin, M. A.; Colvin, D. V. (1970) Breeding and fecundity of six species of voles (Microtus).
J. Mammal. 51:417-419.
Cook, J. C.; Topping, M. S.; Stombaugh, T. A. (1982) Food habits of Microtus ochragaster
and Peromyscus maniculatus in sympatry. Trans. Missouri Acad. Sci. 16: 17-23.
Corthum, D. W., Jr. (1967) Reproduction and duration of placenta! scars in the prairie vole
and the eastern vole. J. Mammal. 48: 287-292.
2-318 Prairie Vole
-------
Dice, L. R. (1922) Some factors affecting the distribution of the prairie vole, forest deer
mouse, and prairie deer mouse. Ecology 3: 29-47.
Dupre, R. K. (1983) A comparison of the water relations of the hispid cotton rat, Sigmodon
hispidus, and the prairie vole, Michrotus ochrogaster. Comp. Biochem. Physiol.
75A: 659-663.
Eadie, R. W. (1952) Shrew predation and vole populations on a localized area. J. Mammal.
33: 185-189.
Fitch, H. S. (1957) Aspects of reproduction and development in the prairie vole (Microtus
ochrogaster). Univ. Kansas Publ., Mus. Nat. Hist. 10: 129-161.
Fleharty, E. D.; Olson, L. E. (1969) Summer food habits of Michrotus ochrogaster and
Sigmodon hispidus. J. Mammal. 50: 475-486.
Fleharty, E. D.; Krause, M. E.; Stinnett, D. P. (1973) Body composition, energy content, and
lipid cycles of four species of rodents. J. Mammal. 54: 426-438.
Gaines, M. S.; Johnson, M. L. (1982) Home range size and population dynamics in the
prairie vole, Microtus ochrogaster. Oikos 39: 63-70.
Gaines, M. S.; Rose, R. K. (1976) Population dynamics of Microtus ochrogaster in eastern
Kansas. Ecology 57: 1145-1161.
Getz, L. L.; Hofmann, J. E.; Klatt, B. J.; et al. (1987) Fourteen years of population
fluctuations of Microtus ochrogaster and M. pennsylvanicus in east central Illinois.
Can. J. Zool. 65: 1317-1325.
Gier, H. T. (1967) The Kansas small mammal census: terminal report. Trans. Kansas Acad.
Sci. 70: 505-518.
Gier, H. T.; Cooksey, B. F., Jr. (1967) Michrotus ochrogaster in the laboratory. Trans.
Kansas Acad. Sci. 70: 256-265.
Golley, F. B. (1961) Interaction of natality, mortality and movement during one annual cycle
in a Microtus population. Am. Midi. Nat. 66: 152-159.
Harvey, M. J.; Barbour, R. W. (1965) Home range of Microtus ochrogaster as determined by
a modified minimum area method. J. Mammal. 46: 398-402.
Jameson, E. W., Jr. (1947) Natural history of the prairie vole (mammalian genus Michrotus).
Misc. Publ. Mus. Nat. Hist. Univ. Kansas 1: 125-151.
Jike, L.; Batzli, G. O.; Getz, L. L. (1988) Home ranges of prairie voles as determined by
radiotracking and by powdertracking. J. Mammal. 69: 183-186.
2-319 Prairie Vole
-------
Johnson, M. L.; Johnson, S. (1982) Voles (Microtus species). In: Chapman, J. A.;
Feldhamer, G. A., eds. Wild mammals of North America. Baltimore, MD: Johns
Hopkins University Press; pp. 326-353.
Jones, J. K. Jr.; Armstrong, R. S.; Hoffman, R. S.; et al. (1983) Mammals of the Great
Northern Plains. Lincoln, NE: University of Nebraska Press.
Kaufman, D. W.; Fleharty, E. D. (1974) Habitat selection by nine species of rodents in
north-central Kansas. Southwest. Nat. 18: 443-451.
Keller, B. L. (1985) Reproductive patterns. In: Tamarin, R. H., ed. Biology of new world
Microtus. American Society of Mammalogists; Special Publication No. 8; pp.
725-778.
Keller, B. L.; Krebs, C. J. (1970) Microtus population biology. III. Reproductive changes in
fluctuating populations of M. ochrogasterand M. pennsylvanicus in southern
Indiana, 1965-1967. Ecol. Monogr. 40: 263-294.
Kenney, A. M.; Evans, R. L.; Dewsbury, D. A. (1977) Postimplantation pregnancy disruption
in Microtus orchogaster, Microtus pennsylvanicus, and Peromyscus maniculatis. J.
Reprod. Pert. 49: 365-367.
Klatt, B. J. (1985) The role of habitat preference and interspecific competition in
determining the local distribution of Microtus pennsylvanicus and M. ochrogaster in
central Illinois (abstract). Bull. Ecol. Soc. Am. 66: 209.
Klatt, B. J.; Getz, L. L. (1987) Vegetation characteristics of Microtus ochragasterand M.
pennsylvanicus habitats in east-central Illinois. J. Mammal. 68: 569-577.
Krebs, C. J. (1977) Competition between Microtus pennsylvanicus and Microtus
ochragaster. Am. Midi. Nat. 97: 42-49.
Kruckenberg, S. M.; Gier, H. T.; Dennis, S. M. (1973) Postnatal development of the prairie
vole, Microtus ochrogaster. Lab. Anim. Sci. 23: 53-55.
Lomolino, M. V. (1984) Immigrant selection, predation, and the distribution of Microtus
pennsylvanicus and Blarina brevicauda on islands. Am. Nat. 123: 468-483.
Martin, E. P. (1956) A population study of the prairie vole (Michrotus ochragaster) in
northeastern Kansas. Univ. Kansas Publ. Mus. Nat. Hist. 8: 361-416.
Martin, E. P. (1960) Distribution of native mammals among the communities of the mixed
prairie. Fort Hays Stud. N. S. Sci. Ser. 1: 1-26.
Meserve, P. L. (1971) Population ecology of the prairie vole, Microtus ochrogaster, in the
western mixed prairie of Nebraska. Am. Woodl. Nat. 86: 417-433.
2-320 Prairie Vole
-------
Morrison, P. R.; Dieterich, R.; Preston, D. (1976) Breeding and reproduction of fifteen wild
rodents maintained as laboratory colonies. Lab. Anim. Care 26: 237-243.
Myers, J. H.; Krebs, C. J. (1971) Genetic, behavioral, and reproductive attributes of
dispersing field voles Microtus pennsylvanicus and Michrotus ochrogaster. Ecol.
Monogr. 41: 53-78.
Nadeau, J. H. (1985) Ontogeny. In: Tamarin, R. H., ed. Biology of new world Microtus. Spec.
Publ. Amer. Soc. Mammal. 8; pp. 254-285.
Nagy, K. A. (1987) Field metabolic rate and food requirement scaling in mammals and
birds. Ecol. Monogr. 57: 111-128.
Ostfeld, R. S.; Pugh, S. R.; Seamon, J. O.; et al. (1988) Space use and reproductive success
in a population of meadow voles. J. Anim. Ecol. 57: 385-394.
Quick, F. W. II (1970) Small mammal populations in an old field community [Ph.D.
dissertation]. Louisville, KY: University of Louisville.
Richmond, M. E. (1967) Reproduction of the vole, Microtus orchogaster [Ph.D.
dissertation]. Columbia, MO: University of Missouri.
Richmond, M. E.; Conaway, C. H. (1969) Management, breeding and reproductive
performance of the vole, Microtus ochrogaster in a laboratory colony. Lab. Anim.
Care 19: 80-87.
Rolan, R. G.; Gier, H. T. (1967) Correlation of embryo and placenta! scar counts of
Peromyscus maniculatis and Microtus orchogaster. J. Mammal. 48: 317-319.
Rose, R. K.; Gaines, M. S. (1978) The reproductive cycle of Microtus orchogaster in eastern
Kansas. Ecol. Monogr. 48: 21-42.
Stahl, W. R. (1967) Scaling of respiratory variables in mammals. J. Appl. Physiol. 22:
453-460.
Stalling, D. T. (1990) Microtus ochrogaster. American Society of Mammalogists; Mammalian
Species No. 355; 9 pp.
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Microtus ochrogaster. J. Mammal. 70: 816-820.
Tamarin, R. H. (1985) Biology of new world Microtus. Spec. Publ. Amer. Soc. Mammal. 8.
Thomas, J. A.; Birney, E. C. (1979) Parental care and mating system of the prairie vole,
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western Kansas. Trans. Kans. Acad. Sci. 42: 515-517.
2-321 Prairie Vole
-------
Wunder, B. A. (1985) Energetics and thermoregulation. In: Tamarin, R. H., ed. Biology of
new world Microtus. Spec. Publ. Amer. Soc. Mammal. 8; pp. 812-844.
Wunder, B. A.; Dobkin, D. S.; Gettinger, R. D. (1977) Shifts of thermogenesis in the prairie
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Mammal. 46: 605-612.
2-322 Prairie Vole
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2.2.9. Meadow Vole (voles)
Order Rodentia Family Muridae (subfamily Arvicolinae). New world voles are small,
herbivorous rodents that reside in all areas of Canada and the United States where there is
good grass cover. Their presence is characterized by narrow runways through matted
grasses. Microtus species are adapted to underground, terrestrial, and sometimes
semiamphibious habitats (Johnson and Johnson, 1982). They are active by day and night,
feeding mainly on shoots, grasses, and bark. Voles are prey for hawks and owls as well as
several mammalian predators such as short-tailed shrews, badgers, and foxes (Johnson
and Johnson, 1982; Eadie, 1952).
Selected species
The meadow vole (Microtus pennsylvanicus) makes its burrows along surface
runways in grasses or other herbaceous vegetation. It is the most widely distributed small
grazing herbivore in North America and is found over most of the northern half of the
United States. Meadow voles have been used in bioassays to indicate the presence of
toxins in their foods (Kendall and Sherwood, 1975, cited in Reich, 1981; Schillinger and
Elliot, 1966). Although primarily terrestrial, the meadow vole also is a strong swimmer
(Johnson and Johnson, 1982).
Body size. The meadow vole measures 8.9 to 13 cm in length (head and body) and
has a 3.6- to 6.6-cm tail. They weigh between 20 and 40 g depending on age, sex, and
location (see table). Mature males are approximately 20 percent heavier than females
(Boonstra and Rodd, 1983). Meadow voles lose weight during the winter, reaching a low
around February, then regain weight during spring and summer, reaching a high around
August in many populations (see table; Iverson and Turner, 1974).
Habitat. The meadow vole inhabits grassy fields, marshes, and bogs (Getz, 1961 a).
Compared with the prairie vole, the meadow vole prefers fields with more grass, more
cover, and fewer woody plants (Getz, 1985; Zimmerman, 1965). The meadow vole also
tends to inhabit moist to wet habitats, whereas the prairie vole is relatively uncommon in
sites with standing water (Getz, 1985).
Food habits. Meadow voles consume green succulent vegetation, sedges, seeds,
roots, bark, fungi, insects, and animal matter (see table). They are agricultural pests in
some areas, feeding on pasture, hay, and grain (Johnson and Johnson, 1982; Burt and
Grossenheider, 1980). At high population densities, the meadow vole has been known to
girdle trees, which can damage orchards (Byers, 1979, cited in Reich, 1981). In seasonal
habitats, meadow voles favor green vegetation when it is available and consume other
foods more when green vegetation is less available (Johnson and Johnson, 1982; Riewe,
1973; Getz, 1985). Although Zimmerman (1965) found some evidence of food selection, he
found that meadow voles generally ate the most common plants in their habitat. Meadow
voles living on prairies consume more seeds and fewer dicots and monocots than voles in
a bluegrass habitat (Lindroth and Batzli, 1984). The meadow vole's large cecum allows it to
have a high digestive efficiency of 86 to 90 percent (Golley, 1960). Coprophagy (eating of
feces) has been observed in this species (Ouellete and Heisinger, 1980).
2-323 Meadow Vole
-------
Temperature regulation and molt. In winter, Microtus species do not undergo
hibernation or torpor; instead, they are active year round (Didow and Hayward, 1969;
Johnson and Johnson, 1982). Behaviors that help meadow voles to maintain their body
temperature include the use of burrows, runways, nests, and snow cover for insulation.
They also can change when they are active; when temperatures exceed 20 C, meadow
voles are most active at night (Getz, 1961b; Johnson and Johnson, 1982). In winter,
meadow voles increase their brown fat content (a major site of thermoregulatory heat
production). Mature individuals average 0.5 percent brown fat in summer, increasing to 1.7
percent in early winter; juveniles average 1.0 percent in the summer, increasing to 2.3
percent in the winter (Didow and Hayward, 1969). Voles undergo three molts: juvenile,
postjuvenile, and adult. The timing varies by species (Johnson and Johnson, 1982). Adult
Arvicolinae also undergo winter and summer molts (Johnson and Johnson, 1982).
Breeding activities and social organization. Meadow voles are polygynous
(McShea, 1989). Males form a hierarchy in which the most dominant male voles breed
(Boonstra and Rodd, 1983). Voles produce litters throughout the breeding season, the
number of litters per season increases with decreasing latitude (Johnson and Johnson,
1982).
Home range and resources. The area encompassed by a meadow vole's home
range depends on season, habitat, population density, and the age and sex of the animal.
Summer ranges tend to be larger than winter ranges, and ranges in marshes tend to be
larger than ranges in meadows (Getz, 1961c; Reich, 1981). Home range size also declines
with increasing population density (Getz, 1961c; Tamarin, 1977a). Female meadow voles
defend territories against other females, whereas male home ranges are larger and overlap
with home ranges of both sexes (Madison, 1980; Ostfeld et al., 1988; Wolff, 1985). Meadow
voles build runways in grasses and vegetation at the ground's surface and use the
runways for foraging about 45 percent of the time, depending on weather and other factors
(Gauthier and Bider, 1987). The meadow vole exhibits daytime activity where dense cover
is available and becomes more crepuscular with less cover (Graham, 1968, cited in Reich,
1981). All Microtus species apparently do some burrowing, excavating underground nests
that are used as nurseries, resting areas, and as shelter from severe weather (Johnson and
Johnson, 1982). Nests are built with the use of dead grass in patches of dense, live grass;
widened spaces, called forms, are used off main runways (Ambrose, 1973).
Population density. Meadow vole population densities fluctuate widely from season
to season and year to year, sometimes crashing to near zero before recovering in a few
years to densities of several hundred per hectare (Boonstra and Rodd, 1983; Lindroth and
Batzli, 1984; Getz et al., 1987; Myers and Krebs, 1971; Taitt and Krebs, 1985). Krebs and
Myers (1974) noted population cycles of 2 to 5 yr, whereas Tamarin (1977b) reported 3- to
4-year population cycles in southeastern Massachusetts. However, Getz et al. (1987) found
no indication of multiannual abundance cycles in their three habitat study (i.e., bluegrass,
tallgrass prairie, and alfalfa) in east central Illinois. Meadow voles avoid short-tailed
shrews (Fulk, 1972), and the vole population density decreases as the number of short-
tailed shrews in the area increases (Eadie, 1952).
2-324 Meadow Vole
-------
Population dynamics. Voles reach sexual maturity usually within several weeks
after birth, with females maturing before males, but still continue to grow for several
months (Johnson and Johnson, 1982). Innes (1978) reported that litter size is independent
of latitude or elevation. However, summer litters were, on average, 14 percent larger than
litters produced during other seasons, and larger females produced larger litters (Keller
and Krebs, 1970). Young from the spring and early summer litters reached adult weight in
about 12 wk (Brown, 1973). Mortality rates are highest in postnestling juveniles and young
adults and lowest in nestlings (ages 1 to 10 d) (Golley, 1961). Dispersing meadow voles
(predominantly young males) tend to weigh less than resident meadow voles (Boonstra et
al., 1987; Myers and Krebs, 1971; Boonstra and Rodd, 1983; Brochu et al., 1988).
Similar species (from general references)
• The California vole (Microtus californicus) is larger than the meadow vole (12
to 14 cm head and body) and is found throughout California and southern
Oregon. It inhabits freshwater and saltwater marshy areas, wet meadows,
and grassy hillsides from the seashore to the mountains and feeds on green
vegetation.
• Townsend's vole (Microtus townsendii) usually is found near water in moist
fields, sedges, tules, and meadows (from tidewater to alpine meadows). Its
range is limited to extreme northwestern California, western Oregon and
Washington, and southern British Columbia (inhabits several islands off the
coast of Washington and British Columbia). It is easily distinguished by its
large size (12 to 16 cm) and black-brown color.
• The montane vole (Microtus montanus) (mountain vole) is slightly larger (10
to 14 cm) than the meadow vole and is found in valleys of the mountainous
Great Basin area of the western and northwestern United States.
• The long-tailed vole (Microtus longicaudus) (tail 5 to 9 cm) is slightly larger
(11 to 14 cm) than the meadow vole. It is found in the western United States
and Canada to Alaska and lives along streambanks, in mountain meadows,
sometimes in dry situations, and in brushy areas during winter. In addition
to grasses and bark, it feeds on bulbs. It nests above ground in winter and
burrows in summer.
• The creeping vole (Microtus oregoni) (Oregon vole) (10 to 11 cm) is an
inhabitant of western Oregon and Washington and extreme northwest
California. Seldom above ground, it spends most of its time burrowing
through forest floor duff or grass roots. It lives in forests, brush, and grassy
areas.
• The sagebrush vole (Lagurus curtatus) (9.7 to 11 cm) lives in loose soil and
arid conditions and feeds on green vegetation, especially sagebrush. It also
burrows around sagebrush; a vole found living in sagebrush is almost
certainly this species.
2-325 Meadow Vole
-------
General references
Burt and Grossenheider (1980); Reich (1981); Johnson and Johnson (1982); Tamarin
(1985).
2-326 Meadow Vole
-------
Meadow Vole (Microtus pennsylvanicus)
Factors
Body Weight
(g)
Pup Growth
Rate (g/d)
Body Fat (g)
Metabolic
Rate
(I02/kg-d)
Metabolic Rate
(kcal/kg-d)
Age/Sex/
Cond./Seas.
A M summer
A F summer
A M spring
A F spring
AM&F
spring
summer
fall
winter
A M avg. all yr
A F avg. all yr
neonate M & F
neonate M & F
birth - 21 days
22 - 33 days
34 - 54 days
55- 103 days
summer:
JF
A F gestating
A F lactating
basal
average daily
A M basal
A F basal
A B avg. daily
A M free-living
A F free-living
Mean
40.0 ± 8.3 SE
33.4 ± 8.2 SE
52.4
43.5
26.0
24.3
17.0
17.5
35.5 ±0.1 SE
39.0 ± 0.3 SE
2.1
2.3 ±0.1 SD
0.95
0.81
0.45
0.19
0.37 ± 0.04 SE
1.20 ± 0.15 SE
0.60 ± 0.09 SE
60.0
82.8±12SD
166
175
395
357
485
Range or
(95% Cl of
mean)
1.6-3.0
43.2-146
(170-747)
(231 -1,020)
Location
Quebec, Canada
Ontario, Canada
Manitoba, Canada
south Indiana
not specified
south Michigan/old field
Alberta, Canada
lab
lab
lab 25-30 °C
Reference
Brochu etal., 1988
Boonstra & Rodd, 1983
Anderson etal., 1984
Myers & Krebs, 1971
Hamilton, 1941
lnnes& Millar, 1981
Golley, 1961
Millar, 1987
Wiegert, 1961
Morrison, 1948
estimated
Pearson, 1947
estimated
Note
No.
1
2
3
4
5
6
10
CO
10
(D
0)
Q.
O
(D
-------
Meadow Vole (Microtus pennsylvanicus)
Factors
Food Ingestion
Rate (g/g-d)
(cal/g-d)
Water
Ingestion
Rate (g/g-d)
Inhalation
Rate (m3/d)
Surface Area
(cm2)
Dietary
Composition
dicot shoots
monocot
shoots
seeds
roots
fungi
insects
dicot shoots
monocot
shoots
seeds
roots
fungi
insects
Age/Sex/
Cond./Seas.
A M short-day
A M long-day
AB
AB
AM
AF
AM
AF
Spring
41
50
1
0
6
2
53
23
7
4
12
1
Mean
0.30-0.35
370 ± 20 SE
410±10SE
0.21 ±0.02SE
0.14
0.052
0.044
161
143
Summer
60
26
9
1
4
0
65
29
1
0
1
4
Range or
(95% Cl of
mean)
Fall
66
9
1
12
10
2
41
12
16
6
20
5
Winter
12
40
13
34
0
1
41
5
36
17
0
1
Location
Russia
NS
NS
Location/Habitat
(measure)
Illinois/bluegrass
(% volume; stomach
contents)
Illinois/tallgrass prairie
(% volume; stomach
contents)
Reference
Ognev, 1950
Dark etal., 1983
Ernst, 1968
estimated
estimated
estimated
Reference
Lindroth & Batzli, 1984
Lindroth & Batzli, 1984
Note
No.
7
8
9
10
11
12
Note
No.
10
CO
10
00
(D
0)
Q.
O
(D
-------
Meadow Vole (Microtus pennsylvanicus)
Population
Dynamics
Home Range
Size (ha)
Population
Density
(IM/ha)
Litter
Size
Litters/Year
Days
Gestation
Age at
Weaning (d)
Age at
Sexual
Maturity
Mortality
Rates
Age/Sex/
Cond./Seas.
A M summer
A F summer
A B summer
A B winter
A M summer
A F summer
AB
AB
AB
fall
winter
spring
summer
F
M
nestlings
juveniles
young adults
adults
old adults
Mean
0.019 ±0.011 SD
0.0069 ±0.0039 SD
0.014
0.0002
0.083 ± 0.037 SD
0.037 ± 0.020 SD
3.82
4.46
6.05
several
21.0 ± 0.2 SD
21
(0-1 Og) 50%
(11-20g) 61%
(21-30g) 58%
(31-50g) 53%
(>50g) 100%
Range
96 - 549
2-28
25-163
28-51
20-51
22-53
38-64
1 -11
1 -9
1 -8
at least 3 wk
at least 6-8 wk
Location/Habitat
Virginia/old field
Montana/alluvial bench
Massachusetts/grassy
meadow
Ontario, Canada/grassland
Illinois/bluegrass
Indiana/grassland
Michigan/grass-sedge
marsh
Manitoba, Canada/NS
Indiana/NS
Pennsylvania/NS
NS/NS
NS/NS
s Michigan/NS
NS/NS
south Michigan/old field
Reference
Madison, 1980
Douglass, 1976
Ostfeld et al., 1988
Boonstra & Rodd, 1983
Lindroth & Batzli, 1984
Myers & Krebs, 1971
Getz, 1961 a
Iverson & Turner, 1976
Corthum, 1967
Coin, 1943
Bailey, 1924
Kenneyetal., 1977
Golley, 1961
Johnson & Johnson, 1982
Golley, 1961
Note
No.
13
13
13
14
2
10
CO
10
(D
0)
Q.
O
(D
-------
Meadow Vole (Microtus pennsylvanicus)
Population
Dynamics
Longevity
Age/Sex/
Cond./Seas.
Mean
2-3 mo
early April
Oct. - Nov.
April -June
fall/winter
summer (females)
winter (males)
Range
< 24 mo
End
mid-October
Location/Habitat Reference
NS Beer & MacLeod, 1961
NS Johnson & Johnson, 1982
Manitoba, Canada
Michigan (fall-winter peak)
Michigan (spring-summer
peak)
Indiana/grassland
Massachusetts/coastal field
Mihok, 1984
Getz, 1960
Getz, 1960
Myers & Krebs, 1971
Tamarin, 1977b
Note
No.
9
Note
No.
15
15
CO
CO
o
(D
0)
Q.
O
1 Cited in Reich (1981) and Johnson and Johnson (1982).
2 Cited in Nadeau (1985).
3 Body weight 35.6 g; temperature not specified; cited in Deavers and Hudson (1981).
4 Temperature 15 to 25°C; weight 26.2 to 32 g.
5 Estimated using equation 3-43 (Boddington, 1978) and body weights from Anderson et al. (1984).
6 Estimated using equation 3-48 (Nagy, 1987) and body weights from Anderson et al. (1984).
7 Cited in Johnson and Johnson (1982).
8 Short-day photoperiod = 10 h of light, 14 of dark; long-day photoperiod = 14 h of light, 10 of dark.
9 Cited in Reich (1981).
10 Estimated using equations 3-17 (Calder and Braun, 1983) and 3-18 and body weights from Anderson et al. (1984).
11 Estimated using equation 3-20 (Stahl, 1967) and body weights from Anderson et al. (1984).
12 Estimated using equation 3-22 (Stahl, 1967) and body weights from Anderson et al. (1984).
13 Cited in Keller (1985).
14 Cited in Johnson and Johnson (1982).
15 Cited in Getz (1961 b).
o_
(D
-------
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2-336 Meadow Vole
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2.2.10. Muskrat (water rats and muskrats)
Order Rodentia Family Muridae. Water rats and muskrats are the most aquatic of
this family of rodents, with most of their lives spent in or near bogs, marshes, lakes or
streams. These two rodents feed mostly on aquatic vegetation. Only one species exists in
each genus (Burt and Grossenheider, 1980).
Selected species
The muskrat (Ondatra zibethicus) is indigenous and common throughout most of
the United States (except in the extreme southeast, central Texas, and most of California)
and Canada (except in the extreme north) (Burt and Grossenheider, 1980). Muskrats feed
primarily on aquatic plants. They are prey for hawks, minks, otters, raccoons, owls, red
fox, dogs, snapping turtles, and water snakes (Bednarik, 1956; Errington, 1939a; Wilson,
1985), and are more vulnerable to predation during times of drought when low water levels
leave their dens or lodges more exposed (Errington, 1939a). Many vertebrates use
muskrat homes for shelter or to find food (Kiviat, 1978). The muskrat is one of the most
valuable fur animals in North America (Dozier, 1953; Perry, 1982). Including the
Newfoundland muskrat, formerly Ondatra obscurus, 16 recognized subspecies of O.
zibethicus exist in North America (Perry, 1982). Of these, O. z. zibethicus (eastern United
States, southeastern Canada), O. z. osoyoosensis (Rocky Mountains, southwestern
Canada), and O. z. rivalicius (southern Louisiana, coasts of Mississippi, western Alabama,
and eastern Texas) are most often studied.
Body size. The muskrat measures 25 to 36 cm (head and body) with a 20- to 25- cm
tail (Burt and Grossenheider, 1980), and adult weights can range from 0.5 kg to over 2 kg
(see Appendix). Willner et al. (1980) reported no sexual dimorphism, whereas Dozier
(1950), Parker and Maxwell (1984), and others (see Appendix) reported that males are
slightly heavier than females. Muskrats tend to be larger and heavier in northern latitudes
(Perry, 1982), although the smallest muskrats are found in Idaho (Reeves and Williams,
1956). Fat levels in adult males increase from spring through fall, and subsequently
decrease from winter to spring (Schacher and Pelton, 1975). In nonpregnant females, fat
levels decrease from winter through summer; in pregnant females, body fat increases from
spring to summer (Schacher and Pelton, 1975).
Habitat. Muskrats inhabit saltwater and brackish marshes and freshwater creeks,
streams, lakes, marshes, and ponds (Dozier, 1953; Johnson, 1925; Kiviat, 1978; O'Neil,
1949). Muskrats that live along the banks or shores of waterways generally excavate dens
in the banks, whereas muskrats living in ponds with ample plant material construct lodges
(Johnson, 1925; Perry, 1982). When available, bank dens seem preferred over constructed
lodges (Johnson, 1925).
Food habits. Muskrats are primarily herbivorous, but some populations are more
omnivorous (Dozier, 1953; Errington, 1939b). Muskrats usually feed at night, diving to
gnaw on aquatic vegetation growing near their houses (Dozier, 1953; Johnson, 1925; Perry,
1982). The roots and basal portions of aquatic plants make up most of the muskrat's diet,
although shoots, bulbs, tubers, stems, and leaves also are eaten (Dozier,
2-337 Muskrat
-------
1950, 1953; Willner et al., 1980; Svihla and Svihla, 1931). Marsh grasses and sedges
(Svihla and Svihla, 1931) and cattails (Johnson, 1925; Willner et al., 1975) seem to be
important muskrat foods; in Maryland, green algae is also important (Willner et al., 1975).
Although muskrats forage near their dens or lodges, they show preferences for some plant
species (e.g., cattails, bulrushes) over others (Bellrose, 1950). Muskrats are a major
consumer of marsh grasses (Kiviat, 1978). They also dig for food on lake and pond
bottoms (Bailey, 1937; Dozier, 1953; Hanson et al., 1989). Among the animals that
muskrats consume are crayfish, fish, frogs, turtles, and young birds (Errington, 1939b;
Johnson, 1925; Willner et al., 1980). Molluscs are an important component of the diet of
some populations (Convey et al., 1989; Neves and Odom, 1989; Parmalee, 1989; Willner et
al., 1980). Young muskrats feed more on bank vegetation than do adults (Warwick, 1940,
cited in Perry, 1982).
Temperature regulation and molt. Active year-round (Kiviat, 1978), muskrats
usually begin their annual molt in the summer, with fur reaching its minimum density
during August (Willner et al., 1980). Muskrats use their dens or lodges to insulate
themselves from summer heat and winter cold (O'Neil, 1949; Willner et al., 1980). During
extreme cold, muskrats may freeze to death if they are unable to plug their den entrances
(Errington, 1939a).
Breeding activities and social organization. Muskrats are solitary or form breeding
pairs that remain in a home range exclusive of other pairs (Errington, 1963; Proulx and
Gilbert, 1983). They are territorial, particularly during peak reproductive activity, with their
houses usually spaced at least 8 m apart (Johnson, 1925; Sather, 1958; Trippensee, 1953).
In southern parts of their range, muskrats breed throughout the year, with late fall and
early spring peaks (O'Neil, 1949; Svihla and Svihla, 1931; Wilson, 1955). In northern
latitudes, breeding occurs only in the spring and summer, with first litters born in late April
or early May (Mathiak, 1966; Beer, 1950; Errington, 1937b; Gashwiler, 1950). Errington
(1937b) found that post part urn estrus occurs in the muskrat, and suggested that the period
between litters is about 30 d. Neonates are almost hairless but by age 2 wk are covered
with fur and able to swim (Errington, 1963).
Home range and resources. Muskrats have relatively small home ranges that vary
in configuration depending on the aquatic habitat (Perry, 1982; Willner et al., 1980). They
build two different types of houses: a main dwelling and a feeding house (feeder) that is
smaller than the main house (Dozier, 1953; Johnson, 1925; Sather, 1958). The feeder
provides protection from the elements and predators when feeding in prime foraging areas,
as well as access to oxygen during frozen conditions. The house provides a dry nest and
stable temperatures. Muskrats usually forage within 5 to 10 m of a house (Willner et al.,
1980). Using radiotelemetry, MacArthur (1978) found muskrats within 15 m of their primary
dwelling 50 percent of the time and only rarely more than 150 m. Mathiak (1966) reported
other experiments showing that muskrats remain close to their dwellings.
In the winter, muskrats build pushups, which are cavities formed in 30 to 46 cm high
piles of vegetation pushed up through holes in the ice of a marsh (Perry, 1982). Muskrats
use pushups as resting places during frozen conditions to minimize their exposure to cold
water (Fuller, 1951). In the summer, muskrats often change the use of their home range in
response to water levels; during droughts they will move if the area
2-338 Muskrat
-------
around the house dries up, which can lead to intense aggression in the more favorable
habitat (Errington, 1939a). Usually only a minor proportion of drought-evicted muskrats
can find new homes (Errington, 1939a). In the winter, droughts can result in severe
mortality (Errington, 1937a).
Population density. Bellrose and Brown (1941, cited in Perry, 1982) concluded that
cattail communities support more muskrat houses than other plant types in the Illinois
River valley. Cattail communities also support high densities of muskrats in other areas
(Errington, 1963; Dozier, 1950). In pond and lake habitats, shoreline length is a more
important factor than overall habitat area in determining muskrat density (Glass, 1952,
cited in Perry, 1982). Many investigators estimate muskrat densities by counting the
number of houses or push-ups and multiplying by a factor ranging from 2.8 (Lay, 1945,
cited in Boutin and Birkenholz, 1987) to 5.0 (Dozier et al., 1948), although this method is
questionable (Boutin and Birkenholz, 1987).
Population dynamics. The age at first breeding varies but usually occurs during the
first spring after birth (Errington, 1963; Perry, 1982). Southern populations produce more
litters but with fewer pups in each than do northern populations (Boyce, 1977; Perry, 1982;
see table). Muskrats in lower quality habitats have both smaller litter sizes and fewer litters
than muskrats in better quality areas (Neal, 1968). They disperse in the spring to establish
breeding territories or to move into uninhabited areas (Errington, 1963). Muskrat
population cycles of 5, 6, and 10 y have been reported (Butler, 1962; Willner et al., 1980);
Perry (1982) summarized several studies that reported cycles ranging from 10 to 14 yr or
more. Butler (1962) found that muskrats follow a 10-yr cycle in most parts of Canada.
Similar species (from general references)
• The Florida water rat (Neofiber alleni) is much smaller (20 to 22 cm) than the
muskrat, with a rounded tail (11 to 17 cm) to distinguish it further. The
Florida water rat inhabits bogs, marshes, weedy lake borders, and savanna
streams, though its range is limited to Florida. It feeds on aquatic plants and
crayfish.
General references
Boutin and Birkenholz (1987); Burt and Grossenheider (1980); Perry (1982); Willner
etal. (1980).
2-339 Muskrat
-------
Muskrat (Ondatra zibethicus)
Factors
Body Weight
(g)
Pup Growth
Rate (gld)
Metabolic
Rate
(I02/kg-d)
Metabolic Rate
(kcal/kg-d)
Age/Sex/
Cond./Seas.
B M winter
B F winter
B M winter
B F winter
B M winter
B F winter
A M spring
A F spring
neonate
neon ate
at weaning
at weaning
0 to 30 d
weaning to 1st
fall; M
F
floating
swimming
floating
swimming
A M basal
A F basal
A M free-living
A F free-living
Mean
1,480
1,350
1, 326 ± 45.9 SE
1,221 ±54.2SE
1,180
1,090
909
837
21.3
200
5.4
7.5
7.1
21 ±7.9SE
38
101
182
71.6
213
216
Range or
(95% Cl of mean)
1,400-1,520
1,300-1,400
730-1,550
770-1,450
16-28
20-25
112-184
4.3 - 5.6
(90 - 505)
(91 -513)
Location
New York
e Tennessee
Nebraska, nc Kansas
Idaho
Iowa
New York
Iowa
New Brunswick, Canada
Iowa/marsh
New Brunswick, Canada/
marsh
lab (water temperature 25°C)
lab (water temperature 25°C)
Reference
Dozier, 1950
Schacher & Pelton, 1978
Sather, 1958
Reeves & Williams, 1956
Errington, 1939b
Dean, 1957
Errington, 1939b
Parker & Maxwell, 1984
Errington, 1939b
Parker & Maxwell, 1980
Fish, 1982
Fish, 1982
estimated
estimated
Note
No.
1
2
10
CO
*».
o
3
-------
Muskrat (Ondatra zibethicus)
Factors
Food
Ingestion
Rate (g/g-d)
Water
Ingestion
Rate (g/g-d)
Inhalation
Rate (m3/d)
Surface Area
(cm2)
Dietary
Composition
cattail
bulrush
burreed
waterstarwort
pondweed
arrowhead
corn
cattail
rush
millet
algae
grass
cord grass
seeds
other
Age/Sex/
Cond./Seas.
greens
greens & corn
AM
AF
AM
AF
AM
AF
Mean
0.34
0.26
0.97
0.98
0.61
0.57
1,221
1,159
59
17
8
5
4
4
2
3
Range or
(95% Cl of mean)
Winter
25-50
10-25
5-10
2- 5
2- 5
2- 5
2- 5
Location
Louisiana, captive
(rivalicius)
ne United States/NS
(rough approximation of %
diet; stomach contents)
Somerset Co., MD/brackish
marsh
(% of diet; stomach
contents)
Reference
Svihla&Svihla, 1931
estimated
estimated
estimated
Reference
Martin etal., 1951
Willner etal., 1975
Note
No.
3
4
5
6
Note
No.
10
CO
3
-------
Muskrat (Ondatra zibethicus)
Dietary
Composition
green algae
3-square rush
switch grass
soft rush
water willow
grass
(Graminae)
other
Population
Dynamics
Home Range
Size (ha)
Population
Density
Litter
Size
Spring
Summer
77
8
8
4
2
1
summer
early summer
late summer
BM
BF
A B spring
A B summer
A B fall
BM
BM
BB
B B summer
B B summer
Fall
0.17 ± 0.0078 SD
0.048 ± 0.024 SD
0.11 ± 0.084 SD
0.17
0.17
9.3 ±1.3 SE/ha
2.6 ± 0.3 SE/ha
6.3 ±1.1 SE/ha
18.7/ha
2.1/ha
28.3/ha
23/km river
48/km river
3.46
4.65
7.1 ±0.2SE
7.3
Winter
Range
1 -74
3-6
1 -12
Location/Habitat
(measure)
Montgomery Co., MD/
freshwater
(% of diet; stomach
contents)
Ontario, Canada/marsh
Ontario, Canada/bay
Iowa/marsh
ne Iowa/open water riverine
Virginia/fringe marsh
Virginia/marsh
Louisiana/Sc/rpus olneyi
marsh
Pennsylvania/riverine (little
vegetation)
Massachusetts/wetland,
river (sedges)
Louisiana/marsh
Virginia/marsh
Iowa/riverine
Wisconsin/marsh
Reference
Willner etal., 1975
Reference
Proulx& Gilbert, 1983
Proulx & Gilbert, 1983
Neal, 1968
Clay & Clark, 1985
Halbrook, 1990
O'Neil, 1949
Brooks & Dodge, 1986
Brooks & Dodge, 1986
O'Neil, 1949
Halbrook, 1990
Clay & Clark, 1985
Mathiak, 1966
Note
No.
Note
No.
10
CO
*».
10
3
-------
Muskrat (Ondatra zibethicus)
Population
Dynamics
Litters/Year
Days
Gestation
Age at
Weaning
Age at
Sexual
Maturity
Annual
Mortality
Rates
(%)
Longevity
Seasonal
Activity
Mating
Parturition
Dispersal
Age/Sex/
Cond./Seas.
B
adult
juvenile
juvenile
Begin
year-round
late April
early May
late May
Mean
1.7
2.1
5-6
29-30
28 d
6 mo
87
90
67
Peak
winter
spring-summer
June
early July
fall
spring
Range
<7-8
> 22 - 23
21 -30d
< Syr
End
late August
late August
mid-August
Location/Habitat
Idaho/marsh
Maine/wildlife refuge - NS
Louisiana/NS
nw Iowa/marsh
Maine/wildlife refuge - NS
Iowa/marsh
Louisiana/marsh
ne Iowa/riverine
Missouri/NS
Ontario, Canada/marsh
southern latitudes
northern latitudes
Iowa
Maine
Idaho
Ontario, Canada
Iowa
Reference
Reeves & Williams, 1956
Gashwiler, 1950
O'Neil, 1949
Errington, 1937b
Gashwiler, 1950
Errington, 1939b
Svihla&Svihla, 1931
Clay & Clark, 1985
Schwartz & Schwartz, 1959
Proulx& Gilbert, 1983
Reference
O'Neil, 1949; Svihla & Svihla,
1931
Chamberlain, 1951;
Gashwiler, 1950; Reeves &
Williams, 1956
Errington, 1937b
Gashwiler, 1950
Reeves & Williams, 1956
McDonnell & Gilbert, 1981
Errington, 1963
Note
No.
7
Note
No.
10
CO
*».
CO
3
-------
10
CO
Muskrat (Ondatra zibethicus)
1 Estimated using equation 3-43 (Boddington, 1978) and body weights from Sather (1958).
2 Estimated using equation 3-46 (Nagy, 1987) and body weights from Sather (1958).
3 Based on wet weight of food; greens included Panicum hemitomum, P. virgatum, and Spartina patens.
4 Estimated using equation 3-17 (Calder and Braun, 1983) and body weights from Sather (1958).
5 Estimated using equation 3-20 (Stahl, 1967) and body weights from Sather (1958).
6 Estimated using equation 3-22 (Stahl, 1967) and body weights from Sather (1958).
7 Cited in Perry (1982.)
-------
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2-350 Muskrat
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2.2.11. Eastern Cottontail (rabbits)
Order Laqomorpha Family Leporidae. Rabbits and hares are medium-sized grazing
herbivores found throughout North America. Most species are nocturnal and crepuscular.
Many are social, travelling in small groups. Rabbits are prey for large carnivorous birds
and mammals. Most species also are important game animals.
Selected species
The eastern cottontail (Sylvilagus floridanus) is the most widely distributed of the
medium-sized rabbits (Chapman et al., 1982). It is found over most of the eastern half of
the United States and southern Canada and has been widely introduced into the western
United States (Chapman et al., 1980). North of Mexico, 14 subspecies are recognized
(Chapman et al., 1982). The eastern cottontail feeds on green vegetation in summer and
bark and twigs in winter. The cottontail is active from early evening to late morning and is
preyed on by owls, hawks, and carnivorous mammals (Palmer and Fowler, 1975; Burt and
Grossenheider, 1980).
Body size. The eastern cottontail measures 35 to 43 cm in length and weighs 0.7 to
1.8 kg (Lord, 1963; see table) with females slightly larger than the males (Nowak and
Paradiso, 1983; see table). Cottontail body weight varies seasonally, increasing during
spring and summer and declining during winter in some areas; different patterns occur in
other areas (Chapman et al., 1982; Pelton and Jenkins, 1970).
Habitat. The eastern cottontail is unique to the genus because of the large variety
of habitats that it occupies, including glades and woodlands, deserts, swamps, prairies,
hardwood forests, rain forests, and boreal forests (Nowak and Paradiso, 1983). Open
grassy areas generally are used for foraging at night, whereas dense, heavy cover typically
is used for shelter during the day (Chapman et al., 1982). During winter, cottontails rely
more on woody vegetation for adequate cover (Allen, 1984).
Food habits. During the growing season, cottontails eat herbaceous plants (e.g.,
grasses, clover, timoth, alfalfa). During the winter in areas where herbaceous plants are
not available, they consume woody vines, shrubs, and trees (e.g., birch, maple, apple)
(Chapman et al., 1982). In Ohio, bluegrass and other grasses made up a large portion of
the eastern cottontail's diet, except during snow cover (Chapman et al., 1982). During the
winter in Connecticut, the principle diet of eastern and New England cottontails consists of
bark and twigs, shrubs and vines, berries, and willow (Dalke and Sime, 1941). In
agricultural areas, corn, soybeans, wheat, and other crops may comprise a large portion of
their diet (Chapman et al., 1982). Younger rabbits prefer the more succulent weedy forbs
that contain more digestible energy and protein (Chapman et al., 1982). Coprophagy
(ingestion of feces) has been reported in S. floridanus (Kirkpatrick, 1956).
Temperature regulation and molt. Eastern cottontails do not undergo hibernation or
torpor; they are active all year, showing peaks of daily activity at dawn and dusk (Chapman
et al., 1980). Adults molt gradually over about 9 mo of the year, with two peak molting
periods (Spinner, 1940). In Connecticut, the spring peak occurs in May and
2-351 Eastern Cottontail
-------
June and the fall peak occurs in September and October (Spinner, 1940). In Texas, spring
and fall molts peak in April and October, respectively (Bothma and Teer, 1982).
Breeding activities and social organization. Breeding activity begins later at higher
elevations and at higher latitudes (Conaway et al., 1974), by January in Alabama and by late
March in southern Wisconsin (Chapman et al., 1980). Several studies have shown that
continued harsh winter weather may delay the onset of the breeding season (Hamilton,
1940; Conaway and Wight, 1962; Wight and Conaway, 1961). Breeding seasons are longer
in the southern states (Lord, 1960). The onset of breeding varies between different
populations and within the same population from year to year (Chapman et al., 1980).
Males may fight to establish dominance hierarchies for access to females (Chapman and
Ceballos, 1990; Nowak and Paradiso, 1983). Lagomorphs in general are induced ovulators,
and cottontails in particular demonstrate a synchronized breeding season, with conception
immediately after the birth of a litter (Chapman et al., 1982).
Home range and resources. Cottontails are found in a variety of habitats that
contain weedy forbs and perennial grasses; they prefer thick, short, woody perennials that
provide escape sites (Chapman and Ceballos, 1990). Cottontails usually do not defend
territories; the home ranges of different age and sex groups tend to overlap, especially in
fall and winter when they look for areas offering a combination of food and cover
(Chapman et al., 1980, 1982). Home ranges are smaller when thick vegetation provides
abundant food and larger in habitats with less food (Chapman et al., 1982). Home ranges
also are smaller during severe winter weather than at other times (Chapman et al., 1982).
During the breeding season, females build elaborate nests within slanting holes in the
ground where they give birth to their altricial (helpless) young. These burrows are
vulnerable to flooding (Chapman et al., 1982). The size of male home ranges during the
breeding season can be more than double that in winter (Nowak and Paradiso, 1983; Trent
and Rongstad, 1974).
Population density. Population density depends on the availability of resources
(e.g., food, cover) in an area, and tends to cycle over a period of several years (Chapman
and Ceballos, 1990). Usual densities range from 1 to 5 animals per hectare, although
values as high as 14 per hectare have been reported (Chapman and Ceballos, 1990;
Chapman et al., 1982).
Population dynamics. The eastern cottontail exhibits the highest fecundity of the
genus; they often produce 25 to 35 young per year (Chapman and Ceballos, 1990).
Gestation lasts approximately 1 mo (Chapman et al., 1982). Females may produce five to
seven litters per year, and juvenile breeding has been reported (Chapman et al., 1982). The
first and last litters of the year are usually the smallest (Chapman et al., 1977). Cottontails
have more litters with fewer young each in the southern states (Lord, 1960). Young leave
the nest when about age 14 to 16 d, although they may not be fully weaned until a few
weeks later (Ecke, 1955). Female cottontails are capable of breeding by age 5 mo, and
males as early as 3 mo (Bothma and Teer, 1977). Adult mortality is high, from
approximately 65 to 75 percent per year in some places (Eberhardt et al., 1963). Juvenile
mortality is even higher, between 85 and 90 percent in the same areas (Eberhardt et al.,
1963).
2-352 Eastern Cottontail
-------
Similar species (from general references)
• The mountain cottontail (Sylvilagus nuttallii) (Nuttall's cottontail) is smaller
(30 to 36 cm in length and 0.7 to 1.3 kg) than the eastern cottontail. The only
cottontail through most of its range - the western United States - it lives in
thickets and sagebrush, around loose rocks, cliffs, and mountains. In the
southwest, it lives in forests.
• The New England cottontail (Sylvilagus transitionalis) is similar in size to the
eastern cottontail and inhabits brushy areas, open forests, and mountain
terrain in New England, extending down the Appalachians into the southern
United States. In recent years, it has disappeared throughout much of the
northeastern United States, apparently because of competition with S.
floridanus.
• The desert cottontail (Sylvilagus audubonii) (Audubon's cottontail) (30 to 38
cm in length and 0.6 to 1.2 kg) is common in valleys in the arid southwest,
although its range extends south to Mexico and north into the Rocky
Mountains. It inhabits open plains, foothills, and low valleys and also areas
of grass, sagebrush, pinyons and junipers. It is most active from late
afternoon throughout the night.
• The brush rabbit (Sylvilagus bachmani) (28 to 33 cm; 0.6 to 0.8 kg) is usually
seen around thick cover and rarely uses a burrow. It feeds on green
vegetation, including lawns when in suburban areas. The species is found
along the Pacific coast from the Columbia River in the north to the tip of Baja
California in the south.
• The marsh rabbit (Sylvilagus palustris) is similar in size to the eastern
cottontail and ranges from southeastern North Carolina to Florida. As the
name implies, it inhabits swamps and hummocks, as well as wet
bottomlands. Mostly nocturnal, it feeds on marsh vegetation, rhizomes, and
bulbs.
• The swamp rabbit (Sylvilagus aquaticus) is similar in size to the eastern
cottontail and is a good swimmer found in swamps, marshes, and wet
bottomlands. It ranges primarily in the south, from Texas eastward. It nests
beneath logs or in the bases of stumps, rarely using a burrow and may harm
crops near swamps.
• The pygmy rabbit (Sylvilagus idahoensis) is markedly smaller (22 to 28 cm;
0.2 to 0.5 kg) than the eastern cottontail, lacks a conspicuous tail, and is
considered by some to be a distinct genus (Brachylagus). Its range is
limited to several western states, where it inhabits clumps of tall sagebrush.
It is mostly nocturnal.
• The white-tailed jackrabbit (Lepus townsendii), larger (46 to 56 cm; 2.2 to 4.5
kg) than the eastern cottontail, is limited to the northern United States
2-353 Eastern Cottontail
-------
west of the Great Lakes, into southern Canada. It inhabits open, grassy, or
sagebrush plains and may damage hay crops and small trees.
• The black-tailed jackrabbit (Lepus californicus) (43 to 53 cm; 1.3 to 3.1 kg) is
the most common jackrabbit in the grasslands and open areas of the
western United States, where it inhabits open prairies and deserts with little
vegetation. It is mostly nocturnal.
• The snowshoe hare (Lepus americanus) (33 to 46 cm; 0.9 to 1.8 kg) inhabits
swamps, forests, and thickets in the northern United States and Canada.
During summer, it feeds on succulent vegetation and during winter on twigs,
buds, and bark. Its home range is about 4 ha, but populations fluctuate
widely.
General references
Allen (1984); Burt and Grossenheider (1980); Chapman et al. (1980, 1982); Lord
(1963); Nowak and Paradiso (1983); and Palmer and Fowler (1975).
2-354 Eastern Cottontail
-------
Eastern Cottontail (Sylvilagus floridanus)
Factors
Body Weight
(g)
Growth Rate
(9/d)
Metabolic Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Water
Ingestion
Rate (g/g-d)
Age/Sex/
Cond./Seas.
AM
AF
A B winter
A B spring
A B summer
AB fall
A B not breed.
A B not breed.
A B not breed.
AB
neonate
age:
10d
30 d
50 d
101 d
149 d
day 0 - 30
day 11 -30
day 31 - 50
day 51 -100
day 101 -150
A B basal
A B free-living
AB
Mean
1,134±122SD
1,244 ± 165 SD
1,176
1,286
1,197
1,255
1,229 ± 113 SD
1,313 ±141 SD
1,132±136SD
1,231 ±164
42.2
58
159
401
822
1,106
3.2
3.7
8.8
11.3
6.4
71
203
0.097
Range or
(95% Cl of mean)
801 -1,411
842-1,533
793-1,671
898-1,630
910-1,608
886-1,669
1,093-1,461
986-1,671
793-1,579
700-1,800
36.0 - 49.0
(77 - 535)
Location (subspecies)
w Maryland, West Virginia
Georgia
all areas combined
Georgia
mountain
coastal
Piedmont
Illinois
Alabama
Illinois
Illinois
Reference
Chapman & Morgan, 1973
Pelton & Jenkins, 1970
Pelton & Jenkins, 1970
Lord, 1963
Hill, 1972b
Lord, 1963
Lord, 1963
estimated
estimated
estimated
Note
No.
1
2
3
4
10
CO
Ol
Ol
m
0)
(0
^
o
s
o
I
-------
Eastern Cottontail (Sylvilagus floridanus)
Factors
Inhalation
Rate (m3/d)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
AB
Dietary
Composition
trees
shrubs & vines
herbs
grasses, sedges,
rushes
crops
woody plants
forbs
grasses
bluegrass
orchard grass
timothy grass
Nodding wild rye
Canada goldenrod
red clover
unidentified
Mean
0.63
1,254
13
4
44
26
13
17
19
64
34
4
5
5
-
-
52
2
2
23
56
17
23
30
47
34
1
12
11
-
-
42
Range or
(95% Cl of mean)
7
27
34
30
2
20
46
34
25
-
7
8
3
6
51
Winter
39
40
5
6
10
100
32
1
1
4
-
-
62
Location (subspecies)
Location (subspecies)/
Habitat(measure)
Connecticut (mallarus)!
various
(% frequence of occurrence;
observations of feeding on
plants)
Maryland/forest
(% frequency of occurrence;
stomach contents)
Ohio (mearnsi)INS
(% frequency of occurrence;
scats)
(in winter, woody tissues
predominated in the
unidentified category)
Reference
estimated
estimated
Dalke&Sime, 1941
(85% for mallarus
subspecies,
remainder for similar
species S. transitionalis)
Spencer & Chapman, 1986
Dusi, 1952
Note
No.
5
6
Note
No.
10
CO
Ol
m
0)
(0
^
o
s
o
I
-------
Eastern Cottontail (Sylvilagus floridanus)
Population
Dynamics
Home Range
Size (ha)
Population
Density
(N/ha)
Litter
Size
Litters/Year
Days
Gestation
Age/Sex/
Co nd. /Seas.
A M winter
A F winter
A M winter
A M spring
A M summer
A M fall
A F winter
A F spring
A F summer
A F fall
A M spring
AM
early summer
late summer
A F spring
A F summer
fall
fall
winter
summer
fall
spring
Mean
3.05 ± 0.72 SE
2.99 ± 0.28 SE
3.2
7.2
7.8
3.1
2.1
2.8
2.4
1.5
2.8
4.0
1.5
1.7
0.8
1.1 ±0.41 SD
4.2
10.1
3.7
3.5 ± 0.042 SE
5.3
6.0
4.6
28
Range
0.41 to 2.08
3.0 - 5.9
0.67-1.5
5-7
25-35
Location (subspecies)/Habitat
Wisconsin/wood lot
c Pennsylvania/mixed
c Pennsylvania/mixed
sw Wisconsin/woodlot
c Michigan/woods,
marsh, fields
Illinois/old field
sw Wisconsin/farm
Alabama/across six habitats
lllinois/NS
Missouri/wildlife area
w Maryland/NS
several locations and
habitats
several locations and
habitats
Reference
Dixon etal., 1981
Althoff and Storm, 1989
Althoff and Storm, 1989
Trent & Rongstad, 1974
Eberhardt et al., 1963
Lord & Casteel, 1960
Trent & Rongstad, 1974
Hill, 1972c
Lord, 1963
Conaway et al., 1963
Chapman etal., 1977
Chapman etal., 1980
Chapman etal., 1982
Note
No.
7
10
CO
Ol
m
0)
(0
^
o
s
o
I
-------
Eastern Cottontail (Sylvilagus floridanus)
Population
Dynamics
Age at
Weaning
Age at
Sexual
Maturity
Annual
Mortality
Rates (%)
Longevity
Seasonal
Activity
Mating
Age/Sex/
Co nd. /Seas.
F
M
BB
BB
B
Begin
mid-March
year-round
April
August
September
February
March
Mean
20 - 25 days
80
65±7SD
1.25
Peak
January- April
May - July
October
Sept. - Oct.
April
May- June
Range
3 -6 months
3-6 months
End
mid-September
August
December
November
July
August
Location (subspecies)/Habitat
lllinois/NS
s Texas/grassland
Missouri/NS
sw Wisconsin/farm
Illinois/sanctuary
Kentucky/NS
Location
Connecticut
s Texas
we New York
s Texas
Connecticut
s Texas
Connecticut
Reference
Ecke, 1955
Lord, 1961, Negus, 1959b
Conaway & Wight, 1963
Trent & Rongstad, 1974
Lord, 1963
Bruna, 1952
Dalke, 1942
Both ma & Teer, 1977
Hamilton, 1940
Both ma & Teer, 1982
Spinner, 1940
Both ma & Teer, 1982
Spinner, 1940
Note
No.
8
9
Note
No.
9
10
CO
Ol
CO
m
0)
-------
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management of the red foxes in Wisconsin. Wise. Dept. Nat. Resour.; Tech. Bull.
105; 56 pp.
Prouty, J. (1937) Cottontails of Massachusetts [master's thesis]. MA: Massachusetts State
College.
Rongstad, O. J. (1966) Biology of penned cottontail rabbits. J. Wildl. Manage. 30: 312-319.
Sandt, J. L.; McKee, R. M. (1978) Upland wildlife investigations. Unpublished Federal Aid
Performance Report (Maryland); W-47-7; 4 pp.
Schierbaum, D. (1967) Job completion report, evaluation of cottontail rabbit productivity.
Albany, NY: Pittman-Robertson Proj. W-84-R-12; 21 pp.
Seton, E. T. (1929) Lives of game animals. Garden City, NY: Doubleday, Doran and Co., Inc.
Sheffer, D. E. (1957) Cottontail rabbit propagation in small breeding pens. J. Wildl. Manage.
21:90.
Spencer, R. K.; Chapman, J. A. (1986) Seasonal feeding habits of New England and eastern
cottontails. Proc. Penn. Acad. Sci. 60: 157-160.
Spinner, G. P. (1940) Molting characteristics in the eastern cottontail rabbits. J. Mammal.
21:429-434.
Stahl, W. R. (1967) Scaling of respiratory variables in mammals. J. Appl. Physiol. 22:
453-460.
Trent, T. T.; Rongstad, O. S. (1974) Home range and survival of cottontail rabbits in
southwestern Wisconsin. J. Wildl. Manage. 38: 459-472.
2-363 Eastern Cottontail
-------
Trethewey, D. E.; Verts, B. J. (1971) Reproduction in eastern cottontail rabbits in western
Oregon. Am. Midi. Nat. 86: 463-476.
Wainright, L. C. (1969) A literature review on cottontail reproduction. Colo. Div. Game, Fish
Parks, Spec. Rep. No. 19; 24 pp.
Wight, H. M.; Conaway, C. H. (1961) Weather influences on the onset of breeding in
Missouri cottontails. J. Wildl. Manage. 25: 87-89.
2-364 Eastern Cottontail
-------
2.3. REPTILES AND AMPHIBIANS
Table 2-3 summarizes the species of reptiles and amphibians included in this
section. For range maps, refer to the general references identified in the individual species
profiles. The remainder of this section is organized by species in the order presented in
Table 2-3. The availability of information in the published literature varies substantially
among species, which is reflected in the profiles. The measures used to describe body
length are included in each species profile. Body weight is reported as fresh wet weight
(including the shell for turtles), unless otherwise noted.
Unlike birds and mammals for which a single common name usually covers all
subspecies, many reptile and amphibian subspecies are recognized by different common
names. For example, there are two subspecies of Rana clamitans: the green frog and the
bronze frog (Section 2.3.7). There are four subspecies of Terrapene Carolina: eastern box
turtle, three-toed box turtle, Florida box turtle, and Gulf Coast box turtle (Section 2.3.3). In
this case, other species exist that are also known as box turtles: the ornate and desert box
turtles belong to the species T. ornata. For species that could be confused with other
species unless a subspecies common name is used, we selected the common name of the
most widespread subspecies to use in the tables and titles of the species profile. As with
the other species in the Handbook, however, the profile covers all subspecies for the
selected species that were represented in the literature reviewed.
In these profiles, we use the word hibernation for the period of dormancy that
reptiles and amphibians undergo during winter, when they change their metabolism to
accommodate the low (often near freezing) temperatures and lack of food (and oxygen).
Use of the word for this group is controversial, however, because the word was developed
initially to describe mammalian winter dormancy. Some investigators argue that a different
word, brumation, should be established to describe the overwintering dormancy and
associated metabolic changes for reptiles and amphibians (Hutchison, 1979). Others
disagree, because significant physiological changes also occur in reptiles and amphibians
during winter dormancy. They argue that, although the physiological changes are different
from those in mammals, the word hibernation is a general term that does not specify what
2-365
-------
Table 2-3. Reptiles and Amphibians Included in the Handbook
Order
Common name
Scientific name
Section
Chelydridae
Emydidae
Colubridae
Salamandridae
Ranidae
snapping turtle
painted turtle
eastern box turtle3
racer
Chelydra serpentina
2.3.1
Chrysemys pi eta 2.3.2
Terrapene Carolina carolina2.3.3
Coluber constrictor
2.3.4
northern water snake3 Nerodia sipedon sipedon 2.3.5
eastern newt
green frog3
bullfrog
Notophthalmus viridescens2.3.6
Rana clamitans clamitans 2.3.7
Rana catesbeiana 2.3.8
Additional subspecies also are included in the profile.
metabolic changes occur to allow overwintering in a dormant state (Gatten, 1987). We
have chosen this latter interpretation for the Handbook.
References
Gatten, R. E., Jr. (1987) Cardiovascular and other physiological correlates of hibernation in
aquatic and terrestrial turtles. Am. Zool. 27: 59-68.
Hutchison, V. H. (1979) Thermoregulation. In: Harless, M.; Morlock, H., eds. Turtles:
perspectives and research. Toronto, Canada: John Wiley and Sons; pp. 207-227.
2-366
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2.3.1. Snapping Turtle (snapping turtles)
Order Testudines, Family Chelydridae. Snapping turtles are among the largest of
the freshwater turtles. They are characterized by large heads with powerful hooked jaws.
There are only two species of this family in North America (the snapping turtle, including
both the common and Florida snapping turtles, and the alligator snapping turtle).
Selected species
The snapping turtle (Chelydra serpentina) is primarily aquatic, inhabiting freshwater
and brackish environments, although they will travel overland (DeGraaf and Rudis, 1983;
Ernst and Barbour, 1972; Smith, 1961). There are two subspecies recognized in North
America that are primarily distinguished by range: C. s. serpentina (the common snapping
turtle, which is the largest subspecies, primarily occupies the United States east of the
Rockies, except for the southern portions of Texas and Florida), and C. s. osceola (the
Florida snapping turtle, found in the Florida peninsula) (Conant and Collins, 1991). In this
profile, studies refer to the serpentina subspecies unless otherwise noted.
Body size. Adult snapping turtles are large, 20 to 37 cm in carapace length, and
males attain larger sizes than females (Congdon et al., 1986; Ernst and Barbour, 1972;
Galbraith et al., 1988). In a large oligotrophic lake in Ontario Canada, adult males averaged
over 10 kg, whereas the females averaged 5.2 kg (Galbraith et al., 1988). In other
populations, the difference in size between males and females often is less (Congdon et al.,
1986; Galbraith et al., 1988; Hammer, 1969). They reach sexual maturity at approximately
200 mm in carapace length (Mosimann and Bider, 1960). The cool, short activity season in
more northern areas results in slower growth rates and longer times to reach sexual
maturity (Bury, 1979).
Habitat. In the east, snapping turtles are found in and near permanent ponds, lakes,
and marshes. However, in the arid west, the species is primarily found in larger rivers,
because these are the only permanent water bodies (Toner, 1960, cited in Graves and
Anderson, 1987). They are most often found in turbid waters with a slow current (Graves
and Anderson, 1987). They spend most of their time lying on the bottom of deep pools or
buried in the mud in shallow water with only their eyes and nostrils exposed. Froese
(1978) observed that young snapping turtles show a preference for areas with some
obstructions that may provide cover or food.
Food habits. Snapping turtles are omnivorous. In early spring, when limited
aquatic vegetation exists in lakes and ponds, they may eat primarily animal matter;
however, when aquatic vegetation becomes abundant, they become more herbivorous
(Pell, 1941, cited in Graves and Anderson, 1987). Young snapping turtles are primarily
carnivorous and prefer smaller streams where aquatic vegetation is less abundant (Lagler,
1943; Pell, 1941, cited in Graves and Anderson, 1987). Snapping turtles consume a wide
variety of animal material including insects, crustaceans, clams, snails, earthworms,
leeches, tubificid worms, freshwater sponges, fish (adults, fry, and eggs), frogs and toads,
salamanders, snakes, small turtles, birds, small mammals, and carrion and plant material
including various algae (Alexander, 1943; Graves and Anderson, 1987; Hammer, 1969;
2-367 Snapping Turtle
-------
Punzo, 1975). Budhabatti and Moll (1988) observed no difference between the diets of
males and females who fed at the surface, midpelagic, and benthic levels. Bramble (1973)
suggested that the pharyngeal mechanism of feeding (i.e., drawing water with food objects
into the mouth) prevents snapping turtles from ingesting food above the air-water
interface.
Temperature regulation and daily activities. Snappers are most active at night.
During the day, they occasionally leave the water to bask on shore, but basking is probably
restricted by intolerance to high temperatures and by rapid loss of moisture (Ernst and
Barbour, 1972). In a study in Ontario, Canada, Obbard and Brooks (1981) found that the
turtles were active in the early morning and early evening and basked in the afternoon but
were rarely active at night. Active turtles were found in deeper waters than inactive
snappers (Obbard and Brooks, 1981). Cloacal temperatures of 18.7 to 32.6 C were
reported for snapping turtles captured in the water in Sarasota County, Florida, between
May and October (Punzo, 1975).
Hibernation. Snapping turtles usually enter hibernation by late October and emerge
sometime between March and May, depending on latitude and temperature. To hibernate,
they burrow into the debris or mud bottom of ponds or lakes, settle beneath logs, or retreat
into muskrat burrows or lodges. Snapping turtles have been seen moving on or below the
ice in midwinter. Large congregations sometimes hibernate together (Budhabatti and Moll,
1988; Ernst and Barbour, 1972).
Breeding activities and social organization. Mating occurs any time turtles are
active from spring through fall, depending on latitude (Ernst and Barbour, 1972). Some
investigators believe that male snapping turtles are territorial (Kiviat, 1980; Pell, 1941, cited
in Galbraith et al., 1987), but Galbraith et al. (1987) doubts that males defend their home
ranges against other males. Sperm may remain viable in the female for several years
(Smith, 1956). Nesting occurs from late spring to early fall, peaking in June (Ernst and
Barbour, 1972). Hammer (1969) observed that larger, older females nested earlier in the
season than did smaller, younger ones. Females often move up small streams to lay eggs
(Ewert, 1976, cited in Graves and Anderson, 1987). The nest site may be in the soil of
banks or in muskrat houses but more commonly is in the open on south-facing slopes and
may be several hundred meters from water (DeGraaf and Rudis, 1983). The turtle digs a 4-
to 7-in cavity on dry land, preferably in sand, loam, or vegetable debris. The duration of
incubation is inversely related to soil temperature (Ernst and Barbour, 1972; Yntema, 1978,
cited in Graves and Anderson, 1987). In more northerly populations, hatchlings may
overwinter in the nest (DeGraaf and Rudis, 1983).
Home range and resources. Most turtles stay primarily within the same marsh or in
one general area from year to year ((Hammer, 1969; Obbard and Brooks, 1981). The
summer home range includes a turtle's aquatic foraging areas, but females may need to
travel some distance outside of the foraging home range to find a suitable nest site
(DeGraaf and Rudis, 1983). Obbard and Brooks (1980) found that females tagged at their
nesting site moved an average of 5.5 km (± 1.8 SD) from the nest site afterwards. Lonke
and Obbard (1977) observed that 91.9 percent of the turtles in one population returned to
the same nesting site a year after having been tagged there. Home ranges overlap both
between and within sexes (Obbard and Brooks, 1981). Young snapping turtles use
2-368 Snapping Turtle
-------
different habitats than adults; they tend to remain in small streams until shortly before
maturity, when they migrate to habitats preferred by adults (e.g., ponds, marshes, lakes)
(Hammer, 1971; Minton, 1972, cited in Graves and Anderson, 1987).
Population density. The density of snapping turtles appears to be positively
correlated with the productivity of the surface water body (e.g., density in a eutrophic
surface water body is higher than in an oligotrophic lake) (Galbraith et al., 1988). Specific
habitat characteristics and intraspecific interactions contribute to the variability of
observed population densities in snapping turtles (Froese and Burghardt, 1975).
Population dynamics. Females do not begin laying eggs until age 6 to 19 yr
depending on latitude and when they reach an appropriate size (approximately 200 mm
carapace) (Galbraith et al. 1989; Mosimann and Bider, 1960). Males mature a few years
earlier than females (see table). Females may lay one or two clutches per season (Minton,
1972, cited in Graves and Anderson, 1987). Clutch size increases with female body size;
Congdon et al. (1987) calculated the relationship between clutch size (CS) and plastron
length (PL in mm) fora population in southeastern Michigan:
CS = -21.227 + 0.242 PL, (r2 = 0.409, n = 65).
Clutch size has also been positively correlated with latitude (Petokas and Alexander, 1980).
Hammer (1969) found that mammalian predators destroyed over 50 percent of the turtle
nests in a South Dakota marsh, and in undisturbed nests, hatchling success was less than
20 percent. Petokas and Alexander (1980) observed a 94 percent predation rate of nests
under study in northern New York. Adult mortality is low, corresponding with the long
lives exhibited by these turtles (see table).
Similar species (from general references)
• The alligator snapping turtle (Macroclemys temmincki) is much larger (16 to
68 kg; 38 to 66 cm carapace) than the common snapping turtle and is one of
the largest turtles in the world. Its range is from northern Florida to east-
central Texas and north in the Mississippi Valley.
General references
Conant and Collins (1991); DeGraaf and Rudis (1983); Ernst and Barbour (1972);
Graves and Anderson (1987).
2-369 Snapping Turtle
-------
Snapping Turtle (Chelydra serpentina)
Factors
Body Weight
(kg)
Egg Weight
(g)
Body Length
(mm carapace)
Age/Sex/
Cond./Seas.
A M summer
A F summer
J B summer
A M summer
A F summer
J B summer
AM
AF
JB
at hatching
at hatching
mm carapace:
118
127
134
167
192
220
age in years
1
2
3
4
5
6
Mean
10.5 ±2.85SD
5.24 ± 0.85 SD
1.15±0.80SD
5.52 ± 2.23 SD
5.03±1.12SD
1.40±0.20SD
4.16 ± 0.28 SE
3.16 ± 0.20 SE
0.80 ± 0.07 SE
0.0057
0.0089
0.33
0.44
0.53
1.03
1.51
2,362
11.1
9.6
9.3
62±4.5SD
102±5.8SD
137±9.4SD
168 ± 14.2 SD
198 ± 13.7 SD
222 ± 12.9 SD
Range or
(95% Cl of mean)
7-15
5.7-13.8
54-66
83 - 108
124-145
146-184
177-211
204 - 238
Location
Ontario, Canada/large
oligotrophic lake
Ontario, Canada/eutrophic
pond
Michigan
NS
NS
Massachusetts
NS
northern New York
South Carolina
New Jersey
Michigan
Reference
Galbraithetal., 1988
Galbraithetal., 1988
Congdon etal., 1986
Ernst & Barbour, 1972
Ewert, 1979
Graham & Perkins, 1976
Ernst & Barbour, 1972
Petokas & Alexander, 1980
Congdon etal., 1986
Hotaling etal., 1985
Gibbons, 1968
Note
No.
10
CO
-g
o
CO
3
0)
-o
•o
5'
(Q
(D
-------
Snapping Turtle (Chelydra serpentina)
Factors
Metabolic Rate
(I02/kg-d)
Metabolic Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Age/Sex/
Cond./Seas.
7.18 kg, rest
25°C
A F basal
A M basal
B summer
Dietary Composition
adults & juveniles:
plants
animals
adults:
fish
vegetation
clams
mud & rocks
adults & juveniles:
(plants)
algae
(animals)
crayfish
fiddler crab
sucker
bullhead
sunfish
unknown fish
(miscellaneous)
Mean
2.54
3.2
3.0
Spring
Summer
35-70
6-35
83.7
13.6
0.2
2.5
(36.5)
12.8
(54.1)
8.9
2.7
3.2
6.3
7.5
12.4
(9.4)
Range or
(95% Cl of mean)
0.01 -0.016
Fall
Winter
Location
New York/captivity
location not specified
(% of diet; measure NS)
Tennessee/embayment
(% wet volume; gastro-
intestinal tract contents)
Connecticut/lakes, ponds,
streams, swamps
(% wet volume; stomach
contents)
Reference
Lynn & von Brand, 1945
estimated
Kiviat, 1980
Smith, 1956
Meyers-Schoene & Walton,
1990
Alexander, 1943
Note
No.
1
2
Note
No.
3
CO
CO
3
0)
TS
•D
5'
(Q
(D
-------
Snapping Turtle (Chelydra serpentina)
Population
Dynamics
Home Range
Size (ha)
Population
Density
(IM/ha)
Clutch Size
Clutches/Yea
r
Days
Incubation
Age at Sexual
Maturity (yr)
Age/Sex/
Cond./Seas.
A M summer
A F summer
A M summer
A B summer
AM
A F non breed
A M summer
B B summer
B B summer
B B summer
A B summer
F nesting
F nesting
M
F nesting
Mean
0.7 ± 0.29 SD
3.79±1.46SD
3.21 ±2.67SD
3.44 ± 2.18 SD
8.9
7.2
1.5
2.3 ± 1.45 SD
60.4
29.3 ± 27.6 SD
59
49.0
27.9 ± 0.76 SE
16.6 ± 1.6 SD
>1
105
6-8
9-10
4 5
17-19
Range or
(95% Cl of mean)
0.24-1.3
2.5-5.19
0.95 - 8.38
1.0-4.9
40.3 - 95.0
4.4 - 65.9
31 -87
12-41
14-20
1 -2
90-119
67-73
at least 14 to 15
Location/Habitat
Ontario, Canada/lake
Ontario, Canada/lake
New York/fresh tidal
wetland
Ontario, Canada/
oligotrophic lake
oligotrophic waters
eutrophic pond
eutrophic ponds (other
studies)
Tennessee/pond
South Dakota/marsh
se Michigan/NS
Florida/NS
Indiana/NS
NS/summarizing other
studies
Ontario, Canada/lake
se Wisconsin/NS
New York/NS
lowa/NS
Ontario, Canada/riverine,
mixed forest
Reference
Galbraithetal., 1987
Obbard & Brooks, 1981
Kiviat, 1980
Galbraithetal., 1987
Galbraithetal., 1988
Galbraithetal., 1988
Galbraithetal., 1988
Froese & Burghardt, 1975
Hammer, 1969
Congdon etal., 1987
Iverson, 1977
Minton, 1972
Ernst & Barbour, 1972
Obbard & Brooks, 1981
Ewert, 1979
Pell, 1941
Christiansen & Burken, 1979
Galbraithetal., 1989
Note
No.
4
5
6
7
8
10
CO
-g
10
CO
3
0)
TS
•D
5'
(Q
(D
-------
Snapping Turtle (Chelydra serpentina)
Population
Dynamics
Length at
Sexual
Maturity
Annual
Mortality
Rates (%)
Longevity (yr)
Seasonal
Activity
Mating
Nesting
Hatching
Hibernation
Age/Sex/
Cond./Seas.
AB
AB
AB
Begin
April
early June
mid-June
May
late May
early June
August
late August
October
late September
mid-October
Mean
200 mm carapace
145 mm plastron
Peak
June
mid-June
June
early to mid-June
mid-June
September
Range or
(95% Cl of mean)
3-7
at least 24
at least 19
End
November
end of June
September
late June
end of June
October
early October
March-May
mid-March
early May
Location/Habitat
Quebec, Canada/NS
Tennessee/NS
NS/NS
Michigan/marsh
South Carolina/river
Location
depends on latitude
New York
Florida
depends on latitude
northern New York
South Dakota
depends on latitude
se Michigan
depends on latitude
Iowa
Ontario, Canada
Reference
Mosimann & Bider, 1960
White & Murphy, 1973
Galbraith & Brooks, 1987
Gibbons, 1987
Gibbons, 1987
Ernst & Barbour, 1972
Kiviat, 1980
Punzo, 1975
Ernst & Barbour, 1972
Petokas & Alexander, 1980
Hammer, 1969
Ernst & Barbour, 1972
Congdon etal., 1987
Ernst & Barbour, 1972
Christiansen & Burken, 1979
Obbard & Brooks, 1981
Note
No.
9
10
Note
No.
10
CO
-g
CO
CO
3
0)
TS
•D
5'
(Q
(D
1 Cited in Sievert et al. (1988).
2 Estimated assuming temperature of 20 C, using equation 3-50 (Robinson et al., 1983) and body weights from Congdon et al. (1986), after
subtracting 30 percent of body weight to eliminate the weight of the shell (Hall, 1924). More information on estimating energy budgets for reptiles
is provided in Congdon etal. (1982).
3 Method of estimating percent diet not specified.
4 Summary of six field studies, including the author's.
5 Summary of data from various authors for eleven eutrophic ponds.
6 Cited in Petokas and Alexander (1980).
7 Cited in Graves and Anderson (1987).
-------
Snapping Turtle (Chelydra serpentina)
8 Cited in Galbraith et al. (1989).
9 Cited in Bury (1979).
10 Cited in Frazer et al. (1991).
10
CO
CO
3
0)
-o
•o
5'
(Q
(D
-------
References (including Appendix)
Alexander, M. M. (1943) Food habits of the snapping turtle in Connecticut. J. Wildl. Manage.
7: 278-282.
Barbour, R. W. (1950) The reptiles of Big Black Mountain, Harlan County, Kentucky. Copeia
1950: 100-107.
Bramble, D. M. (1973) Media dependent feeding in turtles. Am. Zool. 13: 1342.
Breckenridge, W. J. (1944) Reptiles and amphibians of Minnesota. Minneapolis, MN:
University of Minnesota Press.
Budhabhatti, J.; Moll, E. O. (1988) Diet and activity patterns of the common snapping turtle,
Chelydra serpentina (Linnaeus) at Chain O'Lakes State Park, Lake County, Illinois
(abstract only). Bull. Ecol. Soc. Am. Suppl. 69: 86.
Bury, R. B. (1979) Population ecology of freshwater turtles. In: Harless, M.; Morlock, H.,
eds. Turtles: perspectives and research. Toronto, Canada: John Wiley and Sons,
Inc.; pp. 571-602.
Bush, F. M. (1959) Foods of some Kentucky herptiles. Herpetologica 15: 73-77.
Cahn, A. R. (1937) The turtles of Illinois. Illinois Biol. Monogr. 35: 1-218.
Carr, A. F. (1952) Handbook of turtles. Ithaca, NY: Comstock.
Christiansen, J. L.; Burken, R. R. (1979) Growth and maturity of the snapping turtle
(Chelydra serpentina) in Iowa. Herpetologica 35: 261-266.
Conant, R.; Collins, J. T. (1991) A field guide to reptiles and amphibians - eastern and
central North America. Boston, MA: Houghton Mifflin Co.
Congdon, J. D.; Gibbons, J. W. (1985) Egg components and reproductive characteristics of
turtles: relationships to body size. Herpetologica 41: 194-205.
Congdon, J. D.; Dunham, A. E.; Tinkle, D. W. (1982) Energy budgets and life histories of
reptiles. In: Gans, C., ed. Biology of the reptilia. v. 13. New York, NY: Academic
Press; pp. 233-271.
Congdon, J. D.; Greene, J. L.; Gibbons, J. W. (1986) Biomass of freshwater turtles: A
geographic comparison. Am. Midi. Nat. 115: 165-173.
Congdon, J. D.; Tinkle, D. W.; Rosen, P. C. (1983) Egg components and utilization during
development in aquatic turtles. Copeia 1983: 264-268.
2-375 Snapping Turtle
-------
Congdon, J. D.; Breitenbach, G. L.; van Loben Sels, R. C.; et al. (1987) Reproduction and
nesting ecology of snapping turtles (Chelydra serpentina) in southeastern Michigan.
Herpetologica 43: 39-54.
DeGraaf, R. M.; Rudis, D. D. (1983) Amphibians and reptiles of New England. Amherst, MA:
University of Massachusetts Press; p. 42.
Ernst, C. H. (1968) A turtle's territory. Int. Turtle Tortoise Soc. J. 2: 9-34.
Ernst, C. H. (1971) Population dynamics and activity cycles of Chrysemys picta in
southeastern Pennsylvania. J. Herpetol. 140: 191-200.
Ernst, C. H.; Barbour, R. W. (1972) Turtles of the United States. Lexington, KY: University
Press of Kentucky.
Ewert, M. A. (1976) Nests, nesting and aerial basking of Macroclemys under natural
conditions, and comparisons with Chelydra (Testudines: Chelydridae).
Herpetologica 32: 150-156.
Ewert, M. A. (1979) The embryo and its egg: development and natural history. In: Harless,
M.; Morlock, H., eds. Turtles: perspectives and research. Toronto, Canada: John
Wiley and Sons, Inc.; pp. 333-413.
Frazer, N. B.; Gibbons, J. W.; Greene, J. L. (1991) Growth, survivorship and longevity of
painted turtles Chrysemys picta in a southwestern Michigan marsh. Am. Midi. Nat.
125: 245-258.
Froese, A. D. (1978) Habitat preferences of the common snapping turtle, Chelydra s.
serpentina (Reptilia, Testudines, Chelydridae). J. Herpetol. 12: 53-58.
Froese, A. D.; Burghardt, G. M. (1975) A dense natural population of the common snapping
turtle (Chelydra s. serpentina). Herpetologica 31: 204-208.
Galbraith, D. A.; Brooks, R. J. (1987) Survivorship of adult females in a northern population
of common snapping turtles, Chelydra serpentina. Can. J. Zool. 65: 1581-1586.
Galbraith, D. A.; Chandler, M. W.; Brooks, R. J. (1987) The fine structure of home ranges of
male Chelydra serpentina: are snapping turtles territorial? Can. J. Zool. 65:
2623-2629.
Galbraith, D. A.; Bishop, C. A.; Brooks, R. J.; et al. (1988) Factors affecting the density of
populations of common snapping turtles (Chelydra serpentina serpentina). Can. J.
Zool. 66: 1233-1240.
Galbraith, D. A.; Brooks, R. J.; Obbard, M. E. (1989) The influence of growth rate on age
and body size at maturity in female snapping turtles (Chelydra serpentina). Copeia
1989: 896-904.
2-376 Snapping Turtle
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Gerholdt, J. E.; Oldfield, B. (1987) Chelydra serpentina serpentina (common snapping
turtle), size. Herpetol. Rev. 18: 73.
Gibbons, J. W. (1968) Growth rates of the common snapping turtle, Chelydra serpentina, in
a polluted river. Herpetologica 24: 266-267.
Gibbons, J. W. (1987) Why do turtles live so long? BioSci. 37: 262-269.
Graham, T. E.; Perkins, R. W. (1976) Growth of the common snapping turtle, Chelydra s.
serpentina, in a polluted marsh. Bull. Md. Herpetol. Soc. 12: 123-125.
Graves, B. M.; Anderson, S. H. (1987) Habitat suitability index models: snapping turtle. U.S.
Fish Wildl. Serv. Biol. Rep. 82(10.141); 18 pp.
Hall, F. G. (1924) The respiratory exchange in turtles. J. Metab. Res. 6: 393-401.
Hammer, D. A. (1969) Parameters of a marsh snapping turtle population, La-creek Refuge,
South Dakota. J. Wildl. Manage. 33: 995-1005.
Hammer, D. A. (1971) The durable snapping turtle. Nat. Hist. 80: 59-65.
Hotaling, E. C.; Wilhoft, D. C.; McDowell, S. B. (1985) Egg position and weight of hatchling
snapping turtles, Chelydra serpentina, in natural nests. J. Herp. 19: 534-536.
Hutchison, V. H. (1979) Thermoregulation. In: Harless, M.; Morlock, H., eds. Turtles:
perspectives and research. Toronto, Canada: John Wiley and Sons, Inc.; pp.
207-227.
Iverson, J. B. (1977) Reproduction in freshwater and terrestrial turtles of north Florida.
Herpetologica 33: 205-212.
Kiviat, E. (1980) A Hudson River tide-marsh snapping turtle population. In: Trans.
Northeast. Sec. Wildl. Soc. 37th Northeast, Fish and Wildl. Conf.; April 27-30, 1980;
Ellenville, NY; pp. 158-168.
Lagler, K. F. (1943) Food habits and economic relations of the turtles of Michigan with
special reference to game management. Am. Midi. Nat. 29: 257-312.
Lagler, K. F.; Applegate, V. C. (1943) Relationship between the length and the weight in the
snapping turtle Chelydra serpentina Linnaeus. Am. Nat. 77: 476-478.
Lonke, D. J.; Obbard, M. E. (1977) Tag success, dimensions, clutch size and nesting site
fidelity for the snapping turtle, Chelydra serpentina (Reptilia, Testudines,
Chelydridae), in Algonquin Park, Ontario, Canada. J. Herpetol. 11: 243-244.
Lynn, W. G.; von Brand, T. (1945) Studies on the oxygen consumption and water
metabolism of turtle embryos. Biol. Bull. 88: 112-125.
2-377 Snapping Turtle
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Macnamara, C. (1919) Notes on turtles. Ottawa Natural. 32: 135.
Major, P. D. (1975) Density of snapping turtles, Chelydra serpentina in western West
Virginia. Herpetologica 31: 332-335.
Meyers-Schone, L.; Walton, B. T. (1990) Comparison of two freshwater turtle species as
monitors of environmental contamination. Oak Ridge, TN: Oak Ridge National Lab.;
Environmental Sciences Division Publication No. 3454. ORNL/TM-11460.
Minton, S. A., Jr. (1972) Amphibians and reptiles of Indiana. Indianapolis, IN: Indiana
Academy of Science.
Moll, E. O. (1979) Reproductive cycles and adaptations. In: Harless, M.; Morlock, H., eds.
Turtles: perspectives and research. Toronto, Canada: John Wiley and Sons, Inc.;
pp. 305-331.
Mosimann, J. E.; Bider, J. R. (1960) Variation, sexual dimorphism, and maturity in a Quebec
population of the snapping turtle, Chelydra serpentina. Can. J. Zool. 38: 19-38.
Obbard, M. E. (1983) Population ecology of the common snapping turtle, Chelydra
serpentina, in north-central Ontario [Ph.D. dissertation]. Guelph, Ontario Canada:
University of Guelph.
Obbard, M. E.; Brooks, R. J. (1980) Nesting migrations of the snapping turtle (Chelydra
serpentina). Herpetologica 36: 158-162.
Obbard, M. E.; Brooks, R. J. (1981) A radio-telemetry and mark-recapture study of activity
in the common snapping turtle, Chelydra serpentina. Copeia 1981: 630-637.
Pearse, A. S. (1923) The abundance and migration of turtles. Ecology 4: 24-28.
Pell, S. M. (1940) Notes on the food habits of the common snapping turtle. Copeia 2: 131.
Pell, S. M. (1941) Notes on the habits of the common snapping turtle, Chelydra serpentina
(Linn.) in central New York [master's thesis]. Ithaca, NY: Cornell University.
Petokas, P. J.; Alexander, M. M. (1980) The nesting of Chelydra serpentina in northern New
York. J. Herpetol. 14: 239-244.
Punzo, F. (1975) Studies on the feeding behavior, diet, nesting habits and temperature
relationships of Chelydra serpentina osceola (Chelonia: Chelydridae). J. Herp. 9:
207-210.
Robinson, R. W.; Peters, R. H.; Zimmermann, J. (1983) The effects of body size and
temperature on metabolic rate of organisms. Can. J. Zool. 61: 281-288.
2-378 Snapping Turtle
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Sievert, L. M.; Sievert, G. A.; Cupp, P. V., Jr. (1988) Metabolic rate of feeding and fasting
juvenile midland painted turtles, Chrysemys picta marginata. Comp. Biochem.
Physiol. A Comp. Physiol. 90: 157-159.
Smith, H. M. (1956) Handbook of amphibians and reptiles of Kansas. Univ. Kansas Mus.
Nat. Hist. Misc. Publ. 9; pp. 134-136.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28:
118-120.
Toner, G. C. (1960) The snapping turtle. Can. Audubon 22:97-99.
White, J. B.; Murphy, G. G. (1973) The reproductive cycles and sexual dimorphism of the
common snapping turtle, Chelydra serpentina serpentina. Herpetologica 29:
240-246.
Wilhoft, D. C.; del Baglivo, M. G.; del Baglivo, M. D. (1979) Observations of mammalian
predation of snapping turtle nests (Reptilia, Testudines, Chelydridae). J. Herpetol.
13: 435-438.
Yntema, C. L. (1968) A series of stages in the embryonic development of Chelydra
serpentina. J. Morphol. 125: 219-252.
Yntema, C. L. (1970) Observations on females and eggs of the common snapping turtle,
Chelydra serpentina. Am. Midi. Nat. 84: 69-76.
Yntema, C. L. (1978) Incubation times for eggs of the turtle Chelydra serpentina
(Testudines: Chelydridae) at various temperatures. Herpetologica 34: 274-277.
2-379 Snapping Turtle
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Page 2-380 was left blank.
-------
2.3.2. Painted Turtle (pond and marsh turtles)
Order Testudines, Family Emydidae. Pond and marsh turtles (i.e., sliders, cooters,
red-bellied turtles, and painted turtles) are small to medium-sized semiaquatic turtles well
known for basking in the sun. Painted turtles are the most widespread of these in North
America, ranging across the continent.
Selected species
The painted turtle (Chrysemys picta) is largely aquatic, living in shallow-water
habitats, and is among the most conspicuous of the basking turtles. There are four
subspecies in the United States (only one reaching slightly into Canada), distinguished by
color variations, body size, and range: C. p. picta (eastern painted turtle; 11.5 to 15.2 cm;
range Nova Scotia to Alabama), C. p. marginata (midland painted turtle; 11.5 to 14 cm;
range southern Quebec and southern Ontario to Tennessee), C. p. dorsalis (southern
painted turtle; 10 to 12.5 cm; range southern Illinois to the Gulf), and C. p. belli! (western
painted turtle; the largest of the subspecies, 9 to 18 cm; range southwest Ontario and
Missouri to the Pacific Northwest) (Conant and Collins, 1991). C. p. dorsalis is the smallest
subspecies and also one of the smallest emydid turtles in North America (Moll, 1973).
Hybridization occurs between subspecies in areas where their ranges overlap (e.g., belli! x
marginata hybrids may occur in areas of Michigan) (Snow, 1980).
Body size. Painted turtles are medium-sized turtles (10 to 18 cm). Males are
smaller than females; adult males average from 170 to 190 g, whereas adult females
average from 260 to 330 g in some populations (Congdon et al., 1986; Ernst 1971b). In
general, the shell comprises approximately 30 percent of the total wet weight of turtles of
this size (Hall, 1924). Frazer et al. (1991) estimated a relationship between plastron length
(PL in mm) and age (t in years) for a population in Michigan in the 1980's using von
Bertalanffy growth equations:
PL = 111.8(1 - 0.792e'0184t) for males, and
PL = 152.2(1 - 0.852e'0128t) for females.
Congdon et al. (1982) reported a relationship between plastron length (PL in mm) and body
weight (Wt in grams) for painted turtles:
loge(Wt) = -6978 + 2.645 loge(PL).
Eggs weigh 4 to 6 g, and neonates retain a large yolk mass that they draw on for the first
few months of life (Cagle, 1954).
Habitat. Painted turtle habitat requirements include soft and muddy bottoms,
basking sites, and aquatic vegetation (Sexton, 1959). Painted turtles prefer slow-moving
shallow water such as ponds, marshes, ditches, prairie sloughs, spring runs, canals, and
occasionally brackish tidal marshes (Conant and Collins, 1991). They frequent areas with
floating surface vegetation for feeding and for cover (Sexton, 1959). These areas tend to
2-381 Painted Turtle
-------
be warmer than more open water, which is important in the early fall as temperatures begin
to drop (Sexton, 1959). For winter hibernation or dormancy, painted turtles seek deeper
water (Sexton, 1959). If outlying marsh areas are dry during the summer, the turtles may
return to the more permanent bodies of water sooner (McAuliffe, 1978). Painted turtles
sometimes inhabit stagnant and polluted water (Smith, 1956).
Food habits. Painted turtles are omnivorous. Depending on habitat and on age,
painted turtles may consume predominantly vegetation or predominantly animal matter.
Marchand (1942, cited in Mahmoud and Klicka, 1979) found in one population that juveniles
consumed approximately 85 percent animal matter and 15 percent plant matter, whereas
the adults were primarily herbivorous, consuming 88 percent plant matter and 12 percent
insects and amphipods. Knight and Gibbons (1968) found oligochaets, cladocera,
dragonfly nymphs, lepidopteran larvae, and tendipedid larvae and pupae to dominate the
animal component of the diet and filamentous algae to dominate the plant component of
the diet in a population living in a polluted river in Michigan. Adult painted turtles in a
Pennsylvania population were found to consume only 40 percent plant matter (Ernst and
Barbour, 1972), whereas in a Michigan marsh and elsewhere, painted turtles of all ages
apparently consumed 95 to 100 percent plant matter (Cahn, 1937, cited in Smith, 1961;
Gibbons, 1967). Some carrion also may be consumed (Mount, 1975).
Temperature regulation and daily activities. Painted turtles are diurnal and usually
spend their nights sleeping submerged (Ernst, 1971c). During the day, they forage in the
late morning and late afternoon and bask during the rest of the day (Ernst, 1971c). Active
feeding does not occur until water temperatures approach 20 C, and these turtles are most
active around 20.7 to 22.4°C (Ernst, 1972; Ernst and Barbour, 1972; Hutchinson, 1979).
Basking is most frequent in the spring, summer, and fall, but occasionally painted turtles
bask during warm spells in the winter (Ernst and Barbour, 1972). Sexton (1959) divided the
annual activity cycle of painted turtles into five parts: (1) the prevernal, which begins with
the final melting of winter ice and lasts until late March, or when the turtles begin to move
in mass out of the hibernation ponds; (2) the vernal, from late March to late May, when the
submerged aquatic plants important to the turtles grow to the surface of the water (the
initiation of feeding and mating activities and the emergence of the hatchling turtles from
the nests of the previous year also occur during this season); (3) the aestival, extending
from June through August, when the turtles forage, grow, nest, and return to their winter
hibernation ponds; (4) the autumnal, including September through November or when a
permanent ice cover forms; and (5) the winter season, which lasts while the water is
permanently covered with ice.
Hibernation. Most painted turtles become dormant during the colder months but
will become active during warm periods in the winter (Ernst and Barbour, 1972). C. picta
usually hibernates in muddy bottoms of ponds (DeGraaf and Rudis, 1983). Taylor and Nol
(1989) found painted turtles overwintering in an Ontario pond in areas with a mean water
depth of 0.32 m (range 0.2 to 0.48 m), mean sediment depth of 0.79 m (0.5 to 0.95 m), and
mean sediment temperature of 4.1 C (3 to 6 C). During hibernation, painted turtles shift
toward more anaerobic metabolism, supported by glycolysis of liver and skeletal muscle
glycogen (Seymour, 1982). After emerging from hibernation, the turtles convert the
accumulated lactate to glucose in the liver (using aerobic metabolism) (Seymour, 1982).
2-382 Painted Turtle
-------
Breeding activities and social organization. Mating usually occurs in spring and
summer but may continue into the fall (Ernst, 1971c; Gibbons, 1968a; Gist et al., 1990).
Nesting occurs somewhat later (Cagle, 1954; Ernst and Barbour, 1972; Moll 1973). Eggs
are often laid in high banks (DeGraaf and Rudis, 1983). The species does not appear to be
territorial and can be found in large aggregations, particularly at favorite basking sites
(Ernst, 1971c).
Home range and resources. In spring, as the winter ice melts, many painted turtles
move away from the ponds in which they hibernated to more shallow ponds and marshes
with surface vegetation (Sexton, 1959). Movements averaging 60 to 140 meters
characterized one population in Michigan (Sexton, 1959). The summer home range
includes the painted turtle's foraging areas and basking sites. Females find nesting sites
on dry land outside of the foraging range; Congdon and Gatten (1989) found nests to
average 60 meters from the edge of a foraging marsh. Females initiate nesting migrations
during daylight hours, and most finish their nests before dark on the same day (Congdon
and Gatten, 1989). In winter, painted turtles generally move back to the deeper ponds for
hibernation (DeGraaf and Rudis, 1983).
Population density. Reported densities range from 11.1/ha in Saskatchewan
(MacCulloch and Secoy, 1983) to 830/ha in Michigan marshes (Frazer et al., 1991).
Accurate censuses are difficult, however (Bayless, 1975), and the distribution of painted
turtles in summer is highly clumped, corresponding to the patches of floating aquatic
vegetation (Sexton, 1959).
Population dynamics. Sexual maturity is attained in about 2 to 7 years, depending
on the sex and size of the turtle and growing season (Christiansen and Moll, 1973; Ernst
and Barbour, 1972). Males reach sexual maturity 1 to a few years earlier than females
(Moll, 1973). Once sexual maturity is reached, growth of painted turtles slows or
essentially ceases (Ernst and Barbour, 1972). Older, larger females tend to produce larger
clutch sizes and larger eggs than younger, smaller females (Mitchell, 1985). In more
southerly populations, painted turtles produce more clutches annually with fewer eggs
each than in more northerly populations (Moll, 1973; Snow, 1980; Schwarzkopf and Brooks,
1986). Predation causes most nest losses, usually within the first 2 days after laying
(Tinkle et al., 1981). The duration of the incubation period depends on soil temperature,
and hatchlings may overwinter in the nest in more northerly populations (Gibbons and
Nelson, 1978).
Similar species (from general references)
Many species of pond and marsh turtles can be found in similar habitats; however,
there are important dietary differences among species that can affect exposure to
environmental contaminants, as described below. Size is listed according to carapace
length, which is longer than plastron length.
cooters
The Florida cooter (Pseudemys floridana) is larger (23 to 33 cm) than the
painted turtle. The floridana subspecies ranges from the coastal plain of
2-383 Painted Turtle
-------
Virginia to eastern Texas and north in the Mississippi Valley to southern
Illinois, while the peninsularis subspecies is restricted to the Florida
peninsula. The Florida cooter resides in permanent bodies of water. In their
first year, young cooters feed on both aquatic plant and animal life; later they
become totally herbivorous.
The river cooter (Pseudemys concinna), composed of five subspecies, also
is larger (23 to 33 cm) than the painted turtle. It inhabits coastal plains
ranging from southeastern Virginia to Georgia, southeast into Florida, west
into Texas and New Mexico, and north in the Mississippi Valley to southern
Illinois. It is chiefly a resident of streams and relatively large lakes. In their
first year, young river cooters are omnivorous; the adults are almost entirely
herbivorous.
The Texas river cooter (Pseudemys texana) (18 to 25.5 cm) prefers rivers but
can be found in smaller creeks and ditches. Its range is restricted to most of
central and southeastern Texas.
red-bellied turtles
The Florida red-bellied turtle (Pseudemys nelsoni) is larger (20 to 31 cm)
than the painted turtle and has a range in the Florida peninsula and
panhandle. It can be found basking on logs over fresh to moderately
brackish water, and it prefers abundant submerged aquatic vegetation, its
principal food.
The Alabama red-bellied turtle (Pseudemys alabamensis) is larger (23 to 33
cm) than the painted turtle and is found only in the lower portion of the
Mobile Bay drainage in Alabama. It prefers fresh to moderately brackish
water with abundant aquatic vegetation, its principal food.
The red-bellied turtle (Pseudemys rubriventris) is much larger (25 to 32 cm)
than the painted turtle and is found in the mid-Atlantic states and eastern
Massachusetts.
sliders
The pond slider (Trachemys scripta) is similar in size or a little larger (12 to
20 cm) than the painted turtle and has three subspecies ranging from
southeastern Virginia to northern Florida and west to New Mexico. During
the first year, pond sliders are principally carnivorous, consuming aquatic
insects, crustaceans, molluscs, and tadpoles. As they mature, sliders
become herbivorous, consuming a wide variety of aquatic plants.
The big bend slider (Trachemys gaigeae) (12 to 20 cm) is similar to the pond
slider in size and habits. It is abundant locally in its limited range along the
upper Rio Grande and some of its tributaries.
2-384 Painted Turtle
-------
General references
Behler and King (1979); Conant and Collins (1991); Congdon et al. (1986); Ernst and
Barbour(1972); Moll (1973); Sexton (1959).
2-385 Painted Turtle
-------
Painted Turtle (Chrysemys picta)
Factors
Body Weight
(g)
Body Length
(mm plastron)
(mm plastron)
(mm carapace)
Egg Weight (g)
Growth Rate
Age/Sex/
Cond./Seas.
AF
AM
AF
AM
JB
at hatching
at hatching
AF
AM
AF
AM
JB
AF
AM
JB
initial mass
initial mass
final mass
J F - 1 yr
J F - 2 to 3 yr
J F - 4 to 5 yr
J F - 6 to 7 yr
AF-8to12yr
AF->12yr
Mean
266.5 ±60.1 SD
189.1 ±52.3SD
326.7 ± 4.95 SE
176.9 ± 1.92 SE
64.2±1.59SE
3.7 ±0.2 SD
4.1 ±0.61 SD
157±2.6SE
132±2.9SE
125.1 ±0.64SE
99.9 ± 0.48 SE
65.0 ± 0.65 SE
134.2 ±0.81 SE
109.7 ± 0.54 SE
71.5 ± 0.69 SE
6.17
6.65 ± 0.67 SD
8.62±1.06SD
35 mm/yr
19 -20 mm/yr
12 mm/yr
8 - 10 mm/yr
3-6 mm/yr
< 3 mm/yr
Range or
(95% Cl of mean)
83.5 - 450.3
102.0-274.5
3.5 - 3.9
136-185
96-155
Location (subspecies)
Pennsylvania (picta x
marginata)
Michigan
central Virginia (picta)
Iowa
Wisconsin (foe////)
Michigan
Michigan
Georgia (dorsalis)
Iowa
Quebec, Canada (marginata)
(measured using plastron)
Reference
Ernst, 1971 b
Congdon etal., 1986
Mitchell, 1985
Ratterman & Ackerman,
1989
Moll, 1973
Congdon etal., 1986
Congdon etal., 1986
Congdon & Gibbons,
1985
Ratterman & Ackerman,
1989
Christens & Bider, 1986
Note
No.
10
CO
00
o>
TJ
0)
(D
Q.
(D
-------
Painted Turtle (Chrysemys picta)
Factors
Metabolic Rate
(I02/kg-d)
Metabolic Rate
(kcal/d,
averaged over
1 year)
Food Ingestion
Rate (g/g-d)
Water
Ingestion
Rate (g/g-d)
Inhalation
Rate
(m3/kg-d)
Age/Sex/
Cond./Seas.
adults;
25°C
I and, rest
water,
swim
juv.; 25°C
feeding
1 -day fast
10-day fast
19-day fast
JF-yr
1
J F - yr 3
J F - yr 5
J F - yr 7
A F - yr 9
AF-yr
AF-yr
11
13
AB
A B summer
A B resting
Dietary Composition
all ages:
plants
Mean
0.73 ± 0.44 SD
0.22 ± 0.32 SD
0.39 ± 0.68 SD
5.06 ± 0.42 SE
3.44 ± 0.29 SE
1.98 ± 0.13 SE
1.57 ± 0.19 SE
0.06
0.30
0.53
0.77
1.12
1.23
1.28
0.02
0.0025 ±0.0005 SE
Spring
Range or
(95% Cl of mean)
up to 0.025
0.016 - 0.022
Summer Fall Winter
>95
Location (subspecies)
North Carolina
NS (marginata)
Michigan (marginata)
Wisconsin (belli!) (lab)
Pennsylvania (lab)
NS (lab)
Reference
Stockard & Gatten, 1983
Sievert et al., 1988
Congdon etal., 1982
Trobec & Stanley, 1971
Ernst, 1972
Milsom & Chan, 1986
Location/Habitat
(measure) Reference
Michigan/marsh Gibbons, 1967
(% wet weight; stomach
contents)
Note
No.
1
2
3
4
5
6
Note
No.
10
CO
00
TJ
0)
(D
Q.
(D
-------
Painted Turtle (Chrysemys picta)
Dietary Composition
all ages:
plants
animals
Oligochaeta
Cladocera
Odonata nymphs
Lepidoptera larvae
Tendipedidae larva
Tendipedidae pupae
detritus
adults:
snails
amphipods
crayfish
insects
fish
other animals
algae
vascular plants
other plants
Population
Dynamics
Movements
(m)
Population
Density
(N/ha)
Spring
31.6
77.3
-
1.5
60.0
1.0
30.8
36.7
7.8
A B spring
A B summer
A B fall
B B summer
BB
BB
BB
Summer
38.7
72.3
30.0
48.5
38.3
50.0
7.7
10.0
1.9
12.1
3.0
7.5
11.5
13.0
14.1
14.7
24.1
0.8
Fall
63 - 144
86-91
88-130
11.1
590
828
Winter
Range or
(95% Cl of mean)
up to 301
up to 300
up to 336
98-410
240 - 941
Location/Habitat
(measure)
Michigan/polluted river
(% wet weight; stomach
contents)
Pennsylvania (picta)INS
(% wet volume; stomach
contents)
season not specified
Michigan (marginata)INS
Saskatchewan, Canada
(de//;7)/river
Michigan (marginata)lponds,
marsh
Pennsylvania/pond, marsh
Michigan/lake, marsh
Reference
Knight & Gibbons, 1968
Ernst & Barbour, 1972
Sexton, 1959
MacCulloch & Secoy, 1983
Sexton, 1959
Ernst, 1971c
Frazer etal., 1991
Note
No.
Note
No.
7
10
CO
00
00
TJ
0)
(D
Q.
(D
-------
Painted Turtle (Chrysemys picta)
Population
Dynamics
Clutch Size
Clutches/Year
Days
Incubation
Age at Sexual
Maturity (yr)
Age/Sex
Cond./Seas.
F
M
F
M
F
M
F
M
Mean
19.8
10.7
7.6
4.8
1 -2
1 -2
>2
>3
5-6
3
8
4
6
5
4-5
2-3
Range or
(95% Cl of mean)
17-23
4-16
2-11
2-9
2
2
3
5
65-80
60-65
72-99
Location/Habitat
Saskatchewan, Canada
(de//;7)/creek
Wisconsin (de//;7)/NS
Michigan (marginata)INS
Tennessee (dorsalis x
marginata)INS
Ontario, Canada/NS
Michigan (be//// x marginata)
INS
Illinois (be//// x marginata)
/kettle ponds
Tennessee, Louisiana
(dorsalis and d. x
marginata)INS
se Pennsylvania/NS
se Wisconsin/NS (natural)
nw Minnesota/NS (natural)
New Mexico (de//;7)/NS
Wisconsin (be///'/)/NS
Pennsylvania (picta)INS
Tennessee (dorsalis x
marginata)INS
Reference
MacCulloch & Secoy, 1983
Moll, 1973
Congdon & Tinkle, 1982
Moll, 1973
Schwarzkopf & Brooks,
1986
Snow, 1980
Moll, 1973
Moll, 1973
Ernst, 1971c
Ewert, 1979
Ewert, 1979
Christiansen & Moll, 1973
Christiansen & Moll, 1973
Ernst & Barbour, 1972
Moll, 1973
Note
No.
10
CO
00
TJ
0)
(D
Q.
(D
-------
Painted Turtle (Chrysemys picta)
Population
Dynamics
Length at
Sexual
Maturity
(mm plastron)
Annual
Mortality Rates
(%)
Longevity
Seasonal
Activity
Mating
Nesting
Hatching
Hibernation
Age/Sex
Cond./Seas.
M
F
M
F
M
F
AF
AM
AB
JB
M
F
late April
March
June
June
late May
September
August
late October
late October
Mean
90
120-130
70
120-125
123
150
54
April - early May
October
June
late summer
Range or
(95% Cl of mean)
88 - 170
132-205
0-14
2-46
4-6
up to 31 yrs
up to 34 yrs
End
mid-June
May
July
July
late June
spring
September
late March
April
Location/Habitat
northern Michigan
(marginata, dorsalis)INS
southern Illinois (marginata,
dorsalis)INS
New Mexico (de//;7)/NS
Saskatchewan, Canada, Ml,
NY, NE/NS
Virginia/NS
Michigan/marsh
se Pennsylvania
Michigan
Ohio
se Pennsylvania
Illinois, Kansas
se Michigan (marginata)
se Michigan (marginata)
Illinois (marginata)
Kansas (bellii)
se Michigan (marginata)
Kansas (bellii)
Reference
Cagle, 1954
Cagle, 1954
Christiansen & Moll, 1973
Zweifel, 1989
Mitchell, 1988
Frazeretal., 1991
Ernst, 1971c
Gibbons, 1968a
Gistetal., 1990
Ernst, 1971c
Smith, 1956, 1961
Tinkle etal., 1981
Tinkle etal., 1981
Cahn, 1937
Smith, 1956
Congdon etal., 1982
Smith, 1956
Note
No.
8
8
Note
No.
9
10
CO
u>
o
TJ
0)
(D
Q.
(D
-------
Painted Turtle (Chrysemys picta)
1 Average mass of test animals resting on land and in water = 215 g (79 to 395 g) and of test animals swimming and measured for existence
metabolism = 143 g (79 to 297 g).
2 Average weight of juvenile turtles = 7.7 g.
3 Based on an annual energy budget estimated by the authors assuming that females lay one clutch of eggs per year after their seventh year.
4 See Chapters 3 and 4 for approaches to estimating food ingestion rates from metabolic rate and diet.
5 Uptake of water by turtles held in tap water.
6 Measured as evaporative water loss.
7 Spring: from hibernation to other ponds; summer: back to hibernation ponds; fall: to deep-water areas for hibernation.
8 Cited in Frazeretal., 1991.
9 Cited in Smith, 1961.
CO
TJ
0)
(D
Q.
(D
-------
References (including Appendix)
Bayless, L. E. (1975) Population parameters for Chrysemys picta in a New York pond. Am.
Midi. Nat. 93: 168-176.
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
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Breckenridge, W. J. (1944) Reptiles and amphibians of Minnesota. Minneapolis, MN:
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Breitenbach, G. L.; Congdon, J. D.; van Loben Sels, R. C. (1984) Winter temperatures of
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76-81.
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eds. Turtles: perspectives and research. Toronto, Canada: John Wiley and Sons,
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Cagle, F. R. (1954) Observations on the life cycles of painted turtles (Genus Chrysemys).
Am. Midi. Nat. 52: 225-235.
Cahn, A. R. (1937) The turtles of Illinois. Illinois Biol. Monogr. 1-218.
Christens, E.; Bider, J. R. (1986) Reproductive ecology of the painted turtle (Chrysemys
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Christiansen, J. L.; Moll, E. O. (1973) Latitudinal reproductive variation within a single
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central North America. Boston, MA: Houghton Mifflin Co.
Congdon, J. D.; Gatten, R. E., Jr. (1989) Movements and energetics of nesting Chrysemys
picta. Herpetologica 45: 94-100.
Congdon, J. D.; Gibbons, J. W. (1985) Egg components and reproductive characteristics of
turtles: relationships to body size. Herpetologica 41: 194-205.
Congdon, J. D.; Tinkle, D. W. (1982) Reproductive energetics of painted turtle (Chrysemys
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2-392 Painted Turtle
-------
Congdon, J. D.; Dunham, A. E.; Tinkle, D. W. (1982) Energy budgets and life histories of
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Congdon, J. D.; Greene, J. L.; Gibbons, J. W. (1986) Biomass of freshwater turtles: a
geographic comparison. Am. Midi. Nat. 115: 165-173.
DeGraaf, R. M.; Rudis, D. D. (1983) Amphibians and reptiles of New England. Amherst, MA:
University of Massachusetts Press.
Ernst, C. H. (1971a) Sexual cycles and maturity of the turtle, Chrysemys picta. Biol. Bull.
140: 191-200.
Ernst, C. H. (1971b) Growth of the painted turtle, Chrysemys picta, in southeastern
Pennsylvania. Herpetologica 27: 135-141.
Ernst, C. J. (1971c) Population dynamics and activity cycles of Chrysemys picta in
southeastern Pennsylvania. J. Herpetol. 5: 151-160.
Ernst, C. H. (1972) Temperature-activity relationship in the painted turtle, Chrysemys picta.
Copeia 1972: 217-222.
Ernst, C. H.; Barbour, R. W. (1972) Turtles of the United States. Lexington, KY: University
Press of Kentucky.
Ewert, M. A. (1979) The embryo and its egg: development and natural history. In: Harless,
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Wiley and Sons, Inc.; pp. 333-413.
Frazer, N. B.; Gibbons, J. W.; Greene, J. L. (1991) Growth, survivorship and longevity of
painted turtles Chrysemys picta in a southwestern Michigan marsh. Am. Midi. Nat.
125: 245-258.
Gemmell, D. J. (1970) Some observations on the nesting of the western painted turtle,
Chrysemys picta belli, in northern Minnesota. Can. Field-Nat. 84: 308-309.
Gibbons, J. W. (1967) Variation in growth rates in three populations of the painted turtle,
Chrysemys picta. Herpetologica 23: 296-303.
Gibbons, J. W. (1968a) Reproductive potential, activity and cycles in Chrysemys picta.
Ecology 49: 399-409.
Gibbons, J. W. (1968b) Population structure and survivorship in the painted turtle,
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Gibbons, J. W. (1987) Why do turtles live so long? BioSci. 37: 262-269.
2-393 Painted Turtle
-------
Gibbons, J. W.; Nelson, D. H. (1978) The evolutionary significance of delayed emergence
from the nest by hatchling turtles. Evolution 32: 297-303.
Gist, D. H.; Michaelson, J. A.; Jones, J. M. (1990) Autumn mating in the painted turtle,
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Hall, F. G. (1924) The respiratory exchange in turtles. J. Metab. Res. 6: 393-401.
Hutchinson, V. H. (1979) Thermoregulation. In: Harless, M.; Morlock, H., eds. Turtles:
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Iverson, J. B. (1982) Biomass in turtle populations: a neglected subject. Oecologia (Berl.)
55: 69-76.
Knight, A. W.; Gibbons, J. W. (1968) Food of the painted turtle, Chrysemys picta in a
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Lagler, K. F. (1943) Food habits and economic relations of the turtles of Michigan with
special reference to game management. Am. Midi. Nat. 29: 257-312.
Legler, J. M. (1954) Nesting habits of the western painted turtle, Chrysemys picta belli
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Lynn, W. G.; von Brand, T. (1945) Studies on the oxygen consumption and water
metabolism of turtle embryos. Biol. Bull. 88: 112-125.
MacCulloch, R. D.; Secoy, D. M. (1983) Demography, growth, and food of western painted
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Mahmoud, I. Y.; Klicka, J. (1979) Feeding, drinking, and excretion. In: Harless, M.; Morlock,
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Marchand, L. J. (1942) A contribution to a knowledge of the natural history of certain
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McAuliffe, J. R. (1978) Seasonal migrational movements of a population of the western
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Herpetol. 12: 143-149.
Milsom, W. K.; Chan, P. (1986) The relationship between lung volume, respiratory drive and
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Mitchell, J. C. (1985) Female reproductive cycle and life history attributes in a Virginia
population of painted turtles, Chrysemys picta. J. Herpetol. 19: 218-226.
2-394 Painted Turtle
-------
Mitchell, J. C. (1988) Population ecology and life histories of the freshwater turtles
Chrysemys picta and Sternotherus odoratus in an urban lake. Herpetol. Monogr. 2:
40-61.
Moll, E. O. (1973) Latitudinal and intersubspecific variation in reproduction of the painted
turtle, Chrysemys picta. Herpetologica 29: 307-318.
Morlock, H.; Herrington, S.; Oldham, M. (1972) Weight loss during food deprivation in the
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by flexible-shelled eggs of painted turtles Chrysemys picta on metabolism and
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Pearse, A. S. (1923) The abundance and migration of turtles. Ecology 4: 24-28.
Pope, C. H. (1939) Turtles of the United States and Canada. New York, NY: Alfred A. Knopf.
Powell, C. B. (1967) Female sexual cycles of Chrysemys picta and Clemmys insculpta in
Nova Scotia. Can. Field-Nat. 81: 134-140.
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2-395 Painted Turtle
-------
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Chrysemys picta, on Long Island, New York. Am. Mus. Novit. 2952: 1-55.
2-396 Painted Turtle
-------
2.3.3. Eastern Box Turtle (box turtles)
Order Testudines, Family Emydidae. Box turtles are the most terrestrial of the
Emydid turtles, having close-fitting shells that have allowed them to adapt well to terrestrial
life. They are found throughout the eastern and central United States and into the
southwest. They are omnivorous.
Selected species
The eastern box turtle (Terrapene Carolina Carolina) ranges from northeastern
Massachusetts to Georgia, west to Michigan, Illinois, and Tennessee (Conant and Collins,
1991). There are four subspecies of T. Carolina, all found within the eastern United States:
T. c. Carolina (above), T. c. mayor (Gulf Coast box turtle; the largest subspecies, restricted
to the Gulf Coast), T. c. triunguis (three-toed box turtle; Missouri to south-central Alabama
and Texas), and T. c. bauri (Florida box turtle; restricted to the Florida peninsula and keys)
(Conant and Collins, 1991).
Body size. The eastern box turtle is small, with adults ranging from 11.5 to 15.2 cm
in length (plastron) and approximately 300 to over 400 g. Hatchlings weigh approximately 8
to 10 g. Turtles continue to grow throughout their lives; however, their growth rate slows
after reaching sexual maturity (Ernst and Barbour, 1972), and growth rings are no longer
discernable after 18 to 20 years (Stickel, 1978). Body fat reserves in a Georgia population
averaged 0.058 to 0.060 g of fat per gram of lean dry weight from spring through fall
(Brisbin, 1972).
Habitat. Typical box turtle habitats include open woodlands, thickets, and well-
drained but moist forested areas (Stickel, 1950), but occasionally pastures and marshy
meadows are utilized (Ernst and Barbour, 1972). In areas with mixed woodlands and
grasslands, box turtles use grassland areas in times of moderate temperatures and peak
moisture conditions; otherwise, they tend to use the more moist forested habitats (Reagan,
1974). Many turtles are killed attempting to cross roads, and fragmentation of habitat by
roads can severely reduce populations (DeGraaf and Rudis, 1983; Stickel, 1978).
Food habits. Adult T. Carolina are omnivorous (Ernst and Barbour, 1972). When
young, they are primarily carnivorous, but they become more herbivorous as they age and
as growth slows (Ernst and Barbour, 1972). They consume a wide variety of animal
material, including earthworms, slugs, snails, insects and their larvae (particularly
grasshoppers, moths, and beetles), crayfish, frogs, toads, snakes, and carrion; they also
consume vegetable matter, including leaves, grass, berries, fruits, and fungi (DeGraaf and
Rudis, 1983). A high proportion of snails and slugs may comprise the animal matter in the
diet (Barbour, 1950), and seeds can become an important component of the plant materials
in the late summer and fall (Klimstra and Newsome, 1960).
Temperature regulation and daily activities. The species is diurnal and spends the
night resting in a scooped depression or form that the turtle digs in the soil with its front
feet (Ernst and Barbour, 1972; Stickel, 1950). T. Carolina are most active in temperate,
2-397 Eastern Box Turtle
-------
humid weather (Stickel, 1950). In the summer, they avoid high temperatures during midday
by resting under logs or leaf litter, in mammal burrows, or by congregating in mudholes
(Smith, 1961; Stickel, 1950). In the hottest weather, they may enter shaded shallow pools
for hours or days (Ernst and Barbour, 1972). In the cooler temperatures, they may restrict
their foraging activities to midday (Stickel, 1950). In the laboratory, locomotion is maximal
between 24 and 32 C (Adams et al., 1989). In the field, their mean active body temperature
is approximately 26°C (Brattstrom, 1965, cited in Hutchinson, 1979).
Hibernation. In the northern parts of its range (northeastern Massachusetts,
Michigan, Illinois), the eastern box turtle enters hibernation in late October or November
and emerges in April. In Louisiana, Penn and Pottharst (1940, cited in Ernst and Barbour,
1972) found that T. c. mayor hibernated when temperatures fell below 65°F. To hibernate,
the box turtle burrows into loose soil and debris or mud of ponds or stream bottoms.
Congdon et al. (1989) found a South Carolina population of box turtles to occupy relatively
shallow burrows (less than 4 cm) compared with those occupied by box turtles in colder
regions (up to 46 cm). Dolbeer (1971) found hibernacula of box turtles in Tennessee to be
under 15.5 cm of leaf litter and 5.8 cm of soil on average. In southern states, during rainy
and warm periods, box turtles may become active again (Dolbeer, 1971). In Florida, the
box turtle may be active all year (Ernst and Barbour, 1972).
Breeding activities and social organization. Box turtles are solitary except briefly
during the mating season. Individuals restrict their activities to a foraging home range, but
home ranges of different individuals can overlap substantially (Stickel, 1950). Mating
usually occurs in the spring but may continue into fall, and eggs are laid in late spring and
summer (Ernst and Barbour, 1972). The female digs a 3- to 4-inch cavity in sandy or loamy
soil in which she deposits her eggs and then covers the nest with soil. Nests tend to be
constructed several hundred meters from the female's foraging home range in the warmer
and drier uplands (Stickel, 1989). The duration of incubation depends on soil
temperatures, and sometimes hatchlings overwinter in the nest. The young are
semiaquatic but seldom seen (Smith, 1956).
Home range and resources. Measures of the foraging home range for box turtles
range from .5 ha to just over 5 ha (Dolbeer, 1969; Schwartz et al., 1984). A female may
need to search for suitable nest site (e.g., slightly elevated sandy soils) (Ernst and
Barbour, 1972) outside of her foraging home range (Stickel, 1950). Winter hibernacula tend
to be within the foraging home range (Stickel, 1989).
Population density. Population density varies with habitat quality, but studies
linking density to particular habitat characteristics are lacking. In some areas, population
densities have declined steadily over the past several decades (Schwartz and Schwartz,
1974; Stickel, 1978). Some investigators attribute the decline to increasing habitat
fragmentation and obstacles (e.g., highways) that prevent females from reaching or
returning from appropriate nesting areas (Stickel, 1978; DeGraaf and Rudis, 1983).
Population dynamics. Sexual maturity is attained at about 4 or 5 years (Ernst and
Barbour, 1972) to 5 to 10 years of age (Minton, 1972, cited in DeGraaf and Rudis, 1983).
One to four clutches may be laid per year, depending on latitude (Oliver, 1955, cited in
2-398 Eastern Box Turtle
-------
Moll, 1979; Smith, 1961). Clutch size ranges from three to eight eggs, averaging three to
four in some areas (Congdon and Gibbons, 1985; Ernst and Barbour, 1972; Smith, 1956).
Juveniles generally comprise a small proportion of box turtle populations, for example, 18
to 25 percent in one population in Missouri (Schwartz and Schwartz, 1974) and 10 percent
in a study in Maryland (Stickel, 1950). Some individual box turtles may live over 100 years
(Graham and Hutchinson, 1969, cited in DeGraaf and Rudis, 1983; Oliver, 1955, cited in
Auffenberg and Iverson, 1979).
Similar species (from general references)
• The ornate box turtle (Terrapene ornata ornata) and the desert box turtle
(Terrapene ornata luteola) are similar in size and habits to the eastern box
turtle. They occur in the western, midwestern, and southern midwestern
states. Preferred habitats include open prairies, pastureland, open
woodlands, and waterways in arid, sandy-soil terrains. The ornate box turtle
and desert box turtle forage primarily on insects but also on berries and
carrion.
General references
Behler and King (1979); Conant and Collins (1991); DeGraaf and Rudis (1983); Ernst
and Barbour (1972); Stickel (1950).
2-399 Eastern Box Turtle
-------
Eastern Box Turtle (Terrapene Carolina)
Factors
Body Weight
(g)
Body Fat
(g/g lean dry
weight)
Length
Egg Weight (g)
Metabolic Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Age/Sex/
Cond./Seas.
A F fall
A M fall
A F spring
A M spring
AF
at hatching
2 months
1.3 years
3.3 years
Bfall
B spring
B summer
AF
A
at hatching
A F basal
Mean
381 ±29SE
398 ± 47 SE
388 ± 29 SE
369 ± 47 SE
372
8.8
8.4
21
40
54
0.058 ± 0.014 SE
0.060 ± 0.016 SE
0.059 ± 0.006 SE
129 mm plastron
28 mm carapace
9.02 ± 0.17 SE
5.4
Range or
(95% Cl of mean)
up to 198 mm
carapace
6-11
Location (subspecies)
Georgia (Carolina), captive
Georgia (Carolina)
South Carolina
Florida (major)
Indiana (Carolina)
Tennessee
Georgia (Carolina), captive
South Carolina
NS/NS
NS/NS
South Carolina
NS/NS
Reference
Brisbin, 1972
Brisbin, 1972
Congdon & Gibbons, 1985
Ewert, 1979
Ewert, 1979
Allard, 1948
Brisbin, 1972
Congdon & Gibbons, 1985
Oliver, 1955
Oliver, 1955
Congdon & Gibbons, 1985
Ernst & Barbour, 1972
estimated
Note
No.
1
2
2
3
4
10
o
o
m
0)
-------
Eastern Box Turtle (Terrapene Carolina)
Dietary Composition
snails
crayfish
plants
crickets
unidentified seeds
plant matter
insects (adults)
insects (larvae)
seeds
Gastropoda
Isopoda
Diplopoda
Decapoda
Annelida
mammals
reptiles
birds
Population
Dynamics
Home Range
Size (ha)
Population
Density
(IM/ha)
Spring
35
18
4
8
18
<1
3
2
1
2
1
3
summer
BM
BF
BM
BF
Summer
60
15
12.5
7.5
5
39
12
5
16
6
5
2
2
1
<1
3
1
Fall
20
12
9
33
8
3
5
0
4
2
1
<1
0.46
1.2
1.1
5.2
5.1
2.8 - 3.6
17-35
Winter
Range or
(95% Cl of mean)
Location (subspecies)/
Habitat (measure)
Kentucky (Carolina)!
Cumberland Mountains
(% volume; stomach
contents)
Illinois (caro//na)/forest,
prairie
(% wet volume; digestive
tract)
Tennessee (Carolina)!
woodland
Maryland (Carolina)!
bottomland forest
Missouri (triunguis)lm\xed
woods, fields
Tennessee/woodland
Maryland (triunguis)Norest
Reference
Barbour, 1950
Klimstra & Newsome, 1960
Reference
Dolbeer, 1969
Stickel, 1989
Schwartz et al., 1984
Dolbeer, 1969
Schwartz et al., 1984
Note
No.
Note
No.
5
5
5
10
^
o
m
0)
-------
Eastern Box Turtle (Terrapene Carolina)
Population
Dynamics
Clutch Size
Clutches/Year
Days
Incubation
Age at Sexual
Maturity (yr)
Length at
Sexual
Maturity
(mm carapace)
Longevity (yr)
Seasonal
Activity
Mating
Age/Sex/
Co nd. /Seas.
B
B
B
June
September
August
November
October
Mean
3.4±0.3SE
4
1
99
4-5
5-10
20
spring
Range or
(95% Cl of mean)
2-7
up to 4
78 - 102
69-161
100-130
up to 80
up to 138
End
July
October
September
April
April
Location
(subspecies)/Habitat
South Carolina/NS
Washington, DC/NS
Florida/NS
lllinois/NS
northwest
Minnesota/(natural)
Washington, DC/(natural)
NS/NS
NS/NS
NS/NS
NS/NS
captivity
northern range
ne Carolinas, Washington,
DC
northern range
ne Carolinas
northern range
Missouri (triunguis)
Reference
Congdon & Gibbons, 1985
Smith, 1956
Oliver, 1955
Smith, 1961
Ewert, 1979
Ewing, 1933
Ernst & Barbour, 1972
Minton, 1972
Oliver, 1955
Nichols, 1939a
Oliver, 1955
Ernst & Barbour, 1972
DeGraaf & Rudis, 1983;
Smith, 1956
Ernst & Barbour, 1972
DeGraaf & Rudis, 1983
Ernst & Barbour, 1972
Schwartz & Schwartz, 1974
Note
No.
6
7
8
2
8
2
Note
No.
10
o
10
m
0)
-------
Eastern Box Turtle (Terrapene Carolina)
5 Foraging home range; nest sites can be several hundred meters away from the foraging home range.
6 Cited in Moll (1979).
7 Cited in Ewert (1979).
8 Cited in DeGraaf and Rudis (1983).
10
o
CO
m
0)
-------
References (including Appendix)
Adams, N. A.; Claussen, D. L.; Skillings, J. (1989) Effects of temperature on voluntary
locomotion of the eastern box turtle, Terrapene Carolina Carolina. Copeia 4: 905-915.
Allard, H. A. (1935) The natural history of the box turtle. Sci. Monthly 41: 325-338.
Allard, H. A. (1948) The eastern box-turtle and its behavior, part 1. J. Tenn. Acad. Sci. 23:
307-321.
Auffenberg, W.; Iverson, J. G. (1979) Demography of terrestrial turtles. In: Harless, M.;
Morlock, H., eds. Turtles: perspectives and research. Toronto, Canada: John Wiley
and Sons; pp. 541-569.
Barbour, R. W. (1950) The reptiles of Big Black Mountain, Harlan County, Kentucky. Copeia
1950: 100-107.
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
and amphibians. New York, NY: Alfred A. Knopf, Inc.
Brattstrom, B. H. (1965) Body temperatures of reptiles. Am. Midi. Nat. 73: 376-422.
Breder, R. B. (1927) Turtle trailing: a new technique for studying the life habits of certain
testudinata. Zoologica 9: 231-243.
Brisbin, I. L., Jr. (1972) Seasonal variations in the live weights and major body components
of captive box turtles. Herpetologica 28: 70-75.
Bush, F. M. (1959) Foods of some Kentucky herptiles. Herpetologica 15: 73-77.
Cahn, A. R. (1937) The turtles of Illinois. Illinois Biol. Monogr. 1-218.
Carr, A. F. (1952) Handbook of turtles. Ithaca, NY: Comstock.
Conant, R.; Collins, J. T. (1991) Afield guide to reptiles and amphibians: eastern/central
North America. Boston, MA: Houghton Mifflin Co.
Congdon, J. D.; Gibbons, J. W. (1985) Egg components and reproductive characteristics of
turtles: relationships to body size. Herpetologica 41: 194-205.
Congdon, J. D.; Gatten, R. E., Jr.; Morreale, S. J. (1989) Overwintering activity of box turtles
(Terrapene Carolina) in South Carolina. J. Herpetol. 23: 179-181.
DeGraaf, R. M.; Rudis, D. D. (1983) Box turtle. Amphibians and reptiles of New England.
Amherst, MA: University of Massachusetts Press.
Dickson, J. D., Ill (1953) The private life of the box turtle. Everglades Nat. Hist. 1: 58-62.
2-404 Eastern Box Turtle
-------
Dodge, C. H.; Dimond, M. T.; Wunder, C. C. (1979) The influence of temperature on the
incubation of box turtle eggs (abstract only). Am. Zool. 19: 981.
Dolbeer, R. A. (1969) Population density and home range size of the eastern box turtle
(Terrapene c. Carolina) in eastern Tennessee. A.S.B. Bull. 16: 49.
Dolbeer, R. A. (1971) Winter behavior of the eastern box turtle, Terrapene c. Carolina L., in
eastern Tennessee. Copeia 1971: 758-760.
Ernst, C. H.; Barbour, R. W. (1972) Turtles of the United States. Lexington, KY: University
Press of Kentucky.
Ewert, M. A. (1979) The embryo and its egg: development and natural history. In: Harless,
M.; Morlock, H., eds. Turtles: perspectives and research. Toronto, Canada: John
Wiley and Sons, Inc.; pp. 333-413.
Ewing, H. E. (1933) Reproduction in the eastern box-turtle Terrapene Carolina Carolina.
Copeia 1933: 95-96.
Graham, T. E.; Hutchinson, V. H. (1969) Centenarian box turtles. Int. Turtle Tortoise Soc. J.
3: 24-29.
Hall, F. G. (1924) The respiratory exchange in turtles. J. Metab. Res. 6: 393-401.
Hutchinson, V. H. (1979) Thermoregulation. In: Harless, M.; Morlock, H., eds. Turtles:
perspectives and research. Toronto, Canada: John Wiley and Sons, Inc.; pp.
207-227.
Klimstra, W. D.; Newsome, F. (1960) Some observations on the food coactions of the
common box turtle, Terrapene c. Carolina. Ecology 41: 639-647.
Lynn, W. G.; von Brand, T. (1945) Studies on the oxygen consumption and water
metabolism of turtle embryos. Biol. Bull. 88: 112-125.
Minton, S. A., Jr. (1972) Amphibians and reptiles of Indiana. Indianapolis, IN: Indiana
Academy of Science.
Moll, E. O. (1979) Reproductive cycles and adaptations. In: Harless, M.; Morlock, H., eds.
Turtles: perspectives and research. Toronto, Canada: John Wiley and Sons, Inc.;
pp. 305-331.
Nichols, J. T. (1939a) Data on size, growth and age in the box turtle, Terrapene Carolina.
Copeia 1939: 14-20.
Nichols, J. T. (1939b) Range and homing of individual box turtles. Copeia 1939: 125-127.
Oliver, J. A. (1955) The natural history of North American amphibians and reptiles.
Princeton, NJ: Van Nostrand Co.
2-405 Eastern Box Turtle
-------
Penn, G. H.; Pottharst, K. E. (1940) The reproduction and dormancy of Terrapene major in
New Orleans. Herpetologica 2: 25-29.
Reagan, D. P. (1974) Habitat selection in the three-toed box turtle Terrapene Carolina
triunguis. Copeia 2: 512-527.
Robinson, R. W.; Peters, R. H.; Zimmermann, J. (1983) The effects of body size and
temperature on metabolic rate of organisms. Can. J. Zool. 61: 281-288.
Rosenberger, R. C. (1972) Interesting facts about turtles. Int. Turtle Tortoise Soc. J. 6: 4-7.
Schwartz, C. W.; Schwartz, E. R. (1974) The three-toed box turtle in central Missouri: its
population, home range, and movements. Missouri Dept. Conserv. Terr. Ser. No. 5;
28pp.
Schwartz, E. R.; Schwartz, C. W.; Kiester, A. R. (1984) The three-toed box turtle in central
Missouri, part II: a nineteen-year study of home range, movements and population.
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Nat. Hist. Misc. Publ. 9.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28:
118-120.
Stickel, L. F. (1950) Population and home range relationships of the box turtle, Terrapene c.
Carolina (Linnaeus). Ecol. Monogr. 20: 351-378.
Stickel, L. F. (1978) Changes in a box turtle population during three decades. Copeia 1978:
221-225.
Stickel, L. F. (1989) Home range behavior among box turtles (Terrapene c. Carolina) of a
bottomland forest in Maryland. J. Herpetol. 23: 40-44.
Stickel, L. F.; Bunck, C. M. (1989) Growth and morphometrics of the box turtle, Terrapene c.
Carolina. J. Herpetol. 23: 216-223.
Strang, C. A. (1983) Spatial and temporal activity patterns in two terrestrial turtles. J.
Herpetol. 17: 43-47.
2-406 Eastern Box Turtle
-------
2.3.4. Racer (and whipsnakes)
Order Squamata, Family Colubridae. All racer snakes (Coluber constrictor) and
whipsnakes (Masticophis) belong to the family Colubridae, along with 84 percent of the
snake species in North America. Colubrids vary widely in form and size and can be found
in numerous terrestrial and aquatic habitats. The more terrestrial members of this family
also include some brown and garter snakes; lined snakes; earth snakes; hognose snakes;
small woodland snakes; green snakes; speckled racer and indigo snakes; rat snakes;
glossy snakes; pine, bull, and gopher snakes; kingsnakes and milk snakes; scarlet, long-
nosed, and short-tailed snakes; ground snakes; rear-fanged snakes; and crowned and
black-headed snakes (Conant and Collins, 1991).
Selected species
Racer snakes (Coluber constrictor) are slender and fast moving and are found in a
wide variety of terrestrial habitats. They are one of the most common large snakes in
North America (Smith, 1961). There are 11 subspecies in North America, limited to the
United States and Mexico: C. c. constrictor (northern black racer; southern Maine to
northeastern Alabama), C. c. flaviventris (eastern yellowbelly racer; Montana, western
North Dakota, and Iowa south to Texas), C. c. fox/7 (blue racer; northwest Ohio to eastern
Iowa and southeast Minnesota), C. c. anthicus (buttermilk racer; south Arkansas,
Louisiana, and east Texas), C. c. etheridgei (tan racer; west-central Louisiana and adjacent
Texas), C. c. helvigularis (brownchin racer; lower Chipola and Apalachicola River Valleys in
Florida panhandle and adjacent Georgia), C. c. latrunculus (blackmask racer; southeast
Louisiana along east side of Mississippi River to northern Mississippi), C. c. mormon
(western yellow-bellied racer; south British Colombia to Baja California, east to southwest
Montana, western Wyoming, and western Colorado), C. c. oaxaca (Mexican racer; south
Texas and Mexico), C. c. paludicola (Everglades racer; southern Florida Everglades region
and Cape Canaveral area), and C. c. priapus (southern black racer; southeastern states
and north and west in Mississippi Valley).
Body size. Adult racer snakes are usually 76 to 152 cm in total length (Conant and
Collins, 1991). Brown and Parker (1984) developed an empirical relationship between
snout-to-vent length (SVL)1 and body weight for male and female racers of the mormon
subspecies in northern Utah:
weight (g) = -100.80 + 2.93 SVL (cm) females,j and
weight (g) = -82.65 + 2.57 SVL (cm) males.
The equations apply only over a limited range of body sizes (40 to 70 cm) where the
relationship is approximately linear instead of exponential. Kaufman and Gibbons (1975)
'Measures of SVL exclude the tail. Fitch (1963) estimated that the tail measures 28 percent of the
SVL of young females and 31 percent of the SVL of young males.
jFemales collected when nonreproductive.
2-407 Racer
-------
determined a relationship between length and weight for both sexes of a South Carolina
population:
weight (g) = 0.0003 SVL (cm)2 97 (± °15 2SE) both sexes."
Racers from populations in the northeastern United States tend to be the largest, while
those from the far west and south Texas are the smallest (Fitch, 1963). Just prior to egg-
laying, the eggs can account for over 40 percent of a gravid female's body weight (Brown
and Parker, 1984). At hatching, racers weigh about 8 or 9 g. Weight gain during the first
year is rapid, with both sexes increasing their weight after hatching by approximately 3.2
times in the first year (Brown and Parker, 1984). One-year-old females nearly double their
weight during their second year (Brown and Parker, 1984). By the time females are 3 years
old (when most reach sexual maturity), they are 1.3 times heavier than the males (Brown
and Parker, 1984).
Habitat. Racers can be found in moist or dry areas, abandoned fields, open
woodlands, mountain meadows, rocky wooded hillsides, grassy-bordered streams, pine
flatwoods, roadsides, and marshes from sea level to 2,150 m in elevation (Behler and King,
1979). Racers are partially arboreal (Behler and King, 1979; DeGraaf and Rudis, 1983). C.
c. constrictor seems to prefer forest edges and open grassy, shrubby areas (Fitch, 1963,
1982). In autumn, most C. constrictor move into woodlands to find rock crevices in which
to overwinter (Fitch, 1982).
Food habits. Racers are foraging generalists that actively seek their prey. Their
varied diet includes small mammals (e.g., mice, voles), insects, amphibians (especially
frogs), small birds, birds' eggs, snakes, and lizards (Brown and Parker, 1982; Fitch, 1963;
Klimstra, 1959). In early spring, C.c. flaviventris feeds primarily on mammals and from
May to October feeds primarily on insects (Klimstra, 1959). They often capture new prey
before fully digesting previously captured prey (Fitch, 1982). Females, which are larger
than males, tend to consume a higher proportion of vertebrate prey than do the males
(Fitch, 1982). Males tend to spend more time climbing among foliage in low shrubs and
trees and consuming insects (Fitch, 1982).
Temperature regulation and daily activities. C. constrictor is diurnal and spends a
good portion of the daylight hours foraging (Vermersch and Kuntz, 1986). The species is
fast moving and may be encountered in almost any terrestrial situation (Fitch, 1982).
Hammerson (1987) observed California racers to bask in the sun after emerging from their
night burrows or crevices until their internal body temperature reached almost 34 C, after
which they would begin actively foraging. When temperatures are moderate, racers will
spend much of their time during the day in the open above ground; at high temperatures,
racers may retreat underground (Brown and Parker, 1982). Although racers are good
climbers, they spend most of their time on the ground (Behler and King, 1979). When
searching for food or being pursued, the racer snake will not hesitate to climb or swim
(Smith, 1961).
K95 percent confidence interval for constant (intercept in log-transform regression) = 0.00015 to
0.00058.
2-408 Racer
-------
Hibernation. In fall, racers move to their hibernacula fairly directly and begin
hibernation soon thereafter (Brown and Parker, 1982; Fitch, 1963). Racers hibernate in
congregations of tens to hundreds of snakes (Brown and Parker, 1984), sometimes with
copperheads and rattlesnakes, often using deep rock crevices or abandoned woodchuck
holes (Parker and Brown, 1973). They are among the earliest snakes to emerge from
hibernation (DeGraaf and Rudis, 1983).
Breeding activities and social organization. The species breeds in the spring or
early summer. Racers defend home territories (DeGraaf and Rudis, 1983; Smith, 1956).
Eggs are laid in the summer in rotting wood, stumps, decaying vegetable matter, or loose
soil and hatch about 2 months later (Behler and King, 1979; DeGraaf and Rudis, 1983).
More than one male may mate with one female in a breeding season. Eggs may double in
size before hatching by absorbing water from the surrounding soil (Fitch, 1963).
Home range and resources. C. c. constrictor appears to have a definite home range
(Smith, 1956) and requires large tracts of mixed old fields and woodlands (M. Klemens,
pers. comm., cited in DeGraaf and Rudis, 1983). Fitch (1963) described four types of
movement depending on the season and activity: (1) those in areas where hibernation
occurs (e.g., rocky ledges), (2) seasonal migration between hibernation and summer
ranges during spring and fall, (3) daily activities within a home range during the active
season, and (4) wandering movements during which the racer shifts its activities.
Population density. Population densities of between 0.3 and 7 active snakes per
hectare have been recorded in different habitats and areas (Fitch, 1963; Turner, 1977).
Data on population densities are limited due to the difficulty in accurately censusing
snakes.
Population dynamics. Male racers can reach sexual maturity by 13 to 14 months,
whereas females tend not to mature until 2 or 3 years of age (Behler and King, 1979; Brown
and Parker, 1984). Adult females produce at most a single clutch each year (some may
reproduce only in alternate years) (Fitch, 1963). In general, the number of eggs in a clutch
is proportional to the size of the female and ranges from 4 to 30 eggs (Fitch, 1963).
Incubation lasts approximately 40 days to 2 months, depending on temperature (Behler and
King, 1979; Smith, 1956). Juvenile snakes suffer higher mortality rates (e.g., 80 percent)
than adult snakes (e.g., 20 percent) (Brown and Parker, 1984).
Similar species (from general references)
• The eastern coachwhip (Masticophis flagellum flagellum) (black phase) is
similar in size and ranges from North Carolina and south Florida to Texas,
Oklahoma, and Kansas.
• The western coachwhip (Masticophis flagellum testaceus) is similar in size
to the racer. It ranges from western Nebraska south to Mexico.
• The central Texas whipsnake (Masticophis taeniatus girardi), Schott's
whipsnake (Masticophis taeniatus schotti), and Ruthven's whipsnake
2-409 Racer
-------
(Masticophis taeniatus ruthveni) are all similar in size to the racer and are
restricted to southern Texas and northern Mexico.
• The Sonora whipsnake (Masticophis bilineatus) can be slightly larger (76 to
170 cm) than the racer and is found from Arizona southwest to New Mexico
and Mexico.
• The striped racer (Masticophis lateralis) is also similar in size to the racer
snake. It ranges from south-central Washington southeast in Great Basin to
southern New Mexico and western and central Texas, south to west-central
Mexico.
• The desert striped whipsnake (Masticophis taeniatus taeniatus) is similar to
the central Texas whipsnake. It ranges from northern Texas and northern
California to Washington state.
General references
Behler and King (1979); Brown and Parker (1984); Conant and Collins (1991);
DeGraaf and Rudis (1983); Fitch (1963).
2-410 Racer
-------
Racer Snake (Coluber constrictot)
Factors
Body Weight
(g)
Age/Sex/
Cond./Seas.
males:
yrs/mm SVL
<1 266
1 420
2 486
3 520
4 541
5 564
6 573
females:
yrs/mm SVL
<1 272
1 430
2 524
3 575
4 599
5 620
6 632
males:
yrs/mm SVL
2 615
3 706
4 757
5 806
6 827
7 845
8 868
Mean
8.3
27.0
41.0
49.1
53.4
60.4
61.2
8.8
28.4
51.6
66.2
71.4
79.4
84.0
68.2
102.1
139.0
152.4
175.9
181.2
217.5
Range or
(95% Cl of mean)
Location (subspecies)
Utah (mormon)
Utah (mormon)
Kansas (flaviventris)
Reference
Brown & Parker, 1984
Brown & Parker, 1984
Fitch, 1963
Note
No.
10
o
(D
-------
Racer Snake (Coluber constrictot)
Factors
Body Weight
(g)
(continued)
Egg Weight (g)
Juvenile
Growth Rate
(g/d)
Body
Temperature
(•C)
Metabolic Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Age/Sex/
Cond./Seas.
females:
yrs/mm SVL
2 644
3 810
4 866
5 914
6 965
7 974
neon ate
21 5 mm SVL
female size:
892 mm SVL
773 mm SVL
size NS
both sexes;
0 to 10 wks
A B summer
A B summer
M basal
F basal
B B: spring
through fall
Mean
83.5
149.4
212.3
209.6
245.9
251.3
4.16
5.5
4.9
7.8 ± 0.17 SE
0.116
31.8 ± 0.20 SE
26 - 27 (mode)
6.78
6.19
0.02
Range or
(95% Cl of mean)
2.4 - 5.8
4.4-6.0
4.4 - 5.2
5.9-10.8
18.6-37.7
15.5-32.4
Location (subspecies)
Kansas (flaviventris)
Kansas (flaviventris)
Kansas (flaviventris)
Utah (mormon)
Kansas (flaviventris)
Utah (mormon)
Kansas (flaviventris)
Kansas (flaviventris)
Reference
Fitch, 1963
Fitch, 1963
Fitch, 1963
Brown & Parker, 1984
Fitch, 1963
Brown, 1973
Fitch, 1963
estimated
Fitch, 1982
Note
No.
1
2
3
4
10
A.
_1
10
o
(D
-------
Racer Snake (Coluber constrictot)
Dietary Composition
insects
small mammals
amphibians
reptiles
birds
other
small mammals
orthopterans
lizards
snakes
misc. insects
birds
frogs
mice
orthopterans
lizards
frogs
snakes
crickets
Population
Dynamics
Home Range
Size (ha)
Population
Density
(N/ha)
Spring
20
62
5
7
4
2
Age/Sex/
Co nd. /Seas.
A F summer
A M summer
A B summer
BB
Summer
40
27
13
8
6
6
65.7
14.3
9.2
4.2
1.9
3.5
1.2
15.4
4.6
61.5
12.6
5.1
0.8
Fall
64
21
3
8
4
Mean
1.8
3.0
7.0
0.32
Winter
Range or
(95% Cl of mean)
Location/Habitat
(measure)
s Illinois/pastures, meadows
(% volume; digestive tracts)
Kansas (flaviventris)!
locations throughout state
(% wet weight; scats and
stomach contents)
Kansas (flaviventris)!
woodland, grassland
(% wet weight; stomach
contents)
Location (subspecies)/
Habitat
Kansas (flaviventris)!
woodland, grassland
Kansas (flaviventris)!
upland prairie, weeds,
grasses
Utah (mormon)/desert shrub
Reference
Klimstra, 1959
Fitch, 1963
Fitch, 1963
Fitch, 1963
Fitch, 1963
Brown & Parker, 1984
Note
No.
5
Note
No.
10
^
_1
CO
o
(D
-------
Racer Snake (Coluber constrictot)
Population
Dynamics
Clutch Size
Clutches/Year
Days
Incubation
Age at Sexual
Maturity
Annual
Mortality Rates
(%)
Longevity
(yr)
Seasonal
Activity
Mating
Nesting
Hatching
Age/Sex/
Co nd. /Seas.
average
average
average
summer
summer
F
M
B 2yrs
B 3 - 6 yrs
B7yrs
AB
April
May
April
June
June
late August
Mean
16.8
12.6
5.28 ± 0.24 SE
0.5
51
45-50
2 - 3 years
13 - 14 months
58
25-30
38
May
mid-late August
Range or
(95% Cl of mean)
7-31
7-21
4-8
up to 1
43-63
up to 20
June
early June
May
July
early August
early September
Location (subspecies)/
Habitat
NS (constrictorjINS
NS (pr/apus)/NS
Utah (mormon)/desert shrub
Kansas (flaviventris)!
woodland, grassland
Kansas (flaviventris)l\ab
Utah (mormon)/desert
Kansas (flaviventris)!
woodland, grassland
Kansas (flaviventris)!
woodland, grassland
Utah (mormon)/cold desert
shrub
Kansas (flaviventris)
NS (constrictor)
Texas (flaviventris)
Virginia, Carolinas
Texas (flaviventris)
Kansas (flaviventris)
Utah (mormon)
Reference
Fitch, 1963
Fitch, 1963
Brown & Parker, 1984
Fitch, 1963
Fitch, 1963
Brown & Parker, 1984
Fitch, 1963
Fitch, 1963
Brown & Parker, 1982
Reference
Fitch, 1963
DeGraaf & Rudis, 1983
Vermersch and Kuntz, 1986
Martofetal., 1980
Vermersch and Kuntz, 1986
Fitch, 1963
Brown & Parker, 1982
Note
No.
6
6
Note
No.
10
_1
*».
o
(D
-------
Racer Snake (Coluber constrictot)
Seasonal
Activity
Hibernation
Begin
late
November
early October
Peak
End
early April
early May
Location (subspecies)
Kansas (flaviventris)
Utah (mormon)
Reference
Fitch, 1963
Brown & Parker, 1982
Note
No.
10
A.
_1
Ol
1 Ten-week period from hatching to hibernation.
2 Active snakes under natural conditions; cited in Brown and Parker (1982).
3 Estimated assuming temperature of 20 C using Equation 3-50 (Robinson et al., 1983) and body weights of 3-year-old snakes from Fitch (1963).
4 Author estimated that the snakes eat approximately four times their body weight over the 213-day active season from spring through fall.
5 Size of snakes not specified; captured within the range of C. c. flaviventris and C. c. priapus.
6 Author summarizing own work and unspecified other studies.
o
(D
-------
References (including Appendix)
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
and amphibians. New York, NY: Alfred A. Knopf, Inc.
Brown, W. S. (1973) Ecology of the racer, Coluber constrictor mormon (Serprentes,
Colubridae), in a cold temperate desert in northern Utah [Ph.D. dissertation]. Salt
Lake City, UT: University of Utah.
Brown, W. S.; Parker, W. S. (1982) Niche dimensions and resource partitioning in a great
basin desert snake community. U.S. Fish Wildl. Serv. Wildl. Res. Rep. 13: 59-81.
Brown, W. S.; Parker, W. S. (1984) Growth, reproduction and demography of the racer,
Coluber constrictor mormon, in northern Utah. In: Seigel, R. A.; Hunt, L. E.; Knight,
J. L.; et al., eds. Vertebrate ecology and systematics. Lawrence, KS: Museum of
Natural History, The University of Kansas; pp. 13-40.
Conant, R.; Collins, J. T. (1991) Afield guide to reptiles and amphibians: eastern/central
North America. Boston, MA: Houghton Mifflin Co.
Corn, P. S.; Bury, R. B. (1986) Morphological variation and zoogeography of racers
(Coluber constrictor) in the central Rocky mountains. Herpetologica 42: 258-264.
DeGraaf, R. M.; Rudis, D. D. (1983) Racer snake. Amphibians and reptiles of New England.
Amherst, MA: University of Massachusetts Press; pp. 68.
Fitch, H. S. (1963) Natural history of the racer Coluber constrictor, v. 15. Lawrence, KS:
University of Kansas Publications, Museum of Natural History; pp. 351-468.
Fitch, H. S. (1982) Resources of a snake community in prairie woodland habitat of
northeastern Kansas. In: Scott, N. J., Jr., ed. Herpetological communities. U.S. Fish
Wildl. Serv. Wildl. Res. Rep. 13; pp. 83-98.
Gibbons, J. W.; Semlitsch, R. D. (1991) Guide to the reptiles and amphibians of the
Savannah River site. Athens, GA: The University of Georgia Press.
Hammerson, G. A. (1987) Thermal behaviour of the snake Coluber constrictor in
west-central California. J. Therm. Biol. 12: 195-197.
Kaufman, G. A.; Gibbons, J. W. (1975) Weight-length relationship in thirteen species of
snakes in the southeastern United States. Herpetologica 31: 31-37.
Klimstra, W. D. (1959) Foods of the racer, Coluber constrictor, in southern Illinois. Copeia
1959: 210-214.
Mart of, B. S.; Palmer, W. M.; Bailey, J. R.; et al. (1980) Amphibians and reptiles of the
Carolinas and Virginia. Chapel Hill, NC: University of North Carolina Press.
2-416 Racer
-------
Parker, W. S.; Brown, W. S. (1973) Species composition and population changes in two
complexes of snake hibernacula in northern Utah. Herpetologica 29: 319-326.
Pope, C. H. (1944) Amphibians and reptiles of the Chicago area. Chicago, IL: Chicago
Natural History Museum Press.
Robinson, R. W.; Peters, R. H.; Zimmermann, J. (1983) The effects of body size and
temperature on metabolic rate of organisms. Can. J. Zool. 61: 281-288.
Ruben, J. A. (1976) Aerobic and anaerobic metabolism during activity in snakes. J. Comp.
Physiol. B: Metab. Transp. Funct. 109: 147-157.
Smith, H. M. (1956) Handbook of amphibians and reptiles of Kansas. Univ. Kansas Mus.
Nat. Hist. Misc. Publ. 9; 356 pp.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28.
Turner, F. B. (1977) The dynamics of populations of squamates, crocodilians and
rhynchocephalians. In: Gans, C.; Tinkle, D. W., eds. Biology of the reptilia: v. 7. New
York, NY: Academic Press; pp. 157-264.
Uhler, F. M.; Cottom, C.; Clarke, T. E. (1939) Food of snakes of the George Washington
National Forest, Virginia. Trans. North Am. Nat. Resour. Wildl. Conf. No. 4; pp.
605-622.
Vermersch, T. G.; Kuntz, R. E. (1986) Snakes of south central Texas. Austin, TX: Eakin
Press; pp. 18-19.
Wright, A. H.; Wright, A. A. (1957) Handbook of snakes: v. 2. Ithaca, NY: Comstock.
2-417 Racer
Page 2-418 was left blank.
-------
2.3.5. Northern Water Snake (water snakes and salt marsh snakes)
Order Squamata, Family Colubridae. Water snakes and salt marsh snakes (genus
Nerodia) belong to the family Colubridae, along with 84 percent of the snake species in
North America. Colubrids vary widely in form and size and can be found in numerous
habitats, including terrestrial, arboreal, aquatic, and burrowing. The more aquatic types of
snakes in this family include water snakes, salt marsh snakes, swamp snakes, brown
snakes, and garter and ribbon snakes (Conant and Collins, 1991).
Selected species
The northern water snake (Nerodia sipedon sipedon) is largely aquatic and riparian.
It ranges from Maine and southern Quebec to North Carolina. It also inhabits the uplands
of western North Carolina and adjacent portions of Tennessee and Virginia, and its range
extends west to eastern Colorado (Conant and Collins, 1991). Three additional subspecies
are recognized, distinguished by range and habitat: N. s. pleuralis (midland water snake;
ranges from Indiana to Oklahoma and the Gulf of Mexico and south of the mountains to the
Carolinas, preferring fast-moving streams), N. s. insularum (Lake Erie water snake;
inhabits islands of Put-in-Bay, Lake Erie), and N. s. williamengelsi (Carolina salt marsh
water snake; inhabits the Outer Bank islands and mainland coast of Pamlico and Core
sounds, North Carolina) (Behler and King, 1979; Conant and Collins, 1991).
Body size. The northern water snake is typically 61 to 107 cm in total length
(Conant and Collins, 1991). Island populations of the species tend to be larger than
mainland ones (King, 1986). King (1986) estimated the relationship between snout-to-vent
length (SVL)' and body weight for Lake Erie water snakes (N. s. insularum):
weight (g) = 0.0005 SVL (cm)307 all snakes;
weight (g) = 0.0009 SVL (cm)288 females; and
weight (g) = 0.0008 SVL (cm)298 males.
Kaufman and Gibbons (1975) determined a relationship between length and weight for both
sexes of a South Carolina population:
weight (g) = 0.0004 SVL (cm)315 (± °12 SE) all snakes
(95% Cl for intercept = 0.00015 to 0.0011). Immediately after emergence from hibernation,
females begin to gain weight and continue gaining weight until giving birth in late summer.
Weight loss associated with parturition in one population ranged from 28.2 to 45.5 percent
of the female's weight just prior to parturition (King, 1986).
'Measures of SVL exclude the tail. Kaufman and Gibbons (1975) estimated that the tail represents
21.8 percent (± 0.010 SE) of the total length of a female and 25.7 percent (± 0.006 SE) of the
total length of a male.
2-419 Northern Water Snake
-------
Habitat. The northern water snake prefers streams but can be found in lakes and
ponds and nearby riparian areas (King, 1986; Smith, 1961). In the Carolinas and Virginia,
they can be found from mountain lakes and streams to large coastal estuaries (Martof et
al., 1980). They are absent from water bodies with soft muddy bottoms which may
interfere with foraging (Lagler and Salyer, 1945). In Lake Erie, N. s. insularum occurs in
shoreline habitats where rocks or vegetation provide refugia (King, 1986).
Food habits. Northern water snakes consume primarily fish and amphibians and, to
a lesser extent, insects and small mammals (Raney and Roecker, 1947; Smith, 1961). Diet
varies according to the age (and size) of the snake and food availability (DeGraaf and
Rudis, 1983). Young snakes forage in shallow riffles and cobble bars, primarily waiting for
prey to move within range (letter from K.B. Jones, U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory, to Susan B. Norton, January 6, 1992).
Tadpoles comprise a large proportion of the diet of young snakes"1 in some areas (Raney
and Roecker, 1947). Adults are strong swimmers and can swim and dive for fish
midstream, often capturing large specimens (e.g., 20 to 23 cm brown trout; 19 cm bullhead;
20+ cm lamprey) (Lagler and Salyer, 1945). They also tend to consume bottom-dwelling
fish species (e.g., suckers) (Raney and Roecker, 1947). In New York, Brown (1958) found
that N. s. sipedon consumed the most food between June and August; they consumed little
during the remaining months prior to hibernation.
Temperature regulation and daily activities. The northern water snake is active
both day and night but is most active between 21 and 27 C (Brown, 1958; Smith, 1961).
During the day, they are found in areas that provide basking sites and are not found in
heavily shaded areas (DeGraaf and Rudis, 1983; Lagler and Salyer, 1945). They may
become inactive and seek shelter, however, if temperatures exceed 27°C (Brown, 1958;
Lagler and Salyer, 1945). They become torpid at temperatures less than 10 C (Brown,
1958).
Hibernation. In autumn, the N. sipedon leaves the aquatic habitats to overwinter in
rock crevices or in banks nearby (DeGraaf and Rudis, 1983; Fitch, 1982).
Breeding activities and social organization. The northern water snake breeds
primarily in early spring, and the young are born from late summer to fall (i.e., viviparous)
(DeGraaf and Rudis, 1983). The rate of development before hatching is temperature
dependent (Bauman and Metter, 1977).
Home range and resources. The northern water snake usually stays in the same
area of a stream, in the same pond, or in an adjacent pond for several years (Fraker, 1970).
Snakes along streams have larger home ranges than snakes in ponds and lakes (Fraker,
1970). Fraker (1970) found that for large ponds (e.g., 1,500 to 2,000 m2), the home range of
an individual snake is essentially the entire pond. In fish hatcheries with smaller ponds,
individual snakes frequent more than one pond (Fraker, 1970).
mSnakes less than 36 cm in length for this example.
2-420 Northern Water Snake
-------
Population density. Population density estimates for water snakes usually are
expressed relative to a length of shoreline. Values from 34 to 380 snakes per km of
shoreline have been reported for streams and Lake Erie islands (see table).
Population dynamics. Northern water snakes reach sexual maturity at 2 or 3 years
of age, with males generally maturing earlier and at a smaller size than females (Feaver,
1977, cited in King, 1986; King, 1986). Clutch sizes vary from 5 or 10 to 50 or 60 depending
on location and on female size (see table). The proportion of females breeding in a given
year increases with increasing female size, as does clutch size and offspring weight (King,
1986). King determined the relationship of litter size to female SVL for Lake Erie water
snakes (N. s. insularum):
litter size = -12.45 + 0.41 SVL (cm).
Feaver (1977, cited in King, 1986) determined the relationship for a Michigan population:
litter size = -23.55 + 0.55 SVL (cm).
Females produce only one clutch per year (Beatson, 1976). Information on annual
survivorship of juveniles or adults was not identified in the literature reviewed.
Similar species (from general references)
• The Mississippi green water snake (Nerodia cyclopion) can be slightly larger
(76 to 114 cm) than the northern water snake and is found in quiet waters of
the Mississippi Valley.
• The blotched water snake (Nerodia erythrogaster transversa) is larger than
the northern water snake (76 to 122 cm) and is found in western Missouri and
Kansas to northeastern Mexico.
• The northern copperbelly (Nerodia erythrogaster neglecta) is larger than the
northern water snake (76 to 122 cm) and ranges from western Kentucky to
southeastern Illinois and to Michigan.
• The redbelly water snake (Nerodia erythrogaster erythrogaster) of the
midwestern United States is close in size to the water snake. It is best suited
to swampy areas and sluggish streams.
• The yellowbelly water snake (Nerodia erythrogaster flavigaster) is found in
the lower Mississippi Valley and adjacent areas. Like the redbelly, it is
similar in size to the water snake and likely to be found in swampy areas and
sluggish streams.
• The banded water snake (Nerodia fasciata fasciata) is similar in size, and its
range includes the coastal plain, North Carolina to Mississippi.
2-421 Northern Water Snake
-------
• The broad banded water snake (Nerodia fasciata confluens) (56 to 90 cm)
occurs in the Mississippi River delta region in marshes, swamps, and
shallow waters, including brackish waters along the Gulf Coast.
• The Florida water snake (Nerodia fasciata pictiventris) is similar in size to the
northern water snake and ranges from the extreme southeast of Georgia to
the southern tip of Florida. It lives primarily in shallow freshwater habitats.
• Harter's water snake (Nerodia harteri) is relatively small (51 to 76 cm) and is
found in central Texas.
• The diamondback water snake (Nerodi rhombifer rhombifer) can be slightly
longer (76 to 122 cm) than the northern water snake and is more thick-bodied
than most Nerodia. Its range extends south from the Mississippi Valley into
Mexico.
• The Gulf salt marsh snake (Nerodia clarkii clarkii) inhabits the Gulf Coast
from west-central Florida to southern Texas. It is abundant in coastal salt
meadows, swamps, and marshes.
• The Atlantic salt marsh snake (Nerodia clarkii taeniata) is restricted to
Volusia County along the Atlantic Coast of north Florida.
• The mangrove salt marsh snake (Nerodia clarkii compressicauda) is small
(38 to 76 cm) and inhabits the mangrove swamps of Florida's lower coasts.
Dietary differences are evident among these species. Mushinsky et al. (1982) found
in Louisiana forested wetlands that N. erythrogasterand N. fasciata change from a diet of
fish to one dominated by frogs when they exceed an SVL of 50 cm. N. rhombifer and N.
cyclopion, on the other hand, consume primarily fish throughout their lives, although the
species and size composition of their diet changes as they grow larger (Mushinsky et al.,
1982). As N. rhombifer exceeds 80 cm SVL, it begins to prey upon larger fish that occupy
deeper open-water habitats. N. cyclopion eats a larger proportion of centrarchid fish as its
body size increases. In a study of the diet of N. rhombifer, Plummer and Goy (1984) found
a relationship between the SVL of the snakes and the standard length (SL) of the fish prey
(defined as 80 percent of total length):
SLfish (cm) = -5.9 + 0.23 SVLsnake (cm) for males, and
SLfish (cm) = -3.6 + 0.17 SVLsnake (cm) for females.
The regression lines are not significantly different, however.
General references
Behlerand King (1979); Conant and Collins (1991); DeGraaf and Rudis (1983); King
(1986).
2-422 Northern Water Snake
-------
Water Snake (Nerodia sipedon)
Factors
Body Weight
(g)
Length
(mm)
Juvenile
Growth Rate
(9/d)
Metabolic
Rate
(I02/kg-d)
Food
Ingestion Rate
(g/g-d)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
AB
JB1 yr
JB2yr
JM3yr
A B 5 - 6 yr
neonate B
AM
AF
JB1 yr
JB2yr
JM3yr
A B 5 - 6 yr
neonate
J1 yr
J2yr
J3yr
B resting:
15°C
2 5°C
35°C
JB1 yr
JB2yr
JM3yr
A B 5 - 6 yr
155mmSVL
Mean
207
7.0±2.3SD
29.0 (N = 2)
53.2 (N = 1)
210.0 ± 65 SD
4.8
620 SVL
745 SVL
285 total
496 total
607 total
868 total
181 SVL
0.18 ± 0.08 SD
0.42
0.80
0.607 ± 0.035 SE
3.29 ± 0.10 SE
7.33 ± 0.23 SE
0.088
0.043
0.043
0.061
131.16
Range or
(95% Cl of mean)
up to 480
5.3-10.4
25.2 - 32.7
114-255
3.6-6.6
125 -210 SVL
0.13-0.27
0.40 - 0.45
0.39 - 0.94
2.81 - 4.44
5.70 - 9.99
Location (subspecies)
Kansas
New York (sipedon)
Ohio, Ontario (insularum)
Ohio, Ontario (insularum)
New York (sipedon)
Ohio, Ontario (insularum)
New York (sipedon)
Oklahoma, Nerodia
rhombifera
(similar species)
New York (sipedon)
Arkansas, Nerodia
fhomb'rfera (similar
species)
Reference
Fitch, 1982
Brown, 1958
King, 1986
King, 1989
Brown, 1958
King, 1986
Brown, 1958
Gratz & Hutchinson, 1977
Brown, 1958
Baeyens & Rountree, 1983
Note
No.
1
2
1
3
10
10
CO
o
3-
(D
T
I
I-K
(D
T
CO
0)
-------
Water Snake (Nerodia sipedon)
Dietary Composition
Esocidae
Catostomidae
Percidae
Proteidae
Cyprinidae
Centrarchidae
crawfish
trout
non-trout fish
unidentified fish
Crustacea
Amphibia
birds & mammals
unidentified
minnows
darters
Amphibia
sculpin (Cottidae)
trout perch
(Percopsis)
game fishes (Perca)
burbot (Lota)
catfish (Ictaluridae)
Population
Dynamics
Population
Density
(N/km shore)
Spring
Age/Sex/
Co nd. /Seas.
AB
B B summer
Summer
7.0
22.5
15.7
51.9
1.5
0.3
1.5
64
7
1
1
14
12
1
Fall
9.1
1.4
52.8
2.2
2.8
14.1
17.4
Mean
138
34-41
0.3
Winter
Range
22 - 381
Location (subspecies)/
Habitat (measure)
Georgia/aquatic (NS)
(% wet volume;
stomach contents)
season not specified
n lower Michigan/streams
(% wet weight;
stomach contents)
n lower Michigan/lakes
(% volume; stomach
contents)
Ohio, Ontario (insularum)!
Lake Erie islands
Kansas (s/'pedon)/stream
Reference
Campetal., 1980
Alexander, 1977
Brown, 1958
Reference
King, 1986
Beatson, 1976
Note
No.
4
5
Note
No.
10
^
10
O
3-
(D
T
I
I-K
(D
T
CO
0)
-------
Water Snake (Nerodia sipedon)
Population
Dynamics
Litter Size
Litters/Year
Days Gestation
Age at Sexual
Maturity (d)
Length at
Sexual
Maturity
(mm SVL)
Seasonal
Activity
Mating
Age/Sex/
Co nd. /Seas.
F
M
F
M
F
M
F
M
mid-May
Mean
11.8
20.8 ± 8.2 SD
22.9
33
1
1
58
34 mo
23 - 24 mo
3yrs
2 yrs
590
430
April - May
May
Range
4-24
6-34
9-50
13-52
476 - 649
375 - 425
End
mid-June
Location (subspecies)/
Habitat
Michigan (s/pecton)/ponds,
marshes
Ohio, Ontario (insularum)!
Lake Erie islands
Ohio, Ontario (insularum)!
Lake Erie islands
Illinois (p/eura//s)/NS
central Missouri
(s/pecton)/fish hatchery
Kansas (s/pecton)/stream
central Missouri
(s/pecton)/fish hatchery
Michigan (s/pecton)/ponds,
marshes
Ohio, Ontario (insularum)!
Lake Erie islands
Michigan (s/'pedon)/ponds,
marshes
Ohio, Ontario (insularum)!
Lake Erie islands
Kansas (sipedon)
Michigan (sipedon)
central Missouri (sipedon)
Reference
Feaver, 1977
Camin & Ehrlich, 1958
King, 1986
Smith, 1961
Bauman & Metter, 1977
Beatson, 1976
Bauman & Metter, 1977
Feaver, 1977
King, 1986
Feaver, 1977
King, 1986
Reference
Smith, 1956
Feaver, 1977
Bauman & Metter, 1977
Note
No.
6
6
6
Note
No.
6
10
10
Ol
o
3-
(D
T
I
I-K
(D
T
CO
0)
-------
Water Snake (Nerodia sipedon)
Seasonal
Activity
Parturition
Begin
late August
mid-August
mid-October
November
Peak
late summer
End
September
late September
mid-April
late March
Location (subspecies)
Illinois (sipedon)
Ohio, Ontario (insularum)
Virginia, Carolinas (sipedon)
Ohio, Ontario (insularum)
Michigan (sipedon)
Reference
Smith, 1961
King, 1986
Martofetal., 1980
King, 1986
Feaver, 1977
Note
No.
6
1 SVL = snout-to-vent length, which excludes the tail beyond the vent.
2 Total = total length, from nose to tip of tail.
3 Snakes in captivity; mean temperatures = 23 C. Snakes fed fish (one fed frogs).
4 Collected whenever they were found; thought to be active in area from May to September.
5 Months of collection and size of snakes not specified.
6 Cited in King (1986).
10
10
o>
o
3-
(D
T
I
I-K
(D
T
CO
0)
-------
References (including Appendix)
Aldridge, R. D. (1982) The ovarian cycle of the water snake, Nerodia sipedon, and effects of
hypophysectomy and gonadotropin administration. Herpetologica 38: 71-79.
Alexander, G. (1977) Food of vertebrate predators on trout waters in north central lower
Michigan. Michigan Academician 10: 181-195.
Baeyens, D. A.; Rountree, R. L. (1983) A comparative study of evaporative water loss and
epidermal permeability in an arboreal snake, Opheodrys aestivus, and a
semi-aquatic snake, Nerodia rhombifera. Comp. Biochem. Physiol. 76A: 301-304.
Barbour, R. W. (1950) The reptiles of Big Black Mountain, Harlan County, Kentucky. Copeia
1950: 100-107.
Bauman, M. A.; Metter, D. E. (1977) Reproductive cycle of the northern watersnake Natrix s.
sipedon (Reptilia. Serpentes, Colubridae). J. Herpetol. 11: 51-59.
Beatson, R. R. (1976) Environmental and genetical correlates of disruptive coloration in the
watersnake, Natrix s. sipedon. Evolution 30: 241-252.
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
and amphibians. New York: Alfred A. Knopf, Inc.
Brown, E. E. (1958) Feeding habits of the northern watersnake, Natrix sipedon sipedon
Linnaeus. Zoologica (N.Y.) 43: 55-71.
Bush, F. M. (1959) Foods of some Kentucky herptiles. Herpetologica 15: 73-77.
Camin, J. H.; Ehrlich, P. R. (1958) Natural selection in water snakes (Natrix sipedon L.) on
islands in Lake Erie. Evolution 12: 504-511.
Camp, C. D.; Sprewell, W. D.; Powders, V. N. (1980) Feeding habits of Nerodia taxispilota
with comparative notes on the foods of sympatric congeners in Georgia. J.
Herpetol. 14: 301-304.
Conant, R.; Collins, J. T. (1991) Afield guide to reptiles and amphibians: eastern/central
North America. Boston, MA: Houghton Mifflin Co.
DeGraaf, R. M.; Rudis, D. D. (1983) Watersnake. Amphibians and reptiles of New England.
Amherst, MA: University of Massachusetts Press.
Feaver, P. E. (1977) The demography of a Michigan population of Natrix sipedon with
discussions of ophidian growth and reproduction [Ph.D. dissertation]. Ann Arbor,
Ml: University of Michigan.
2-427 Northern Water Snake
-------
Fitch, H. S. (1982) Resources of a snake community in prairie woodland habitat of
northeastern Kansas. In: Scott, N. J., Jr., ed. Herpetological communities. U.S. Fish
Wildl. Serv. Wildl. Res. Rep. 13; pp 83-98.
Fraker, M. A. (1970) Home range and homing in the watersnake, Matrix s. sipedon. Copeia
1970: 665-673.
Gratz, R. K.; Hutchinson, V. H. (1977) Energetics for activity in the diamondback water
snake, Natrix Rhombifera. Physiol. Zool. 50: 99-114.
Justy, G. M.; Mallory, F. F. (1985) Thermoregulatory behaviour in the northern watersnake,
Nerodia s. sipedon, and the eastern garter snake, Thamnophis s. sirtalis. Can.
Field-Nat. 99: 246-249.
Kaufman, G. A.; Gibbons, J. W. (1975) Weight-length relationship in thirteen species of
snakes in the southeastern United States. Herpetologica 31: 31-37.
King, R. B. (1986) Population ecology of the Lake Erie watersnake, Nerodia sipedon
insularum. Copeia 1986: 757-772.
King, R. B. (1989) Body size variation among island and mainland snake populations.
Herpetologica 45: 84-88.
Lagler, K. F.; Salyer, J. C., II. (1945) Food and habits of the common watersnake, Natrix
sipedon, in Michigan. Pap. Michigan Acad. Sci., Arts and Letters 31: 169-180.
Martof, B. S.; Palmer, W. M.; Bailey, J. R.; et al. (1980) Watersnake. Amphibians and
reptiles of the Carolinas and Virginia. Chapel Hill, NC: University of North Carolina
Press.
Mushinsky, H. R.; Hebrard, J. J.; Vodopich, D. S. (1982) Ontogeny of water snake foraging
ecology. Ecology 63: 1624-1629.
Plummer, M. V.; Goy, J. M. (1984) Ontogenetic dietary shift of water snakes (Nerodia
rhombifera) in a fish hatchery. Copeia 1984: 550-552.
Raney, E. C.; Roecker, R. M. (1947) Food and growth of two species of watersnakes from
western New York. Copeia 1947: 171-174.
Smith, H. M. (1956) Watersnake. Handbook of amphibians and reptiles of Kansas. Univ.
Kansas Mus. Nat. Hist. Misc. Publ. 9; 356 pp.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28.
Uhler, F. M.; Cottom, C.; Clarke, T. E. (1939) Food of snakes of the George Washington
National Forest, Virginia. Trans. North Am. Wildl. Nat. Resour. Conf. 4: 605-622.
Wright, A. H.; Wright, A. A. (1957) Handbook of snakes: v. 2. Ithaca, NY: Comstock.
2-428 Northern Water Snake
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2.3.6. Eastern Newt (salamanders)
Order Caudata, Family Salamandridae. Notophthalmus, the genus comprising the
eastern newts, inhabits eastern North America. A different genus, Taricha, comprises the
western newts along the Pacific coast of North America. Unlike other salamanders, the
skin of newts is rough textured, not slimy. Eastern newts are primarily aquatic; western
newts are terrestrial. The life cycle of eastern newts is complex. Females deposit their
eggs into shallow surface waters. After hatching, the larvae remain aquatic for 2 to several
months before transforming into brightly colored terrestrial forms, called efts (Healy, 1974).
Post larva I migration of efts from ponds to land may take place from July through
November, but timing varies between populations (Hurlbert, 1970). Efts live on land (forest
floor) for 3 to 7 years (Healy, 1974). They then return to the water and assume adult
characteristics. In changing from an eft to an adult, the newt develops fins and the skin
changes to permit aquatic respiration (Smith, 1961). Occasionally newts omit the
terrestrial eft stage, especially in the species located in the southeast coastal plain (Conant
and Collins, 1991) and along the Massachusetts coast (Healy, 1974). These aquatic
juveniles have the same adaptations (i.e., smooth skin and flattened tail) as the aquatic
adults but are not sexually mature (Healy, 1973). Under favorable conditions, adults are
permanently aquatic; however, adults may migrate to land after breeding due to dry ponds,
high water temperatures, and low oxygen tension (Hurlbert, 1969). The life cycle of
western newts does not include the eft stage (Conant and Collins, 1991).
Selected species
The eastern newt (Notophthalmus viridescens) has both aquatic and terrestrial
forms. The aquatic adult is usually yellowish-brown or olive-green to dark brown above,
yellow below. The land-dwelling eft is orange-red to reddish-brown, and its skin contains
tetrodotoxin, a neurotoxin and powerful emetic. There are four subspecies of eastern
newts: N. v. viridescens (red-spotted newt; ranges from Nova Scotia west to Great Lakes
and south to the Gulf states), N. v. dorsalis (broken-striped newt; ranges along the coastal
plain of the Carolinas), N. v. louisianensis (central newt; ranges from western Michigan to
the Gulf), and N. v. piaropicola (peninsula newt; restricted to peninsular Florida) (Conant
and Collins, 1991). Neoteny" occurs commonly in the peninsula and broken-striped newts.
In the central newt, neoteny is frequent in the southeastern coastal plain. In the red-
spotted newt, neoteny is rare (Conant and Collins, 1991).
Body size. Adult eastern newts usually are 6.5 to 10.0 cm in total length (Conant
and Collins, 1991). In North Carolina, N. v. dorsalis efts ranged from 2.1 to 3.8 cm snout-to-
vent length (SVL), which excludes the tail, and adults ranged from 2.0 to 4.4 cm SVL
(Harris, 1989; Harris et al., 1988). Healy (1973) found aquatic juveniles 1 year of age to
range from 2.0 to 3.2 cm SVL. Adult eastern newts weigh approximately 2 to 3 g (Gill, 1979;
Gillis and Breuer, 1984), whereas the efts generally weigh 1 to 1.5 g (Burton, 1977; Gillis
and Breuer, 1984).
"Neotenic newts are mature and capable of reproduction but retain the larval form, appearance,
and habits (Conant and Collins, 1991).
2-429 Eastern Newt
-------
Habitat. Larval and adult eastern newts are found in ponds, especially those with
abundant submerged vegetation, and in weedy areas of lakes, marshes, ditches,
backwaters, and pools of shallow slow-moving streams or other unpolluted shallow or
semipermanent water. Terrestrial efts inhabit mixed and deciduous forests (Bishop, 1941,
cited in Sousa, 1985) and are found in moist areas, typically under damp leaves, brush
piles, logs, and stumps, usually in wooded habitats (DeGraaf and Rudis, 1983). Adequate
surface litter is important, especially during dry periods, because efts seldom burrow
(Healy, 1981, cited in Sousa, 1985).
Food habits. Adult eastern newts are opportunistic predators that prey underwater
on worms, insects and their larvae (e.g., mayfly, caddisfly, midge, and mosquito larvae),
small crustaceans and molluscs, spiders, amphibian eggs, and occasionally small fish.
Newts capture prey at the surface of the water and on the bottom of the pond, as well as in
the water column (Ries and Bellis, 1966). The shed skin (exuvia) is eaten and may
comprise greater than 5 percent of the total weight of food items of both the adult and eft
diets (MacNamara, 1977). Snails are an important food source for the terrestrial eft
(Burton, 1976). Efts feed only during rainy summer periods (Behler and King, 1979; Healy,
1973). Healy (1975) noted that in late August and September, efts often were found
clustered around decaying mushrooms feeding on adult and larval dipterans. In a northern
hardwood hemlock forest in New York, MacNamara (1977) found that most prey of adult
migrants and immature efts were from the upper litter layer, soil surface, or low vegetation.
Temperature regulation and daily activities. Adult newts are often seen foraging in
shallow water, and efts are often found in large numbers on the forest floor after it rains
(Behler and King, 1979). Efts may be found on the open forest floor even during daylight
hours (Conant and Collins, 1991), but they rarely emerge if the air temperature is below
10°C (Healy, 1975).
Hibernation. Most adults remain active all winter underwater on pond bottoms or in
streams (DeGraaf and Rudis, 1983). Some adults overwinter on land (Hurlbert, 1970) and
migrate to ponds during the spring to breed (Hurlbert, 1969). If the water body freezes to
the bottom, adults may be forced to hibernate on land or to migrate to another pool (Smith,
1956). Efts hibernate on land, burrowing under logs and debris. Hurlbert (1969) observed
that efts migrated to ponds for the first time in the spring and fall.
Breeding activities and social organization. In south-central New York, breeding
takes place in late winter or early spring, usually in lakes, ponds, and swamps (Hurlbert,
1970). Ovulation and egg deposition occur over an extended period (McLaughlin and
Humphries, 1978). Females overwintering on land can store sperm for at least 10 months
(Massey, 1990). Spawning underwater, the female deposits eggs singly on leaves of
submerged plants, hiding and wrapping each in vegetation (Gibbons and Semlitsch, 1991;
Smith 1956). The time to hatching depends on temperature (DeGraaf and Rudis, 1983).
Smith (1961) found typical incubation periods to be 14 to 21 days in Illinois, whereas the
incubation period observed by Behler and King (1979) was 21 to 56 days.
Growth and metamorphosis. In late summer or early fall, the larvae transform into
either aquatic juveniles or terrestrial efts (Behler and King, 1979). Harris (1987) showed
2-430 Eastern Newt
-------
that low larval density stimulated neoteny in larvae under experimental conditions. Larval
growth rates were higher in ponds with low larval densities (Harris, 1987; Morin et al.,
1983). Growth rates for aquatic juveniles are highest in the spring; however, maximum
seasonal growth for the terrestrial efts occurs between June and September when the
temperature is optimal for active foraging (Healy, 1973).
Home range and resources. For adult newts, Bellis (1968) found the mean distance
between capture and recapture sites to be about 7 m, indicating small home ranges. Harris
(1981, cited in DeGraaf and Rudis, 1983) did not find any defined home range or any
territoriality for males. Most efts around a pond in Pennsylvania remained within 1.5 m of
the shore (Bellis, 1968). Healy (1975) estimated the home range for terrestrial efts in a
Massachusetts woodland to be 270 m2 and located approximately 800 m from the ponds
where the adults and larvae were located.
Population density. Populations of aquatic adults may reach high local densities,
whereas terrestrial efts exhibit lower population densities. Recorded population densities
for terrestrial efts range from 34 per hectare (ranging from 20 to 50 efts per hectare) in a
North Carolina mixed deciduous forest (Shure et al., 1989) to 300 per hectare in a
Massachusetts woodland (Healy, 1975). Harris et al. (1988) observed a density of 1.4 adult
newts per m2 (14,000 adult newts per hectare) in a shallow pond in North Carolina in the
winter, whereas the summer population density was only 0.2 adults per m2 (2,000 adults
per hectare).
Population dynamics. Many populations of the eastern newt reach sexual maturity
when the eft stage returns to the water and changes to the adult form (Healy, 1974).
However, under certain conditions such as low larval density, most of the larvae present
have been shown to metamorphose directly into adults or even into sexually mature larvae
(Harris, 1987). In experimental ponds, densities of 22 larvae per m2 resulted in
metamorphosis to eft by the majority, while a density of 5.5 larvae per m2 resulted in
metamorphosis directly to the adult form or sexual maturation without metamorphosis
(Harris, 1987). Adult density also influences reproduction. Morin et al. (1983) found that
doubling adult density resulted in a reduction of offspring produced to one-quarter that
produced by adults at the lower density (i.e., from 36 offspring per female in tanks
containing 1.1 females per m2 to 9.7 offspring per female in tanks containing 2.2 females
per m2). The adult life expectancy noted by Gill (1978b) was 2.1 breeding seasons for
males and 1.7 breeding seasons for females. Amphibian blood leeches (ectoparasites) are
likely to be a primary source of mortality for adults; they also prey directly on larvae (Gill,
1978a).
Similar species (from general references)
• The black-spotted newt (Notophthalmus meridionalis) is similar in size (7.5
to 11.0 cm) to the eastern newt. It has large black spots and is found in
south Texas in ponds, lagoons, and swamps. There is no eft stage.
• The striped newt (Notophthalmus perstriatus) is smaller (5.2 to 7.9 cm) than
the eastern newt and ranges from southern Georgia to central Florida. It is
found in almost any body of shallow, standing water.
2-431 Eastern Newt
-------
• The western newts (Taricha) are found along the Pacific coast. They do not
undergo the eft stage but rather transform into land-dwelling adults that
return to the water at breeding time.
• Other small salamanders are similar but vary by having slimy skin and
conspicuous costal grooves. They differ in life history, however; in the family
Plethudontidae, all are lungless and breathe through thin, moist skin. Many
are completely terrestrial.
General references
Behlerand King (1979); Conant and Collins (1991); DeGraaf and Rudis (1983);
Hurlbert (1969); Smith (1961).
2-432 Eastern Newt
-------
Eastern Newt (Notophthalmus viridescens)
Factors
Body Weight
(g)
Age/Sex/
Cond./Seas.
adult:
B
F prebreed
F postbreed
M prebreed
M postbreed
B spring
B summer
B winter
Bfall
larvae:
12.8 mm SVL
21.9mmSVL
eft:
B
B
B summer
Mean
2.24 ±0.71 SD
3.05 ± 0.06 SE
2.49 ± 0.06 SE
2.49 ± 0.03 SE
2.76 ± 0.03 SE
1.71 ±0.43SD
2.13 ± 0.44 SD
1.94±0.33SD
1.63±0.28SD
0.04 ± 0.025 SD
0.54 ± 0.167 SD
1.10±0.40SD
1.45
1.23
Range or
(95% Cl of mean)
1.12-3.52
0.42-1.82
0.63-2.17
Location (subspecies)
New York
Virginia
Massachusetts
South Carolina
New York
New Hampshire
(viridescens)
New York
Reference
Gillis & Breuer, 1984
Gill, 1979
Pitkin, 1983
Taylor etal., 1988
Gillis & Breuer, 1984
Burton, 1977
Stefanski etal., 1989
Note
No.
10
CO
CO
m
0)
-------
Eastern Newt (Notophthalmus viridescens)
Factors
Length
(mm SVL)
Larval Growth
Rate (g/d)
Metabolic
Rate
(I02/kg-d)
Age/Sex/
Cond./Seas.
adult:
M
F
B summer
juvenile:
B spring
larvae:
B spring
Bfall
eft:
B (mm total)
B spring
B summer
high density:
-> efts
-> adults
-> neonates
low density:
->efts
-> adults
-> neonates
eftsat15°C:
resting
act ive
Mean
35.0
35.0
38.9
26.1 ±0.35SE
12.3
19.2
50.4 ± 0.5 SE
20.5
32.7
0.00310
0.00421
0.00536
0.00635
0.00685
0.00676
1.47
4.27
Range or
(95% Cl of mean)
24-44
20-42
33-48
20-32
18-41
Location (subspecies)
North Carolina (dorsalis)
New York
Massachusetts (viridescens)
s Illinois
North Carolina (dorsalis)
Massachusetts (viridescens)
New York
North Carolina
high density: 55,000/ha
low density: 220/ha
New York
Reference
Harris etal., 1988
MacNamara, 1977
Healy, 1973
Brophy, 1980
Harris etal., 1988
Healy, 1973
MacNamara, 1977
Harris, 1987
Stefanski etal., 1989
Note
No.
1
1
10
A.
CO
m
0)
-------
Eastern Newt (Notophthalmus viridescens)
Factors
Metabolic Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
basal:
A M postbreed
A F postbreed
larvae (12.8 mm)
eft (71.0 mm)
AM
AF
Dietary Composition
aquatic adults:
Ephemeroptera
Odonata
Lepidoptera
Diptera
other insects
Cladocerans
Amphipoda
Pelycepoda
N. viridescens
larvae
other
Mean
16.2
16.7
43.5
20.1
17
15
7.5
31.9
13.7
5.8
9.9
5.1
5.6
6.2
11.4
3.2
Range or
(95% Cl of mean)
Fall
7.5
1.9
0.9
0.3
0.6
84.1
3.1
1.5
0.0
0.1
Location (subspecies)
Winter
Location (subspecies)/
Habitat (measure)
New Hampshire
(viridescens)lsma\\
oligotrophic lake
(% wet weight; stomach
and gut contents)
Reference
estimated
estimated
estimated
estimated
Reference
Burton, 1977
Note
No.
2a
2b
2c
3
4
Note
No.
10
CO
en
m
0)
-------
Eastern Newt (Notophthalmus viridescens)
Dietary Composition
efts:
Basommatophora
Sty lorn matophora
Acari
Collembola
Thysanoptera
Homoptera
Coleoptera adult
Coleoptera larvae
Lepidoptera larvae
Diptera adult
Diptera larvae
Hymenoptera adult
larvae:
Zygoptera (Odonata)
Chironomidae
(Diptera)
Cladocera
Ostracoda
Hyallela azteca
(Amphipoda)
Sphaerium sp.
(Pelycepoda)
Planorbidae
(Gastropoda)
Rhizopoda (Protozoa)
Spring
Summer
5.5
18.3
13.8
10.4
3.4
4.7
2.3
3.5
7.9
9.7
10.6
5.8
0.8
16.2
12.7
5.3
55.1
9.4
0.5
0.01
Fall
Winter
Location (subspecies)/
Habitat (measure)
New York/leaf litter
surface in forest
(% dry weight; stomach
contents)
New Hampshire
(viridescens)lsma\\
oligotrophic lake
(% wet weight; stomach
and gut contents)
Reference
MacNamara, 1977
Burton, 1977
Note
No.
10
CO
o>
m
0)
-------
Eastern Newt (Notophthalmus viridescens)
Population
Dynamics
Home Range
Size
Population
Density
(IM/ha)
Clutch Size
(eggs)
Days to Hatching
Age/Sex/
Co nd. /Seas.
eft:
B
adult:
summer
A B entire lake
A B fringe only
A winter
A summer
eft spring
eft summer
larvae spring
larvae spring
summer
fall
Mean
0.0087 ha
6.86 m
130-173
50 - 2,600
50,000 ± 9,000 SE
3,000 ±1, 000 SE
300
34
21,000
65,000 ±1 5,000 SE
25,000 ± 5,000 SE
10,000 ± 3,000 SE
200 - 400
14-21
21 -56
Range or
(95% Cl of mean)
0.0028-0.0153
20-50
0 - 350,000
Location (subspecies)/
Habitat
Massachusetts
(viridescens)!
oak/pine forest
Pennsylvania
( viridescens)lpon d
New Hampshire
(viridescens)lsma\\
oligotrophic lake
North Carolina (dorsalis)!
shallow pond
Massachusetts
(viridescens)!
oak/pine forest
North Carolina
( viridescens)lm ixed
deciduous forest
South Carolina/pond,
wetland
North Carolina (dorsalis)!
shallow pond
NS/NS
lllinois/NS
NS/NS
Reference
Healy, 1975
Bellis, 1968
Burton, 1977
Harris etal., 1988
Healy, 1975
Shure etal., 1989
Taylor etal., 1988
Harris etal., 1988
Behler& King, 1979
Smith, 1961
Behler& King, 1979
Note
No.
5
10
A.
CO
m
0)
-------
Eastern Newt (Notophthalmus viridescens)
Population
Dynamics
Age at
Metamorphosis
Age at Sexual
Maturity
Annual
Mortality Rates
(%)
Longevity
(breeding
seasons)
Seasonal
Activity
Mating/Laying
Hatching
Age/Sex/
Co nd. /Seas.
larvae -> eft
eft -> adult
3 - 7 years eft
no eft stage
AF
AM
AF
AM
February -
March
April
June
late April
Mean
2 -3 mo
6 mo
1 - 3 yrs
5 - 6 yrs
2 yrs
54.1 - 59.5
45.8 - 53.1
1.7
2.1
spring
Range or
(95% Cl of mean)
4-8
End
April - May
June
Location (subspecies)/
Habitat
Illinois
(louisianensis)INS
Massachusetts
(v/r;ctescens)/inland
ponds
South Carolina/ponds
Massachusetts
( v/r;ctescens)/inland
ponds
coastal ponds
Virginia/mountain ponds
Virginia/mountain ponds
Location
South Carolina
North Carolina
Virginia
North Carolina
NS
Reference
Smith, 1961
Healy, 1974
Gibbons & Semlitsch,
1991
Healy, 1974
Gill, 1978a
Gill, 1978b
Reference
Gibbons & Semlitsch,
1991
Harris etal., 1988
Gill, 1978a
Harris etal., 1988
Behlerand King, 1979
Note
No.
Note
No.
10
CO
00
m
0)
-------
Eastern Newt (Notophthalmus viridescens)
Seasonal
Activity
Begin
June
mid-August
mid-July
August -Sept.
late March
Peak
August -Sept.
End
September
late November
early November
November
late April
Location
South Carolina
Virginia
New York
Virginia
Virginia
Reference
Gibbons & Semlitsch,
1991
Gill, 1978a
Hurlbert, 1970
Gill, 1978a
Massey, 1990
Note
No.
10
A.
CO
1 "Neonates" refers to newts that become sexually mature in the larval form (i.e., neoteny).
2 Estimated assuming temperature of 20 C using Equation 3-50 (Robinson etal., 1983) and postbreeding body weights from (a) Gill (1979); (b)
Taylor et al. (1988); and (c) Gillis and Breuer (1984). The values for the larvae should be used with caution because these animals are smaller
than any used to develop the allometric equations.
3 See Chapters 3 and 4 for methods of estimating food ingestion rates from metabolic rate and diet.
4 Estimated using Equation 3-26 (Whitford and Hutchinson, 1967) and postbreeding body weights from Gill, 1979.
5 Mean distance between capture and recapture sites, suggesting small home range size.
m
0)
-------
References (including Appendix)
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
and amphibians. New York, NY: Alfred A. Knopf, Inc.
Bellis, E. D. (1968) Summer movement of red-spotted newts in a small pond. J. Herpetol. 1:
86-91.
Bennett, S. M. (1970) Homing, density and population dynamics in the adult newt,
Notophthalmus viridescens Rafinesque [Ph.D. dissertation]. Hanover, NH:
Dartmouth College.
Bishop, S. C. (1941) The salamanders of New York. N. Y. State Mus. Bull. 324; 365 pp.
Brophy, T. E. (1980) Food habits of sympatric larval Ambystoma tigrinumand
Notopthalmus viridescens. J. Herpetol. 14: 1-6.
Burton, T. M. (1976) An analysis of the feeding ecology of the salamanders (Amphibia,
Urodela) of the Hubbard Brook Experimental Forest, New Hampshire. J. Herpetol.
10: 187-204.
Burton, T. M. (1977) Population estimates, feeding habits and nutrient and energy
relationships of Notophthalmus v. viridescens, in Mirror Lake, New Hampshire.
Copeia 1977: 139-143.
Conant, R.; Collins, J. T. (1991) Afield guide to reptiles and amphibians: eastern/central
North America. Boston, MA: Houghton Mifflin Co.
DeGraaf, R. M.; Rudis, D. D. (1983) Amphibians and reptiles of New England. Amherst, MA:
University of Massachusetts Press.
Gage, S. H. (1891) The life history of the vermillion-spotted newt. Am. Nat. 25: 1084-1103.
Gibbons, J. W.; Semlitsch, R. D. (1991) Guide to the reptiles and amphibians of the
Savannah River Site. Athens, GA: University of Georgia Press.
Gill, D. E. (1978a) The metapopulation ecology of the red-spotted newt, Notophthalmus
viridescens (Rafinesque). Ecol. Monogr. 48: 145-166.
Gill, D. E. (1978b) Effective population size and interdemic migration rates in a
metapopulation of the red-spotted newt, Notophthalmus viridescens. Evolution 32:
839-849.
Gill, D. E. (1979) Density dependence and homing behavior in adult red-spotted newts
Notophthalmus viridescens (Rafinesque). Ecology 60: 800-813.
2-440 Eastern Newt
-------
Gillis, J. E.; Breuer, W. J. (1984) A comparison of rates of evaporative water loss and
tolerance to dehydration in the red-eft and newt of Notophthalmus viridescens. J.
Herpetol. 18: 81-82.
Harris, R. N. (1981) Intrapond homing behavior in Notophthalmus viridescens. J. Herpetol.
15: 355-356.
Harris, R. N. (1987) Density-dependent paedomorphosis in the salamander Notophthalmus
viridescens dorsalis. Ecology 68: 705-712.
Harris, R. N. (1989) Ontogenetic changes in size and shape of the facultatively
paedomorphic salamander Notophthalmus viridescens dorsalis. Copeia 1989: 35-42.
Harris, R. N.; Alford, R. A.; Wilbur, H. M. (1988) Density and phenology of Notophthalmus
viridescens dorsalis in a natural pond. Herpetologica 44: 234-242.
Healy, W. R. (1973) Life history variation and the growth of the juvenile Notophthalmus
viridescens from Massachusetts. Copeia 1973: 641-647.
Healy, W. R. (1974) Population consequences of alternative life histories in Notophthalmus
v. viridescens. Copeia 1974: 221-229.
Healy, W. R. (1975) Terrestrial activity and home range in efts of Notophthalmus
viridescens. Am. Midi. Nat. 93: 131-138.
Healy, W. R. (1981) Field test of an HSI model for the red-spotted newt (Notophthalmus
viridescens) for the Habitat Evaluation Procedures Group [unpublished material].
Fort Collins, CO: U.S. Fish Wildl. Serv.; 21 pp.
Hurlbert, S. H. (1969) The breeding migrations and interhabitat wandering of the
vermilion-spotted newt, Notophthalmus viridescens (Rafinesque). Ecol. Monogr. 39:
465-488.
Hurlbert, S. H. (1970) The post-larval migration of the red-spotted newt, Notophthalmus
viridescens (Rafinesque). Copeia 1970: 515-528.
Logier, E. B. (1952) The frogs, toads and salamanders of eastern Canada. Toronto, Canada:
University of Toronto Press.
MacNamara, M. C. (1977) Food habits of terrestrial adult migrants and immature red efts of
the red-spotted newt, Notophthalmus viridescens. Herpetologica 33: 127-132.
Massey, A. (1990) Notes on the reproductive ecology of red-spotted newts (Notophthalmus
viridescens). J. Herpetol. 24: 106-107.
McLaughlin, E. W.; Humphries, A. A., Jr. (1978) The jelly envelopes and fertilization of eggs
of the newt, Notophthalmus viridescens. J. Morphol. 158: 73-90.
2-441 Eastern Newt
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Morin, P. J. (1986) Interactions between intraspecific competition and predation in an
amphibian predator-prey system. Ecology 67: 713-720.
Morin, P. J.; Wilbur, H. M.; Harris, R. N. (1983) Salamander predation and the structure of
experimental communities: responses of Notophthalmus and Microcrustacea.
Ecology 64: 1430-1436.
Pitkin, R. B. (1983) Annual cycle of body size and blood parameters of the aquatic adult
red-spotted newt, Notophthalmus viridescens. J. Exp. Zool. 226: 372-377.
Ries, K. M.; Bellis, E. D. (1966) Spring food habits of the red-spotted newt in Pennsylvania.
Herpetologica 22: 152-155.
Robinson, R. W.; Peters, R. H.; Zimmermann, J. (1983) The effects of body size and
temperature on metabolic rate of organisms. Can. J. Zool. 61: 281-288.
Shure, D. J.; Wilson, L. A.; Hochwender, C. (1989) Predation on aposomatic efts of
Notophthalmus viridescens. J. Herpetol. 23: 437-439.
Smith, H. M. (1956) Handbook of amphibians and reptiles of Kansas. Univ. Kansas Mus.
Nat. Hist. Misc. Publ. 9; 356 pp.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28; pp.
118-120.
Sousa, P. J. (1985) Habitat suitability index models: Red-spotted newt. U.S. Fish Wildl.
Serv. Biol. Rep. 82(10.111); 18 pp.
Stefanski, M.; Gatten, R. E.; Pough, F. H. (1989) Activity metabolism of salamanders:
tolerance to dehydration. J. Herpetol. 23: 45-50.
Taylor, B. E.; Estes, R. A.; Pechmann, J. H.; et al. (1988) Trophic relations in a temporary
pond: larval salamanders and their microinvertebrate prey. Can. J. Zool. 66:
2191-2198.
Whitford, W. G.; Hutchinson, V. H. (1967) Body size and metabolic rate in salamanders.
Physiol. Zool. 40: 127-133.
2-442 Eastern Newt
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2.3.7. Green Frog (true frog family)
Order Anura, Family Ranidae. These are typical frogs with adults being truly
amphibious, living at the edge of water bodies and entering the water to catch prey, flee
danger, and spawn (Behlerand King, 1979). This profile covers medium-sized ranids. The
next profile (Section 2.3.8) covers large ranids.
Selected species
The green frog (Rana clamitans) is usually found near shallow fresh water
throughout much of eastern North America. Two subspecies are recognized: R. c.
clamitans (the bronze frog; ranges from the Carolinas to northern Florida, west to eastern
Texas, and north along the Mississippi Valley to the mouth of the Ohio River) and R. c.
melanota (the green frog; ranges from southeastern Canada to North Carolina, west to
Minnesota and Oklahoma but rare in much of Illinois and Indiana, introduced into British
Columbia, Washington, and Utah) (Conant and Collins, 1991).
Body size. The green frog is a medium-sized ranid usually between 5.7 and 8.9 cm
snout-to-vent length (SVL) (Conant and Collins, 1991; Martof et al., 1980). Its growing
period is primarily confined to the period between mid May and mid September (Martof,
1956b). Females are usually larger than males (Smith, 1961). Adults typically weigh
between 30 and 70 g (Wells, 1978). Hutchinson et al. (1968) developed an allometric
equation relating green frog surface area (SA in cm) to body weight (Wt in grams):
SA = 0.997 Wt0712.
This equation also is presented in Chapter 3 as Equation 3-25.
Habitat. Adult green frogs live at the margins of permanent or semipermanent
shallow water, springs, swamps, streams, ponds, and lakes (Wells, 1977). Martof (1953b)
found green frogs primarily to inhabitat the banks of streams. They also can be found
among rotting debris of fallen trees (Behlerand King, 1979; Conant and Collins, 1991).
Juveniles prefer shallower aquatic habitats with denser vegetation than those preferred by
adults (Martof, 1953b). McAlpine and Dilworth (1989) observed that green frogs inhabited
aquatic habitats about two-thirds of the time and terrestrial habitats the remaining time.
Similarly, Martof (1953b) found that the green frog relies on terrestrial habitats for feeding
and aquatic habitats for refuge from desiccation, temperature extremes, and enemies.
Ponds used by green frogs are usually more permanent than those used by other anuran
species (Rough and Kamel, 1984).
Food habits. Adult R. clamitans are terrestrial feeders among shoreline vegetation.
They consume insects, worms, small fish, crayfish, other crustaceans, newts, spiders,
small frogs, and molluscs. Stewart and Sandison (1973) found that terrestrial beetles often
are their most important food item but noted that any locally abundant insect along the
shoreline may be consumed in large numbers. There is a pronounced reduction in food
consumption during the breeding period for both males and females (Mele, 1980). During
the breeding season, males spend most of their energy defending breeding territories, and
2-443 Green Frog
-------
females expend their energy producing eggs (Wells, 1977). Fat reserves acquired during
the prebreeding period compensate for reduced food intake during the breeding period
(Mele, 1980). Jenssen and Klimstra (1966) found that green frogs consume most of their
food in the spring and eat little during the winter. Food eaten in the spring, summer, and
fall consists mostly of terrestrial prey, whereas winter food is composed mostly of aquatic
prey (Jenssen and Klimstra, 1966). Juveniles (sexually immature frogs) eat about half the
volume of food as do adults over the course of a year (Jenssen and Klimstra, 1966).
Tadpoles are herbivorous (DeGraaf and Rudis, 1983). Green frogs eat their cast skins
following molting; the casting of skin is frequent during midsummer (Hamilton, 1948).
Temperature regulation and daily activities. Martof (1953b) found that the green
frog's activity period varies by frog size, with larger frogs being primarily nocturnal, small
frogs being diurnal, and middle-sized frogs (5 to 7 cm SVL) being equally active during day
and night.
Hibernation. Adult green frogs overwinter by hibernating underground or
underwater from fall to spring (Ryan, 1953). Martof (1956a) observed frogs hibernating in
mud and debris at the bottom of streams approximately 1 m deep. Jenssen and Klimstra
(1966) noted that adults usually hibernate in restricted chambers within rock piles or
beneath plant debris, while juveniles are more often found in locations with access to
passing prey. The frogs begin emerging when the mean daily temperature is about 4.4 C
and the maximum temperature is about 15.6 C for 3 to 4 days (Martof, 1953b). Juvenile
frogs enter and exit hibernation after adult frogs (Martof, 1956a).
Breeding activities and social organization. Green frogs breed from spring through
the summer, spawning at night (Smith, 1961; Wells, 1976). Female green frogs stay in
nonbreeding habitat until it is time to spawn (Martof, 1956a). In preparation for breeding,
males establish territories near shore that serve as areas for sexual display and as
defended oviposition sites (Wells, 1977). Males establish calling sites within their
territories where they attempt to attract females (Wells, 1977). Females visit male
territories to mate and lay their egg masses. The masses are contained in films of jelly and
are deposited in emergent, floating, or submerged vegetation; they hatch in about 3 to 6
days (Behler and King, 1979; Martof, 1956a; Ryan, 1953). Adults are solitary during non-
breeding periods (Smith, 1956).
Tadpole and metamorphosis. In the southern part of their range, green frog
tadpoles metamorphose into frogs in the same season in which they hatched, while in the
northern part, 1 or 2 years pass before metamorphosis (Martof, 1956b). Tadpoles that
hatch from egg masses laid in the spring usually metamorphose that fall, while those
hatching from summer-laid eggs typically overwinter as larvae and metamorphose the
following spring (Rough and Kamel, 1984). Ryan (1953) found that most tadpoles are 2.6 to
3.8 cm SVL at the time of transformation. Those that transform in late June or early July
grow rapidly, adding 1.4 to 2.0 cm SVL in the first 2 months and 0.4 to 0.7 cm SVL more
before hibernation. Tadpoles that transform at approximately 3.1 cm SVL may reach
between 5.0 and 5.8 cm SVL before hibernation (Ryan, 1953). Newly transformed frogs
often move from lakes and ponds where they were tadpoles to shallow stream banks,
usually during periods of rain (Martof, 1953b).
2-444 Green Frog
-------
Home range and resources. The species' home range includes its foraging and
refuge areas in and around aquatic environments. During the breeding period, the male's
home range also includes its breeding territory (Wells, 1976). Mart of (1953b) found that
roughly 80 percent of adult frogs captured in the spring and again in the fall occupied the
same home ranges.
Population density. During the breeding season, green frog densities at breeding
ponds can exceed several hundred individuals per hectare (Wells, 1978). Adult male frogs
space their breeding territories about 2 to 3 m apart (Martof, 1953a).
Population dynamics. Sexual maturity is attained in 1 or 2 years after
metamorphosis; individuals may reach maturity at the end of the first year but not attempt
to breed until the next year (Martof, 1956a,b). Most females lay one clutch per year,
although some may lay two clutches, about 3 to 4 weeks apart (Wells, 1976). In natural
populations, green frogs can live to approximately 5 years of age (Martof, 1956b).
Similar species (from general references)
• The river frog (Rana heckscheri) is slightly larger than the green frog (8.0 to
12.0 cm SVL) and is found in swamps from southeast North Carolina to
central Florida and southern Mississippi.
• The leopard and pickerel frogs (Rana pipiens and its relatives, and Rana
palustris) are medium sized and strongly spotted. There are four leopard
frogs whose ranges are mostly exclusive from each other, but overlap with
the green frog. The pickerel frog has a similar range with gaps in the upper
midwest and the southeast.
• The mink frog (Rana septentrionalis) is only slightly smaller (4.0 to 7.0 cm)
and is found on the borders of ponds and lakes, especially near waterlilies.
It ranges from Minnesota to New York, north to Labrador.
• The carpenter frog (Rana virgatipes) is about the same size as the green frog
(4.1 to 6.7 cm) and is closely associated with sphagnum bogs and
grasslands. It has a coastal plain range from New Jersey to Georgia and
Florida.
The bullfrog and pig frog are much larger ranid species and are covered in the next profile
(Section 2.3.8).
General references
Behler and King (1979); Conant and Collins (1991); DeGraaf and Rudis (1983); Mart of
(1953a, b, 1956a, b); Smith (1956, 1961).
2-445 Green Frog
-------
Green Frog (Rana clamitans)
Factors
Body Weight
(g)
Length
(mm SVL)
Metabolic
Rate
(kcal/kg-d)
Food Ingestion
Rate (g/g-d)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
B B
A M breeding
at
metamorphosis
A
A M
A F
J B
basal:
A
at
metamorphosis
A
at
metamorphosis
Dietary Composition
adults:
plant material
Araneae
Coleoptera
Hemiptera
Hymenoptera
Diptera
Ephemeroptera
Mollusca
Lepidoptera
Spring
Mean
49.1 ±20.0SD
44.0 ± 10.0 SD
3
54-102
79.8 ± 8.5 SD
80.3 ± 8.9 SD
32.6
8.08
15.8
17
2
Summer
10.8
12.1
32.8
12.9
14.4
6.8
5.6
5.4
2.5
Range or
(95% Cl of mean)
25.5-103.5
27.0 - 66.0
103 maximum
105 maximum
28.4 - 36.3
Fall
Winter
Location (subspecies)
New Brunswick, Canada
New York (melanota)
New York
NS
s Michigan
s Michigan
Location
(subspecies)/Habitat
(measure)
New York/lake
(% total volume;
stomach contents)
Reference
McAlpine & Dilworth, 1989
Wells, 1978
Rough & Kamel, 1984
Behlerand King, 1979
Martof, 1956b
Martof, 1956b
estimated
estimated
estimated
estimated
Reference
Stewart & Sandison, 1973
Note
No.
1
2
3
4
5
6
Note
No.
7
10
A.
*».
O>
0
(D
3
O
CD
-------
Green Frog (Rana clamitans)
Dietary Composition
adults:
mineral
plant
Pulmonata
Oligochaeta
Amphipoda
Isopoda
Decapoda
Julioforma
Araneida
Odonata
Orthoptera
Hemiptera
Coleoptera
Lepidoptera
Diptera
Hymenoptera
Salientia
Population
Dynamics
Home Range
Size
Population
Density
(N/ha)
Spring
-
5.7
15.7
2.1
1.2
5.6
-
7.5
2.8
1.6
0.9
1.0
9.6
25.4
6.0
9.9
-
Age/Sex/
Co nd. /Seas.
AB
nonbreeding
A M breeding
A M breeding
AM
AF
Summer
-
8.3
18.3
0.8
0.1
1.4
-
0.3
3.4
12.4
3.0
7.0
19.6
7.0
5.2
6.0
-
Fall
-
4.2
6.4
2.3
-
-
4.1
1.7
6.6
5.9
1.5
6.1
15.9
25.1
4.5
13.5
3.9
Mean
0.0065 ± 0.0036 SD
ha
meters shoreline:
4.0 - 6.0
meters shoreline:
1.0-1.5
476
567
Winter
2.6
0.5
11.0
6.4
4.6
4.6
-
-
7.4
-
-
2.2
9.1
-
10.3
-
-
Location
(subspecies (/Habitat
(measure)
s Illinois/swamp, stream
(% wet volume; stomach
contents)
Range or
(95% Cl of mean)
0.0020 - 0.020 ha
Reference
Jenssen & Klimstra, 1966
Location (subspecies)/
Habitat
s Michigan (melanota)!
shallow water
New York (melanota)!
open nearshore areas
of ponds
New York (melanota)!
densely vegetated
nearshore areas of
ponds
New York (melanota)!
artificial pond
Martof, 1953b
Wells, 1977
Wells, 1977
Wells, 1978
Note
No.
Note
No.
8
9
10
0
(D
3
O
CD
-------
Green Frog (Rana clamitans)
Population
Dynamics
Clutch Size
Clutches/Year
Days
Incubation (d)
Age at
Metamorphosi
s
Age at Sexual
Maturity (yr)
Age/Sex/
Co nd. /Seas.
early eggs
late eggs
early eggs
late eggs
AM
AF
B
Mean
4,100
3-6
3-5
3 mo
10 -12 mo
2.5 - 3 mo
11 -12 mo
1 -2
1 -2
1
Range or
(95% Cl of mean)
3,800 - 4,300
1,000-7,000
3,500 - 4,000
1 -2
1 - 2 yrs
Location (subspecies)/
Habitat
s Michigan (melanota)!
pond
New York (melanota)!
shallow ponds
New York (melanota)!
shallow water
New York (melanota)!
shallow ponds
Connecticut (melanota)!
shallow water
New York/ponds, pools
New England
( melanota)!
shallow water
Virginia, Carolinas/
shallow ponds
s Michigan (melanota)!
shallow ponds
s Michigan (melanota)!
shallow ponds
New ork melanota)!
pond
Reference
Martof, 1956a
Wells, 1976
Wright, 1914
Wells, 1976
Babbit, 1937
Ryan, 1953
DeGraaf & Rudis, 1983
Martof etal., 1980
Martof, 1956a, b
Martof, 1956a, b
Wells, 1977
Note
No.
10
10
11
10
A.
*».
00
0
(D
3
O
CD
-------
Green Frog (Rana clamitans)
Seasonal
Activity
Mating/Laying
Meta-
morphosis
eggs laid early
eggs laid late
Hibernation
Begin
May
May
early June
early August
early June
Oct. - Nov.
Oct.
Peak
early June
August, September
next spring
End
mid-August
September
mid-August
late September
mid -July
March - April
late March
Location (subspecies)
s Michigan (melanota)
Illinois (melanota)
New York
s Michigan (melanota)
New York
s Michigan (melanota)
New York
s Michigan (melanota)
New York
Reference
Martof, 1956a
Smith, 1961
Wells, 1976
Martof, 1956b
Rough & Kamel, 1984
Martof, 1956b
Rough & Kamel, 1984
Martof, 1956a
Ryan, 1953
Note
No.
12
12
13
13
10
0
(D
3
1 Weight at metamorphosis can vary by two to four times between the smallest and largest individuals.
2 Estimated assuming temperature of 20 C using Equation 3-50 (Robinson et al., 1983) and body weights from McAlpine and Dilworth (1989).
3 Estimated assuming temperature of 20 C using Equation 3-50 (Robinson et al., 1983) and body weights from Rough and Kamel (1984).
4 See Chapters 3 and 4 for methods of estimating food ingestion rates from metabolic rate and diet.
5 Estimated using Equation 3-25 (Hutchinson et al., 1968) and body weights from McAlpine and Dilworth (1989).
6 Estimated using Equation 3-25 (Hutchinson et al., 1968) and body weights from Rough and Kamel (1984).
7 Season not specified.
8 Daily activity range of nonbreeding frogs.
9 Frogs were initially hand-captured and placed in pond; the numbers given are for those frogs that stayed.
10 Cited in DeGraaf and Rudis (1983).
11 Eggs laid before June.
12 Metamorphosed in the same year eggs were laid.
13 Metamorphosed the year following the season the eggs were laid.
O
CD
-------
References (including Appendix)
Babbitt, L. H. (1937) The amphibia of Connecticut. Hartford, CT: State Geol. and Nat. Hist.
Surv.; Bull. No. 57. 9-50
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
and amphibians. New York: Alfred A. Knopf, Inc.
Bush, F. M. (1959) Foods of some Kentucky herptiles. Herpetologica 15: 73-77.
Conant, R.; Collins, J. T. (1991) Afield guide to reptiles and amphibians. Boston, MA:
Houghton Mifflin Co.
DeGraaf, R. M.; Rudis, D.D. (1983) Green frog. Amphibians and reptiles of New England.
Amherst, MA: University of Massachusetts Press.
Hamilton, W. J., Jr. (1948) The food and feeding behavior of the green frog, Rana clamitans
(Latreille), in New York state. Copeia 1948: 203-207.
Hutchinson, V. H.; Whitford, W. G.; Kohl, M. (1968) Relation of body size and surface area
to gas exchange in anurans. Physiol. Zool. 41: 65-85.
Jenssen, T. A.; Klimstra, W. D. (1966) Food habits of the green frog, Rana clamitans, in
southern Illinois. Amer. Midi. Nat. 76: 169-182.
Martof, B. S. (1953a) Territoriality in the green frog, Rana clamitans. Ecology 34: 165-174.
Mart of, B. S. (1953b) Home range and movements of the green frog, Rana clamitans.
Ecology 34: 529-543.
Martof, B. S. (1956a) Factors influencing size and composition of populations of Rana
clamitans. Am. Midi. Nat. 56: 224-245.
Martof, B. S. (1956b) Growth and development of the green frog, Rana clamitans, under
natural conditions. Am. Midi. Nat. 55: 101-117.
Martof, B. S.; Palmer, W. M.; Bailey, J. R.; et al. (1980). Amphibians and reptiles of the
Carolinas and Virginia. Chapel Hill, NC: University of North Carolina Press.
McAlpine, D. F.; Dilworth, T. G. (1989) Microhabitat and prey size among three species of
Rana (Anura: Ranidae) sympatric in eastern Canada. Can. J. Zool. 67: 2241-2252.
Mele, J. A. (1980) The role of lipids in storage and utilization of energy for reproduction and
maintenance in the green frog, Rana clamitans [Ph.D. dissertation]. New Brunswick,
NJ: Rutgers University.
2-450 Green Frog
-------
Pope, C. H. (1947) Amphibians and reptiles of the Chicago area. Chicago, IL: Chicago Nat.
Hist. Mus. Press.
Pough, F. H.; Kamel, S. (1984) Post-metamorphic physiological change in relation to anuran
life histories. Oecologia 65: 138-144.
Robinson, F. W.; Peters, R. H.; Zimmermann, J. (1983) The effects of body size and
temperature on metabolic rate of organisms. Can. J. Zool. 61: 281-288.
Ryan, R. A. (1953) Growth rates of some ranids under natural conditions. Copeia 1953:73-
80.
Smith, H. M. (1956) Handbook of amphibians and reptiles of Kansas. Univ. Kansas Mus.
Nat. Hist. Misc. Publ. 9.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28.
Stewart, M. M.; Sandison, P. (1973) Comparative food habits of sympatric mink frogs,
bullfrogs, and green frogs. J. Herpetol. 6: 241-244.
Wells, K. D. (1976) Multiple egg clutches in the green frog (Rana clamitans). Herpetologica
32: 85-87.
Wells, K. D. (1977) Territoriality and male mating success in the green frog (Rana
clamitans). Ecology 58: 750-762.
Wells, K. D. (1978) Territoriality in the green frog (Rana clamitans): vocalizations and
agonistic behaviour. Anim. Behav. 26: 1051-1063.
Wright, A. H. (1914) North American anura: life histories of the anurans of Ithaca, New York.
Washington, DC: Carnegie Institute; Publ. No. 197.
2-451 Green Frog
Page 2-452 was left blank.
-------
2.3.8. Bullfrog (true frog family)
Order Anura, Family Ranidae. These are typical frogs with adults being truly
amphibious. They tend to live at the edge of water bodies and enter the water to catch
prey, flee danger, and spawn (Behlerand King, 1979). This profile covers large ranids.
Medium-sized ranids are covered in the previous profile (Section 2.3.7).
Selected species
The bullfrog's (Rana catesbeiana) natural range includes the eastern and central
United States and southeastern Canada; however, it has been introduced in many areas in
the western United States and other parts of North America. It is continuing to expand its
range, apparently at the expense of several native species in many locations (Bury and
Whelan, 1984). There are no subspecies for the bullfrog.
Body size. The bullfrog is the largest North American ranid. Adults usually range
between 9 and 15 cm in length from snout-to-vent length (SVL) and exceptional individuals
can reach one half kilogram or more in weight (Conant and Collins, 1991; Durham and
Bennett, 1963). Males are usually smaller than females (Smith, 1961). Frogs exhibit
indeterminate growth, and bullfrogs continue to increase in size for at least 6 years after
metamorphosis (Durham and Bennett, 1963; Howard, 1981a). Hutchinson et al. (1968)
developed an allometric equation relating bullfrog surface area (SA in cm) to body weight
(Wt in grams):
SA = 0.953 Wt0725.
This equation also is presented in Chapter 3 as Equation 3-24.
Habitat. Adult bullfrogs live at the edges of ponds, lakes, and slow-moving streams
large enough to avoid crowding and with sufficient vegetation to provide easily accessible
cover (Behler and King, 1979). Small streams are used when better habitat is lacking
(Conant and Collins, 1991). Bullfrogs require permanent bodies of water, because the
tadpoles generally require 1 or more years to develop prior to metamorphosis (Howard,
1981b). Small frogs favor areas of very shallow water where short grasses or other
vegetation or debris offer cover (Durham and Bennett, 1963). Larger bullfrogs seem to
avoid such areas (Durham and Bennett, 1963). Tadpoles tend to congregate around green
plants (Jaeger and Hailman, 1976, cited in Bury and Whelan, 1984).
Food habits. Adult R. catesbeiana are indiscriminate and aggressive predators,
feeding at the edge of the water and among water weeds on any available small animals,
including insects, crayfish, other frogs and tadpoles, minnows, snails, young turtles, and
occasionally small birds, small mammals, and young snakes (Behlerand King, 1979;
DeGraaf and Rudis, 1983; Korschgen and Baskett, 1963). Bullfrogs often focus on locally
abundant foods (e.g., cicadas, meadow voles) (Korschgen and Baskett, 1963).
Crustaceans and insects probably make up the bulk of the diet in most areas (Carpenter
and Morrison, 1973; Fulk and Whitaker, 1968; Smith, 1961; Tyler and Hoestenbach, 1979).
Bullfrog tadpoles consume primarily aquatic plant material and some invertebrates,
2-453 Bullfrog
-------
but also scavenge dead fish and eat live or dead tadpoles and eggs (Bury and Whelan,
1984; Ehrlich, 1979).
Temperature regulation and daily activities. Bullfrogs forage by day (Behler and
King, 1979). They thermoregulate behaviorally by positioning themselves relative to the
sun and by entering or leaving the water (Lillywhite, 1970). In one study, body
temperatures measured in bullfrogs during their normal daily activities averaged 30 C and
ranged from 26 to 33°C (Lillywhite, 1970). At night, their body temperatures were found to
range between 14.4 and 24.9 C (Lillywhite, 1970). Tadpoles also select relatively warm
areas, 24 to 30 C (Bury and Whelan, 1984). Despite this narrow range of temperatures in
which bullfrogs normally maintain themselves, they are not immobilized by moderately
lower temperatures (Lillywhite, 1970). The metabolic rate of bullfrogs increases with
increasing body temperature. Between 15 and 25 C, the Q10 for oxygen consumption is
1.87; between 25 and 33 C, the Q10 is 2.41 (Burggren et al., 1983).
Hibernation. Most bullfrogs hibernate in mud and leaves under water beginning in
the fall, but some bullfrogs in the southern states may be active year round (Bury and
Whelan, 1984). They emerge sometime in the spring, usually when air temperatures are
about 19 to 24 C and water temperatures are at least 13 to 14 C (Wright, 1914; Willis et al.,
1956). Bullfrogs emerge from hibernation later than other ranid species (Ryan, 1953).
Breeding activities and social organization. Bullfrogs spawn at night close to
shorelines in areas sheltered by shrubs (Raney, 1940, cited in DeGraaf and Rudis, 1983).
The timing and duration of the breeding season varies depending on the location. In the
southern states, the breeding season extends from spring to fall, whereas in the northern
states, it is restricted to late spring and summer (Behler and King, 1979). Males tend to be
territorial during the breeding season, defending their calling posts and oviposition sites
(i.e., submerged vegetation near shore) (Howard, 1978b; Ryan, 1980). Female visits to the
pond tend to be brief and sporadic (Emlen, 1976). Some males mate with several females
whereas others, usually younger and smaller males, may not breed at all in a given year
(DeGraaf and Rudis, 1983). Females attach their eggs, contained in floating films of jelly, to
submerged vegetation (Behler and King, 1979). Adults are otherwise rather solitary
occupying their own part of a stream or pond (Smith, 1961).
Tadpole and metamorphosis. Eggs hatch in 3 to 5 days (Clarkson and DeVos, 1986;
Smith, 1956). Temperatures above 32 C have been shown to cause abnormalities in
tadpoles and above 35.9 C to kill embryos (Howard, 1978a). Tadpole growth rates increase
with increasing oxygen levels, food availability, and water temperature (Bury and Whelan,
1984). Tadpole gill ventilation at 20 C can generate a branchial water flow of almost 0.3
ml/g-min (Burggren and West, 1982). Metamorphosis from a tadpole to a frog can occur as
early as 4 to 6 months in the southern parts of its range; however, most tadpoles
metamorphose from 1 to 3 years after hatching, depending on latitude and temperature
(DeGraaf and Rudis, 1983; Martof et al., 1980).
Home range and resources. The species' home range includes its foraging areas
and refuges in and around aquatic environments. Home range size decreases with
increasing bullfrog density, and males tend to use larger home ranges than females (Currie
and Bellis, 1969). Bullfrogs tend to stay in the same pools throughout the summer months
2-454 Bullfrog
-------
if the water level is stable (Raney, 1940, cited in DeGraaf and Rudis, 1983). During the
breeding season, adult males establish territories that they defend against conspecific
males (Emlen, 1968). During the non-breeding season, Currie and Bellis (1969) found no
evidence of territorial defense. Males often do not return to the same pond the following
spring (Durham and Bennett, 1963).
Population density. During the breeding season, each breeding male may defend a
few meters of shoreline (Currie and Bellis, 1969; Emlen, 1968). The densities of females
and non-breeding males vary with time of day and season and are difficult to estimate.
Tadpoles can be present locally in extremely high densities (Cecil and Just, 1979).
Population dynamics. Sexual maturity is attained in about 1 to 3 years after
metamorphosis, depending on latitude (Howard, 1978a; Raney and Ingram, 1941, cited in
Bury and Whelan, 1984). Only females that are at least 2 years past metamorphosis mate
during the early breeding season; males and females 1 year past metamorphosis may
breed during the later breeding periods (Howard, 1978a, 1981b). Also, some older females
have been observed to mate and to lay a second clutch during the later breeding period
(Howard, 1978a). Willis et al. (1956) estimated the minimum breeding length for females in
Missouri to be 123 to 125 mm SVL. Mortality of tadpoles is high (Cecil and Just, 1979), and
adult frogs are unlikely to live beyond 5 to 8 years postmetamorphosis (Howard, 1978b). In
some areas, snapping turtles may be responsible for a large component of adult bullfrog
mortality (Howard, 1981a).
Similar species (from general references)
• The pig frog (Rana grylio) is smaller than the bullfrog (8 to 14 cm) and is
found in south South Carolina to south Florida and south Texas.
The remaining ranid species are more similar in size to the green (or bronze) frog. See
Section 2.3.7 for a description of these frogs.
General references
Behler and King (1979); Bury and Whelan (1984); Conant and Collins (1991); DeGraaf
and Rudis (1983); Smith (1961).
2-455 Bullfrog
-------
Bullfrog (Rana catesbeiana)
Factors
Body Weight
(g)
Metabolic Rate
(I02/kg-d)
Metabolic Rate
(kcal/kg-d)
Age/Sex/
Cond./Seas.
BB
AB
young tadpole
1-yr tadpole
post-
emergence:
1 month
2 months
3 months
4 months
at metamorph.
1 yr B
2yrB
3yrB
4yrB
5yrB
6yr B
tadpole, 25°C
adult resting,
5°C
basal:
2 mo (30 g)
1yr(91g)
BB(143g)
A B (249 g)
Mean
142.8 ± 77.4 SD
249
2.0 ±1.1 SD
35.7 ± 5.2 SD
18
30
42
56
9
91
210
240
260
290
360
2.6±0.2SE
1.0
9.1
7.0
6.3
5.5
Range or
(95% Cl of mean)
9.5 - 274.0
13-42
19-52
27-77
41 -101
total length:
(84 mm)
(240 mm)
(307 mm)
(320 mm)
(335 mm)
(348 mm)
(356 mm)
0.31 -2.3
Location
New Brunswick, Canada
central Arkansas
Kentucky
Louisiana/lab
east central Illinois
NS/lab
NS/NS
Reference
McAlpine & Dilworth, 1989
McKamie & Heidt, 1974
Viparina & Just, 1975
Modzelewski & Culley, 1974
Durham & Bennett, 1963
Burggren etal., 1983
Hutchinson etal., 1968
estimated
Note
No.
1
2
3
4
5
10
^
Ol
CO
c
o
CD
-------
Bullfrog (Rana catesbeiana)
Factors
Food Ingestion
Rate (g/g-d)
Surface Area
(cm2)
Age/Sex/
Cond./Seas.
(13-42g)
(18-52g)
(28-77g)
(40-100g)
2 mo (30 g)
1yr(91g)
BB(143g)
A B (249 g)
Dietary
Composition
adults:
Decapoda-Astacidae
Lepidoptera
Coleoptera
(Lampryidae)
(Chrysomelidae)
(Carabidae)
Pulmonata-Zonitidae
Chilipoda
sand, rock, gravel
adults:
plant
animal
(Odonata)
(Coleoptera)
(Hemiptera)
(Hymenoptera)
(Amphibia)
unaccounted
Mean
0.071
0.059
0.040
0.033
11
25
35
52
Summer
47.7
19.0
16.0
(5.8)
(5.8)
(4.1)
8.3
7.7
1.2
19.7
65.2
(8.8)
(15.8)
(0.5)
(2.2)
(26.4)
15.1
Range or
(95% Cl of mean)
Fall
Winter
Location
Louisiana (24 -27°C)
Kentucky/NS
(% wet volume; stomach
contents)
New York/mountain lake
(% volume; stomach
contents)
Reference
Modzelewski & Culley, 1974
estimated
Bush, 1959
Stewart & Sandison, 1973
Note
No.
6
Note
No.
10
^
Ol
CO
c
o
CD
-------
Bullfrog (Rana catesbeiana)
Dietary
Composition
adults:
frogs
tadpoles
shiners
other fish
Gastropoda
crayfish
other Crustacea
Arachnida
Coleoptera (adult)
Diptera (larvae)
Hemiptera
Population
Dynamics
Home Range
Size (m radius)
Population
Density
(N/ha)
Clutch Size
Clutches/Year
Days to
Hatching
Spring
35
8
305
7
55
22
71
3
31
2
41
Age/Sex/
Cond./Seas.
A M non breed
A F non breed
A M territory
B B (1960)
BB(1961)
tadpoles:
November
March
May
93% of F
7% of F
Summer
33
11
157
2
70
162
42
23
33
7
43
Fall
39
0
25
5
26
18
47
3
15
0
16
Mean
2.9
2.4
2.7
1,376
892
130,000
69,000
16,000
7,360 ±741. 7 SE
1
2
2-4
4-5
Winter
Range or
(95% Cl of mean)
0.76-11.3
0.61 -10.2
10,000 - 20,000
Location/Habitat
(measure)
Missouri/bait minnow pond
(number of items found;
stomach contents)
Ontario, Canada/pond
Michigan/pond
Ontario, Canada/pond
Kentucky/pond
Kansas/NS
New Jersey/pond
Michigan/pond
Arizona, California/river
Kansas/NS
Reference
Corse &Metter, 1980
Currie& Bellis, 1969
Emlen, 1968
Currie& Bellis, 1969
Cecil & Just, 1979
Smith, 1956
Ryan, 1980
Emlen, 1977
Clarkson & DeVos, 1986
Smith, 1956
Note
No.
Note
No.
7
10
Ol
CO
CD
c
o
CD
-------
Bullfrog (Rana catesbeiana)
Population
Dynamics
Age at
Metamor-
phosis
Age at Sexual
Maturity
Annual
Mortality Rates
(%)
Mortality Rates
(%)
Longevity
(yr)
Seasonal
Activity
Mating/Laying
Metamor-
phosis
Age/Sex/
Cond./Seas.
B
B
B
B
M
F
B
A M 1 - 2 yr
A M 2 - 3 yr
A M 3 - 4 yr
A M 4 - 5 yr
tadpoles (to
metamorph.)
AB
February
April
May
late May
August
March
June
July
Mean
1 yr
1 -2yr
2 -Syr
3yr
1 yr after metam.
1 - 2 yr after
metam.
1 - 2 yr after
metam.
58
58
48
77
85.5
May
late June
July
(1st clutch)
(2nd clutch)
late June-Aug.
Range or
(95% Cl of mean)
82.4 - 88.2
up to 5 - 8
End
October
late June
August
July
October
April
early October
Sept., October
Location/Habitat
Carolinas, Virginia/NS
Michigan/pond
New York/NS
Nova Scotia, Canada/NS
Michigan/pond
New York/NS
Michigan/pond
Kentucky/shallow ponds
Michigan/ponds
Location
southern range in N America
California, Arizona
Missouri
northern range in N America
California, Arizona
California, Arizona
Missouri
New York
Reference
Martofetal., 1980
Collins, 1979
Ryan, 1953
Bleakney, 1952
Howard, 1978a
Ryan, 1953
Howard, 1984
Cecil & Just, 1979
Howard, 1978b
Reference
Behler& King, 1979
Clarkson & DeVos, 1986
Willis etal., 1956
DeGraaf & Rudis, 1983;
BehlerS, King, 1979
Clarkson & DeVos, 1986
Clarkson & DeVos, 1986
Willis etal., 1956
Ryan, 1953
Note
No.
8
Note
No.
10
Ol
-------
Bullfrog (Rana catesbeiana)
Seasonal
Activity
Hibernation
Begin
late October
mid-October
Peak
End
late March
March
Location
east central Illinois
Missouri
Reference
Durham & Bennett, 1963
Willis etal., 1956
Note
No.
10
o>
o
CD
c
1 Mean snout-to-vent length (SVL) of frogs was 98 mm SVL and the range was 45 to 128 mm SVL.
2 Age postmetamorphosis; maintained at a temperature of 24 to 27 C and fed mosquitofish, crickets, and earthworms.
3 Restrained, cannulated; weight 5.7 g.
4 Mean weight of frogs was 74.8 g.
5 Estimated assuming temperature of 20 C using Equation 3-50 (Robinson et al., 1983). Body weights (1) for 2-month postmetamorphosis frog
from Modzelewski and Culley (1974); (2) for a 1-year postmetamorphosis frog from Durham and Bennett (1963), Farrar and Dupre (1983); (3) for
both juveniles and adults of both sexes, McAlpine and Dilworth (1989); and (4) for adults of both sexes, McKamie and Heidt (1974).
6 Estimated using Equation 3-24 (Hutchinson et al., 1968) and body weights as described in note 5.
7 Based on average distance between frogs.
8 Cited in Bury and Whelan (1984).
o
CD
-------
References (including Appendix)
Behler, J. L.; King, F. W. (1979) The Audubon Society field guide to North American reptiles
and amphibians. New York, NY: Alfred A. Knopf, Inc.
Bleakney, J. S. (1952) The amphibians and reptiles of Nova Scotia. Can. Field-Nat. 66:
125-129.
Brooks, G. R., Jr. (1964) An analysis of the food habits of the bullfrog by body size, sex,
month, and habitat. Va. J. Sci. 15: 173-186.
Bruneau, M.; Magnin, E. (1980) Croissance, nutrition, et reproduction des ouaouarons Rana
catesbeiana Shaw (Amphibia Anura) des Laurentides au nord de Montreal. Can J.
Zool. 58: 175-183.
Burggren, W. W.; West, N. H. (1982) Changing respiratory importance of gills, lungs and
skin during metamorphosis in the bullfrog Rana catesbeiana. Physiol. Zool. 56:
263-273.
Burggren, W. W.; Feder, M. E.; Pinder, A. W. (1983) Temperature and the balance between
aerial and aquatic respiration in larvae of Rana berlandieri and Rana catesbeiana.
Physiol. Zool. 56: 263-273.
Bury, R. B.; Whelan, J. A. (1984) Ecology and management of the bullfrog. U.S. Fish Wildl.
Serv. Resour. Publ. No. 155; 23 pp.
Bush, F. M. (1959) Foods of some Kentucky herptiles. Herpetologica 15: 73-77.
Carpenter, H. L.; Morrison, E. O. (1973) Feeding behavior of the bullfrog, Rana catesbeiana,
in north central Texas. Bios 44: 188-193.
Cecil, S. G.; Just, J. J. (1979) Survival rate, population density and development of a
naturally occurring anuran larvae (Rana catesbeiana). Copeia 1979: 447-453.
Clarkson, R. W.; DeVos, J. C., Jr. (1986) The bullfrog, Rana catesbeiana Shaw, in the lower
Colorado River, Arizona-California. J. Herpetol. 20: 42-49.
Cohen, N. W.; Howard, W. E. (1958) Bullfrog food and growth at the San Joaquin
Experimental Range, California. Copeia 1958: 223-225.
Collins, J. P. (1975) A comparative study of life history strategies in a community of frogs
[Ph.D. dissertation]. Ann Arbor, Ml: University of Michigan.
Collins, J. P. (1979) Intrapopulation variation in the body size at metamorphosis and timing
of metamorphosis in the bullfrog. Ecology 60: 738-749.
2-461 Bullfrog
-------
Conant, R.; Collins, J. T. (1991) A field guide to reptiles and amphibians - eastern and
central North America. Boston, MA: Houghton Mifflin Co.
Corse, W. A.; Metter, D. A. (1980) Economics, adult feeding and larval growth of Rana
catesbeiana on a fish hatchery. J. Herpetol. 14: 231-238.
Currie, W.; Bellis, E. D. (1969) Home range and movements of the bullfrog, Rana
catesbeiana (Shaw), in an Ontario pond. Copeia 1969: 688-692.
DeGraaf, R. M.; Rudis, D. D. (1983) Amphibians and reptiles of New England. Amherst, MA:
University of Massachusetts Press.
Dowe, B. J. (1979) The effect of time of oviposition and microenvironment on growth of
larval bullfrogs (Rana catesbeiana) in Arizona [master's thesis]. Tempe, AZ: Arizona
State University.
Durham, L.; Bennett, G. W. (1963) Age, growth, and homing in the bullfrog. J. Wildl.
Manage. 27: 107-123.
Ehrlich, D. (1979) Predation by bullfrog tadpoles (Rana catesbeiana) on eggs and newly
hatched larvae of the plains leopard frog (Rana blairi). Bull. Md. Herpetol. Soc. 15:
25-26.
Emlen, S. T. (1968) Territoriality in the bullfrog, Rana catesbeiana. Copeia 1968: 240-243.
Emlen, S. T. (1976) Lek organization and mating strategies of the bullfrog. Behav. Ecol.
Sociobiol. 1: 283-313.
Emlen, S. T. (1977) "Double clutching" and its possible significance in the bullfrog. Copeia
1977:749-751.
Farrar, E. S.; Dupre, R. K. (1983) The role of diet in glycogen storage by juvenile bullfrogs
prior to overwintering. Comp. Biochem. Physiol. A: Comp. Physiol. 75: 255-260.
Frost, S. W. (1935) The food of Rana catesbeiana Shaw. Copeia 1935: 15-18.
Fulk, F. D.; Whitaker, J. O., Jr. (1968) The food of Rana catesbeiana in three habitats in
Owen County, Indiana. Indiana Acad. Sci. 78: 491-496.
George, I. D. (1940) A study of the bullfrog, Rana catesbeiana Shaw, at Baton Rouge,
Louisiana [Ph.D. dissertation]. Ann Arbor, Ml: University of Michigan.
Gibbons, J. W.; Semlitsch, R. D. (1991) Guide to the reptiles and amphibians of the
Savannah River Site. Athens, GA: The University of Georgia Press.
Glass, M. L.; Burggren, W. W.; Johansen, K. (1981) Pulmonary diffusing capacity of the
bullfrog (Rana catesbeiana). Acta Physiol. Scand. 113: 485-490.
2-462 Bullfrog
-------
Hammer, D. A.; Linder, R. L. (1971) Bullfrog food habits on a waterfowl production area in
South Dakota. Proc. SD Acad. Sci. 50: 216-219.
Howard, R. D. (1978a) The influence of male-defended oviposition sites on early embryo
mortality in bullfrogs. Ecology 59: 789-798.
Howard, R. D. (1978b) The evolution of mating strategies in bullfrogs, Rana catesbeiana.
Evolution 32: 850-871.
Howard, R. D. (1981a) Sexual dimorphism in bullfrogs. Ecology 62: 303-310.
Howard, R. D. (1981b) Male age-size distribution and male mating success in bullfrogs. In:
Alexander, R. D.; Tinkle, D. W., ed. Natural selection and social behavior: recent
research and new theory; pp. 61-77.
Howard, R. D. (1984) Alternative mating behaviors of young male bullfrogs. Am. Zool. 24:
397-406.
Hutchinson, V. H.; Whitford, W. G.; Kohl, M. (1968) Relation of body size and surface area
to gas exchange in anurans. Physiol. Zool. 41: 65-85.
Jaeger, R. G.; Hailman, J. P. (1976) Ontogenetic shift of spectral phototactic preferences in
anuran tadpoles. J. Comp. Physiol. Psychol. 90: 930-945.
Korschgen, L. J.; Baskett, T. S. (1963) Foods of impoundment and stream dwelling
bullfrogs in Missouri. Herpetologica 19: 89-97.
Korschgen, L. J.; Moyle, D. L. (1955) Food habits of the bullfrog in central Missouri farm
ponds. Amer. Midi. Nat. 54: 332-341.
Lillywhite, H. B. (1970) Behavioral temperature regulation in the bullfrog, Rana catesbeiana.
Copeia 1970: 158-168.
Martof, B. S.; Palmer, W. M.; Bailey, J. R.; et al. (1980) Amphibians and reptiles of the
Carolinas and Virginia. Chapel Hill, NC: University of North Carolina Press.
McAlpine, D. F.; Dilworth, T. G. (1989) Microhabitat and prey size among three species of
Rana (Anura: Ranidae) sympatric in eastern Canada. Can. J. Zool. 67: 2241-2252.
McAuliffe, J. R. (1978) Biological survey and management of sport-hunted bullfrog
populations in Nebraska. Lincoln, NE: Nebraska Game and Parks Commission; 78
pp.
McKamie, J. A.; Heidt, G. A. (1974) A comparison of spring food habits of the bullfrog, Rana
catesbeiana, in three habitats of central Arkansas. Southwest. Nat. 19: 107-111.
Modzelewski, E. H., Jr.; Culley, D. D., Jr. (1974) Growth responses of the bullfrog, Rana
catesbeiana fed various live foods. Herpetologica 30: 396-405.
2-463 Bullfrog
-------
Oliver, J. A. (1955) The natural history of North American amphibians and reptiles.
Princeton, NJ: Van Nostrand Co.
Raney, E. C. (1940) Summer movements of the bullfrog, Rana catesbeiana (Shaw), as
determined by the jaw-tag method. Am. Midi. Nat. 23: 733-745.
Raney, E. C.; Ingram, W. M. (1941) Growth of tagged frogs (Rana catesbeiana Shaw and
Rana clamitans Daudin) under natural conditions. Am. Midi. Nat. 26: 201-206.
Robinson, R. W.; Peters, R. H.; Zimmermann, J. (1983) The effects of body size and
temperature on metabolic rate of organisms. Can. J. Zool. 61: 281-288.
Ryan, M. J. (1980) The reproductive behavior of the bullfrog (Rana catesbeiana). Copeia
1980: 108-114.
Ryan, R. A. (1953) Growth rates of some ranids under natural conditions. Copeia 1953:
73-80.
Smith, H. M. (1956) Handbook of amphibians and reptiles of Kansas. Univ. Kansas Mus.
Nat. Hist. Misc. Publ. 9.
Smith, P. W. (1961) The amphibians and reptiles of Illinois. III. Nat. Hist. Surv. Bull. 28.
Stewart, M. M.; Sandison, P. (1973) Comparative food habits of sympatric mink frogs,
bullfrogs, and green frogs. J. Herpetol. 6: 241-244.
Storer, T. I. (1922) The eastern bullfrog in California. Calif. Fish and Game 8: 219-224.
Treanor, R. R.; Nichola, S. J. (1972) A preliminary study of the commercial and sporting
utilization of the bullfrog, R. catesbeiana Shaw in California. Calif. Dept. Fish and
Game, Inland Fish. Admin. Rep. 72-4; 23 pp.
Turner, F. B. (1960) Postmetamorphic growth in anurans. Am. Midi. Nat. 64: 327-338.
Tyler, J. D.; Hoestenbach, R. D., Jr. (1979) Differences in food of bullfrogs (Rana
catesbeiana) from pond and stream habitats in southwestern Oklahoma. Southwest.
Nat. 24: 33-38.
Viparina, S.; Just, J. J. (1975) The life period, growth and differentiation of Rana
catesbeiana larvae occurring in nature. Copeia 1975: 103-109.
Weathers, W. W. (1976) Influence of temperature acclimation on oxygen consumption,
haemodynamics and oxygen transport in bullfrogs. Aust. J. Zool. 24: 321-330.
Willis, Y. L.; Moyle, D. L.; Baskett, T. S. (1956) Emergence, breeding, hibernation,
movements and transformation of the bullfrog, Rana catesbeiana, in Missouri.
Copeia 1956: 30-41.
2-464 Bullfrog
-------
Wright, A. H. (1914) North American Anura: life histories of the Anurans of Ithaca, New
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Wright, A. H.; Wright, A. A. (1949) Handbook of frogs and toads of the United States and
Canada. Ithaca, New York: Comstock Publishing Co.
2-465 Bullfrog
-------
3. ALLOMETRIC EQUATIONS
Values for key contact rate factors such as food and water ingestion rates have
been measured for few wildlife species. In this section, we describe allometric equations
that can be used to estimate several exposure factors on the basis of animal body weight
using models derived from taxonomically similar species. We emphasize, however, that
measured values from well-conducted studies on the species of concern are likely to be
more accurate and to have narrower confidence limits.
Allometry is defined as the study of the relationships between the growth and size
of one body part to the growth and size of the whole organism; however, allometric
relationships also exist between body size and other biological parameters (e.g., metabolic
rate). The relationship between the physiological and physical parameters and body
weight frequently can be expressed as:
Y = aWtb±SEofY, or [3-1]
log Y = log a + b log Wt ± SE of log Y [3-2]
where Y is the biological characteristic to be predicted, Wt is the animal's body weight
(mass), a and b are empirically derived constants, and SE is the standard error of the mean
value of the parameter.
Equation 3-2 is the log transformation of Equation 3-1. Equation 3-2 represents a
straight line, with b equal to the slope of the line and log a equal to the Y-intercept of the
line. Values for a and b usually are determined empirically from measured values using
linear regression analysis. Once values are determined for a and b, Equation 3-1 can be
used to predict a value of Y from the body weight of the animal. The SE of Y is the
standard error of the mean Y estimated for the mean of the Wt values; the SE of log Y is
the standard error of the mean log Y estimated for the mean of the log Wt values.
3-1
-------
Allometric equations can be used to estimate parameter values for species for
which measured values are not available. The equations presented in this chapter,
however, should not be used for taxonomic categories other than the category for which
each was developed. For example, equations developed for iguanid lizards cannot be used
for amphibians and should not be used for other groups of reptiles without careful
evaluation of likely differences between the groups. It also is important to remember that
the allometric equations presented in this chapter have been developed using mean values
for a number of species within a taxonomic category. Individual species usually exhibit
values somewhat different from those predicted by an allometric model based on several
species. Furthermore, different-sized individuals within a species and individuals at
varying stages of maturation are likely to exhibit a different allometric relationship between
body weight and the dependent variable. For further discussion of within-species
allometric equations related to growth and reproduction, see Reiss (1989).
In the next five sections, we describe empirically derived allometric equations that
relate food ingestion rates (Section 3.1), water intake rates (Section 3.2), inhalation rates
(Section 3.3), surface area (Section 3.4), and metabolic rate (Section 3.5) to body weight.
As discussed above, most of the allometric models differ for birds, mammals, reptiles, and
amphibians, and many also vary within these taxonomic groups. In Section 3.6, we provide
a summary of operations involving logarithms and powers and unit conversion factors for
those persons who may want to modify allometric equations found in the literature.
Finally, in Section 3.7 we describe how to estimate 95-percent confidence intervals for food
ingestion rates and free-living metabolic rates predicted on the basis of allometric
equations presented in this chapter. We present most equations in the untransformed
form only. For equations for which an investigator reported standard errors for the log
transformation of the relationship, we present the equation both ways. For those persons
interested in estimating confidence intervals for other allometric equations, Peters (1983)
provides a simple review of how to estimate regression statistics for equations of the form
of Equation 3-2. Section 3.8 contains the references for this chapter.
3-2
-------
3.1. FOOD INGESTION RATES
Food ingestion rates vary with many factors, including metabolic rate, the energy
devoted to growth and reproduction, and composition of the diet. The metabolic rate of
free-ranging animals is a function of several factors, including ambient temperature,
activity levels, and body weight. In birds and mammals, thermoregulation can
considerably increase an animal's metabolic requirements during the winter, whereas
reproductive efforts can replace thermoregulation as the predominant extra metabolic
expenditure in the spring and summer. Many reptiles and amphibians, on the other hand,
drop their activity levels and metabolic rates in the winter.
For homeotherms (i.e., animals that maintain a relatively constant body temperature
such as most birds and mammals), metabolic rate generally decreases with increasing
body mass (see Section 3.5). The smallest birds and mammals must consume quantities
of food equal to their body weight or more daily; in contrast, the larger homeotherms may
consume only a small fraction of their body weight in food daily. Herbivores tend to
consume larger quantities of food than carnivores because of the lower energy content of
their food. Ingestion rates, expressed in units of food energy normalized to body size (e.g.,
kcal/kg-day), are not significantly different for herbivores and carnivores (Peters, 1983).
Four-legged poikilotherms (those animals whose usual body temperatures are the same as
that of their environment, such as reptiles and amphibians) exhibit the same slope of
decreasing ingestion rates per unit body weight with increasing body size but show a lower
intercept (i.e., lower ingestion rate for a given body weight) than homeotherms (Nagy,
1987).
The rate of food consumption that an animal must achieve to meet its metabolic
needs can be calculated by dividing its free-living (or field) metabolic rate (FMR) (see
Section 3.5) by the metabolizable energy in its food (Nagy, 1987). Metabolizable energy
(ME) is the gross energy (GE) in a unit of food consumed minus the energy lost in feces
and urine. Assimilation efficiency (AE) equals the ratio ME/GE, or the fraction of GE that is
metabolizable. AE is relatively constant among different groups of consumer species of
mammals and birds that are all either carnivorous, insectivorous, herbivorous, or
3-3
-------
granivorous (Hume, 1982; Peters, 1983; Nagy, 1987; Robbins, 1983). Nagy (1987)
calculated the mean ME (i.e., kilojoules of ME per gram of dry matter) of various diets for
birds and mammals from average values of AE for birds and mammals and typical GE
contents of those diets as reported by Golley (1961) and Robbins (1983). These values are
presented in Table 3-1. (For more information on ME and AE, see Section 4.1.2.) Using the
values presented in Table 3-1, Nagy (1987) developed allometric equations for food
ingestion (Fl) rates as a function of body weight (Wt) for birds, mammals, and lizards using
estimated FMRs and general dietary composition. In the remainder of this section, we
present these equations for birds (Section 3.1.1) and mammals (Section 3.1.2). Section
3.1.3 summarizes Nagy's food ingestion allometric equations for iguanid lizards. We report
this information even though no iguanid lizards were among our selected species because
it is the only information of this type we identified for any amphibian or reptile.
Nagy's (1987) estimates of FMR are based on doubly labeled water measurements
of CO2 production in free-living animals. When performed correctly, this method is more
accurate for estimating the metabolic rate of free-living animals than other methods
commonly used (King, 1974). Other allometric equations for food ingestion rates that we
identified in the open literature are based largely on captive animals without corrections for
the additional energy requirements of free-living animals. For more accurate estimates of
food ingestion rates by type of diet, we recommend following the procedures outlined in
Section 4.1.2 instead of using these generic equations.
3.1.1. Birds
For birds, Nagy (1987) calculated Fl rates (in grams dry matter per day) from ME and
FMR and developed the following equations:
Fl (g/day) = 0.648 Wt0651 (g), or
Fl (kg/day) = 0.0582 Wt0651 (kg)
all birds
[3-3]
Fl (g/day) = 0.398 WtU8bU (g)
passerines
[3-4]
3-4
-------
Table 3-1. Metabolizable Energy (ME) of Various Diets for Birds and Mammals
Diet
insects
fish
vegetation
seeds
nectar
omnivory
Metabolizable Energy
(kJ/g)a (kcal/g)a
18.7
18.0
18.7
16.2
10.3
18.4
20.6
14
= 4.47
= 4.30
= 4.47
= 3.87
= 2.26
= 4.92
= 4.92
= 3.35
Animal Group
mammals
birds
mammals
birds
mammals
mammals
hummingbirds
mammals and birds
ag = grams dry weight.
Source: Nagy, 1987.
Fl (g/day) = 0.301 Wt0751 (g)
non-passerines
[3-5]
Fl (g/day) = 0.495 Wt0-704 (g)
seabirds
[3-6]
where Wt equals the body weight (wet) of the animal in grams (g) or kilograms (kg) as
indicated. We provide the regression statistics for these equations (including sample size
and regression coefficient) and information required to estimate a 95-percent confidence
interval for an Fl rate predicted for a specified body weight in Section 3.7. More accurate
estimates of food requirements can be made from estimates of FMR (Section 3.5), dietary
composition, and AE for the species of interest, as outlined in Section 4.1.2.
3.1.2. Mammals
For placenta! mammals, Nagy (1987) calculated Fl rates (in grams dry matter per
day) from ME and FMR values and developed the following equations:
3-5
-------
Fl (g/day) = 0.235 Wt0822 (g), or
Fl (kg/day) = 0.0687 Wt0822 (kg)
all mammals
[3-7]
Fl (g/day) = 0.621 Wt0564 (g)
rodents
[3-8]
Fl (g/day) = 0.577 Wt0-727 (g)
herbivores
[3-9]
We provide the regression statistics for these equations (including sample size and
regression coefficient) and information required to estimate a 95-percent confidence
interval for an Fl rate predicted for a specified body weight in Section 3.7. More accurate
estimates of food requirements can be made from estimates of FMR (Section 3.5), dietary
composition, and AE for the species of interest, as outlined in Section 4.1.2.
Herbivores tend to consume more food than carnivores or omnivores on a dry-
weight basis because of the lower energy content of the herbivores' diets. On an energy
basis (e.g., kilocalories), the ingestion rates of carnivores and herbivores are not
significantly different (Farlow, 1976):
Fl (kjoule/day) = 971 Wt073 (kg) (r2 = 0.942), or
Fl (kcal/day) = 1.518 Wt073 (g)
Fl (kjoule/day) = 975 Wt070 (kg) (r2 = 0.968), or
Fl (kcal/day) = 1.894 Wt070 (g)
herbivores
carnivores
[3-10]
[3-11]
3.1.3. Reptiles and Amphibians
This section summarizes food ingestion allometric equations for iguanid lizards,
which is the only information of this type we identified for any amphibian or reptile. Nagy
(1987) calculated Fl rates (in grams dry matter per day) from ME and FMR values on spring
and summer days and developed the following equations:
3-6
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Fl (g/day) = 0.019 Wt0841 (g) herbivores [3-12]
Fl (g/day) = 0.013 Wt°773 (g) insectivores [3-13]
Again, on an energy basis, carnivores and herbivores are not significantly different and can
be represented by a single relationship:
Fl (kjoule/day) = 0.224 Wt0799 (g), or all iguanids [3-14]
Fl (kcal/day) = 0.054 Wt°7" (g)
We provide the regression statistics for these equations (including sample size and
regression coefficient) and information required to estimate a 95-percent confidence
interval for an Fl rate predicted for a specified body weight in Section 3.7. More accurate
estimates of food requirements for these and other groups of reptiles and amphibians can
be made from estimates of FMR (Section 3.5), dietary composition, and AE for the species
of interest, as outlined in Section 4.1.2.
Allometric equations for Fl rates for other groups of reptiles and amphibians were
not found. For other groups, we recommend estimating Fl rates from FMR and diet, as
described in Section 4.1.2.
3.2. WATER INTAKE RATES
Daily water requirements depend on the rate at which animals lose water to the
environment due to evaporation and excretion. Loss rates depend on several factors,
including body size, ambient temperature, and physiological adaptations for conserving
water. Drinking water is only one way in which animals may meet their water
requirements. All animals produce some water as a product of their metabolism. The
degree to which metabolic water production and dietary water content can satisfy an
animal's water requirements varies from species to species and with environmental
conditions. Extensive literature describes the allometry of total water flux for various
3-7
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groups of animals. Allometric models to predict drinking water intake, on the other hand,
are limited.
3.2.1. Birds
Based on measured body weights and drinking water values from Calder (1981) and
Skadhauge (1975), Calder and Braun (1983) developed an equation for drinking water
ingestion (Wl) for birds:
WI(L/day) = 0.059 Wt067 (kg) all birds [3-15]
where Wt equals the average body weight in kilograms (kg) of the bird species. This
equation is based on data from 21 species of 11 to 3,150 g body weight. Total water
turnover should be proportional to metabolic rate (body weight to the 3/4 power, see
Section 3.5.2.1). The exponent for Equation 3-15 is not significantly different from 0.75
(Calder and Braun, 1983). Additional sources of water not accounted for in this equation
(metabolic water and water contained in food) also help to balance the animals' daily water
losses. For allometric equations for total water flux (including water obtained from food)
for birds, see Nagy and Peterson (1988).
To estimate daily drinking water intake as a proportion of an animal's body weight
(e.g., as g/g-day), the Wl rate estimated above is divided by the animal's body weight in kg:
Wl (g/g-day) = Wl (kg/kg-day), or [3-16]
= Wl (L/day) / Wt (kg)
In general, birds drink less water than do mammals of equivalent body weights.
Because of their relatively high metabolic rates, the quantity of metabolic water produced
by birds is greater in relationship to body size than that produced by other vertebrates
(Bartholomew and Cade, 1963). In addition, birds are able to conserve water by excreting
nitrogen as uric acid instead of urea (as excreted by mammals); uric acid can be excreted
3-8
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in a semi-solid suspension, whereas urea must be excreted in aqueous solution. On the
other hand, birds exhibit a high rate of water loss from the respiratory system and use
panting and evaporative water loss to prevent overheating at high ambient temperatures.
For example, Dawson (1954) found evaporative losses in two species of towhees to
increase fourfold between 30 and 40 C.
Although birds may satisfy some of their water needs by oxidative food metabolism,
it has not been demonstrated that any normally active bird can satisfy its water
requirements with metabolic water alone (Bartholomew and Cade, 1963). The balance
must be obtained from water contained in foods such as insects or succulent plant
material and from drinking water.
As would be expected, birds drink more water at warmer temperatures to make up
for evaporative losses. Seibert (1949) found that juncos (weighing 16 to 18 g) consumed
an average of 11 percent of their body weight in water daily at an ambient temperature of
0°C, 16 percent at 23°C, and 21 percent at 37°C. The white-throated sparrow increased
water consumption from 18 percent of its body weight at 0°C to 27 percent at 23°C and 44
percent at 37°C.
Water consumption rates per unit body weight also tend to decrease with increasing
body weight within a species. For example, in white leghorn chickens, water intake per
gram of body weight is highest in the youngest chicks (45 percent of the body weight at 1
week when chicks average 62 g) and decreases with age thereafter (13 percent of the body
weight at 16 weeks when chicks average 2.0 kg) until egg-laying, when water consumption
increases for the production of eggs (24 percent of the body weight for laying hens)
(Medway and Kare, 1959).
Some species obtain more of their daily water needs from their diet and therefore
drink less water than others; therefore, measured water ingestion values from well-
conducted studies should be used when available. In the absence of measured values,
Equation 3-15 should provide a reasonable central value. Additional information required
to estimate a 95-percent confidence interval was not provided along with this equation.
3-9
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3.2.2. Mammals
Based on measured body weights and drinking water values from Calder (1981) and
Skadhauge (1975), Calder and Braun (1983) developed an allometric equation for drinking
water ingestion (Wl) for mammals:
Wl (L/day) = 0.099 Wt°90 (kg) all mammals [3-17]
where Wt equals the average body weight in kilograms (kg). Additional sources of water
not accounted for in this equation (i.e., metabolic water and water contained in food) help
to balance the animals' daily water losses. The empirically determined exponent of 0.90
does not suggest a simple physiological explanation. If total water turnover (metabolic
water combined with water obtained from food) is proportional to metabolic rate (body
weight to the 3/4 power, see Section 3.5.2.1), then drinking water ingestion would be
expected to scale similarly, as was the case for birds (see Section 3.2.1). For allometric
equations relating body weight to total water flux (including water obtained from food) for
mammals, see Nagy and Peterson (1988).
To normalize drinking water intake to body weight (e.g., as g/g-day; see Chapter 4,
Equation 4-4), the Wl rate estimated above is divided by the animal's body weight in kg:
NWI (g/g-day) = Wl (kg/kg-day), or [3-18]
= Wl (L/day) / Wt (kg)
We present normalized drinking water intakes in the species profiles.
3.2.3. Reptiles and Amphibians
Allometric equations relating body weight to drinking water ingestion rates were not
identified for reptiles and amphibians. The water balance of these groups is complex, in
part because they can absorb water through their skin as well as drink water and extract
water from their food (Duellman and Trueb, 1986; Minnich, 1982). The relative
3-10
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contribution of these three routes of water intake depends on the species, habitat,
temperature, and body surface area. In general, the skin of reptiles is less permeable than
that of amphibians. Aquatic turtles (e.g., snapping turtle, painted turtle) also may ingest
large amounts of water when feeding on aquatic plants and animals; however, the
magnitude of such ingestion has not been quantified (Mahmoud and Klicka, 1979). For
further discussion of water balance for these groups, see Duellman and Trueb (1986),
Feder and Burggren (1992), Minnich (1982), and Nagy and Peterson (1988).
3.3. INHALATION RATES
Inhalation rate is one of the respiratory parameters needed to estimate potential
exposure of wildlife to airborne contaminants. Inhalation rates vary with species, body
size, body temperature, ambient temperature, and activity levels. When inhalation rate is
increased, either because of increased activity levels or to promote evaporative cooling,
exposure to airborne contaminants may be increased. As discussed in Section 4.1.4, an
inhalation toxicologist should be consulted when assessing this pathway because
additional respiratory parameters also must be considered (see U.S. EPA, 1990).
3.3.1. Birds
Lasiewski and Calder (1971) developed an allometric relationship for inhalation rate
(IR) associated with standard metabolism (i.e., post-digestive, at rest) for non-passerine
birds (N = 6 species ranging in weight from 43 to 88,000 grams). They excluded
passerines, which have a somewhat higher metabolic rate than non-passerines (see
Section 3.5):
IR (ml/min) = 284 Wt077 (kg), or all non-passerines [3-19]
IR (m3/day) = 0.4089 Wt°77 (kg), or
IR (m3/day) = 0.002002 Wt°77 (g)
As noted above, these inhalation rates were associated with standard metabolic rates.
Free-living metabolic rates are likely to be higher by a factor of at least 2 or 3 (see Section
3-11
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3.5); therefore, IRs estimated from these equations should be adjusted accordingly (e.g.,
multiplied by 2 or 3) although IRs might not be directly proportional to metabolic rate.
3.3.2. Mammals
Using measured values from several reports of respiration rates in mammals
(covering 691 data points), Stahl (1967) developed an allometric relationship for inhalation
rate with body size for mammals (N = 691, r = 0.98, SE Y = 45):
IR (ml/min) = 379 Wt°80 (kg), or all mammals [3-20]
IR (m3/day) = 0.5458 Wt°80 (kg), or
IR (m3/day) = 0.002173 Wt080 (g)
As for the equations given for birds, these IRs were associated with standard metabolic
rates. Field metabolic rates are likely to be higher by a factor of at least 2 or 3 (see Section
3.5); therefore, IRs determined from these equations should be adjusted accordingly (e.g.,
multiplied by 2 or 3, although IRs may not be directly proportional to metabolic rate).
3.3.3. Reptiles and Amphibians
In contrast to the fairly regular breathing patterns of most birds and mammals, most
reptiles breath air in distinct episodes. They may take single breaths, or exhibit an episode
of several breaths, and then hold their breath for varying lengths of time (Milsom and Chan,
1986). Inhalation rate varies for reptiles and amphibians not only with body size and
activity level, as for birds and mammals, but also with body temperature. Some gas
exchange occurs normally through the integument of both reptiles and amphibians
(Duellman and Trueb, 1986; Li My white and Maderson, 1982). Moreover, for semiaquatic
species, a significant proportion of gas exchange can occur underwater through the skin,
reducing the need to inspire air (Seymour, 1982). For example, in adult bullfrogs, gas
exchange through the skin can account for 18 percent of total oxygen uptake (Burggren
and West, 1982). Given the complexity of the subject, we refer those interested in
3-12
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inhalation exposures for reptiles or amphibians to more specific treatments of these topics
(e.g., Duellman and Trueb, 1986; Feder and Burggren, 1992; Gans and Dawson, 1976;
Jackson, 1979; Hutchinson et al., 1968; Li My white and Maderson, 1982).
3.4. SURFACE AREAS
The degree to which an animal may absorb contaminants through direct contact
with its skin depends on many factors, including the surface area of the skin available for
contact. Summarizing measured surface areas for more than 100 animals reported by
Hemmingsen (1960), Schmidt-Nielsen (1970, 1972) determined that animals have surface
areas that usually are approximately twice that of a sphere of the same weight (assuming a
specific gravity of 1 for both the sphere and the animal). The permeability of an animal's
skin to contaminants, however, depends on characteristics of the skin (e.g., presence of
keratinized scales) as well as the contaminant (e.g., molecule size, lipophilicity). This
section presents allometric equations for estimating skin surface area; characteristics
affecting skin permeability are not discussed.
3.4.1. Birds
In studies of avian thermal biology, skin surface area is commonly estimated using
Meeh's (1879, cited in Walsberg and King, 1978) formula with Rubner's (1883, cited in
Walsberg and King, 1978) constant of 10:
SAskin(cm2)= 10 Wt°667(g) all birds [3-21]
where SAskin is the skin surface area beneath the feathers and Wt is body weight (Walsberg
and King, 1978). Although Rubner's constant of 10 was derived originally from domestic
fowl, Drent and Stonehouse (1971) have verified the formula for birds in a variety of taxa
and of weights spanning three orders of magnitude. For passerines, beak surface area
tends to be about 1 percent (range 0.7 percent to 1.6 percent of 10 passerine species) of
skin surface area, and leg surface area about 7 percent (range 5.9 percent to
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7.9 percent of 10 passerine species) (Walsberg and King, 1978). These ratios would be
expected to vary for many non-passerines (e.g., herons, woodcock).
3.4.2. Mammals
Summarizing data from more than 100 mammals, Stahl (1967) developed a
relationship between surface and body weight:
SAskin(m2)= 0.11 Wt°65(kg),or
SAskin(cm2)= 12.3 Wt°65(g)
all mammals
[3-22]
This relationship is very similar to that developed for birds (Equation 3-21).
3.4.3. Reptiles and Amphibians
Surface area has been found to be a different function of body weight for adult
amphibians than for birds or mammals (Hutchinson et al., 1968; Whitford and Hutchinson,
1967):
SAskin(cm2)= 1.131 Wt°579(9)
SAskin(cm2)= 0.953 Wt°725(g)
SAskin(cm2)= 0.997 Wt°712(g)
SAskin (cm2) = 8.42 Wt°694 (g)
all frogs
bullfrog
green frog
salamanders
[3-23]
[3-24]
[3-25]
[3-26]
Models by which to estimate surface areas for turtles (exclusive of the shell and
plastron) and snakes were not found. The general formula for the surface area of a
cylinder can be used to approximate the surface area of a snake if the length and girth are
known or estimated.
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3.5. ALLOMETRIC EQUATIONS FOR METABOLIC RATE
The allometric equations for estimating food ingestion rates provided in Section 3.1
were derived using very simple assumptions about the energetic content and digestibility
of the diet for the species included in the regression equations. Consequently, the
equations will provide only very rough estimates of food ingestion rates for any given
species. For a site-specific exposure assessment, it may be more appropriate to evaluate
ingestion rates for a diet that is likely to represent the species and study area. The caloric
content and percent water, fat, and protein of wildlife diets vary not only among species,
but also among individuals within the same species depending on factors such as location,
time of year, age, and sex. If one can estimate the energetic requirements of the animal in
the field and its dietary composition for a specified situation, one can estimate food
ingestion rates for that diet and situation. In the remainder of this section, we discuss
metabolic rate and provide allometric equations to estimate field free-living metabolic rates
(FMRs) for wildlife species. Chapter 4 describes how to use FMR estimates and
information about the energy content of specific diets to estimate food ingestion rates.
Several factors influence metabolic rates of free-ranging animals, including body
size, body temperature, and type and level of activity. For homeotherms, metabolic energy
must be expended to keep core body temperature within relatively narrow limits. At
moderate ambient temperatures, homeotherms lose heat to the surrounding environment
as rapidly as they gain it and therefore need not expend extra metabolic energy to maintain
core body temperature. That range of ambient temperatures over which an animal's
metabolic rate is at a minimum and constant level is called the thermoneutral zone. Below
the thermoneutral zone, the organism loses heat to the environment and must increase its
metabolic activity to compensate. Above the thermoneutral zone, the organism gains heat
from its environment and must increase its metabolic rate to use evaporation to cool its
body.
Thermoneutral zones vary somewhat among species depending upon the insulating
properties and color of the fur or feathers, surface-to-volume ratios, and other factors. The
degree to which metabolic rate increases with changes in ambient temperature outside of
3-15
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the thermoneutral zone is referred to as the temperature coefficient (TC). Temperature
coefficients also vary with body size, insulation, and other factors.3
There are several ways to measure and express metabolic rate, including basal
metabolic rate (BMR), resting metabolic rate (RMR), existence metabolic rate (EMR),
average daily metabolic rate (ADMR), and free-living or field metabolic rate (FMR). The
different measures are distinguished by the range of animal activities included in the
measure:
• Basal metabolic rate (BMR), also sometimes labeled standard metabolic rate
(SMR), represents the minimal value of heat production for homeotherms.
BMR must be measured within the thermoneutral zone of ambient
temperatures when the animal is at rest and in a post-absorptive state (i.e.,
all food has been digested) (Gessaman, 1973).
• Standard metabolic rate (SMR) has been used in the literature in more than
oneway. Many authors define SMR as BMR (see above). Others use SMR if
the thermoneutral zone has not been defined so that some cost of
thermoregulation may be included (Bennett and Harvey, 1987).
• Resting metabolic rate (RMR) is usually measured at temperatures below the
thermoneutral zone when the animal is at rest, but not post-absorptive (i.e.,
the animal is eating regularly and may be expending energy to digest its
food). The RMR exceeds the BMR by the heat liberated in the digestion of
food (i.e., the specific dynamic action, or SDA) and by some cost of
thermoregulation. RMR and BMR are usually measured using indirect
calorimetry (i.e., oxygen consumption and carbon dioxide production) over a
period of 1 to 3 hours.
aWater has a much higher heat conductance than air. When submerged or swimming, the degree
to which metabolic rate increases with decreasing water temperature depends on the animal's
insulation (e.g., whether the fur traps an air layer next to the skin over part or all of the body or
whether there is an insulative layer of blubber), duration of submergence, and body size.
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• Existence metabolic rate (EMR) is the metabolic rate necessary for an animal
to maintain itself in captivity without a change in body weight. EMR is
greater than RMR due to the cost of locomotor and other activities required
for self-maintenance. Most researchers measure EMR on the basis of food
consumption and energy excretion at a constant weight over the period of
several days or weeks (Kendeigh, 1969).
• Average daily metabolic rate (ADMR) is usually measured over 24 hours at a
temperature similar to the animal's natural environment and with food and
water available ad libitum. ADMR is the sum of BMR and the metabolic costs
of thermoregulation, digestion, and daily activities.
• Free-living or field metabolic rate (FMR) can be measured using doubly-
labeled water, and it represents the total daily energy requirement for an
animal in the wild. FMR includes the costs of BMR, SDA, thermoregulation,
locomotion, feeding, predator avoidance, alertness, posture, and other
energy expenditures. Various models and measures have indicated that a
constant value of approximately three times BMR is a reasonable estimate of
FMR for birds and mammals (Lamprey, 1964; Buechner and Golley, 1967;
Koplin et al., 1980), although more precise estimates also have been
developed (see Sections 3.5.1.3, 3.5.2.3, and 3.5.3.2).
FMR also has been used in the literature to represent fasting metabolic rate (e.g.,
Gessaman, 1973), but we do not discuss fasting metabolic rate estimates in this Handbook.
The relationships between metabolic rate and body weight fall into two broad
categories: those for homeothermic animals (i.e., most birds and mammals), and those for
poikilothermic animals (i.e., most reptiles and amphibians). For poikilotherms, metabolic
rate must be related to body temperature. It also is important to remember that
poikilotherms can adjust their body temperatures relative to ambient temperatures
3-17
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somewhat by modifying their behavior (e.g., basking in the sun, adopting postures to
minimize or maximize absorption of solar radiation).
Allometric models relating metabolic rate to body size for birds and mammals are
described in Sections 3.5.1 and 3.5.2, respectively. Allometric models for reptiles and
amphibians are described in Section 3.5.3. We have attempted to identify the most
accurate allometric equations currently available for estimating free-living metabolic rates.
We also present allometric equations for basal and existence metabolism, which in
combination with appropriate information on activity budgets and energy costs can be
used to estimate field metabolic rates. Furthermore, measures of basal and existence
metabolism are available for considerably more species than are measures (or estimates)
of free-living metabolic rates. Consequently, more allometric models have been developed
that distinguish the metabolic rate-weight relationship among taxonomic groups using
measures of basal and existence metabolism than using measures of field metabolic rates.
We caution users to pay close attention to the units for the parameters in the allometric
equations. For most equations, energy is expressed as kcal (with the exception of some
equations for reptiles and amphibians). Mass may be expressed either in g or kg,
depending on how the equation was reported.
We emphasize that the literature on allometric relationships and metabolic rate is
extensive and complex. We provide a very simplified overview that should be of
assistance for screening-level exposure assessments only. For additional information on
methods of estimating metabolic costs of free-ranging animals, please consult expert
reviews on the subject (e.g., Bennett and Dawson, 1976; Bennett and Harvey, 1987; Ellis,
1984; Cans and Dawson, 1976; Gessaman, 1973; Kendeigh et al., 1977; King, 1974; Peters,
1983; Robinson et al., 1983; Wiens, 1984).
3.5.1. Birds
In birds, metabolic rate generally decreases with increasing body mass. Several
authors have found passerine birds to have higher metabolic rates overall for their body
size than non-passerines (Lasiewski and Dawson, 1967; Nagy, 1987; Kendeigh, 1970;
3-18
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Zar, 1968). In this section, we present allometric models for three measures of metabolic
rate on the basis of body size in birds: basal metabolic rate (BMR), existence metabolic
rate (EMR), and field metabolic rate (FMR). All equations take the general form of Y = aWtb,
but can also be represented in their log-transformed form (the equation of a straight line).
We conclude this section by discussing the influence of ambient temperature on avian
metabolic rates. Additional information required to estimate a 95-percent confidence
interval (Cl) for a predicted FMR (the expression of metabolic rate that is generally most
appropriate for wildlife exposure assessments) is provided in Section 3.7.
3.5.1.1. Basal Metabolic Rate
Several investigators have derived values for the constants a and b for the equation
relating BMR to body weight (Wt) from empirical data on birds. Lasiewski and Dawson
(1967) compiled body weight and BMR for almost 100 species of birds. They found BMR
for passerines to be higher than BMR for non-passerines (i.e., the Y-intercept for
passerines is higher than the Y-intercept for non-passerines):
Passerines
log BMR (kcal/day) = 2.11 + 0.724 log Wt (kg) ± 0.113, or [3-27]
BMR (kcal/day) = 128 Wt0724 (kg)
Non-passerines
log BMR (kcal/day) = 1.89 + 0.723 log Wt (kg) ± 0.068, or [3-28]
BMR (kcal/day) = 77.6 Wt0723 (kg)
Ellis (1984) found the Y-intercept for seabirds" to be somewhat higher than the Y-
intercept for non-passerines determined by Lasiewski and Dawson (1967):
bSeabirds included penguins, albatross, petrels, shearwaters, pelicans, skuas, gulls, terns, noddys,
murres, cormorants, and frigatebirds.
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Seabirds
log BMR (kcal/day) = 1.96 + 0.721 log Wt (kg) (no SE provided), or [3-29]
BMR (kcal/day) = 91.2 Wt0721 (kg)
Zar (1968) reexamined the data compiled by Lasiewski and Dawson (1967) and
developed models for relating BMR to body weight (kg) for several orders and families of
birds (Table 3-2). These may be used to estimate whether the FMR for a species of interest
is likely to fall above or below that predicted on the basis of the allometric equations
derived for "all birds."
3.5.1.2. Existence Metabolic Rates
Kendeigh (1970) developed allometric equations for EMRs as a function of weight
(Wt) at 30 C separately for passerines and for non-passerines. As was the case for BMRs,
passerines showed higher EMRs than did non-passerines:
Passerines (N = 15 species)
log EMR (kcal/day) = 0.1965 + 0.6210 log Wt (g) ± 0.0633, or [3-30]
EMR (kcal/day) = 1.572 Wt06210 (g), or
log EMR (kcal/day) = 2.060 + 0.6210 log Wt (kg), or
EMR (kcal/day) = 114.8 Wt06210 (kg)
Non-passerines (N = 9 species)
log EMR (kcal/day) = -0.2673 + 0.7545 log Wt (g) ± 0.0630, or [3-31]
EMR (kcal/day) = 0.5404 Wt07545 (g), or
log EMR (kcal/day) = 1.996 + 0.7545 log Wt (kg), or
EMR (kcal/day) = 99.03 Wt07545 (kg), or
The average increase of EMR at 30 C over BMR is 31 and 26 percent in passerine and non-
passerine species, respectively (Kendeigh, 1970). At 0 C, on the other hand, EMR of
passerine and non-passerine species is similar, indicating that non-passerines are affected
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Table 3-2. Allometric Equations for Basal Metabolic Rate (BMR) in Birds3
Avian group
Apodiformes
Strigiformes
Columbiformes
Galliformes
Falconiformes
Anseriformes
Ciconiiformes
Passe riformes
Corvidae
Ploeceidae
Fringillidae
All Nonpasserines
All Species
Number
of data
points a
9
7
10
13
5
9
7
48
8
17
19
72
120
114
66.4
92.1
72.6
65.3
95.8
86.9
129
126
164
125
78.5
86.3
log a
2.06
1.82
1.96
1.86
1.82
1.98
1.94
2.11
2.10
2.21
2.10
1.90
1.94
b
0.769
0.69
0.858
0.698
0.648
0.634
0.737
0.724
0.709
0.794
0.714
0.723
0.668
SEb of SEb of
mean mean
BMR log BMR
0.201
11.1
2.68
15.3
45.3
23.4
22.0
8.71
23.3
1.40
1.02
42.8
52.8
0.0558
0.0989
0.0491
0.0904
0.108
0.0524
0.0464
0.0806
0.147
0.0808
0.0473
0.111
0.133
''Values for the equation relating BMR to body weight (Wt): log BMR (kcal/day) = log a + b log Wt (kg).
"Estimated from the mean log Wt used to develop the allometric equation.
Source: Zar, 1968.
more by cold than passerines. Kendeigh (1970) estimated the equation for all bird species
(N = 24)atO°Ctoequal:
All birds (24 species)
log EMR (kcal/day) = 0.6372 + 0.5300 log Wt (g) ± 0.0613, or
EMR (kcal/day) = 4.337 Wt05300 (g)
[3-32]
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The equations also indicate that smaller species are affected more by cold than are larger
species. The slopes of the regression lines for EMR on body weight is less steep at 0 C
than at 30 C, indicating that small birds must increase heat production more than large
birds to regulate body temperature during cold weather.
To normalize EMR to body weight, divide the daily EMR by body weight:
NEMR (kcal/kg-day) = EMR (kcal/day) / Wt (kg) [3-33]
3.5.1.3. Free-Living Metabolic Rate
FMRs have been measured using doubly-labeled water (DLW) to measure CO2
production in animals in t |