EPA/600/A-93/159
ECOTOXICOLOGICAL PRINCIPLES FOR AVIAN FIELD STUDIES
USING RADIOTELEMETRY OR REMOTE SENSING
Anne Fairbrother
U.S. Environmental Protection Agency
Environmental Research Laboratory
200 SW 35th Street
Corvallis, OR 97333
In this section, I will provide a wildlife toxicologist's
perspective of avian field studies. I will focus my remarks on
the type of information needed when conducting studies in field
situations to determine how a specific use of a single pesticide
affects indigenous birds. I view radiotelemetry as only one
subset of wildlife ecotoxicological studies that could be done,
although it is a powerful tool for determining how free-ranging
animals come in contact with a variety of contaminated
environments and what the short and long-term effects might be.
I will make no attempt in my remarks to limit myself to
discussions of applications of extant technologies. Rather, I
will discuss the information that we wish to gain and the context
in which it will be used. By stating the needs of the end-user,
I hope to provide a challenge to telemetry experts to advance the
engineering aspects of radiotelemetry and other remote sensing
technologies. Hopefully, this will provide us with better tools
for collecting ecologically relevant data in a cost-effective,
real-time fashion.
APPROACH
Put succinctly, the objective of a pesticide field study
usually is to test the null hypothesis that application of a
pesticide will have no effect on indigenous birds. Of course,
this simple statement leads to many further questions: what is
the ecological significance of "effect"? what do we mean by "no"
effect? what do we know about dose-response relationships? is
the "application" a single application or multiple applications?
what is the time period of concern? I will not attempt to
-------
address broad ecological concerns at this time, but will limit my
comments to direct, biological and toxicological responses of
birds to a pesticide applied under a selected field regime.
Within this context, the wildlife toxicologist is interested in
gathering information in three general areas: (1) what can we
observe about birds' movements and behavior patterns that are
likely to result in their exposure to the chemical; (2) what is
the actual exposure of each individual, and the population, to
the chemical; and (3) what are the physiological and behavioral
consequences to the individual and population of chemical
exposure (including mortality and reproductive endpoints)? Once
we have this information, we can develop simple cause-and-effect
relationships between pesticide application and bird responses.
Given an appropriate study design, we can make further inferences
about how the observed responses vary depending upon the
application rate (dose-response relationships) or the relative
hazards of various compounds (comparative risk), and differences
in the magnitude of the effects on the various species present
(comparative toxicology). What are examples of the type of data
we collect in order to develop these cause-and-effect
relationships?
Location and Movement: One vital piece of information is
knowledge of the location of the population of birds of interest
within the study area, in three-dimensional space. Latitude and
longitude coordinates are needed in order to know when the birds
are in the field to which the pesticide is being applied.
Multiple readings over time are needed to know when the birds are
present and, therefore, have the potential to be exposed to the
chemical. Spatial movement patterns can also provide information
about what the bird is doing (flying, resting, feeding, nesting)
which, in turn, provides keys to exposure potential as well as
information about the effect of the pesticide application (did
behaviors change after the spray event in a manner that differs
from control plots?). Data about movement in the third dimension
-------
(elevation) can be used to augment information about certain
behaviors (flying versus moving on the ground) and to infer
others (are canopy-dwelling birds spending too much time on the
ground?). Knowing the location of birds in real time is also
useful for retrieving carcasses (from pesticide-induced mortality
or other causes) for quantifying mortality and for diagnostic
procedures or for capturing live birds for sampling purposes.
Special modifications (e.g., mortality switches, activity
recorders, physiological-measurement devices) are useful but
technologically difficult additions.
Behavior; Once we know where the birds are located, we then need
to know what they are doing there and if their behaviors are
altered due to the pesticide application. In particular, we are
interested in determining the effects of pesticide applications
on those behaviors that will impact population demographics,
i.e., mortality, natality, and dispersal. It is important to
gather information about mortality in a time-dependent fashion.
In other words, we wish to know when birds die as well as how
many die. This will contribute to our ability to link mortality
to the pesticide application, both by a time association and
through various biochemical procedures (e.g., cholinesterase
activity) that degrade with time after death. Ultimately, we
calculate the survival rate, rather than mortality rate, but
these data are obviously related.
Reproduction; Reproduction is another behavior that we typically
measure. Reproduction is, actually, the sum of a series of
integrated behaviors. We use the word "reproduction" to
encompass the entire process from mating behaviors, through
actual fertilization, egg incubation, and raising of young until
they leave the nest. In strict ecological terms, we should
include the period from fledging (leaving the nest) until the
individual matures and engages in mating behaviors itself.
However, I will leave the discussion of the postfledging time to
-------
the ecologists and focus on the period from initiation of mating
behaviors until the young fledge.
Mating behaviors in birds can be very complex and frequently
rely on visual cues. Conspicuousness or condition of plumage is
a factor in mate selection which could be altered by pesticide
exposure (1). Birds must initiate appropriate behaviors in the
correct sequence and phenology and then must be able to respond
appropriately to behaviors of conspecifics. This type of
behavior has both learned and innate components so it is not
surprising that neurotropic pesticides have been shown to alter
these patterns (2-4). Once mating has occurred, egg production
can be reduced due to pesticide exposure (5,6) as can proper
formation of the egg and eggshell (7,8). Information about
fertility and eggshell quality generally is gathered in
controlled laboratory studies, but it would be extremely useful
to be able to gather similar data in the field to expand our
knowledge about interspecific differences and the interactions of
other environmental stressors (parasites, disease, extreme
weather) with pesticide exposure. Nesting behaviors (amount of
time spent sitting on eggs, how frequently the eggs are turned,
whether the nest is incubated until term or abandoned early) have
only occasionally been studied in relation to pesticide effects
(9-11) but provide additional clues about cause-and-effect
relationships relative to the final reproductive output.
Physiological Effects (Biomarkers): In addition to gathering
data on pesticide effects on survival and reproduction,
ecotoxicological studies would benefit from data concerning
sublethal physiological effects. This area of study has largely
been ignored to date due to the difficulty of obtaining the
required information. Examples of questions that could be
addressed within an ecological context include, but certainly are
not limited to: (1) does exposure to pesticide applications
change the metabolic rates of the birds, thereby altering the
-------
amount of food and subsequent foraging time needed for survival
or reproductive efforts (12) ; (2) does exposure to pesticides
make birds more susceptible to concomitant environmental
stressors such as disease and parasitism (13); and (3) do
pesticides change hormone production patterns and interfere with
growth and reproduction patterns or other more subtle behaviors
(9)? Answers to these types of questions would help to make
definitive cause-and-effect relationships between pesticide
application and subsequent changes in the local populations.
More importantly, they would provide clues to the mechanisms by
which the pesticides exert their effects on the birds. This
would provide us with stronger predictive models about the
ecotoxicological effects of pesticides and allow modifications of
application regimes or new pesticide formulations to be made with
a strong scientific basis. Remote sensing applications for
monitoring physiological measurements will be discussed in more
detail in another chapter.
DISCUSSION
It is very important in field studies to know how much
exposure to the pesticide each individual has received. Without
this information, cause-and-effect relationships must, therefore,
be based on strong correlative relationships. There also are
available surrogate measures (biomarkers) of exposure such as
cholinesterase activity in brain and plasma (14) and chemical
residue on crop and stomach contents. For some chemicals, we
have direct exposure measurements through analysis of residues of
parent compounds or breakdown products (e.g., oxones) in various
tissues and excreta. Tissue residue studies are not ideal,
however, as the current generation of pesticides frequently do
not leave such residues. Those that do generally require
destructive sampling of the animal and provide information only
about the amount of chemical present at the time of sampling.
Excreta measures of chemical content would be non- destructive
and could be sampled repeatedly through time. Excreta collected
-------
from nests can be related to a specific individual (or two), but
this restricts our ability to measure what is occurring in non-
nesting birds or during the portion of the day when the bird is
not in the nest. Merely locating the individual coincident with
pesticide application in time and space does not provide a
measure of exposure. For example, foliage can provide shelter
from exposure while preening activities can increase total
exposure. Therefore, I challenge you to begin thinking about how
remote sensing technologies could be applied to this problem of
exposure assessment. From an ecotoxicological point of view,
this is the weakest part of pesticide risk assessment studies.
SUMMARY
In summary, ecotoxicological studies for pesticide risk
assessments strive to develop cause-and-effect relationships
between pesticide application and adverse effects on birds (both
as individuals and as populations) and to determine the
mechanisms by which the observed effects occur. In order to
accomplish this, data are collected to determine if the location
of the birds put them into potential contact with the pesticide,
how the pesticide changes behaviors and the physiology of the
animals, and how these changes result in increased mortality and
reduced reproduction. Radiotelemetry and other remote sensing
technologies can be powerful tools to aid in gathering this data.
Hopefully, the summary presented here will leave you with
thoughts about how to extend the current capabilities of these
tools yet continue to provide information in real-time and in a
user-friendly fashion.
DISCLAIMER
The information in this document has been funded by the U.S.
Environmental Protection Agency. It has been subjected to Agency
review and approved for publication.
-------
REFERENCES
1. Hamilton, W.D. and M. Zuk. 1982. Heritable true fitness
and bright birds: A role for parasites? Science 218:384-
387.
2. Forsyth, D.J. 1980. Effects of dietary fenitrothion on the
behavior and survival of captive white-throated sparrows.
In: I.W. Varty, ed. Environmental surveillance in Mew
Brunswick, 1978-79. Effects of spray operations for forest
protection against spruce budworm. Committee for
Environmental Monitoring of Forest Insect Control
Operations, Dept. For. Res., Univ. New Brunswick,
Fredericton, pp. 27-28.
3. Grue, C.E. and B.K. Shipley. 1981. Interpreting population
estimates of birds following pesticide applications —
behavior of male starlings exposed to an organophosphate
pesticide. Stud. Avian Biol. 6:292-296.
4. Busby, D.G., L.M. White and P.A. Pearce. 1990. Effects of
aerial spraying of fenitrothion on breeding white-throated
sparrows. J. Appl. Icol. 27:743-755.
5. Stromborg, K.L. 1981. Reproductive tests of diazinon on
bobwhite quail. In: D.W. Lamb and E.E. Kenaga, ed., Avian
and Mammalian Wildlife Toxicology: Second Conference. ASTM
STP757. American Society for Testing and Materials,
Philadelphia, PA pp. 19-30.
6. Rattner, B.A., L. Sileo and C.G. Scanes. 1982. Oviposition
and the plasma concentration of LH, progesterone and
corticosterone in bobwhite quail (Colinus virginianus) fed
parathion. J, Reprod. Fert. 66:147-155.
-------
7. Bennett, J.K. and R.S. Bennett. 1990. Effects of dietary
methyl parathion on northern bobwhite egg production and
eggshell quality. Environ. Toxicol. Chem. 9:1481-1485.
8. Scott, M.L. J.R. Zimmermann, S. Marinsky, P.A. Mullenhoff,
G.L. Rumsey and R.W. Rice. 1975. Effects of PCBs, DDT, and
mercury compounds upon egg production, hatchability, and
shell quality in chickens and Japanese quail. Poultry Sci.
54:350-368.
9. Bennett, R.S., B.A. Williams, D.W. Schmedding and J.K.
Bennett. 1991. Effects of dietary exposure to methyl
parathion on egg laying and incubation in mallards.
Environ. Toxicol. Chem. 10:501-507.
10. White, D.H., C.H. Mitchell and E.G. Hill. 1983. Parathion
alters incubation behavior of laughing gulls. Bull.
Environ. Contam. Toxicol. 31:93-97.
11. Busby, D.G., L.M. White and P.A. Pearce. 1990. Effects of
areal spraying of fenitrothion nonbreeding white-throated
sparrow. J. Appl. Ecol. 27:743-755.
12. Dominguez, S.E., J.L. Menkel, A. Fairbrother, B.A. Williams,
and R.W. Tanner. Effect of 2,4-dinitrophenol on metabolic
rate of bobwhite quail. J. Appl. Toxicol. Phamacol. (in
press).
13. Porter, W.P., R. Hinsdill, A. Fairbrother., L.J. Olson, J.
Jaeger, T.M. Yuill, S. Bisgaard, W.G. Hunter, and K. Nolan.
1984. Toxicant-disease-environment interactions associated
with suppression of immune system, growth, and reproduction.
Science. 224:1014-1017.
-------
14. Mineau, P. 1991. Choiinesterase-inhibiting Insecticides:
Their Impact on Wildlife and the Environment. Elsevier.
Amsterdam, The Netherlands. 348pp.
-------
M TECHNICAL REPORT DATA
(rtcnt ma Instmeiioiu on the re vent he fort eom/rf
1. REPORT NO,
EPA/600/A-93/159
2.
PB93-212793
a.TITLt AND SUBTITLE
Ecotoxicological Principles for Avian Field
Studies Using Radiotelemetry or Remote Sensing
I. REPORT DATE
». PERFORMING ORGANIZATION CODE
7. AUTMOR(S)
Anne Fairbrother
I. PERFORMING ORGANIZATION REPORT NO,
•.PERFORMING ORGANIZATION NAME AND ADDRESS
US EPA, ERL-Corvallis, OR
1C. PROGRAM ELEMENT MO.
lireONTRACT/QRANT NO.
12. tPONSORlNC AGENCY NAME AND ADDRESS
US Environmental Protection Agency
Environmental Research Laboratory
200 SW 35th Street
Corvallis, OR 97333
13. TYPE OP REPORT AND PERIOD COVERED
Symposium paper
14. SPONSORING AGENCY CODE
EPA/600/02
IB, SUPPLEMENTARY NOTES
1993. Pellston Workshop;
Asilomar, CA.
Radiotelemetry for Avian Field Studies,
IS. ABSTRACT
In this section, I will provide a wildlife toxicologist's perspective
of avian field studies. I will focus my remarks on the type of
information needed when conducting studies in field situations to
determine how a specific use of a single pesticide affects indigenous
birds. I view radiotelemetry as only one subset of wildlife
ecotoxicologieal studies that could be done, although it is' a powerful
tool for determining how free-ranging animals come in contact with a
variety of contaminated environments and what the short and long-term
effects might be. I will make no attempt in my remarks to limit myself
to discussions of applications of extant technologies. Rather, I will
discuss the information that we wish to gain and the context in which
it will be used. By stating the needs of the end-user, I hope to
provide a challenge to telemetry experts to advance the engineering
aspects of radiotelemetry and other remote sensing technologies.
Hopefully, this will provide us with better tools for collecting
ecologically relevant data in a cost-effective, real-time fashion.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
radiotelemetry, birds,
remote sensing, pesticides
S. DISTRIBUTION STATEMENT
Release to Public
»» SECURITY. Ct,ASS (T*H Htpertj
UncTas smear
21. NO. Of PACES
9
»0 SECURITY CLASS
Unclassified
22. PRICE
KPA P»rm §220-1 (»-7J)
------- |