Biological Services Program
FWS/OBS-80/16
MARCH 1980
The Effects of Low Levels of
Oil on Aquatic Birds
A Non-technical Summary of Research Activities
FY76 through FY78
Interagency Energy-Environment Research and Development Program
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
AND
Fish and Wildlife Service
U.S. Department of the Interior

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FWS/0BS-80/16
March 1980
THE EFFECTS OF LOW LEVELS OF OIL ON AQUATIC BIRDS
A Non-technical Summary of Research Activities
FY76 through FY78
by
John 0. Biderman
and
William H. Drury
College of the Atlantic
Bar Harbor, Maine 04609
Project Officer
David M. Smith
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
NASA-SIidell Computer Complex
1010 Gause Boulevard
SIidel 1, Louisiana 70458
This study was conducted
in cooperation with the
Environmental Protection Aqency
Office of Research and Development
Performed for
Coastal Ecosystems Project
Biological Services Proqram
Fish and Wildlife Service
U.S. Department of the Interior

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PREFACE
This report summarizes the research conducted from 1 July 1C75 to 30 Septem-
ber 1978 by the U.S. Fish and Wildlife Service (FWS) about the effects of
petroleum on aquatic birds. The following assessments were made:
1.	Effects of oiling on hatchability of eggs.
2.	Effects of oil ingestion on physiological condition and
survival of birds.
3.	Effects of oil ingestion on reproduction in birds.
4.	Accumulation and loss of oil by birds.
5.	Development of analytical methods for identification and quantifi-
cation of oil breakdown products in tissues and eggs of ducks.
Research was funded by the Environmental Protection Agency (EPA) Federal
Interagency Energy-Environment Research and Development Program and the FWS
Environmental Contaminants Evaluation Program, with Dr. Allan Hirsch, Chief,
Office of Biological Services, serving as FWS coordinator. Coastal Ecosys-
tems Project contacts were Drs, William Palmisano and Howard Tait. Mr.
Clinton Hall served as EPA's coordinator. The research was conducted at the
Patuxent Wildlife Research Center, under the direction of Dr. Lucille F.
Stickel and Dr. Michael P. Dieter.
Questions about this research and requests for this publication should be
directed to:
Information Transfer Specialist
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
NASA-SIidel 1 Computer Complex
1010 Gause Blvd.
Slidell, LA 70458
Cover Photo by Kirke A. King
This report should be cited as follows:
Biderman, J. 0. and W. H. Drury. 1980. The effects of low levels of oil on
aquatic birds. U.S. Fish and Wildlife Service, Biological Service Pro-
gram. FWS/0BS-80/16. 5 pp.

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THE EFFECTS OF LOW LEV&S OF OIL ON AQUATIC BIRDS
INTRODUCTION
The effects of ma;or oil spills on aquatic birds have been well documented
in the popular media, with dramatic pictures of oil-soaked birds that have
washed up on ocean shores. These reports have focused attention on catas-
trophic spills. Consequently, in the minds of many people, the environmental
hazards of petroleum have been equated with the problems of large spills.
Massive spills appear to account for only 35% of all the oil spilled into
ocean waters. The effects of the less obvious but chronic presence of small-
er quantities of oil, or of dispersed amounts from large spills, are now
being investigated.
Over the past few years, biologists at the Patuxent Wildlife Research Center
(PKRC} of the U.S. Fish and Wildlife Service have been investigating how
small quantities of oil affect aquatic birds. The results demonstrate that
even miniscule amounts of oil can have serious effects on the reproduction
of birds. These studies have been presented in published and unpublished
reports, A technical summary and list of publications is provided in Stickel
and Dieter (1979) for those who wish to review the results in detail.
The important concept to keep in mind is that the reproductive output of a
group of birds, year after year, has more effect on maintaining the popula-
tion than does the random mortality of some individuals. Therefore, chronic
effects such as those we describe below can have serious consequences.
TYPES AND METHOD5 OF STUDIES
The studies have involved experiments carried out both in the field and on
captive birds. In the laboratory, the preferred species is the mallard duck.
Mallards are raised easily in captivity, and their eggs are readily hatched
in artificial incubators. A test group and a control group are maintained
under similar circumstances except for the introduction of an oil contami-
nant. Tests 1n the field have Involved ducks, terns, gulls, and herons.
There it 1s sometimes difficult to be absolutely certain of the experimental
circumstances, but usually the experimental group 1s selected randomly in a
breeding colony of birds, and the control group is a similar, but untreated
sample, 1n the same colony. Sometimes eggs collected 1n the field have been
brought back to the laboratory for experiments.
The questions under consideration in these studies were:
If an Incubating adult's plumage becomes lightly contaminated with oil*
can the oil be transferred to the eggs? If so, what would be the ef-
fects on the developing embryos, on the hatching of eggs, and on the
health of the chick?
What would be the effects if a bird swallows oil, either with its food,
or while cleaning the oil off its feathers? How would consumption of
oil affect the health of the adults and their ability to reproduce?
How would feeding oil to young birds affect their growth, health and
survival?
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How might oil be passed through the food chain? That is, if prey items
come in contact with the oil, can contaminants be passed on to preda-
tory birds and thus accumulate in their tissues?
Finally, where and how are petroleum residues accumulated in the tis-
sues of birds, what is the pathological effect of this contamination,
and how can we detect chemically the presence of petroleum-derived
hydrocarbons.
CHEMICAL STUDIES
Methods have been developed for analyzing petroleum hydrocarbons in the tis-
sues of birds. It is difficult to detect petroleum residues, because oil is
such a complex substance, and because hydrocarbon compounds are so common in
the environment. Also, the ways in which different components of oil are
metabolized may change the relative amounts of different residues. The
methods developed involve quantification of key petroleum-derived compounds
using the techniques of gas chromatography and mass spectrometry. The re-
sults have made it possible for these assays to be standardized between
laboratories.
EFFECTS OF OIL ON EGGS
Aquatic birds often are observed to have varying amounts of oil on their
plumage, and presumably that oil can be transferred from an incubating adult
to its clutch of eggs. Evidence for this will be discussed below, but first
we will examine the toxicity of petroleum to eggs.
Studies were conducted with mallard eggs on which minute amounts of oil,
from 50 microliters down to a few microliters, were applied to shells.
(Fifty microliters 1s the amount contained 1n about one-half drop from an
average household eyedropper.) The result was a marked depression 1n hatch-
ing success. With 50 microliters, mortality of the embryos was 100*; with
five microliters It was from 25% to 90% depending on the kind of crude oil
used. Usually the death of embryos began within three days of the applica-
tion of oil.
This result 1s highly repeatable, and has occurred 1n other species tested
in the field and In the laboratory. Species 1n which significant embryo
mortality has been demonstrated are Louisiana heron, common elder, great
black-backed gull, laughing gull, and Sandwich tern.
Researchers treated a sample of eggs 1n a colony of great black-backed gulls
at the Isles of Shoals, Maine, by applying 20 microliters of oil to each
egg. As they monitored the colony, the hatching success of the treated eggs
was one-half that of the control group, and the success of the surviving
chicks to fledge was one-third the average of those In untreated nests.
In general, young embryos seem particularly susceptible to the toxic effects
of oil. In particular, studies made on mallard eggs and, for comparison's
sake, on chicken eggs, have shown that embryonic absorption of the oil and
hence mortality seem to occur at a specific point 1n development, when a
certain membrane 1s developing Inside the shells.
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It had been assumed in the past that the viscous corrponents of petroleum
actually smothered the embryo by blocking off the pores in the shell through
which it respires* But even when mallard eggs were partially coated with
these viscous substances they did not die. Therefore, a direct biochemical
toxic effect seems to be taking place. Studies have shown that the so-called
"aromatic" hydrocarbons present in petroleum are the toxic agents. (An
aromatic hydrocarbon is defined chemically as one that possesses at least
one benzene ring.}
Experiments with mallard eggs showed that if the oil was allowed to
"weather" for two or three weeks, by sitting in the open air, the toxic
effect was reduced, but there was mortality of embryos nevertheless. This
is particularly significant because it suggests that the effects of an oil
spill can linger. Indeed, oil can be deposited by tides on shores and
marshes, trapped there in sediments, and then be resuspended in the water on
subsequent tides.
The discovery that minute quantities of oil can cause embryo mortality makes
it important to determine whether oil on the feathers of adults can be
transferred to the eggs. In one study, a sample of laughing gulls in a
breeding colony bad their breast feathers treated with 2.5 milliliters of
fuel oil and then were released. Forty-one percent of the eggs of this group
failed to hatch, while only 2% of the eggs of the control group failed.
Floating oil is less likeTy to contaminate the feathers of birds which spend
most of their time airborne Jfor example, gulls) than these which spend most
of their time swimming. So another approach to the question Involved captive
mallards. Two groups had their pools treated with high and low concentra-
tions of oil respectively. {''High" was defined as a thick slick, while "low"
was defined as a trace but visible amount.) A third group was used as a
control. Incubating females were allowed to swim 1n the oiled water. Hatch-
ing success of the group exposed to the low concentration was only slightly
less than the control group (85% compared to 95t), but quite low (45Jfj for
the group exposed to the high concentration of oil.
There also are effects of oil on embryos other than outright death. When
just one microliter of oil Is applied to day-old eggs, many of the embryos
survive, but a significant number of them have deformities that include bill
malformations, Incomplete bone formation, and stunted growth. Many of these
deformities, of course, would ultimately kill the chick.
EFFECTS OF OIL INGESTION
To assess the effects of Ingested oil, mallard ducks were fed quantities of
oili or toxic components of oil, 1n their regular diet. Doses represented
amounts that a duck conceivably could Ingest at the site of an oil spill.
The results indicate that adult birds are able to eat quite a large amount
of oil without exhibiting any ill effects. In fact, pt\ysiotog1cal tests
indicate that their liver function becomes more active and adequately com-
pensates for the addition of hydrocarbons 1n their systems. However, the
outcome was not so benign for ducks kept 1n a situation of "stress". Mal-
lards that were kept 1n salt water and in a cold environment {just a bit
over freezing) perished when they had oil added to their diets. Since the
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physiological systems of the birds were already working hard to handle the
environmental stress, the addition of the oil was, so to speak, the last
straw.
Mallard ducklings were fed oil in their diets froir the time of hatching to
eight weeks of age. There was no mortality among the chicks, but several
physiological changes were noted. Very small concentrations of oil damaged
the liver and kidneys. Certain behavioral reactions of the ducklings were
slower than normal, a factor which could affect their survival. At higher
concentrations, some birds failed to develop flight feathers, and their
growth was seriously inhibited. Presumably, the stunting of growth can be
expected to have serious consequences for aquatic bird species that go
through a post-fledging period when they are still being fed by the adults
but are learning to feed for themselves.
Some mortality is normal for young of even the most successful species. For
example, about a third of the young of certain gulls die during the month
when they become independent of their parents and another 20% die before
mid-winter. These proportions are even larger for birds such as ducks,
which lay more eggs in a clutch. For all species meeting these conditions,
as most aquatic birds do, the young which develop sooner and begin learning
to feed earlier are more likely to survive. We would expect, then, that
oil-induced retardation of development would ultimately increase mortality
of young birds.
While it has been shown that adult birds can generally ingest oil without
immediate illness or death, it is also important to know whether the oil
would affect their ability to reproduce. When a group of laying mallards
were fed traces of oil in their diets over a 90-day period, their egg pro-
duction dropped to 50% that of the controls. Production dropped to zero
when they were given another kind of oil. The petroleum seemed to retard
maturation of the egg cells. Also, vanadium, a metal component of many
crude oils, seems to interfere with calcium mobilization in laying female
ducks. Calcium mobilization is necessary for the formation of the egg shell
and growth of the embryo's bones.
TRANSMISSION OF OIL RESIDUES THROUGH THE FOOD CHAIN
Experiments were conducted with mallard ducks and freshwater crayfish to
learn if components of oil could be transmitted to the birds through eating
contaminated food items. Crayfish can be satisfactorily raised 1n captivity,
and are readily eaten by mallards. Some of the crayfish were kept 1n tanks
into which oil had been introduced. 011 was absorbed Into the exoskeleton
and flesh of crayfish, but evidence showed that their levels of contamina-
tion would decrease gradually if they were moved to clean water.
To examine whether oil absorbed by the crayfish was Incorporated and accum-
ulated by the ducks, a certain amount of the naphthalene components of the
oil was chemically "tagged" with a radioactive carbon Isotope. In this way,
any tissue of the ducks could be sampled for radioactivity; the amount of
radioactivity would correspond to the amount of tagged naphthalene they had
accumulated. The studies showed that naphthalene, one of the aromatic hydro-
carbons, was readily taken up by the ducks, and accumulated 1n several tis-
sues of their bodies.
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SUMMARY
The reproductive period, including the time of growth and development of the
young, is a highly sensitive time for any animal when physiological systems
are acting at critical rates. Any slight interference, such as the addition
of a stressful or toxic agent is likely to be disastrous. It has been de-
monstrated that exposure of adult waterbirds or their developing young to
slight amounts of petroleum can seriously interfere with the reproductive
process. Effects can range from interference with the physiology of repro-
duction to killing of embryos, production of developmental defects, stunting
of growth and impairment of survival ability when birds are stressed. Oil
can"be taken up by adults in their food or picked up on their feathers, and
from them can be transferred to eggs or nestlings.
Managers should be conscious of these effects, which though less apparent in
nature, may in fact be more serious than the infrequent ki11-offs occurring
after catastrophic spills. For it may well turn out that a chronic reduc-
tion in reproductive success may be the most significant effect of oil
pollution on populations of aquatic birds.
REFERENCES
Stickel, L.F. and M.P. Dieter. 1979. Ecological and physiological/ toxlco-
logical effects of petroleum on aquatic birds. U.S. Fish and Wildlife
Service, Biological Services Program. FWS/OBS-79/23. 14 pp.
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