Type: Game
Species: Anas rubripes
Common Name: Black Duck
The American Black Duck is a species of duck that closely resembles female
mallards. The black duck is mostly dark brown in color with some black, has short legs, a
yellow/green bill which looks duller on the females than does the males, and also the
males have a blue patch bordered with black on its wing. There are other species of duck
that look similar, for instance the Mottled duck and the Gadwall. (8) Both the male and
female look very similar with the females being a lighter tone and both have the a lighter
head and neck than the rest of their body. The average size for the black duck is 20-24
inches in length and weighs around 2.5lbs. (24)
The Black duck is a dabbling species of duck meaning that they tip their head into
the water and lift their tails up in the air in order to search for food in the water or mud.
As with other dabbling duck species the black duck takes off straight from the water to
fly which is much different than diving ducks in that they have to run across the water to
pick up enough speed to fly. (23)
Ecosystem association(s)
Black ducks prefer living in coastal brackish marshes and bays not far from
agricultural lands, focused near the water. They also favor wooded areas and will nest in
many different types of housing such as old bird nests, muskrat lodges, on the ground or
in tree cavities. Black duck also prefer being close to the edge of some body of water but
can be found as far as one-half mile from the water’s edge. (1)
Black Duck seem to be able to adjust to noise that they hear on a continuous basis,
such as aircraft near an air base, better than other species like the wood duck (Conomy.)
This idea may suggest that the black duck (anas rubripes) may have more habitat
availability if they can become accustomed to loud noise. (10) As noted in research
dealing with noise effects on black duck populations it has also been found that hiking
trails, 1 trail, near nesting areas may not directly affect nesting site success. Variables
such as type of habitat that an area is in, predation rates, i.e. feral cats that have been
accidentally released into an area with a nesting site, and the amount of cues from
humans being near a site may affect nesting rates (Olson.) (11)
Population Ecology
Black Ducks pairs are usually formed by autumn but can continue into winter,
with nesting periods going from March through June, and incubation periods lasting 2333 days. Seven to 12 eggs usually make up the clutch size, however if a clutch is
destroyed birds may renest. The Fledge period usually lasts 8-10 weeks and maturity is
reached at 1 year. (1) Pair bonds may be broken at varying times, with males typically
remaining with their females about 2 weeks into the incubation period. (23)
Black duck mostly migrate along the Atlantic Coast from Maine to Florida, with
most being found on coastal wetlands. Large amounts of the black duck seem to gather
between Long Island and North Carolina for their Wintering grounds. When Black duck
are away from the coast, they seem to use large river valleys such as those of the
Tennessee, Detroit and upper Illinois rivers. (6)
The Black duck species seems to show dominance toward other individuals of the
same species according to age class, whether or not individuals have a mate, and the sex
of the individuals (Hepp.) (9)
Of the approximate 220,000 black duck that are counted for in the winter survey
around 20,000 of those reside in the Chesapeake Bay area and along the eastern shore of
Virginia, which are both wintering areas for black duck. Although the Eastern shore of
Virginia is considered a wintering area it is also on the Southern edge of the black duck
breeding territory. There are challenges to productive black duck breeding habitat that the
species continues to face including: land use changes, erosion of marsh areas, and
increases of predator communities. (19)
Average survival for male and female black ducks banded as adults show that in
North Carolina the mean survival rates are as follows: adult males: 68.5% and adult
females: 50.6%. The annual recovery rates for male and female black duck are as
follows: adult males: 2.8% and adult females: 3.3%. Winter bandings show rates for adult
male black ducks in North Carolina as follows: Canadian Recovery Rate: 0.5%, U.S.
Recovery Rate: 2.6%, Average Mortality Rate: 31.5%, Canadian Kill Rate: 1.9%, U.S.
Kill Rate: 7.8%, Due to Hunting: 30.8%. (21)
Food and Cover (including predators and predation)
Black ducks use a wide assortment of habitats and because of this it is difficult to
determine specific requirements on a wide standard. Although as stated before these duck
prefer wooded areas over the related Mallards. Black duck also use marshes for brood
rearing and in the winter they congregate on large bodies of water on or near coastlines
focusing on the plant food. (2)
Active Beaver ponds are directly correlated to increasing brood sizes and this can
be credited as appropriate cover that has been formed from steady water levels. (5)
Depending on the area black duck ducks have a diet that is similar to mallards.
They consume plant seeds but not those used in agriculture. Some seeds in their diet
include: water smartweed, primrose-willow, wild-millet, and love grass, they also
consume other forms of vegetation and animal matter also makes up a part of their diet.
(14)
When black duck are using coastal marshes as their primary habitat they seem to
be more omnivorous than many other duck species, which dabble, by consuming
mollusks, crustaceans, and arthropods. Up half of their diet still consists of vegetable
matter, such as seeds and roots. (17)
Cover that black rely on depends on the area to which they are in and the time of
year, i.e. wintering season, breeding season, rearing season. Some cover types that black
duck rely on are: lakes or ponds with emergent vegetation, lakes with rocky shores, lakes
with unconsolidated shores, lakes or ponds with aquatic vegetation, and estuarine
intertidal emergent areas. (20)
Coastal areas or areas that free of ice in the winter are required for feeding.
Protection from Winter Storms is another key element that the black duck needs such as
in open water or along high banks along open water or large estuaries. To ensure a
greater chance of survival by getting enough food and the right kind of cover the black
duck should go to both marine and estuarine habitats to have both variables offered. (22)
Diseases
The three most devastating diseases to affect the black duck species include: Duck
plague (a herpesvirus), avian botulism, and avian cholera. The National Wildlife Health
Center has recorded the percentages of duck mortality rates between the years of 19701997; duck plague: 27.3%, avian botulism: 22.7%, avian cholera: 3%, other causes: 47%.
Sarcosporidiosis, a body parasite, has been reported in muscle tissue of black duck
in Northern states. The nematode, which causes duckling mortality, also infects mature
animals. (3)
The duck plague virus is transmitted through direct contact with individuals who
have the disease or from direct contact with environments which harbors the virus,
particularly water, and vertical transmission of the herpes virus can occur. Usually the
disease is most rampant from late winter to late spring. The virus has also been detected
in healthy populations of wild non-migratory waterfowl, such as the Canada goose and
the Mallard. “The wild mallard has been identified as one of the primary waterfowl
species associated with the annual initiation of duck plague die-offs, especially in Britian”
(Van Dorssen and Kunst 1955). Black ducks are extremely susceptible to the virus, as
populations are often found intermingling with mallards. (15)
Economics/Management
As is the case with many game species, black duck management research and
conservation is heavily funded. In 2009 Partner Contributions to the Black Duck Joint
Venture Program (BDJV) collected $773,923 for research on Black Ducks, but total
contributions reached 1,881,838 USD (7).
Due to the heavy funding for black duck management, there are more management
practices in place for the species. For younger individuals of black ducks, regulations that
are more restrictive can decrease the amount of hunting pressure and thus lead to
increased survival rates. In aging populations the amount of survival plateaus and harvest
rates no longer play a role in adult individual survival (Francis). (12)
Another important aspect of black duck management is habitat conservation and
preservation. Although it is believed that habitat loss will affect black duck populations
the outcome is not known for the species in direct relation to how habitat changes, i.e.
forest removal, can affect the waterfowl populations (Rusch et al. 1989). (13)
Speculations can be made about the effect of habitat loss, but more research is still
needed for further study. Wetlands and other areas that black ducks are dependent upon
should be managed thoroughly to help in achieve healthy populations of the species.
Luckily, much of the land which black ducks are located is privately owned. This is
significant because private owners are an untapped resource for helping to manage the
black duck species. In addition to benefiting the waterfowl, private land habitat
management can help to improve the landowner’s view of the land’s natural value and
give landowner’s a better understanding of the land’s potential for future management
reference. Research has shown that black duck habitat “Management practices may
include moist-soil management of impoundments for invertebrate production, periodic
burning of Scirpus marshes for seed production and rejuvenation, and trapping programs
for targeted predator species” (Krementz). (18) Due to the sensitivity of black duck habitat, it
is crucial to use all resources to ensure conservation and protection.
A key aspect of managing any animal species is knowing the population size. This
information is used in order to find out births and deaths per year, and to manage the size
of the population. Despite this importance, it has been found very difficult to survey the
black duck species. One major factor for this inability to survey is due to their habitat,
such as boreal forests of Eastern North America. In order for wildlife managers to get
accurate estimates of total numbers for black duck that were harvested, killed, and those
that survived black ducks must be banded. To get a more accurate estimate the banding
must take place annually. (16)
In order to get a better understanding of black duck populations satellite telemetry
studies are being conducted to obtain data of movement patterns including: migration
routes, timing of migration, staging and stop-over areas, winter habitat use and breeding
grounds affiliations. (19)
Challenges (including climate change)
Though the Black Duck is not considered endangered the population has been on
the downturn especially since the 1950s. As with many other species humans are causing
extensive damage especially on breeding and wintering grounds. Black duck and
Mallards are also hybridizing in turn only declining the population of the true Black duck
even more. Presently some other threats on black duck populations include: acid
rain,pesticide use, invasive species and wetland filling for developmental use.
Future threats to Black Duck populations will include loss of habitat from sea
level rise and other habitat changes due to Global warming.(4)
In 1976 the secretary of the interior ruled that steel shot had to be used in areas
where lead poisoning was prevalent where 5% of the gizzards in the local harvest of
black ducks and mallards contained lead shot (Longcore et al. 1982). With the use of
steel shot the amount of lead in gizzards of the ducks were reduced to 34 percent. Even
with these positive notes ammunition manufacturers and waterfowl hunters greatly
opposed the steel shot policy due to crippling loss, gun damage, and cost.(5)
If food is available the body fat of black ducks will most likely remain constant, however
just as with other animal species changes in their surrounding environment, i.e. habitat loss
around a lake, forest or wetland, can also prevent black ducks from being healthy. During the
winter months black ducks seem to have a harder time keeping their body mass up due to the fact
that it is more difficult to forage during cold periods. (14)
Works Cited
1. Snyder, S. A. 1993. Anas rubripes. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire
Sciences Laboratory (Producer). < http://www.fs.fed.us/database/feis/>. Accessed 20 Sept 2013.
2. Spencer, Howard E. 1986. Black duck. In: Di Silvestro, Roger L., ed. Audubon Wildlife
Report. New York: The National Audubon Society: 855-869. [21635]
3. Longcore, Jerry R., Daniel G. Mcauley, Gary R. Hepp and Judith M. Rhymer. 2000. American
Black Duck (Anas rubripes), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell
Lab of Ornithology; Retrieved from the Birds of North America Online
4. Wells, V. (2007) Birder's Conservation Handbook: 100 North American Birds at Risk.
Princeton University Press, New Jersey.
5. Bolen, E.G., Robinson, W.L. 2003. Wildlife Ecology and Management. Fifth Edition.
University of North Carolina at Wilmington, North Carolina, and Northern Michigan University,
USA.
6. Ducks Unlimited. 2013. American Black Duck. <http://www.ducks.org/hunting/waterfowlid/american-black-duck>. Accessed 20 Sept 2013.
7. BDJV. 2009. BDJV 2009 Annual Report. Unpublished Report. 13 pages.
8. The Cornell Lab of Ornithology. 2011. American Black Duck.
<http://www.allaboutbirds.org/guide/American_Black_Duck/id>. Accessed 9 Nov 2013.
9. Hepp, G. 1989. Benefits, Costs, and Determinants of Dominance in American Black Ducks.
<http://www.jstor.org.prox.lib.ncsu.edu/stable/info/4534772>. Accessed 9 Nov 2013.
10. Conomy, J. 1998. Do Black Ducks and Wood Ducks Habituate to Aircraft Disturbance?
<http://www.jstor.org/stable/info/3802568>. Accessed 9 Nov 2013.
11. Olson, R. 1998. Effects of Human Disturbances on Success of Artificial Duck Nests
<http://www.jstor.org/stable/3802569>. Accessed 10 Nov 2013.
12. Francis, C. 1998. Effect of Restrictive Harvest Regulations on Survival and Recovery Rates
of American Black Duck. <http://www.jstor.org/stable/3802021>. Accessed 10 Nov 2013.
13. Nichols, J. 1991. Science, Population Ecology, and the Management of the American Black
Duck. <http://www.jstor.org/stable/3809533>. Accessed 10 Nov 2013.
14. U.S. Fish and Wildlife Service (USFWS). 2012. Tennessee National Wildlife Refuge. New
Program to Aid American Black Duck Research.
<http://www.fws.gov/tennesseerefuge/blackduckresearch.htm>. Accessed 10 Nov 2013.
15. Thomas, N.J., D.B. Hunter, and C.T. Atkinson., editor. 2007. Infectious Diseases of Wild
Birds. Blackwell Publishing Professional, Ames, Iowa, USA.
16. Rusch, D.H., C.D. Ankney., H. Boyd., J.R. Longcore., F. Montalbano. III., J.K. Ringelman.,
V.D. Stotts. 1989. Population Ecology and Harvest of the American Black Duck: A Review.
<http://www.jstor.org/stable/3782702>. Accessed 10 Nov 2013.
17. BirdWeb. 2013. homepage.
<http://http://www.birdweb.org/birdweb/bird/american_black_duck>. Accessed 10 Nov 2013.
18. U.S. Fish and Wildlife Service (USFWS). 1990. American Black Duck Anas rubripes.
Patuxent Wildlife research Center Laurel, Maryland.
<http://www.dnr.state.md.us/irc/docs/00000260_16.pdf>. Accessed 11 Nov 2013.
19. Virginia Department of Game and Inland Fisheries. 2013. American Black Duck Anas
Rubripes. <http://www.dgif.virginia.gov/wildlife/waterfowl/black-duck/>. Accessed 11 Nov
2013.
20. U.S. Fish and Wildlife Service (USFWS). 2001. Gulf of Maine Watershed Habitat Analysis.
American Black Duck Habitat Model.
<http://www.fws.gov/r5gomp/gom/habitatstudy/metadata/black_duck_model.htm>. Accessed 11
Nov 2013.
21. U.S. Fish and Wildlife Service (USFWS). 1992. Population Characteristics and Simulation:
Modeling of Black Ducks.
<http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=0CHsQFjAJ&
url=http%3A%2F%2Fwww.dtic.mil%2Fcgibin%2FGetTRDoc%3FAD%3DADA322806&ei=RzNUrHOItSssATqo4HACg&usg=AFQjCNF5s-MzaD7Y1CfMAqi1gM0E21x0A&bvm=bv.56643336,d.cWc>. Accessed 11 Nov 2013.
22. Byerly, T., Fabritius, S,. 2013. Kids’ Inquiry of Diverse Species. American Black Duck.
<http://www.biokids.umich.edu/critters/Anas_rubripes/>. Accessed 11 Nov 2013.
23. New Hampshire Public Television (NHPTV). 2013. Nature Works. American Black Duck.
<http://www.nhptv.org/natureworks/americanblackduck.htm>. Accessed 11 Nov 2013.
24. Fuller, J., 2011. North Carolina Wildlife Resource Commission: Black Duck: North Carolina
Wildlife profiles.
<http://www.ncwildlife.org/Portals/0/Learning/documents/Profiles/blackduck091411.pdf>.
Accessed 11 Nov 2013.
Type: Game
Species: Sylvilagus palustris
Common Name: Marsh Rabbit
Marsh rabbits are medium-sized nocturnal rabbits with short, rounded ears and small feet.
Adults can range from 14-16 inches and weigh 2-3.5 pounds. The rabbits are dark brown to
reddish brown in color with a dark color belly. The distinguishing trait that separates the species
from other cottontails would be the dark color of the underside of their tail; underneath other
cottontail rabbit tails is white in color. This rabbit has three subspecies: the Carolina Marsh
rabbit (Sylvilagus palustris palustris), Florida Marsh rabbit (Sylvilagus palustris paludicola) and
Lower Keys Marsh rabbit (Sylvilagus palustris hefneri). The Lower Keys subspecies S. p. hefneri
is the most identified subspecies. (1, 2)
Ecosystem association(s)
The marsh rabbit’s range is restricted to the Coastal Plain of the southeastern U.S. It can
be confined solely to marsh habitats starting from the Dismal Swamp of southeastern Virginia,
through eastern North Carolina, southeastern South Carolina, southern Georgia, southern
Alabama, and most of Florida (Chapman and Willner 1981; Chapman and Ceballos 1990). S. p.
hefneri can be found exclusively in the Upper and Lower Keys of Florida. These rabbits are also
most commonly found in brackish water areas, although at one point in time they were
associated with freshwater marshes (Chapman). Unlike most rabbits, the marsh rabbit requires
close access to water.
Population Ecology
To date, little is known about the population size of the marsh rabbit. The marsh rabbit
does not have a long lifespan; it is said to only live up to 4 years of age in the wild but one
specimen at about 7 years old has set the captivity age maximum. The Lower Keys marsh rabbits
were reported to be unevenly distributed throughout the Lower Florida Keys and have been listed
on the IUCN Red List as an endangered species. The cause of the decline in this subspecies
appears to be a result of habitat fragmentation and relatively small, isolated subpopulations (5).
These rabbits breed all throughout the year and with multiple partners during the
breeding season. Researchers and scientists have categorized their unique breeding behavior as
promiscuous. The female rabbit will average 6 liters per year with anywhere from 2-5 offspring.
Although these animals mate all year long, the Lower Keys marsh rabbit appears to have the
highest proportion of females with litters in March and September. The offspring are altricial blind, and completely helpless. Their eyes do not open until they are about 4 to 5 days old, and
the juvenile rabbits are nursed until they are 14 to 15 days old. Due to this behavior, the juveniles
are more susceptible to predation. This is the reason why a large percentage of marsh rabbits do
not survive past the age of one year (6; Chapman and Feldhamer, 1982, Jones, 1997).
Food and Cover (including predators and predation)
While herbivores have similar diets, there are many variations in the selection and eating
habits between different species. Specifically, in marsh rabbits, which are herbivores, select
different species of plants depending on the season. Selection is based on what is available to the
rabbits, and what will sustain the rabbits nutritionally. Studies have shown that marsh rabbits
tend to select plant species such as centella, marsh pennywort (Hydrocotyle sp.), cattail, rush
(Juncus sp.), and water hyacinths (Piaropus crassipes) (Chapman and Willner 1981). Their diet
may also consist of blackberry, greenbrier, and other woody and semi-woody plants. Food
selection can also vary on the location of the rabbits. For example, in the Florida Keys over 70%
of the marsh rabbits in a study had diet consisting of two grasses (Sporobolus virginicus and
Spartina spartinae), a succulent shrub (Borrichia frutescens), and one tree species (Laguncularia
racemosa) (Chapman and Feldhamer, 1982). While the specific species of plant selected by the
rabbits can vary based on location, during the winter when green vegetation is scarce marsh
rabbits resort to eating bark. When conditions are especially harsh, marsh rabbits will resort to
eating their own feces, a process known as coprophagy, in order to retrieve extra nutrients. In
addition to the variation in the selection of nutrients, Marsh rabbits are nocturnal in nature and
tend to feed only at night. This adaptation can reduce predation upon the species, ultimately
increasing survival rate.
Marsh rabbits require specific habitat requirements for a successful and healthy
population. In Florida, adult marsh rabbit populations seem to establish their nesting areas/home
ranges in small patches of habitat. Generally, the female constructs the nests out of soft grasses
and its own fur. In addition, nests are most often found along the water’s edge. This is an
important requirement because it allows the rabbits ready access to a water source. In fact, this
habitat requirement is so heavily preferred that the rabbits have adapted to have characteristics
such as furless feet with long claws. These adaptations lead to the behaviors such as submerging
themselves in the water, and only keeping its nose and eyes above the surface. (6) This
swimming technique allows the rabbits to escape quickly from predators. Furthermore, the marsh
rabbit will find habitat in hollow logs, groups of cattails, grasses, dense thickets and abandoned
burrows (6).
The marsh rabbit has two main predators that impact their population, the great-horned
owl (Bubo virginianus) and the marsh hawk (Circus cyaneus). Infant and juvenile marsh rabbits
are also often prey of the Eastern diamondback rattlesnakes (Crotalus adamanteus) and water
moccasins (Agkistrodon piscivorus). Other less common predators include bobcats (Lynx rufus),
barn owls (Tyto alba), barred owls (Strix varia), red-tailed hawks (Buteo jamaicensis), bald
eagles (Haliaeetus leucocephalus) and red wolves (Canis rufus). While red wolves have only
recently been reintroduced, studies have shown that marsh rabbits are the more heavily preyed
upon in the areas where the wolves have been reintroduced (Chapman and Willner 1981; Jones,
1997; “Virginia Department of Game and Inland Fisheries, 2007”). Despite the marsh rabbits
nocturnal habits, they are still a major food source for other species higher in the trophic level.
Diseases
Marsh rabbits tend to be hosts to the ticks, fleas, rabbit ticks and warble flies (8). The
rabbit tick is said to be the main vector of the disease tularemia but other ticks and fleas can
carry the disease. As stated by the Centers for Disease Control and Prevention, tularemia is
caused by the bacterium Francisella tularensis. Also, it states this disease is zoonotic, therefore
humans are susceptible to infection as well. Transmission can be through direct contact with the
flesh or blood of an infected rabbit, even rabbits that are not properly cooked can transmit the
disease. Typical symptoms include sudden fever, chills, headaches, diarrhea, joint pain, muscle
aches, dry cough and progressive weakness. This disease can even cause the development of
pneumonia. Though this disease has only about a 7% fatality rate in humans, tularemia is fatal to
rabbits (Chapman and Feldhamer, 1982; 14).
Marsh rabbits are also the host of ticks that carry Rocky Mountain Spotted fever. CDC
states this disease is caused by the bacterium Rickettsia rickettsii and can potentially fatal to
humans. This bacteria can be transferred into humans through the bite of an infected tick species.
Typical symptoms include a fever, headache, abdominal pain, vomiting, and muscle pain.
Though absent the first few days, a rash may develop as well. (Chapman and Feldhamer, 1982;
Jones, 1997, 14).
Economics/Management
The United States Fish and Wildlife Service listed the Lower Keys marsh rabbit
subspecies in 1990 as endangered. The current population size has not been estimated, but The
United States Fish and Wildlife Service (1999) is currently developing a recovery plan for the
subspecies. Since the marsh rabbit’s population has been declining due to habitat loss and
fragmentation, it is best to target these areas when developing and implementing a management
plan.
There are two different levels that need to be targeted when managing; the species level
and the habitat level. For the species level, information is needed on the distribution and status of
the marsh rabbit. Specifically, the population of the marsh rabbit needs to be determined and
consistently known in order to develop any effective management practice. The best way to gain
more information on this subject would be to conduct more aerial and ground surveys that
demonstrate a distinct range of the marsh rabbit. In addition, it would be beneficial to conduct
absent and present surveys throughout the different seasons to determine when the species
occupies certain areas during a specific time. Keeping the marsh rabbit protected under the law
will help prevent a decline from human made fragmentation. Lastly for species level
management, regulation of poaching, hunting and predation need to be implemented by creating
boundaries and limits (13). For example, in South Carolina hunting is controlled by the
Department of Natural Resources, where they have a bag limit set of 5 rabbits (6).
Habitat level management should begin with the prevention of degradation of todays’
marsh rabbits habitat. There should be a type of protection and management of the areas that
these rabbits are present on. Rules and regulations need to be set for both public and private
lands. Also being that the numbers of rabbit habitat sites are relatively low for the Lower Keys
subspecies, some sites need to be created or restored. In order to do this information on how a
specific habitat affects the survival, distribution and abundance of the marsh rabbit needs to be
researched and verified (13).
On both levels, public awareness and installing a stewardship should be done to get the
participation of the landowners. The more help from people the more knowledge and
effectiveness there will be in managing for this species (13).
Challenges (including climate change)
The marsh rabbit is classified as an endemic species. Thus, meaning this species has
“evolved in an environment with reduced levels of competition, predation, and disease, and are
thus more susceptible to extinction.” (13)
Works Cited
1.
Bachman, J., 1837. Description of a new species of hare found in South Carolina. Journal of
the Academy of Natural Sciences of Philadelphia, 7:194-199.
2.
Bowers, N., Bowers, R.; Kaufman, K. (2007). Kaufman Field Guide to Mammals of North
America (12th ed.). Houghton Mifflin Harcourt. p. 26.
3.
Centers for Disease Control and Prevention [CDC] < http://www.cdc.gov/>. Accessed 15 Nov
2013.
4.
Chapman, J., Feldhamer, G. 1982. Wild Mammals of North America. Baltimore, Maryland,
USA: The Johns Hopkins University Press.
5.
Chapman, J, A and Willner, Gale. 1981. Sylvilagus palustris. Mammalian Species 153: 1-3.
6.
Encyclopedia of Life. Sylvilagus palustris Marsh Rabbit. <http://eol.org/pages/115738/details>.
Accessed 15 Nov 2013./
7.
Faulhaber, C. A. & Smith, A. T. (2008). "Sylvilagus palustris". IUCN Red List of Threatened
Species. Version 2011.2. International Union for Conservation of Nature.
<http://www.iucnredlist.org/details/41303/0>. Accessed 01 Nov 2013.
8.
Jones, M. 1997. "North Carolina Wildlife Profiles" (On-line). Wildlife Profiles: Marsh Rabbit,
Sylvilagus palustris.
<http://www.ncwildlife.org/pg07_wildlifespeciescon/Profiles/rabbitmarsh.pdf>. Accessed 26
Oct 2013.
9.
Nelson, E, W. 1909. The Rabbits of North America.. North American Fauna: Number 29: pp. 1
– 314.
10. Red Orbit: your Universe Online. Marsh rabbit Sylvilagus palustris.
<http://www.redorbit.com/education/reference_library/science_1/mammalia/1112527873/marshrabbit-sylvilagus-palustris/>. Accessed 15 Nov 2013.
11. Thompson, leah. Animal Diversity Web. Sylvilagus palustris Marsh Rabbit.
<http://animaldiversity.ummz.umich.edu/accounts/Sylvilagus_palustris/>. Accessed 15 nov 2013.
12. Tomkins, I. R. 1935. The marsh rabbit: an incomplete life history. J. Mamm., 16:201-205.
13. U.S. Fish & Wildlife Service. (1999, May 18). Lower Keys Rabbit Sylvilagus palustris hefneri.
Retrieved from Multi-Species Recovery Plan for South Florida:
<http://www.fws.gov/verobeach/MSRPPDFs/LowerKeysRabbit.pdf>. Accessed 15 Nov 2013.
14. Virginia Department of Game and Inland Fisheries. 2007. Marsh Rabbit (Sylvilagus palustris).
<http://www.dgif.virginia.gov/wildlife/rabbit/marsh-rabbit.asp>. Accessed 12 Oct 2013.
Type: Endangered
Species: Glaucomys sabrinus coloratus
Common Name: Carolina Northern Flying Squirrel
The Carolina Northern flying squirrel is a small, nocturnal rodent. A subspecies of the
Northern flying squirrel, it is found across southern regions of the Appalachian mountains, more
specifically across North Carolina, Tennessee, and Virginia. As the name describes, the squirrel
can “fly,” but perhaps glide is a better word. A lightly furred membrane, attached along the
sides, arms, and legs of the animal, flattens out and allows the squirrel to move efficiently from
tree to tree. Unfortunately, this squirrel is not able to “flap” its webbing and begin flying from
any location; it has to have momentum and the help of gravity to glide to it’s desired destination.
Biologists first noted the presence of the Carolina Northern flying squirrel in North
Carolina in the 1950’s, but before then it had been presented in other states, namely Virginia.
Ecosystem association(s)
The Carolina Northern flying squirrel prefers high-elevation forests of the mountain
ranges it resides in, most often in hardwood and spruce/fir conifers (Currie). The forest or stand
usually will contain old trees and debris on the forest floor, both characteristics that are specific
to an old-growth forest. Because of the different aspects required by the squirrel in a habitat, it’s
range in North Carolina, Tennessee, and Virginia is limited. Northern Hardwood and
Spruce/conifer forests found at the elevation best suited to the squirrels; usually above 4500 feet;
are increasingly rare, due to the previous and current value of those wood types, and with clearcutting of forests in general (Currie). Most large populations of the close relative, Glaucomys
Sabrinus, are found in old-growth stands, as these forests are generally more suited to producing
the mycorrhizal fungi component of the squirrels diet. Although this research was collected
using a relative of the Carolina Northern flying squirrel, it is generally accepted that the eating
patterns would be similar. It is not believed that the Carolina Northern Squirrel absolutely must
live in an old growth forest, especially if the new-growth forest contains at least some trees with
old-growth characteristics. Individuals captured and scat samples found in new growth forest
suggest a lower intake of fungi, but overall health was not affected (Rosenberg.)
Population Ecology
Nest sites and relative distance are used to define populations. The actual distance varies
based on the regions and states where the squirrels are nesting. It has been proposed that many
different types of squirrels, not only the Carolina Northern flying squirrel, use multiple nests
either as an adaptation to food availability and location, or as a predator avoidance method
(Carey.) Female and male squirrels nest separately, and in sites located in Virginia, researchers
found that males tend to have further distances between nests than do females. It is believed that
this leads to a greater amount of prospective reproductive experiences, and may even be an
adaption for such reason (Hackett.)
In areas of Virginia where the range of the Virginia Northern flying squirrel overlaps the
range of the Carolina Northern flying squirrel, researchers have found evidence that both species
eat and compete for the same types of sporocarps and fungi (Mitchell.)
Food and Cover
The main constituents of the Carolina Northern flying squirrel’s diet are lichens and
mosses, but it will eat insects, seeds or other types of vegetation (Fact Sheet). Hypogeous
sporocarps of mycorrhizal fungi, or truffles, are thought to make up a portion of the Northern
Flying squirrels a close relative that lives in Oregon and other western states. It has been
researched and deduced that these truffles are not as vital to the Carolina northern flying
squirrels that reside mostly in Appalachian areas (Loeb et al.) Evidence supports a theory that
G.s coloratus may forage for fungal food material underground during the winter (Parrish).
The typical nest of a squirrel would be found in a tree cavity of the Northern Hardwoods.
Summer nests may be built of leaves and found in foliage of conifer trees, or the nest from the
winter can be maintained. Squirrels are not limited to only cavities in trees; nest were found in
the crooks of large limbs and the trunk, in stick nests, and in moss nests (Cowan.)
In Oregon, the most notable predator of the Northern flying squirrel is the Spotted owl. It
is thought that the predation from this species affects the population in an additive mortality
manner, not a compensatory one. Although the owl population and species varies greatly in the
Appalachian mountains versus Oregon, it can be inferred that some Carolina Northern Squirrel
populations suffer losses due to owls.
The G.s. coloratus is considered predominantly a herbivore, meaning that most
everything consumed by the animal is of plant origin, and not animals or insects.
Diseases
Although it has not been specifically reported in the Carolina Flying squirrel, Sylvatic
Typhus is an infectious disease that is associated with flying squirrels and/or contact with their
nests. It is not known whether or not the Glaucomys sabrinus coloratus is a host for the bacteria
Rickettsia prowazekii, but close relatives to the squirrel are frequent hosts. These bacteria can be
transferred to humans, and can cause symptoms such as fever, headache, muscle aches, and
confusion. The epidemic and louse-borne strain of typhus is usually seen in times of social unrest,
natural disasters, or wars. Currently it has not been determined why the two strains differ in
severity from the Sylvatic Typhus. However, the risk of infection is correlated with the exposure
time with the squirrel. As with any disease persons with compromised immune systems are at the
greatest risk. Sylvatic Typhus is diagnosed with a blood test, and is treated with antibiotics. No
deaths have been reported since the recognition of the diseases in 1976 (Sylvatic Typhus Fact
Sheet.)
In addition to Sylvatic Typhus, Carolina Northern flying squirrels suffer from rabies. No
occurrence of rabies has been found with the Carolina Northern flying squirrel, but that is not to
say it has not happened. In a normal day the squirrel typically would not be viewable by standard
eyes, as it is nocturnal. Ecologists must work to know the location of nest sites and are then able
to observe the animals, but no records of rabies could be located.
Economics/Management
Habitat and diet are often considered together when considering management practices,
because they are two of the most important, if not the most important aspects when it comes to
any animal. These squirrels are limited to a very specific rangeland, and this may be caused by a
stenophagic diet. Stenophagy refers to eating only a few types of food. If Carolina Northern
flying squirrels only eat a few types of lichens, then of course it would live where those lichens
grow. On the other hand, a restricted range may cause stenophagy, meaning that the squirrel
adapts to eating things that occur in its habitat. Ecologists prefer to think of these together, as it
is often impossible to know which caused the other, or if they occurred simultaneously. It’s
often easier to manage a species by considering these factors as if they are one. In almost every
circumstance, the health of the habitat is positively correlated with the amount of food growing
or living in the ecosystem.
The species from which the Carolina Northern flying squirrel is a subset, the Northern
flying squirrel and its close relative the Southern flying squirrel; are often managed to reduce the
risk of typhus and overall parasite spread. Both of these populations occur in higher numbers
and have larger ranges than the Carolina Northern flying squirrel, so problems are more likely to
occur. Human-animal interaction incidents have occurred with these more popular species, most
commonly when the squirrel chooses to nest in a human dwelling, such as in the attic.
Nest boxes are often used to encourage the Carolina Northern flying squirrel to reside in
an area that it may not normally, or to increase the population in an existing residential area.
Nest boxes can include but are not limited to owl nest boxes, blue-bird nest boxes, and even
gourds at times. Animals that are rehabilitated and re-introduced into the wild are often
introduced with a nest box.
Challenges (including climate change)
Due to the degree of selectivity for the Carolina Flying Squirrels’ nest area they have
been strongly affected by tree loss, such as deforestation. While some tree loss can be accounted
for by obvious means such as clear-cutting and the removal of trees to build residential areas;
some loss is caused by less obvious suspects. The balsam wooly adelgid is an insect introduced
to North America from Europe in the early 1900’s. This insect bores into the main bark and
stem of the fir tree, leaving it injured and highly susceptible to other tree-degrading fungi and
eventually death (Ragenovich 2006.) The United States Fish and Wildlife service recognized the
Carolina northern flying squirrel as endangered in July of 1985, and it remains on the endangered
species list today (U.S. Fish and Wildlife Service, 1990.)
Hybridization is a main concern for these squirrels as their natural habitat continues to
change. As the weather fluctuates year to year, and even decade to decade, animals including the
Carolina Northern flying squirrel adapt by possibly changing the area in which they live. This
causes great concern if the new areas overlap to a native species, as characteristics of an invasive
animal may develop. Although humans are not directly placing the species into it’s new location,
climate change is directly correlated with global warming, which has been linked to human
activities. An invasive species may not only compete with the native, it may attempt to
reproduce and form a new species, or a hybrid species. It is not fully known whether or not the
Carolina Northern flying squirrel has had this issue previously, but research in the Northwestern
part of the United States suggests hybridization of the Northern flying squirrel and the Southern
flying squirrel. Evidence has however shown that genetic variability within the Northern flying
squirrel is high when compared to that of the Southern flying squirrel. Many accept this to mean
that very few, if any, bottleneck incidents have occurred. A bottleneck is when two groups of the
same species are separated by some means, and eventually adapt into two different species
(Arbogast.)
Because funding to research this animal was not granted until 1985 when it was officially
placed on the endangered list, little is known about it. Much more has been presented on close
relatives such as the Virginia Northern flying squirrel (Glaucomys sabrinus fuscus) and the
southern flying squirrel (Glaucomys volans.) Ecologists and wildlife managers are currently
working together to determine the best management practices to re-populate the regions with
these squirrels, but many factors are involved. Deforestation and competition from other squirrel
species are just two of the challenges faced by Northern Carolina flying squirrels. When
managing to increase the population of a species, it is best to use the bottom-up approach, that is
manage what the species eats instead of managing what eats the species. The problem many are
running into is how to manage specifically just for the Glaucomys sabrinus coloratus, when other
species have overlapping ranges and habitats. In order to manage in the most efficient way, the
entire community must be considered before any actions are taken.
Works Cited
1. Arbogast, B.S Et al. 2005. Conservation genetics of endangered flying squirrels (Glaucomys)
from the Appalachian mountains of eastern North American. Animal Conservation 8:123-133
2. Carey, A. B. 1995. Sciurids in Pacific Northwest managed and old-growth forests. Ecol. App.,
5:648–661.
3. Cowan, 1. M. 1936. Nesting habits of the flying squirrel Glaucomys sabrinus. Journal of the
Mammal. 17: 58-60.
4. Currie, R., and Cameron, S. 2011. Carolina Northern Flying Squirrel 5 year review: summary
and evaluation. U.S. Fish and Wildlife Service, Southeast region, Asheville Ecological Services
Field Office, Asheville, North Carolina, USA.
5. Garroway, C.J. 2010. Climate change induced hybridization in flying squirrels. Global Change
Biology 16:113-121.
6. Hackett, H.M., and Pagels, J.F. Nest site characteristics of the Endangered Northern Flying
Squirrel (Glaucomys sabrinus coloratus) in Southwest Virginia. American Midland Naturalist
150:321-331
7. Loeb, S.C., Tainter, F.H., and Cazares E. 2000. Habitat Associations of Hypogeous Fungi in
the Southern Appalachians: Implications for the Endanered Northern Flying Squirrel
(Glaucomys sabrinus coloratus) The American Midland Naturalist 144(2):286-296.
8. Mitchell, D. Et al. 2001. Spring and Fall Diet of the Endangered West Virginia Northern
Flying Squirrel (Glaucomys Sabrinus Fuscus) American Midland Naturalist. 146:49-443.
9. Parrish, N.A. 2012. Habitat Analysis of a disjunct population of the Carolina Northern Flying
Squirrel (Glaucomys Sabrinus Coloratus.) Thesis.
10. Ragenovich, I.R., and Mitchell, R.G. 2006. Balsam Wooly Agelgid. Forest Insect and
Disease Leaflet. U.S. Department of Agriculture Forest Service
11. Rosenberg, D.K., and Anthony, R.G. 1991. Characteristics of Northern Flying Squirrel
populations in young-second and old-growth forests in western Oregon. Canadian Journal of
Zoology 70: 161-166.
12. U.S. Fish and Wildlife Service. 1990. Appalachian Northern Flying Squirrels (Glaucomys
sabrinus fuscus and Glaucomys sabrinus coloratus) Recovery Plan. Newton Corner, MA. pp 53.
13. Zimmerman S, Elizabeth A. S Flying Squirrels in nest boxes. sialis.org, Woodstock CT.
Retrieved from Sialis online: http://www.sialis.org
14. Northern Flying Squirrel Fact Sheet. North Carolina Wildlife Resources Commission
15. Sylvatic Typhus Fact Sheet. Pennsylvania Department of Health.
Type: Other
Species: Pelecanus occidentalis
Common Name: Brown Pelican
Adult Brown Pelicans can be described as large, well built seabirds approximately 39.453.9 in in length. The pelicans have thin, long necks, long bills with a stretchy throat pouch used
for hunting their prey, and long, broad wings helpful for gliding. The typical wingspan for
Brown Pelicans is 78.7 inches, or 6.5 feet. Brown Pelican plumage consists of a yellow head,
white throats, reddish brown necks, and gray-brown wings and bodies. Juvenile Brown Pelicans
are gray-brown with a white belly and breast. (Cornell).
Ecosystem association(s)
Brown Pelicans have a broad range which extends through much of the south east and
south west United States, down into countries in both Central and South America. More
specifically the range extends from the west coast of California down to the coast of Ecuador, all
the way to towards Virginia. Brown Pelicans favor habitat in estuaries and other coastal marine
habitats throughout their range.
The migration patterns of Brown Pelicans are highly variable from resident to longdistant migrant and seasonal movements can vary depending on where in the range they are
living (Cornell), usually the warmer and more abundant the nesting ground, the less likely there
is to be migration. Many Atlantic populations will migrate northward for breeding season, which
is in the summer, and then return southward in the fall. Pacific populations leave California and
near by areas after breeding and migrate northward, even going as far north as British Columbia,
returning back to breeding areas in the winter (Cornell).
When not in nesting grounds Brown Pelicans are found on “offshore islands, beaches,
open sea (for feeding), harbors, marinas, estuaries, and break waters,” (U.S. Department of the
Interior). Overall, the Brown Pelican’s habitat and interaction with the ecosystem varies, and is
dependent upon whether it is breeding season for the birds.
Population Ecology
In addition to having variable locations of habitats throughout the year, Brown Pelicans
vary on the number of individuals within a colony. During the non-breeding seasons Brown
Pelicans will travel in small groups or pairs. However, during the breeding season pelicans will
travel to warm nesting grounds in large colonies. The number of nesting pairs depends on the
size of the island and the number of resources available, but can be anywhere from 900-4,600
pairs of birds (U.S. Fish and Wildlife Service).
The typical Brown Pelican nesting site is very specific and devoid of other live since
human and mammalian interference can lead to egg and nestling deaths. The distance from the
nesting island to mainland averages around 13km, with older and more persistent colonies being
more isolated than newer colonies (Visser et. al). Additionally, the average size for colonized
nesting islands of the Brown Pelicans was 36 ha (Visser et. al). Both the male and female
pelicans share the role of caretaker during breeding season, switching off between hunting and
watching over the nests.
Food and Cover
The main constituents of the Brown Pelican’s diet are small fish species, such as Gulf
menhaden, mullet, Atlantic threadfin, spot, and pinfish (Visser et. al). Brown Pelicans are one of
the most unique sea bird hunters. In fact, this species is the only pelican species that plunge dives
for food, regularly diving anywhere from 10-30 feet in the air, although heights have been
recorded up to 100 feet (U.S. Department of the Interior). The force of the impact from the
pelican’s dive stuns the fish so that the pelicans can scoop the fish into their mouth, and then the
pouch located inside of the mouth. The Brown Pelican’s pouch can hold up to 3 gallons of water
(U.S. Department of the Interior), allowing them to drain out excess water without losing their
prey. Typically, the pelicans hunt 5-40 miles from their colonies – only venturing out large
distances when absolutely necessary. All of the traits make the Brown Pelican a remarkable and
unique hunter.
As noted earlier, Brown Pelicans have specific nesting habitats. During breeding months,
the Brown Pelican can be found on colonized islands with “70% open water within 20 km
surrounding the island,” (Eggert et. al). This provides the pelicans with enough access to waters
for hunting, yet far enough away from the mainland to avoid predators and human disturbances.
Brown pelicans prefer nest in shrubs, however when shrub habitat is not available they will nest
on the ground or in dune habitats. When the Brown pelicans select dune habitat it is extremely
important that the habitat is at least 30 cm above mean seal level (Visser et. al) to help buffer the
nests from any stochastic events. In addition, it is crucial that the nesting colony sites have
beaches for adult pelicans to dry after prolonged time spent in the water. Adequate beach space
is also a key factor as fledglings can develop better flying skills in a safe place; not enough space
on the island could force the birds into the ocean where they are at a high risk for predation.
Research has show that “an average beach width of 33m at colonized islands” (Visser et. al) was
required for a successful colony. Due to the unique nature of nesting sites for Brown Pelicans,
specific criteria are needed for successful breeding.
Additionally, Brown Pelicans choose colony locations that are devoid of predators. The
selection of smaller islands lacking large amounts of vegetation usually allows for the absence of
predators in breeding grounds, however a few colonies are prone to predation. While there may
be the presence of small mammals like rats, they do not pose a significant threat to the
reproductive success of the pelicans (Visser et. al). Real threats are posed by coyotes, dogs,
bobcats, and in some cases mink (Visser et. al). In the cases where there is the threat of predation,
the colony will be abandoned after a few, likely unsuccessful breeding seasons.
Diseases
One disease faced by brown pelicans is parasitism of the soft tick Carios capensis on
nestling pelicans. The soft tick can successfully reproduce to high densities in the nesting
materials of brown pelicans during their breeding season. The tick’s ability to breed intensively,
coupled with high number of nesting adults and the long-term time periods of nesting locations
makes infestation between nests especially high (Norcross et. al). Due to the vulnerable state of
the nestling pelicans they are more prone to parasitism in an infected nest than the adults (Eggert
et. al). Once a nestling pelican is infested with the ticks, they then deplete the energy reserves of
the young birds and can cause serious depletions in body mass and high increases in the stress
and ultimately the production of the hormone corticosterone (Eggert et. al). While in small
quantities this hormone can cause behaviors which increase survival, prolonged secretion can
lead to suppression in the immune system and catabolism in the muscle (Eggert et. al). Prolonged
parasitism by the ticks can also release the stress response in adult pelicans. In adults “high
levels of C. capensis infestation in pelican colonies have been associated with the abandonment
of nests and desertion of young,” (Duffy). Overall, the soft ticks have the potential to seriously
affect the nestling survival for the brown pelican.
Another common disease found in Brown Pelicans is parasitism by parasitic worms. As
many other species of birds the brown pelican is a terminal host for parasitic worms, specifically
Petagiger sp., Echinochasmus sp., Phagicola longus, Mesostephanus appendiculatoides,
Contracaecum multipapillatum, and C. bioccai (Oswald). Many of these worms are ingested
from their prey, especially from mullets. The parasitic worms live in the intestine of the brown
pelicans, however they do not pose serious negative impacts on healthy pelicans. Unhealthy
brown pelicans are drained nutritionally and are put at a higher risk for infections and additional
pathogens (Oswald).
Overall, brown pelicans face diseases typical of any avian species. Most of these diseases
do not affect the overall health of the adult pelicans, but can have a significant negative effect on
the nestling pelicans and can ultimately infestation of certain parasites can cause drastic
reductions in nestling survival rates.
Economics/Management
Due to effective management methods such as bird banding, protected nesting sites, and
artificial nest sites, the brown pelicans have recovered from their position as an endangered
species (Oswald). Management in North Carolina in particular varies because brown pelicans
weren’t reported until 1929 when 14 nests were found near Ocracoke in the Pamlico Sound
(Wilkinson et. al). Since the 1950’s the North Carolina Museum of Natural History (now NC
Museum of Natural Sciences) began banding pelican chicks. Then in 1972 J. Parnell and R.
Soots began banding and studying brown pelicans on a regular basis (Wilkinson et. al). This was
the beginning of the studying of the nature of brown pelicans and helped form the management
techniques used today.
Another helpful management technique is the protection of nesting sites. Despite the
distances from the mainland, human disturbance still affects many nestlings and nesting adult
brown pelicans. Mainly the people fishing in the surf disturb colony sites, and often times
anglers aren’t aware of the negative impacts their presence has on the colony. According to
research done, “human disturbance has been show to affect reproductive success of Brown
Pelicans,” (Visser et. al). Therefore, to prevent further human disturbances on the nests a 300 ft
buffer between the nests and human visitors are required (this is for both on land and in water)
(Visser et. al).
An additional wildlife management too, and perhaps the most successful practice is
adding dredged-material islands for the pelicans to nest on. In North Carolina the addition of
dredged-mateiral islands “was the beginning of a dramatic increase in nesting birds and nesting
sites,” (Wilkinson et. al). The coast of NC saw increases from 14 nests in 1942, to 1500 nests in
1978, and up to 3900 nests in 1991 (Wilkinson et. al). This is a clear indicator of the successful
habitat created by dredging.
Challenges (including climate change)
While there are many challenges facing the brown pelican today, few has had as great of
an impact as oil spills, erosion near nesting sites, ruined nesting sites, and over wintering. The
first of these problems, oil spills, have the greatest immediate impact on the species. Research
from an oil spill in 1982 from an unknown vessel shows the effects that oil spill can have on
Brown Pelicans. Approximately 80,000 gallons of No. 6 diesel oil were spilled in the Cape Fear
River estuary near Wilmington, North Carolina. According to the journal “the spill occurred 21
to 26 km upstream from two Brown Pelican… nesting islands on which 300 to 325 nests were
located. Most clutches had been completed with the oil spilled,” (Parnell et. al). While the spill
missed the island birds who were not trapped in the oil spill transferred oil from their feathers to
the eggs. Oil on avian embryos can have a huge effect on the success rates of the hatchlings, but
“sensitivity of avian embryos to oil contamination decreases with age of the embryo,” (Parnell et.
al). The scientists were able to date the contamination period of the eggs to around 2 weeks.
While there was significant decrease in the hatching success of the eggs, around 2.17 eggs
hatched per nest from the entire population (Parnell et. al), on a larger scale this could have a
detrimental effect on the entire population. There was a clear reduction in the hatching success of
Brown Pelican eggs after being exposed to the oil contamination from the plumage. According to
the article “Had eggs been oiled earlier in the incubation period and had a significant portion of
the colony been affected, the impact on reproductive success could have been much more severe,”
(Parnell et. al). As fossil fuel use in the US increases, there could be the potential for more spills
that could have a continued detrimental effect on the Brown Pelican species.
In addition to oil spills, Brown Pelicans face challenges climate changes. While these
threats are less transparent and harder to predict, there are still serious challenges that the brown
pelican species will have to face in the future due to the changing climate. Despite the pelican’s
ability to migrate between breeding and wintering habitat and ability to withstand higher
temperatures, if current increasing temperature trends continue the pelican’s breeding grounds
will become too thermally stressful to have successful reproduction rates. Breeding and
migrating uses considerable amounts of energy, nesting sites are fully exposed to elements, and
pelican’s are central foragers. All of these factors will increase thermal stress on the birds and
lead to undergo significant reduced reproductive success and ultimately affect the future of the
species (Oswald). Despite the variability in the predictions for climate change, it is clear that the
increasing temperatures at pelican breeding sites will have a significant negative effect on the
reproduction and success of nestling pelicans.
Works cited
1. Cornell University. 2011. The Cornell Lab of Ornithology.
<http://www.allaboutbirds.org/guide/Brown_pelican/id>. Accessed 19 Oct 2013.
2. D.C. Duffy. 1983. The ecology of tick parasitism on densely nesting Peruvian seabirds
Ecology, 64: 110–119.
3. Lisa M.F. Eggert, Patrick G.R. Jodice, Kathleen M. O’Reilly. 2009. Stress response of brown
pelican nestlings to ectoparasite infestation. General and Comparative Endocrinology, 166: 33–
38.
4. OSWALD, S. A. and ARNOLD, J. M. 2012. Direct impacts of climatic warming on heat
stress in endothermic species: seabirds as bioindicators of changing thermoregulatory constraints.
Integrative Zoology, 7: 121–136.
5. James F. Parnell, Mark A. Shields and Dargan Frierson, Jr. 1984. Hatching Success of Brown
Pelican Eggs after Contamination with Oil. Colonial Waterbirds 7: 22-24.
6. Jenneke M. Visser, William G. Vermillion, D. Elaine Evers, R. Greg Linscombe, and Charles
E. Sasser. 2005. Nesting Habitat Requirements of the Brown Pelican and Their Management
Implications. Journal of Coastal Research 21: 27 – 35.
7. N.L. Norcross, E.G. Bolen. 2002. Effectiveness of nest treatments on tick infestations in the
eastern brown pelican Wilson Bull., 114: 73–78.
8. Philip M. Wilkinson, Stephen A. Nesbitt, and James F. Parnell. 1994. Recent History and
Status of the Eastern Brown Pelican. Wildlife Society Bulletin 22: 420-430
9. U.S. Department of the Interior. 2013. National Park Service.
<http://www.nps.gov/chis/naturescience/brown-pelican.htm>. Accessed 19 Oct 2013.
10. U.S. Fish and Wildlife Service. 2001. Southeast Louisiana National Wildlife Refuges. Brown
Pelican Habitat. <https://www.fws.gov/breton/pelican_web/pelican_habitat.html>. Accessed 19
Oct 2013.