Wildlife Disease and Environmental Health in Alaska

Environmental health is defined by connections between 

the physical environment, ecological health, and human health. 

Current research within the U.S. Geological Survey (USGS) 

recognizes the importance of this integrated research philosophy, 

which includes study of disease and pollutants as they pertain 

to wildlife and humans. Due to its key geographic location and 

significant wildlife resources, Alaska is a critical area for future 

study of environmental health.

Alaska as a Crossroads

Alaska is an international crossroads for millions of migratory 

birds that journey each spring from wintering areas in Asia, 

South America, and Oceania. Populations of fish and marine 

mammals come to Alaska after migrating through Pacific and 

Arctic Oceans. These intercontinental migratory links could 

play an important role in the transmission of diseases that affect 

wildlife and humans. Key coastal areas offer breeding and 

stopover sites that are ideal settings for exchange of foreign and 

resident pathogens.

Climate Change and Environmental Health

Climate change is predicted to increase the distribution, 

spread, and virulence of some infectious diseases. Arctic 

environments face rapid and dramatic changes that include loss 

of sea ice, permafrost degradation, wetland drying, and related 

alterations in nutrient cycling. Pathogens in these areas are 

expected to respond quickly to new environmental challenges and 

opportunities. Additionally, the detection of relatively high levels 

of contaminants in the Arctic raises concern about the effects of 

local and global pollution on humans and wildlife. As a result, 

certain Arctic wildlife species have been recognized as valuable 

sentinels of anthropogenic change.

Alaska’s position within migratory bird flyways of the Pacific Basin.

The USGS Alaska Science Center

With more than 30 years of ecological research in Arctic 

and sub-Arctic regions and a state-of-the-art molecular genetics 

facility, the Alaska Science Center is uniquely positioned to 

respond to new and existing issues in wildlife disease and 

environmental health. Long-term research and monitoring 

programs focus on a diversity of species including resident and 

migratory birds, caribou, fish, sea otters, polar bears, and walrus 

and provide important baseline information about the health of 

Alaskan wildlife. Ecological data are integrated with surveillance 

efforts to provide a better understanding of the connections 

between climate change, disease, and demographic impacts on 

wildlife populations. This information is valuable to community, 

state, and federal partners, such as the Climate, Ecosystems and 

Human Health Work Group, an inter-agency group that addresses 

the effects of climate change on human health in Alaska.

Environmental health research at the Alaska Science 

Center focuses on

•	 emerging wildlife diseases, particularly related to 

climate change;

•	 movement and transmission of wildlife pathogens; and

•	 demographic and fitness consequences of disease on 

wildlife populations.

Scientific information from this research is used to inform 

decision-making by wildlife management and human 

health agencies.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2013–3027

May 2013 Printed on recycled paper

Black-capped chickadee with a deformed beak. 

Photograph taken by John DeLapp.
Emerging Diseases and Climate Change

Infectious Disease

High latitude regions are responding rapidly to climate 

warming and the resulting changes are expected to influence 

the spread of infectious diseases. Expanded ranges of host 

wildlife, shifts in phenology, and changes in environmental 

conditions may result in transfer of pathogens to new areas and 

to potentially naïve populations. Preliminary evidence suggests 

that changes in pathogen distribution and abundance in the Arctic 

are already underway. However, due in part to the remoteness of 

the area and its challenging environmental conditions, knowledge 

about wildlife disease in Alaska is limited. Scientists at the 

Alaska Science Center work in remote field locations throughout 

Alaska and have the opportunity to identify wildlife and 

environmental health issues as they emerge. 

Environmental Contaminants

Environmental contaminants threaten the health of wildlife 

and humans in the Arctic. Pollutants from lower latitude sources 

travel by large-scale atmospheric transport, driven by global 

wind and water currents, to the Arctic. Climate warming and 

increased anthropogenic activities, such as those related to 

mining and other natural resource extraction, may contribute to 

overall contaminant burdens. Some of these compounds persist 

in the environment for many years and accumulate in living 

organisms, especially in high trophic level predators like marine 

mammals. Contaminants in subsistence foods are of particular 

concern as many indigenous Alaskans rely on traditional 

sources of meat, fish, and berries. The Alaska Science Center 

is working with partners to measure levels of nutrients and 

contaminants in physical and biological samples and to evaluate 

potential effects on wildlife.

A mature blood parasite Haemoproteus nettionis.

Greater white-fronted geese on the Arctic Coastal Plain.

A polar bear with hair loss (alopecia) along its neck. The bear was 

captured by USGS scientists using the immobilizing drug Telazol.

Selected Research at the Alaska Science Center

•	 Avian keratin disorder was first detected among 

resident birds in Alaska in 1999. This debilitating 

condition is characterized by beak deformities and 

it affects a wide range of species. Current studies 

are investigating the causes and consequences of 

this emerging avian disease.

•	 Research on avian influenza has revealed 

important patterns of virus movement and 

transmission in migratory birds. Ongoing work 

includes surveillance for foreign-origin pathogens 

and study of intercontinental links between Asia 

and North America.

•	 Alopecia (loss of fur) and other skin lesions were 

recently observed in polar bears off the northern 

coast of Alaska. Biologists are examining samples 

from afflicted polar bears to identify possible 

causes of these lesions.

•	 Blood parasites (hematozoa), including avian 

malaria, infect resident and migratory bird species 

in Alaska. Current research is investigating 

whether blood parasites have deleterious effects 

on avian populations and if they are sensitive to 

changes in climate.

•	 As part of ongoing climate change research, 

biologists have observed a high rate of 

non-viable eggs in nests of greater white-fronted 

geese. Future analyses will provide insights 

about elevated rates of embryo mortality in birds 

and identify potentially pathogenic bacteria in a 

changing Arctic environment.

•	 Coxiella burnetii, a bacterial pathogen that causes 

disease in animals and humans, was recently 

detected in polar bears, northern fur seals, and soil 

samples in Alaska. Future studies will investigate 

the prevalence of this pathogen in marine and 

terrestrial species.
Tundra swans on Alaskan breeding grounds.

Movement and Transmission of Pathogens

Migration

Both large- and small-scale animal movements have 

important implications for pathogen distribution. Research 

on the migration of waterfowl and other avian species plays 

a key role in evaluating potential routes of disease transport 

by wild birds. The emergence a highly pathogenic strain of 

H5N1 avian influenza virus that causes severe illness in birds 

and humans has heightened concerns about the potential role 

of wild birds in the transfer of disease between flyways. More 

than 2 million individuals of 94 species migrate to Alaska from 

Asia each spring. Recent studies by the Alaska Science Center 

demonstrated that migratory pathways of avian hosts could 

serve as links between H5N1 influenza outbreak sites in Asia 

and breeding areas of birds in Alaska. Waterfowl sampled in 

Alaska carried viruses with Asian-origin genes, and some of 

these viruses were transferred across multiple species.

Transition Zones: New Opportunities for Disease 

Transmission?

Certain landscape features, such as those unique to the Arctic 

coastline, provide critical ecological transition zones that also 

may influence patterns of disease transmission. The intersection 

between sea water, sea ice, terrestrial land mass, and fresh water 

from major river deltas draws a diverse assemblage of species. 

Overlap in these environments creates an opportunity for 

pathogen exchange between primarily marine hosts (like polar 

bears, seals, and walruses) and terrestrial hosts (like caribou, 

gulls, foxes, and grizzly bears). Changing environmental 

conditions, primarily the loss of sea ice, has resulted in larger 

aggregations of birds and mammals on land, forcing more 

frequent encounters between historically segregated species or 

populations. Future investigations will target potential exchange 

of pathogens between marine and terrestrial hosts at these 

transition zones.

Blue-winged teal in Texas. Inset shows avian influenza virus.

Polar bears and gulls feed on a whale carcass on the Arctic coast of 

Alaska. This is a possible transition zone for disease transmission.

Research also has demonstrated that low-pathogenic strains of 

avian influenza viruses may overwinter in Alaskan wetlands and 

therefore be available to re-infect bird populations in subsequent 

years through consumption of virus-contaminated water. 

The Alaska Science Center is studying the detectability and 

persistence of avian influenza viruses in natural water systems 

of Alaska during winter and summer months. Additionally, 

experiments are underway to test the ability of filter-feeding 

invertebrates—common food for water birds—to accumulate 

viable virus and to act as potential disease vectors to avian hosts.

Certain “hot spots,” including in western Alaska, have been 

identified as important surveillance locations to sample for 

diseases that might be introduced from Asia and then transferred 

to other locations. For example, avian influenza and Newcastle 

disease virus were detected in numerous species of waterfowl 

in Alaska and genetic analysis of isolates has implicated 

redistribution of these viruses by migratory birds. Research by 

the Alaska Science Center has recently expanded to include 

study of viruses in Neotropical migrants that provide connections 

between North, Central, and South America.
Muskoxen in northwestern Alaska.

Any use of trade, firm, or product names is for descriptive purposes only and 

does not imply endorsement by the U.S. Government.

Demographic and Fitness Consequences of Disease

Fitness consequences of disease are presumed for wild animals, but are often difficult 

to quantify because sick individuals must be identified and then tracked over time to 

assess condition. The Alaska Science Center is conducting long-term studies that will 

allow an assessment of disease consequences on individual animals. For example, one 

current study addresses the influence of blood parasites on body condition of resident and 

migratory species during breeding and wintering seasons.

Quantifying the demographic impacts of wildlife diseases also will provide a more 

accurate assessment of other mortality factors (for example, hunting or environmental 

stressors associated with climate change) that could be important for management actions. 

An ongoing study of emperor geese in Western Alaska allows for detailed investigation 

of the effects of blood parasites on specific fitness parameters, including reproductive 

success and adult survival. If the rates of infection by blood parasites vary among years in relation to phenology, progressive climate 

change may cause changes in vulnerability to blood parasites.

In another study, the Alaska Science Center has documented surprisingly high mortality (20–30 percent) of adult female musk 

ox during mid- to late summer in northwestern Alaska. Given the magnitude and timing of the observed mortality, and the fact that 

these muskoxen are in good nutritional condition in late winter, a pathogen is suspected to be contributing to the high losses observed. 

Additionally, copper deficiencies have been identified in other Alaskan musk ox, which can result in compromised immune function. 

The Alaska Science Center is currently comparing levels of infection and trace mineral status between the affected population and a 

reference population exhibiting low mortality rates to evaluate relationships between disease and nutrition.

Selected Publications

Bowen, L., Miles, A.K., Murray, M., Haulena, M., Tuttle, J., Van Bonn, W., 

Adams, L., Bodkin, J.L., Ballachey, B., Estes, J., Tinker, M.T., Keister, 

R., and Stott, J.L., 2012, Gene transcription in sea otters (Enhydra lutris): 

Development of a diagnostic tool for sea otter and ecosystem Health, 

Molecular Ecology Resources, v. 12, p. 67–74. DOI: 10.1111/j.1755-

0998.2011.03060.x.

Ely, C.R., Hall, J.S., Schmutz, J.A., Pearce, J.M., Terenzi, J.T., Sedinger, J.S., 

and Ip, H.S., 2013, Evidence that life history characteristics of wild birds 

influence infection rates and exposure to influenza A viruses: PLoS One, v. 8, 

e57614, DOI:10.1371/journal.pone.0057614.

Goldstein, T., Gill, V.A., Tuomi, P., Monson, D., Burdin, A., Conrad, P.A., 

Dunn, J.L., Field, C., Johnson, C., Jessup, D.A., Bodkin, J.L., and 

Doroff, A.M., 2011, Assessment of clinical pathology and pathogen exposure 

in sea otters (Enhydra lutris) bordering the threatened population in Alaska: 

Journal of Wildlife Diseases, v. 47, p. 579–592.

Handel, C.M., Pajot, L.M., Matsuoka, S.M., Van Hemert, C., Terenzi, J., 

Talbot, S.L., Mulcahy, D.M., Meteyer, C.U., and Trust, K.A., 2010, Epizootic 

of beak deformities among wild birds in Alaska—An emerging disease in 

North America?: The Auk, v. 127, p. 882-898. DOI: 10.1525/auk.2010.10111.

Kirk, C.M., Amstrup, S., Swor, R., Holcomb, D. and O’Hara, T.M., 2010, 

Hematology of southern Beaufort Sea polar bears (2005–2007)—Biomarker 

for an Arctic Ecosystem Health Sentinel: EcoHealth, v. 7, no. 3, p. 307–320. 

DOI: 10.1007/s10393-010-0322-1.

Koehler, A.V., Pearce, J.M., Flint, P.L., Franson, J.C., and Ip, H.S., 2008, 

Genetic evidence of intercontinental movement of avian influenza by a 

migratory bird: The Northern Pintail (Anas acuta): Molecular Ecology, v. 17, 

p. 4754–4762. DOI: 10.1111/j.1365-294X.2008.03953.x.

Millen, H.T., Gonnering, J.C., Berg, R.K., Spencer, S.K., Jokela, W.E., 

Pearce, J.M., Borchardt, J.S. and Borchardt, M.A., 2012, Glass wool filters for 

concentrating waterborne viruses and agricultural zoonotic pathogens: Journal 

of Visualized Experiments, no. 61, e3930. DOI:10.3791/3930.

Pearce, J.M., Ramey, A.M., Flint, P.L., Koehler, A.V., Fleskes, J.P., 

Franson, J.C., Hall, J.S., Derksen, D.V. and Ip, H.S., 2009, Avian influenza at 

both ends of a migratory flyway—Characterizing viral genomic diversity to 

optimize surveillance plans for North America: Evolutionary Applications, 

v. 2, p. 457–468. DOI: 10.1111/j.1752-4571.2009.00071.x. 

Pearce, J.M., Reeves, A.B., Ramey, A.M., Hupp, J.W., Ip, H.S., Bertram, M., 

Petrula, M.J., Scotton, B.D., Trust, K.A., Meixell, B., and Runstadler, J.A., 

2011, Interspecific exchange of avian influenza virus genes in Alaska—The 

influence of trans-hemispheric migratory tendency and breeding ground 

sympatry: Molecular Ecology, v. 20, p. 1015–1025. DOI: 10.1111/j.1365-

294X.2010.04908.x.

Ramey, A.M., Ely, C.R., Schmutz, J.A., Pearce, J.M., and Heard, D.J., 2012, 

Molecular detection of hematozoa infections in Tundra Swans relative to 

migration patterns and ecological conditions at breeding grounds: PLoS One, 

v. 7, no. 9, e45789. DOI:10.1371/journal.pone.0045789.

Reeves, A.B, Pearce, J.M., Ramey, A.M., Meixell, B.W., and Runstadler, J.A., 

2011, Interspecies transmission and limited persistence of low pathogenic avian 

influenza genomes among Alaska dabbling ducks: Infection, Genetics, and 

Evolution, v. 11, p. 2004–2010, DOI: 10.1016/j.meegid.2011.09.011. 

Seo, H-J., Kim, H.C., Klein, T.A., Ramey, A.M., Lee, J-H., Kyung, S-G., 

Park, J-Y., Cho, Y.S., Cho, I-S., and Yeh, J-Y, 2013, Molecular detection and 

genotyping of Japanese encephalitis virus in mosquitoes during a 2010 outbreak 

in the Republic of Korea: PLoS One, v. 8, no. 2, e55165, DOI:10.1371/journal.

pone.0055165.

Van Hemert, C., Armien, A.G., Blake, J.E., Handel, C.M., and O’Hara, T.M., 

2013, Macroscopic, histologic, and ultrastructural lesions associated with avian 

keratin disorder in Black-capped Chickadees (Poecile atricapillus): Veterinary 

Pathology, v. 50, iss. 3, p. 500–513. DOI: 10.1177/0300985812469637.

Van Hemert, C., and Handel, C.M., 2010, Beak deformities in Northwestern 

Crows—Evidence of a multispecies epizootic: The Auk, v. 127, no. 4, 

p. 746– 751. DOI: 10.1525/auk.2010.10132.

Van Hemert, C., Handel, C.M., and O’Hara, T.M., 2012, Evidence of accelerated 

beak growth associated with avian keratin disorder in Black-capped Chickadees 

(Poecile atricapillus): Journal of Wildlife Diseases, v. 48, p. 686–694. 

White, J., Mirleau, P., Danchin, E., Mulard, H., Hatch, S.A., Heeb, P., and 

Wagner, R.H., 2010, Sexually transmitted bacteria affect female cloacal 

assemblages in a wild bird: Ecology Letters, v. 13, p. 1515–1524. DOI: 

10.1111/j.1461-0248.2010.01542.x.

Yamaguchi, N., Hupp, J., Higuchi, H., Flint, P., and Pearce, J., 2010, Satellitetelemetry tracking of Northern Pintail Ducks Anas acuta during occurrences of 

the H5N1 virus in Japan: Implications for virus spread: Ibis, v. 152, p. 262–271. 

DOI: 10.1111/j.1474-919X.2010.01010.x.

Publishing support provided by the U.S. Geological Survey,

Tacoma Publishing Service Center

Authors: Caroline Van Hemert, John Pearce, 

 Karen Oakley, and Mary Whalen

For Information Contact:

U.S. Geological Survey

4210 University Dr., Anchorage, AK 99508

http://alaska.usgs.gov