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Karyn Rode, Ph.D.

Nutritional, physiological and population ecology of large mammals with particular focus on polar bears, black bears, grizzly bears, and Pacific walrus and anthropogenic effects on large mammals.

Professional Experience

  • Mar 2012 - Present              Research Wildlife Biologist, USGS Alaska Science Center

  • Oct 2006 - Feb 2012            Wildlife Biologist, US Fish and Wildlife Service Polar Bear Program, Anchorage, Alaska

  • Jan 2006 - Oct 2006            Research Associate, Cornell University, Forest Elephant program

  • June 2002 - Dec 2005         Contract wildlife biologist - Alaska Department of Fish and Game/PhD candidate - Washington State  University

Education and Certifications

  • Ph.D.    Washington State University       Zoology

  • M.S.      Washington State University       Zoology

  • B.S.       Colorado State University            Wildlife Biology

Affiliations and Memberships*

  • 2020 - present         Vice President- Americas, International Association of Bear Research and Management

  • 2017 - present         International Association of Bear Research and Management Grants Review Committee

  • 2017 - present         Member of the American Zoological Association’s Polar Bear Research Council

  • 2015 - present         Member of Science/TEK working group of the US Fish and Wildlife Service Polar Bear Recovery Team

  • 2009 - 2010            Secretary/Treasurer of the Alaska chapter of the Wildlife Society

  • 2008 - present        Member of the International Union for the Conservation of Nature's (IUCN) Polar bear specialist group

  • 2007 - present        Member of the Scientific/TEK working group under the US-Russia polar bear commission

Science and Products

Filter Total Items: 52

Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985–2040

Monitoring changes in the distribution of large carnivores is important for managing human safety and supporting conservation. Throughout much of their range, polar bears (Ursus maritimus) are increasingly using terrestrial habitats in response to Arctic sea ice decline. Their increased presence in coastal areas has implications for bear-human conflict, inter-species interactions, and polar bear h
By
Ecosystems, Alaska Science Center

Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics

Sea ice loss is fundamentally altering the Arctic marine environment. Yet there is a paucity of data on the adaptability of food webs to ecosystem change, including predator-prey interactions. Polar bears (Ursus maritimus) are an important subsistence resource for Indigenous people and an apex predator that relies entirely on the under-ice food web to meet their energy needs. Here, we assessed whe
By
Ecosystems, Alaska Science Center, Fort Collins Science Center

Intrapopulation differences in polar bear movement and step selection patterns

BackgroundThe spatial ecology of individuals often varies within a population or species. Identifying how individuals in different classes interact with their environment can lead to a better understanding of population responses to human activities and environmental change and improve population estimates. Most inferences about polar bear (Ursus maritimus) spatial ecology are based on data from a
By
Ecosystems, Alaska Science Center

The role of satellite telemetry data in 21st century conservation of polar bears (Ursus maritimus)

Satellite telemetry (ST) has played a critical role in the management and conservation of polar bears (Ursus maritimus) over the last 50 years. ST data provide biological information relevant to subpopulation delineation, movements, habitat use, maternal denning, health, human-bear interactions, and accurate estimates of vital rates and abundance. Given that polar bears are distributed at low dens
By
Ecosystems, Alaska Science Center

Summer/fall diet and macronutrient assimilation in an Arctic predator

Free-ranging predator diet estimation is commonly achieved by applying molecular-based tracers because direct observation is not logistically feasible or robust. However, tracers typically do not represent all dietary macronutrients, which likely obscures resource use as prey proximate composition varies and tissue consumption can be specific. For example, polar bears (Ursus maritimus) preferentia
By
Ecosystems, Alaska Science Center, Fort Collins Science Center

Subsurface swimming and stationary diving are metabolically cheap in adult Pacific walruses (Odobenus rosmarus divergens)

Walruses rely on sea-ice to efficiently forage and rest between diving bouts while maintaining proximity to prime foraging habitat. Recent declines in summer sea ice have resulted in walruses hauling out on land where they have to travel farther to access productive benthic habitat while potentially increasing energetic costs. Despite the need to better understand the impact of sea ice loss on ene
By
Ecosystems, Alaska Science Center

New insights into dietary management of polar bears (Ursus maritimus) and brown bears (U. arctos)

Although polar bears (Ursus maritimus) and brown bears (U. arctos) have been exhibited in zoological gardens for centuries, little is known about their nutritional needs. Multiple recent studies on both wild and captive polar bears and brown bears have found that they voluntarily select dietary macronutrient proportions resulting in much lower dietary protein and higher fat or digestible carbohydr
By
Ecosystems, Alaska Science Center

Long-term variation in polar bear body condition and maternal investment relative to a changing environment

In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears (Ursus maritimus). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access marine mammal prey. Because nutritional condition is closely linked to population vital rates, a prog
By
Ecosystems, Alaska Science Center

Fatty acid profiles of feeding and fasting bears: Estimating calibration coefficients, the timeframe of diet estimates, and selective mobilization during hibernation

Accurate information on diet composition is central to understanding and conserving carnivore populations. Quantitative fatty acid signature analysis (QFASA) has emerged as a powerful tool for estimating the diets of predators, but ambiguities remain about the timeframe of QFASA estimates and the need to account for species-specific patterns of metabolism. We conducted a series of feeding experime
By
Ecosystems, Water Resources, Alaska Science Center, Washington Water Science Center

Iñupiaq knowledge of polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska

Successful wildlife management depends upon coordination and consultation with local communities. However, much of the research used to inform management is often derived solely from data collected directly from wildlife. Indigenous people living in the Arctic have a close connection to their environment, which provides unique opportunities to observe their environment and the ecology of Arctic sp
By
Ecosystems, Alaska Science Center

Energetic and health effects of protein overconsumption constrain dietary adaptation in an apex predator

Studies of predator feeding ecology commonly focus on energy intake. However, captive predators have been documented to selectively feed to optimize macronutrient intake. As many apex predators experience environmental changes that affect prey availability, limitations on selective feeding can affect energetics and health. We estimated the protein:fat ratio of diets consumed by wild polar bears us
By
Ecosystems, Alaska Science Center, Fort Collins Science Center

Seal body condition and atmospheric circulation patterns influence polar bear body condition, recruitment, and feeding ecology in the Chukchi Sea

Polar bears (Ursus maritimus) are experiencing loss of sea ice habitats used to access their marine mammal prey. Simultaneously, ocean warming is changing ecosystems that support marine mammal populations. The interactive effects of sea ice and prey are not well understood yet may explain spatial‐temporal variation in the response of polar bears to sea ice loss. Here, we examined the potential com
By
Ecosystems, Alaska Science Center

Non-USGS Publications**

Voorhees, H., R. Sparks, H. P. Huntington, and K. D. Rode. 2014. Traditional knowledge of polar bears (Ursus maritimus) in Northwestern Alaska. Arctic 67(4):523-436. doi:10.14430/arctic4425.
Erlenbach, J. A., K. D. Rode, D. Raubenheimer, and C. M. Robbins. 2014. Macronutrient optimization and energy maximization determine diets of brown bears. Journal of Mammalogy 95(1):160-168. doi:10.1644/13-MAMM-A-161.
Robbins, C. T., C. Lopez-Alfaro, K. D. Rode, Ø. Tøien, and O. L. Nelson. 2012. Hibernation and seasonal fasting in bears: the energetic costs and consequences for polar bears. Journal of Mammalogy 93(6):1493-1503. doi:10.1644/11-MAMM-A-406.1.
Whiteman, J. P., K. A. Greller, H. J. Harlow, L. A. Felicetti, K. D. Rode, and M. Ben-David. 2012. Carbon isotopes in exhaled breath track metabolic substrates in brown bears (Ursus arctos). Journal of Mammalogy 93:413-421. doi:10.1644/11-MAMM-S-178.1.
Gleason, J. S. and K. D. Rode. 2009. Polar bear distribution and habitat association reflect long-term changes in fall sea ice conditions in the Alaskan Beaufort Sea. Arctic 62(4):405-417.
Schliebe, S. L., K. D. Rode, J. S. Gleason, J. Wilder, K. M. Proffitt, T. J. Evans, and S. Miller. 2008. Effects of sea ice extent and food availability on spatial and temporal distribution of polar bears during the fall open-water period in the Southern Beaufort Sea. Polar Biology 31(8):999-1010. doi:10.1007/s00300-008-0439-7.
Stirling, I., A. E. Derocher, W. Gough, and K. D. Rode. 2008. Response to Dyck et al. (2007) on polar bears and climate change in western Hudson Bay. Ecological Complexity 5(3):193-201. doi:10.1016/j.ecocom.2008.01.004.
Rode, K. D., S. C. Amstrup, and E. V. Regehr. 2007. Polar bears in the southern Beaufort Sea III: Stature, mass, and cub recruitment in relationship to time and sea ice extent between 1982 and 2006. USGS Administrative Report, 31 p.
Robbins, C. T., J. K. Fortin, K. D. Rode, S. D. Farley, L. A. Shipley, and L. A. Felicetti. 2007. Optimizing protein intake as a foraging strategy to maximize mass gain in an omnivore. Oikos 116(10):1675-1682. doi:10.1111/j.0030-1299.2007.16140.x.
Fortin, J. K., S. D. Farley, C. T. Robbins, and K. D. Rode. 2007. The role of salmon and berries in determining fall weight gains in brown bears. Ursus 18(1):19-29. doi:10.2192/1537-6176(2007)18[19:DASOBS]2.0.CO;2.
Rode, K. D., S. D. Farley, and C. T. Robbins. 2006. Behavioral responses of brown bears mediate nutritional impacts of experimentally introduced tourism. Biological Conservation 133(1):70-80. doi:10.1016/j.biocon.2006.05.021.
Rode, K. D., C. A. Chapman, L. D. McDowell, and C. A. Stricker. 2006. Nutritional mechanisms of population regulation across habitats and logging intensities in redtail monkeys (Cercopithecus ascanius). Biotropica 38:625-634. doi:10.1111/j.1744-7429.2006.00183.x.
Rode, K. D., P. I. Chiyo, C. A. Chapman, and L. D. McDowell. 2006. Nutritional ecology of elephants in Kibale National Park, Uganda, and its relationship with crop raiding behaviour. Journal of Tropical Ecology 22(4):441-449. doi:10.1017/S0266467406003233. https://doi.org/10.1017/S0266467406003233

Rode, K. D., S. D. Farley, and C. T. Robbins. 2006. Sexual dimorphism, reproductive strategy, and human activities determine resource use by brown bears. Ecology 87(10):2636-2646. doi:10.1890/0012-9658(2006)87[2636:SDRSAH]2.0.CO;2.
Danish, L., C. A. Chapman, C. O'Driscoll Worman, K. D. Rode, and M. B. Hall. 2006. The role of sugar content in diet selection in redtail and red colobus monkeys. In Feeding Ecology in apes and other primates. Cambridge University Press, UK.
Chapman, C. A., L. J. Chapman, K. D. Rode, and L. D. McDowell. 2003. Variation in the nutritional value of primate foods: Among trees, time periods, and areas. International Journal of Primatology 24(2):317-337. doi:10.1023/A:1023049200150.
Rode, K. D., C. A. Chapman, L. J. Chapman, and L. D. McDowell. 2003. Mineral resource availability and consumption by colobus monkeys in Kibale National Park, Uganda. International Journal of Primatology 24(3):541-573. doi:10.1023/A:1023788330155.
Chapman, C. A., L. J. Chapman, M. Cords, M. Gauthua, A. Gautier-Hion, J. E. Lambert, K. D. Rode, C. E. G. Tutin, and L. J. T. White. 2002. Variation in the Diets of Cercopithecus Species: Differences Within Forests, Among Forests, and Across Species. In The Guenons: Diversity and Adaptation in African Monkeys. M. Glenn and M. Cords (eds.). Plenum Press New York City, NY, USA.
Rode, K. D., C. T. Robbins, and L. A. Shipley. 2001. The constraints on herbivory by bears. Oecologia 128(1):62-71. doi:10.1007/s004420100637.
Rode, K. D. and C. T. Robbins. 2000. Why bears consume mixed diets during fruit abundance. Canadian Journal of Zoology 78(9):1-6. doi:10.1139/z00-082.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

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A polar bear in a pool.

Q&A: Polar Bears and Zoos

Polar bears are found throughout the circumpolar Arctic and roam across miles of sea ice and land. They prefer to eat blubber, especially from seals that are also found on the sea ice. However, the sea ice habitat of polar bears is changing rapidly with substantial recent declines in the extent of sea ice in the Arctic. These changes are leading polar bears to spend more time on land in some areas...
By
Alaska Science Center
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Q&A: Polar Bears and Zoos

Polar bears are found throughout the circumpolar Arctic and roam across miles of sea ice and land. They prefer to eat blubber, especially from seals that are also found on the sea ice. However, the sea ice habitat of polar bears is changing rapidly with substantial recent declines in the extent of sea ice in the Arctic. These changes are leading polar bears to spend more time on land in some areas...
Learn More
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A polar bear walks across rubble ice in the Alaska portion of the southern Beaufort Sea

Distribution and Movements of Polar Bears

Polar bears are tied to the sea ice for nearly all of their life cycle functions. Most important of these is foraging, or access to food. Polar bears almost exclusively eat seals, and they are equally as dependent upon the sea for their nutrition as are seals, whales, and other aquatic mammals. Polar bears are not aquatic, however, and their only access to the seals is from the surface of the sea...
By
Species Management Research Program, Alaska Science Center
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Distribution and Movements of Polar Bears

Polar bears are tied to the sea ice for nearly all of their life cycle functions. Most important of these is foraging, or access to food. Polar bears almost exclusively eat seals, and they are equally as dependent upon the sea for their nutrition as are seals, whales, and other aquatic mammals. Polar bears are not aquatic, however, and their only access to the seals is from the surface of the sea...
Learn More
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Polar bear still hunting at a seal breathing hole

Health and Energetics of Polar Bears

Research in this focal area is centered on (i) collecting data on a variety of systems that help determine and mediate polar bear health and energetics, and (ii) developing monitoring and surveillance programs for detecting changes in population health over time. Additionally, this work will allow us to develop an understanding of how polar bear populations will respond to a variety of stressors...
By
Species Management Research Program, Alaska Science Center
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Health and Energetics of Polar Bears

Research in this focal area is centered on (i) collecting data on a variety of systems that help determine and mediate polar bear health and energetics, and (ii) developing monitoring and surveillance programs for detecting changes in population health over time. Additionally, this work will allow us to develop an understanding of how polar bear populations will respond to a variety of stressors...
Learn More
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Polar bear mother and two cubs on the Beaufort Sea ice.

Polar Bear Research

Polar bears (Ursus maritimus) are one of 4 marine mammal species managed by the U.S. Department of Interior. The USGS Alaska Science Center leads long–term research on polar bears to inform local, state, national and international policy makers regarding conservation of the species and its habitat. Our studies, ongoing since 1985, are focused on population dynamics, health and energetics...
By
Ecosystems, Land Management Research Program, Species Management Research Program, Alaska Science Center
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Polar Bear Research

Polar bears (Ursus maritimus) are one of 4 marine mammal species managed by the U.S. Department of Interior. The USGS Alaska Science Center leads long–term research on polar bears to inform local, state, national and international policy makers regarding conservation of the species and its habitat. Our studies, ongoing since 1985, are focused on population dynamics, health and energetics...
Learn More
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Walruses resting on an ice floe

Walrus Research

The USGS Alaska Science Center conducts long-term research on the Pacific walrus to provide scientific information to Department of Interior management agencies and Alaska Native co-management partners. In addition, the USGS Pacific walrus research program collaborates with the U.S. Fish and Wildlife Service (USFWS) and the State of Alaska’s Department of Fish and Game and Alaska Native co...
By
Ecosystems, Land Management Research Program, Species Management Research Program, Alaska Science Center
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Walrus Research

The USGS Alaska Science Center conducts long-term research on the Pacific walrus to provide scientific information to Department of Interior management agencies and Alaska Native co-management partners. In addition, the USGS Pacific walrus research program collaborates with the U.S. Fish and Wildlife Service (USFWS) and the State of Alaska’s Department of Fish and Game and Alaska Native co...
Learn More
Filter Total Items: 17

Polar Bear Continuous Time-Correlated Random Walk (CTCRW) Location Data Derived from Satellite Location Data, Chukchi and Beaufort Seas, July-November 1985-2017

his dataset consists of one table with estimated locations of adult female polar bears during July-November 1985-2017, used for quantifying changes in summer land use over time. Locations were estimated with a Continuous Time-Correlated Random Walk (CTCRW) model fit to satellite tracking from radio-collared adult female polar bears. All bears included in this data set were captured and instrumente
By
Alaska Science Center

Metabolic Rates Measured in Three Captive Adult Female Walruses (Odobenus rosmarus divergens) While Resting and Diving

This dataset contains measurements of oxygen consumption and carbon dioxide production of 3 adult female walruses (Odobenus rosmarus divergens) while resting and diving at the Oceanografic Aquarium in Valencia, Spain. Oxygen consumption and carbon dioxide production was measured for walruses via a respiratory dome while resting at the water surface and after swimming and diving.
By
Alaska Science Center

Protein and Fat Consumption of Zoo Polar Bears in 14-day Ad Libitum Trials, 2019-2020

This is a single table containing measures of the amount of fat and meat consumed by 4 adult female and 5 adult male polar bears in U.S. zoos when provided both food sources ad libitum for 12-14 days. Trial length was intended to be 14 days, but trial dietary items ran out for two bears prior to the end of the trial (i.e., at 12 and 13 days instead of 14 days). The data set includes the weight of
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Alaska Science Center

Denning Phenology, Den Substrate, and Reproductive Success of Female Polar Bears (Ursus maritimus) in the southern Beaufort Sea 1986-2013 and the Chukchi Sea 1987-1994

These data represent estimates of den entrance and exit dates for female polar bears in the southern Beaufort and Chukchi Seas based on temperature sensor data obtained from satellite collars. An algorithm described in Olson et al. (2017) was used to determine whether the female entered a den and further analyses using temperature data as described in Olson et al. (2017) were used to assess den en
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Alaska Science Center

Carbon and Nitrogen Isotope Concentrations in Polar Bear Hair and Prey from the Alaska Beaufort and Chukchi Seas, 1978-2019

This dataset includes carbon and nitrogen isotope concentrations measured in polar bear hair and marine mammal prey samples collected 1978-2017 in the Beaufort and Chukchi Seas. Marine mammal prey samples were collected opportunistically either from polar bear seal kill sites or from marine mammals harvested by Native hunters. Hair was collected from polar bears captured on the sea ice or land in
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Alaska Science Center

Fatty Acid Composition of Polar Bear Adipose Tissue and Ringed and Bearded Seal Blubber Collected in the Chukchi Sea, 2008-2017

These data are the fatty acid compositions (in %) of adipose tissue samples collected from polar bears and of blubber samples collected from ringed and bearded seal killed by polar bears in the Chukchi Sea, 2008-2017. The dataset includes sex, age, and age class of the bears that were sampled. The data are provided as % of each fatty acid identified via nomenclature that describes the structure of
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Alaska Science Center

Serum Urea and Creatinine Levels of Spring-Caught Polar Bears (Ursus maritimus) in the Southern Beaufort and Chukchi Seas

These data are serum urea nitrogen and creatinine levels for polar bears captured in the southern Beaufort Sea 1983-2016 and the Chukchi Sea 1987-1993 and 2008-2017. The dataset includes relevant information about the bears that were captured including the latitude and longitude of their capture location, capture date, age class and sex, the age and number of cubs accompanying an adult female, and
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Alaska Science Center

Measurement Data of Polar Bears Captured in the Chukchi and Southern Beaufort Sea, 1981-2017

This dataset includes measures collected on polar bears captured in the Chukchi and Beaufort Seas, 1981-2017 by the U.S. Geological Survey and U.S. Fish and Wildlife Service. Data collected include body length, body mass, axillary girth, skull width and tail lengths. Bears were also aged as described in the methods. For some bears, an adipose tissue sample was collected and percent lipid content w
By
Alaska Science Center

Accelerometer Data from Collared Female Polar Bears in the Beaufort Sea, 2009-2016

This dataset includes accelerometer data collected on collars deployed on female polar bears in the southern Beaufort Sea from 2009-2016. The accelerometer was built in to collars by Telonics, Inc. and provides a single activity value of the number of seconds active per time interval of data collection. Data were collected every 15-30 minutes. GPS and ARGOs locations collected via collars were use
By
Alaska Science Center

Data from a Circumpolar Survey on Recreational Activities in Polar Bear Habitat, 2017-2018

These data are the responses of researchers, managers, community members, and tour guides who live or work in polar bear habitats anywhere within their range to inquiries about the types, frequency, and potential impacts of recreational activities. Respondents answered a series of questions on their background and experience with polar bears and the geographic area in which they are familiar. Resp
By
Alaska Science Center

Denning Behavior Classifications Using Temperature Sensor Data on Collars Deployed on Polar Bears in the Southern Beaufort Sea, 1986-2013

These data include two spreadsheets. The first is average daily temperatures received via satellite transmitting collars deployed on polar bears in the southern Beaufort Sea 1986-2013. The second is denning classifications for adult female polar bears in the southern Beaufort Sea using the temperature data. Denning was classified using a control chart-based algorithm applied to the temperature d
By
Alaska Science Center

Fatty Acid Signature Data of Chukchi Sea Polar Bears, 2008-2015

These data were collected to gain insights into the diet composition of Chukchi Sea polar bears. These data were collected to gain insights into the diet composition of Chukchi Sea polar bears.
By
Alaska Science Center
Graphical abstract showing role of diet and food intake affecting polar bear population dynamics in southern Beaufort Sea.
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Three Sea World Orlando marine mammal trainers measure healthy mature female walrus.
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Adult female walrus being measured by two marine mammal trainers at Indianapolis Zoo
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Scientist checking vitals on polar bear on the Chukchi Sea
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Adult Male polar bear walking towards seal on frozen landscape. Footprints are visible in the snow.
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Image: Taking Polar Bear Blood Samples
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Image: Taking Polar Bear Blood Samples
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Large polar bear walking near water on Barter Island, Alaska. Hills in the background.
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Polar Bears Unlikely to Thrive on Land-based Foods

ANCHORAGE, Alaska — A team of scientists led by the U.S. Geological Survey found that polar bears, increasingly forced on shore due to sea ice loss...

Read Article

Science and Products

  • Publications
    Filter Total Items: 52

    Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985–2040

    Monitoring changes in the distribution of large carnivores is important for managing human safety and supporting conservation. Throughout much of their range, polar bears (Ursus maritimus) are increasingly using terrestrial habitats in response to Arctic sea ice decline. Their increased presence in coastal areas has implications for bear-human conflict, inter-species interactions, and polar bear h
    By
    Ecosystems, Alaska Science Center

    Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics

    Sea ice loss is fundamentally altering the Arctic marine environment. Yet there is a paucity of data on the adaptability of food webs to ecosystem change, including predator-prey interactions. Polar bears (Ursus maritimus) are an important subsistence resource for Indigenous people and an apex predator that relies entirely on the under-ice food web to meet their energy needs. Here, we assessed whe
    By
    Ecosystems, Alaska Science Center, Fort Collins Science Center

    Intrapopulation differences in polar bear movement and step selection patterns

    BackgroundThe spatial ecology of individuals often varies within a population or species. Identifying how individuals in different classes interact with their environment can lead to a better understanding of population responses to human activities and environmental change and improve population estimates. Most inferences about polar bear (Ursus maritimus) spatial ecology are based on data from a
    By
    Ecosystems, Alaska Science Center

    The role of satellite telemetry data in 21st century conservation of polar bears (Ursus maritimus)

    Satellite telemetry (ST) has played a critical role in the management and conservation of polar bears (Ursus maritimus) over the last 50 years. ST data provide biological information relevant to subpopulation delineation, movements, habitat use, maternal denning, health, human-bear interactions, and accurate estimates of vital rates and abundance. Given that polar bears are distributed at low dens
    By
    Ecosystems, Alaska Science Center

    Summer/fall diet and macronutrient assimilation in an Arctic predator

    Free-ranging predator diet estimation is commonly achieved by applying molecular-based tracers because direct observation is not logistically feasible or robust. However, tracers typically do not represent all dietary macronutrients, which likely obscures resource use as prey proximate composition varies and tissue consumption can be specific. For example, polar bears (Ursus maritimus) preferentia
    By
    Ecosystems, Alaska Science Center, Fort Collins Science Center

    Subsurface swimming and stationary diving are metabolically cheap in adult Pacific walruses (Odobenus rosmarus divergens)

    Walruses rely on sea-ice to efficiently forage and rest between diving bouts while maintaining proximity to prime foraging habitat. Recent declines in summer sea ice have resulted in walruses hauling out on land where they have to travel farther to access productive benthic habitat while potentially increasing energetic costs. Despite the need to better understand the impact of sea ice loss on ene
    By
    Ecosystems, Alaska Science Center

    New insights into dietary management of polar bears (Ursus maritimus) and brown bears (U. arctos)

    Although polar bears (Ursus maritimus) and brown bears (U. arctos) have been exhibited in zoological gardens for centuries, little is known about their nutritional needs. Multiple recent studies on both wild and captive polar bears and brown bears have found that they voluntarily select dietary macronutrient proportions resulting in much lower dietary protein and higher fat or digestible carbohydr
    By
    Ecosystems, Alaska Science Center

    Long-term variation in polar bear body condition and maternal investment relative to a changing environment

    In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears (Ursus maritimus). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access marine mammal prey. Because nutritional condition is closely linked to population vital rates, a prog
    By
    Ecosystems, Alaska Science Center

    Fatty acid profiles of feeding and fasting bears: Estimating calibration coefficients, the timeframe of diet estimates, and selective mobilization during hibernation

    Accurate information on diet composition is central to understanding and conserving carnivore populations. Quantitative fatty acid signature analysis (QFASA) has emerged as a powerful tool for estimating the diets of predators, but ambiguities remain about the timeframe of QFASA estimates and the need to account for species-specific patterns of metabolism. We conducted a series of feeding experime
    By
    Ecosystems, Water Resources, Alaska Science Center, Washington Water Science Center

    Iñupiaq knowledge of polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska

    Successful wildlife management depends upon coordination and consultation with local communities. However, much of the research used to inform management is often derived solely from data collected directly from wildlife. Indigenous people living in the Arctic have a close connection to their environment, which provides unique opportunities to observe their environment and the ecology of Arctic sp
    By
    Ecosystems, Alaska Science Center

    Energetic and health effects of protein overconsumption constrain dietary adaptation in an apex predator

    Studies of predator feeding ecology commonly focus on energy intake. However, captive predators have been documented to selectively feed to optimize macronutrient intake. As many apex predators experience environmental changes that affect prey availability, limitations on selective feeding can affect energetics and health. We estimated the protein:fat ratio of diets consumed by wild polar bears us
    By
    Ecosystems, Alaska Science Center, Fort Collins Science Center

    Seal body condition and atmospheric circulation patterns influence polar bear body condition, recruitment, and feeding ecology in the Chukchi Sea

    Polar bears (Ursus maritimus) are experiencing loss of sea ice habitats used to access their marine mammal prey. Simultaneously, ocean warming is changing ecosystems that support marine mammal populations. The interactive effects of sea ice and prey are not well understood yet may explain spatial‐temporal variation in the response of polar bears to sea ice loss. Here, we examined the potential com
    By
    Ecosystems, Alaska Science Center

    Non-USGS Publications**

    Voorhees, H., R. Sparks, H. P. Huntington, and K. D. Rode. 2014. Traditional knowledge of polar bears (Ursus maritimus) in Northwestern Alaska. Arctic 67(4):523-436. doi:10.14430/arctic4425.
    Erlenbach, J. A., K. D. Rode, D. Raubenheimer, and C. M. Robbins. 2014. Macronutrient optimization and energy maximization determine diets of brown bears. Journal of Mammalogy 95(1):160-168. doi:10.1644/13-MAMM-A-161.
    Robbins, C. T., C. Lopez-Alfaro, K. D. Rode, Ø. Tøien, and O. L. Nelson. 2012. Hibernation and seasonal fasting in bears: the energetic costs and consequences for polar bears. Journal of Mammalogy 93(6):1493-1503. doi:10.1644/11-MAMM-A-406.1.
    Whiteman, J. P., K. A. Greller, H. J. Harlow, L. A. Felicetti, K. D. Rode, and M. Ben-David. 2012. Carbon isotopes in exhaled breath track metabolic substrates in brown bears (Ursus arctos). Journal of Mammalogy 93:413-421. doi:10.1644/11-MAMM-S-178.1.
    Gleason, J. S. and K. D. Rode. 2009. Polar bear distribution and habitat association reflect long-term changes in fall sea ice conditions in the Alaskan Beaufort Sea. Arctic 62(4):405-417.
    Schliebe, S. L., K. D. Rode, J. S. Gleason, J. Wilder, K. M. Proffitt, T. J. Evans, and S. Miller. 2008. Effects of sea ice extent and food availability on spatial and temporal distribution of polar bears during the fall open-water period in the Southern Beaufort Sea. Polar Biology 31(8):999-1010. doi:10.1007/s00300-008-0439-7.
    Stirling, I., A. E. Derocher, W. Gough, and K. D. Rode. 2008. Response to Dyck et al. (2007) on polar bears and climate change in western Hudson Bay. Ecological Complexity 5(3):193-201. doi:10.1016/j.ecocom.2008.01.004.
    Rode, K. D., S. C. Amstrup, and E. V. Regehr. 2007. Polar bears in the southern Beaufort Sea III: Stature, mass, and cub recruitment in relationship to time and sea ice extent between 1982 and 2006. USGS Administrative Report, 31 p.
    Robbins, C. T., J. K. Fortin, K. D. Rode, S. D. Farley, L. A. Shipley, and L. A. Felicetti. 2007. Optimizing protein intake as a foraging strategy to maximize mass gain in an omnivore. Oikos 116(10):1675-1682. doi:10.1111/j.0030-1299.2007.16140.x.
    Fortin, J. K., S. D. Farley, C. T. Robbins, and K. D. Rode. 2007. The role of salmon and berries in determining fall weight gains in brown bears. Ursus 18(1):19-29. doi:10.2192/1537-6176(2007)18[19:DASOBS]2.0.CO;2.
    Rode, K. D., S. D. Farley, and C. T. Robbins. 2006. Behavioral responses of brown bears mediate nutritional impacts of experimentally introduced tourism. Biological Conservation 133(1):70-80. doi:10.1016/j.biocon.2006.05.021.
    Rode, K. D., C. A. Chapman, L. D. McDowell, and C. A. Stricker. 2006. Nutritional mechanisms of population regulation across habitats and logging intensities in redtail monkeys (Cercopithecus ascanius). Biotropica 38:625-634. doi:10.1111/j.1744-7429.2006.00183.x.
    Rode, K. D., P. I. Chiyo, C. A. Chapman, and L. D. McDowell. 2006. Nutritional ecology of elephants in Kibale National Park, Uganda, and its relationship with crop raiding behaviour. Journal of Tropical Ecology 22(4):441-449. doi:10.1017/S0266467406003233. https://doi.org/10.1017/S0266467406003233

    Rode, K. D., S. D. Farley, and C. T. Robbins. 2006. Sexual dimorphism, reproductive strategy, and human activities determine resource use by brown bears. Ecology 87(10):2636-2646. doi:10.1890/0012-9658(2006)87[2636:SDRSAH]2.0.CO;2.
    Danish, L., C. A. Chapman, C. O'Driscoll Worman, K. D. Rode, and M. B. Hall. 2006. The role of sugar content in diet selection in redtail and red colobus monkeys. In Feeding Ecology in apes and other primates. Cambridge University Press, UK.
    Chapman, C. A., L. J. Chapman, K. D. Rode, and L. D. McDowell. 2003. Variation in the nutritional value of primate foods: Among trees, time periods, and areas. International Journal of Primatology 24(2):317-337. doi:10.1023/A:1023049200150.
    Rode, K. D., C. A. Chapman, L. J. Chapman, and L. D. McDowell. 2003. Mineral resource availability and consumption by colobus monkeys in Kibale National Park, Uganda. International Journal of Primatology 24(3):541-573. doi:10.1023/A:1023788330155.
    Chapman, C. A., L. J. Chapman, M. Cords, M. Gauthua, A. Gautier-Hion, J. E. Lambert, K. D. Rode, C. E. G. Tutin, and L. J. T. White. 2002. Variation in the Diets of Cercopithecus Species: Differences Within Forests, Among Forests, and Across Species. In The Guenons: Diversity and Adaptation in African Monkeys. M. Glenn and M. Cords (eds.). Plenum Press New York City, NY, USA.
    Rode, K. D., C. T. Robbins, and L. A. Shipley. 2001. The constraints on herbivory by bears. Oecologia 128(1):62-71. doi:10.1007/s004420100637.
    Rode, K. D. and C. T. Robbins. 2000. Why bears consume mixed diets during fruit abundance. Canadian Journal of Zoology 78(9):1-6. doi:10.1139/z00-082.

    **Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

  • Science
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    A polar bear in a pool.

    Q&A: Polar Bears and Zoos

    Polar bears are found throughout the circumpolar Arctic and roam across miles of sea ice and land. They prefer to eat blubber, especially from seals that are also found on the sea ice. However, the sea ice habitat of polar bears is changing rapidly with substantial recent declines in the extent of sea ice in the Arctic. These changes are leading polar bears to spend more time on land in some areas...
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    Alaska Science Center
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    Q&A: Polar Bears and Zoos

    Polar bears are found throughout the circumpolar Arctic and roam across miles of sea ice and land. They prefer to eat blubber, especially from seals that are also found on the sea ice. However, the sea ice habitat of polar bears is changing rapidly with substantial recent declines in the extent of sea ice in the Arctic. These changes are leading polar bears to spend more time on land in some areas...
    Learn More
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    A polar bear walks across rubble ice in the Alaska portion of the southern Beaufort Sea

    Distribution and Movements of Polar Bears

    Polar bears are tied to the sea ice for nearly all of their life cycle functions. Most important of these is foraging, or access to food. Polar bears almost exclusively eat seals, and they are equally as dependent upon the sea for their nutrition as are seals, whales, and other aquatic mammals. Polar bears are not aquatic, however, and their only access to the seals is from the surface of the sea...
    By
    Species Management Research Program, Alaska Science Center
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    Distribution and Movements of Polar Bears

    Polar bears are tied to the sea ice for nearly all of their life cycle functions. Most important of these is foraging, or access to food. Polar bears almost exclusively eat seals, and they are equally as dependent upon the sea for their nutrition as are seals, whales, and other aquatic mammals. Polar bears are not aquatic, however, and their only access to the seals is from the surface of the sea...
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    Polar bear still hunting at a seal breathing hole

    Health and Energetics of Polar Bears

    Research in this focal area is centered on (i) collecting data on a variety of systems that help determine and mediate polar bear health and energetics, and (ii) developing monitoring and surveillance programs for detecting changes in population health over time. Additionally, this work will allow us to develop an understanding of how polar bear populations will respond to a variety of stressors...
    By
    Species Management Research Program, Alaska Science Center
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    Health and Energetics of Polar Bears

    Research in this focal area is centered on (i) collecting data on a variety of systems that help determine and mediate polar bear health and energetics, and (ii) developing monitoring and surveillance programs for detecting changes in population health over time. Additionally, this work will allow us to develop an understanding of how polar bear populations will respond to a variety of stressors...
    Learn More
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    Polar bear mother and two cubs on the Beaufort Sea ice.

    Polar Bear Research

    Polar bears (Ursus maritimus) are one of 4 marine mammal species managed by the U.S. Department of Interior. The USGS Alaska Science Center leads long–term research on polar bears to inform local, state, national and international policy makers regarding conservation of the species and its habitat. Our studies, ongoing since 1985, are focused on population dynamics, health and energetics...
    By
    Ecosystems, Land Management Research Program, Species Management Research Program, Alaska Science Center
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    Polar Bear Research

    Polar bears (Ursus maritimus) are one of 4 marine mammal species managed by the U.S. Department of Interior. The USGS Alaska Science Center leads long–term research on polar bears to inform local, state, national and international policy makers regarding conservation of the species and its habitat. Our studies, ongoing since 1985, are focused on population dynamics, health and energetics...
    Learn More
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    Walruses resting on an ice floe

    Walrus Research

    The USGS Alaska Science Center conducts long-term research on the Pacific walrus to provide scientific information to Department of Interior management agencies and Alaska Native co-management partners. In addition, the USGS Pacific walrus research program collaborates with the U.S. Fish and Wildlife Service (USFWS) and the State of Alaska’s Department of Fish and Game and Alaska Native co...
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    Ecosystems, Land Management Research Program, Species Management Research Program, Alaska Science Center
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    Walrus Research

    The USGS Alaska Science Center conducts long-term research on the Pacific walrus to provide scientific information to Department of Interior management agencies and Alaska Native co-management partners. In addition, the USGS Pacific walrus research program collaborates with the U.S. Fish and Wildlife Service (USFWS) and the State of Alaska’s Department of Fish and Game and Alaska Native co...
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  • Data
    Filter Total Items: 17

    Polar Bear Continuous Time-Correlated Random Walk (CTCRW) Location Data Derived from Satellite Location Data, Chukchi and Beaufort Seas, July-November 1985-2017

    his dataset consists of one table with estimated locations of adult female polar bears during July-November 1985-2017, used for quantifying changes in summer land use over time. Locations were estimated with a Continuous Time-Correlated Random Walk (CTCRW) model fit to satellite tracking from radio-collared adult female polar bears. All bears included in this data set were captured and instrumente
    By
    Alaska Science Center

    Metabolic Rates Measured in Three Captive Adult Female Walruses (Odobenus rosmarus divergens) While Resting and Diving

    This dataset contains measurements of oxygen consumption and carbon dioxide production of 3 adult female walruses (Odobenus rosmarus divergens) while resting and diving at the Oceanografic Aquarium in Valencia, Spain. Oxygen consumption and carbon dioxide production was measured for walruses via a respiratory dome while resting at the water surface and after swimming and diving.
    By
    Alaska Science Center

    Protein and Fat Consumption of Zoo Polar Bears in 14-day Ad Libitum Trials, 2019-2020

    This is a single table containing measures of the amount of fat and meat consumed by 4 adult female and 5 adult male polar bears in U.S. zoos when provided both food sources ad libitum for 12-14 days. Trial length was intended to be 14 days, but trial dietary items ran out for two bears prior to the end of the trial (i.e., at 12 and 13 days instead of 14 days). The data set includes the weight of
    By
    Alaska Science Center

    Denning Phenology, Den Substrate, and Reproductive Success of Female Polar Bears (Ursus maritimus) in the southern Beaufort Sea 1986-2013 and the Chukchi Sea 1987-1994

    These data represent estimates of den entrance and exit dates for female polar bears in the southern Beaufort and Chukchi Seas based on temperature sensor data obtained from satellite collars. An algorithm described in Olson et al. (2017) was used to determine whether the female entered a den and further analyses using temperature data as described in Olson et al. (2017) were used to assess den en
    By
    Alaska Science Center

    Carbon and Nitrogen Isotope Concentrations in Polar Bear Hair and Prey from the Alaska Beaufort and Chukchi Seas, 1978-2019

    This dataset includes carbon and nitrogen isotope concentrations measured in polar bear hair and marine mammal prey samples collected 1978-2017 in the Beaufort and Chukchi Seas. Marine mammal prey samples were collected opportunistically either from polar bear seal kill sites or from marine mammals harvested by Native hunters. Hair was collected from polar bears captured on the sea ice or land in
    By
    Alaska Science Center

    Fatty Acid Composition of Polar Bear Adipose Tissue and Ringed and Bearded Seal Blubber Collected in the Chukchi Sea, 2008-2017

    These data are the fatty acid compositions (in %) of adipose tissue samples collected from polar bears and of blubber samples collected from ringed and bearded seal killed by polar bears in the Chukchi Sea, 2008-2017. The dataset includes sex, age, and age class of the bears that were sampled. The data are provided as % of each fatty acid identified via nomenclature that describes the structure of
    By
    Alaska Science Center

    Serum Urea and Creatinine Levels of Spring-Caught Polar Bears (Ursus maritimus) in the Southern Beaufort and Chukchi Seas

    These data are serum urea nitrogen and creatinine levels for polar bears captured in the southern Beaufort Sea 1983-2016 and the Chukchi Sea 1987-1993 and 2008-2017. The dataset includes relevant information about the bears that were captured including the latitude and longitude of their capture location, capture date, age class and sex, the age and number of cubs accompanying an adult female, and
    By
    Alaska Science Center

    Measurement Data of Polar Bears Captured in the Chukchi and Southern Beaufort Sea, 1981-2017

    This dataset includes measures collected on polar bears captured in the Chukchi and Beaufort Seas, 1981-2017 by the U.S. Geological Survey and U.S. Fish and Wildlife Service. Data collected include body length, body mass, axillary girth, skull width and tail lengths. Bears were also aged as described in the methods. For some bears, an adipose tissue sample was collected and percent lipid content w
    By
    Alaska Science Center

    Accelerometer Data from Collared Female Polar Bears in the Beaufort Sea, 2009-2016

    This dataset includes accelerometer data collected on collars deployed on female polar bears in the southern Beaufort Sea from 2009-2016. The accelerometer was built in to collars by Telonics, Inc. and provides a single activity value of the number of seconds active per time interval of data collection. Data were collected every 15-30 minutes. GPS and ARGOs locations collected via collars were use
    By
    Alaska Science Center

    Data from a Circumpolar Survey on Recreational Activities in Polar Bear Habitat, 2017-2018

    These data are the responses of researchers, managers, community members, and tour guides who live or work in polar bear habitats anywhere within their range to inquiries about the types, frequency, and potential impacts of recreational activities. Respondents answered a series of questions on their background and experience with polar bears and the geographic area in which they are familiar. Resp
    By
    Alaska Science Center

    Denning Behavior Classifications Using Temperature Sensor Data on Collars Deployed on Polar Bears in the Southern Beaufort Sea, 1986-2013

    These data include two spreadsheets. The first is average daily temperatures received via satellite transmitting collars deployed on polar bears in the southern Beaufort Sea 1986-2013. The second is denning classifications for adult female polar bears in the southern Beaufort Sea using the temperature data. Denning was classified using a control chart-based algorithm applied to the temperature d
    By
    Alaska Science Center

    Fatty Acid Signature Data of Chukchi Sea Polar Bears, 2008-2015

    These data were collected to gain insights into the diet composition of Chukchi Sea polar bears. These data were collected to gain insights into the diet composition of Chukchi Sea polar bears.
    By
    Alaska Science Center
  • Multimedia
    Graphical abstract showing role of diet and food intake affecting polar bear population dynamics in southern Beaufort Sea.
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    Three Sea World Orlando marine mammal trainers measure healthy mature female walrus.
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    Adult female walrus being measured by two marine mammal trainers at Indianapolis Zoo
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    Scientist checking vitals on polar bear on the Chukchi Sea
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    Adult Male polar bear walking towards seal on frozen landscape. Footprints are visible in the snow.
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    Image: Taking Polar Bear Blood Samples
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    Image: Taking Polar Bear Blood Samples
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    Large polar bear walking near water on Barter Island, Alaska. Hills in the background.
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  • News
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    Polar Bears Unlikely to Thrive on Land-based Foods

    ANCHORAGE, Alaska — A team of scientists led by the U.S. Geological Survey found that polar bears, increasingly forced on shore due to sea ice loss...

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*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government