Polar bear laying down to dry after a swim in the Chukchi sea.
Polar Bear Research Active
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, distribution and movements, maternal denning, and methods development. The majority of our research focuses on the two polar bear subpopulation’s whose range includes Alaska: the Southern Beaufort Sea subpopulation that ranges between the North Slope of Alaska and western Canada and the Chukchi Sea or Alaska-Chukotka subpopulation that ranges between the northwest coast of Alaska and eastern Russia. The overarching goal of our research is to assess current and projected future responses of polar bears to a rapidly changing Arctic environment.
Return to Ecosystems >> Marine Ecosystems
Video: Polar Bear Collar Cam
Video: About the Polar Bear Research Program
Video: Melting Arctic Sea Ice Threatens Polar Bears
Population Dynamics
Information on the status and trends of polar bear populations are needed to inform management of polar bears under US laws and international agreements. The USGS maintains a long-term research program focused on the population dynamics of the southern Beaufort Sea polar bear population. In addition, the USGS collaborates with the US Fish and Wildlife Service in population studies in the Chukchi Sea. To estimate both the population size and vital rates, we have used mark-recapture studies relying on physical capture of bears, primarily during the spring. We are currently developing an analytical approach that will allow us to integrate additional types of data (e.g., spatial data, non-invasively collected genetic data) into the modeling process to provide improved assessments of population status. Results of past studies have allowed us to assess the relationships between population vital rates and environmental change, which provides our partners with information needed to inform management decisions.
Health and Energetics
The warming climate has the potential to drive significant changes in the health and energetics of Arctic fauna, particularly those dependent on sea ice habitats like polar bears. An animal’s health and energetic state reflects the interaction between its behavioral choices and the environment. Because of this, measuring changes in health and energetics has potential for revealing important associations between environmental stressors and population dynamics. 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 modulated by climate change, including contaminant and pathogen exposures, changes in food web structure and prey accessibility, and changes in spatial distribution.
Distribution and Movements
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 ice. Over the past 25 years, the summer sea ice melt period has lengthened, and summer sea ice cover has declined by over half a million square miles. In winter, there have been dramatic reductions in the amount of old ice, predominantly in the western Arctic. This loss of stable old ice has catalyzed additional losses of sea ice cover each summer because the thinner younger ice is more easily melted during the recent warmer summers. Research in this focal area seeks to develop a better understanding of how changes in the distribution and characteristics of sea ice habitat are likely to affect polar bear fitness, distribution, and interactions with people. If we know how polar bears respond to changes in ice quantity and quality, we will be able to predict how forecasted changes in the ice may affect future polar bear populations. This will give managers the best chance of adapting strategies to assure the long-term persistence of polar bears in a changing ice environment.
Maternal Denning
Pregnant polar bears enter maternity dens in October or early November, give birth to cubs in December or early January, and exit dens in March or early April. Historically, most polar bears from the Southern Beaufort Sea population constructed maternity dens on the sea ice. However, over the last three decades, as sea ice has become thinner and more prone to fragmentation, there has been a landward shift in the distribution of dens. Based on data collected from radio-tagged adult female bears, maternal denning now occurs at relatively high densities along the central and eastern Arctic coastal plain of Alaska. The availability of denning habitat― mediated by landscape features that facilitate the formation of snow drifts― appears to increase in the eastern portion of the Alaska coastal plain. In the Chukchi Sea, polar bears historically denned primarily on land in both Russia and the Alaska. In recent years as sea ice extent has retreated further north in the fall, Chukchi Sea polar bears have shifted land-based denning northward primarily on Wrangel and Herald Islands in Russia and rarely on the Alaskan coast. Identifying factors influencing the distribution of dens and denning duration will allow us to better monitor reproductive success and mitigate the potential for disturbance of denned bears from anthropogenic activities.
Below are other science projects associated with this project.
Below are data or web applications associated with this project.
Pathogen and Contaminant Exposure Data from Southern Beaufort Sea Polar Bears, 2007-2014
Polar Bear Continuous Time-Correlated Random Walk (CTCRW) Location Data Derived from Satellite Location Data, Southern Beaufort Sea, 1986-2016
Innate Immunity and Stress and Reproductive Hormone Metrics for Southern Beaufort Sea Polar Bears, 2013-2015
Protein and Fat Consumption of Zoo Polar Bears in 14-day Ad Libitum Trials, 2019-2020
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
Cortisol Concentration Data from Polar Bear (Ursus maritimus) Hair Collected in the Bering, Chukchi, and Beaufort seas, Alaska, 1983-1989, 2004-2006, and 2008-2016
Carbon and Nitrogen Isotope Concentrations in Polar Bear Hair and Prey from the Alaska Beaufort and Chukchi Seas, 1978-2019
Fatty Acid Composition of Polar Bear Adipose Tissue and Ringed and Bearded Seal Blubber Collected in the Chukchi Sea, 2008-2017
Serum Urea and Creatinine Levels of Spring-Caught Polar Bears (Ursus maritimus) in the Southern Beaufort and Chukchi Seas
Multistate capture and search data from the southern Beaufort Sea polar bear population in Alaska, 2001-2016
Polar Bear Microsatellite Data Southern Beaufort Sea 2010-2013
Catalogue of Polar Bear (Ursus maritimus) Maternal Den Locations in the Beaufort and Chukchi Seas and Nearby Areas, 1910-2018
Below are multimedia associated with this project.
Polar bear laying down to dry after a swim in the Chukchi sea.
Polar bears spend much of their lives in and around water, and they are well adapted for swimming.
Polar bears spend much of their lives in and around water, and they are well adapted for swimming.
This video was edited and compiled from raw footage recorded by a camera equipped radio collar that was put on a female polar bear in the Beaufort Sea during April 2014 by the US Geological Survey. This new type of camera technology was developed by videographer Adam Ravetch with the support of the World Wildlife Fund.
This video was edited and compiled from raw footage recorded by a camera equipped radio collar that was put on a female polar bear in the Beaufort Sea during April 2014 by the US Geological Survey. This new type of camera technology was developed by videographer Adam Ravetch with the support of the World Wildlife Fund.
Large polar bear being weighed by Anthony Pagano and Todd Atwood
Large polar bear being weighed by Anthony Pagano and Todd Atwood
Spring 2014. USGS scientists conduct a health evaluation of a young male polar bear in the Arctic as part of the annual southern Beaufort Sea population survey. The bear is sedated for approximately an hour while the team records a variety of measurements and collects key biological samples.
Spring 2014. USGS scientists conduct a health evaluation of a young male polar bear in the Arctic as part of the annual southern Beaufort Sea population survey. The bear is sedated for approximately an hour while the team records a variety of measurements and collects key biological samples.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
A polar bear is being subjected to the enhanced sampling protocol for suspected alopecic bears. In the photo, we're using the tape measure to demonstrate the size of the area of hair loss on the neck. This photo was taken on the sea ice north of Utqiagvik, Alaska.
A polar bear is being subjected to the enhanced sampling protocol for suspected alopecic bears. In the photo, we're using the tape measure to demonstrate the size of the area of hair loss on the neck. This photo was taken on the sea ice north of Utqiagvik, Alaska.
A polar bear walks across rubble ice in the Alaska portion of the southern Beaufort Sea, April 8, 2011
A polar bear walks across rubble ice in the Alaska portion of the southern Beaufort Sea, April 8, 2011
George Durner and Jennifer Wiley working on an anesthetized polar bear
George Durner and Jennifer Wiley working on an anesthetized polar bear
A view of a pressure ridge in the sea ice in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
A view of a pressure ridge in the sea ice in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An adult male polar bear still-hunting at a seal hole on the sea ice of the southern Beaufort Sea.
An adult male polar bear still-hunting at a seal hole on the sea ice of the southern Beaufort Sea.
This image is of a polar bear and their cub.
This image is of a polar bear and their cub.
Polar bears along sea ice in the Arctic Ocean.
Polar bears along sea ice in the Arctic Ocean.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
Female and two young-of-the-year cubs polar bears on the sea ice
Female and two young-of-the-year cubs polar bears on the sea ice
A view from the inside of a polar bear den in the Chukchi Sea, Alaska
A view from the inside of a polar bear den in the Chukchi Sea, Alaska
Below are publications associated with this project.
Efficacy of bear spray as a deterrent against polar bears
Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985–2040
Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics
Modeling the spatial and temporal dynamics of land-based polar bear denning in Alaska
Comparisons of Coupled Model Intercomparison Project Phase 5 (CMIP5) and Coupled Model Intercomparison Project Phase 6 (CMIP6) sea-ice projections in polar bear (Ursus maritimus) ecoregions during the 21st century
Using in situ/ex situ research collaborations to support polar bear conservation
Evaluating the efficacy of aerial infrared surveys to detect artificial polar bear dens
Intrapopulation differences in polar bear movement and step selection patterns
The role of satellite telemetry data in 21st century conservation of polar bears (Ursus maritimus)
Summer/fall diet and macronutrient assimilation in an Arctic predator
Distinct gut microbiomes in two polar bear subpopulations inhabiting different sea ice ecoregions
Below are news stories associated with this project.
Below are partners associated with this project.
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, distribution and movements, maternal denning, and methods development. The majority of our research focuses on the two polar bear subpopulation’s whose range includes Alaska: the Southern Beaufort Sea subpopulation that ranges between the North Slope of Alaska and western Canada and the Chukchi Sea or Alaska-Chukotka subpopulation that ranges between the northwest coast of Alaska and eastern Russia. The overarching goal of our research is to assess current and projected future responses of polar bears to a rapidly changing Arctic environment.
Return to Ecosystems >> Marine Ecosystems
Video: Polar Bear Collar Cam
Video: About the Polar Bear Research Program
Video: Melting Arctic Sea Ice Threatens Polar Bears
Population Dynamics
Information on the status and trends of polar bear populations are needed to inform management of polar bears under US laws and international agreements. The USGS maintains a long-term research program focused on the population dynamics of the southern Beaufort Sea polar bear population. In addition, the USGS collaborates with the US Fish and Wildlife Service in population studies in the Chukchi Sea. To estimate both the population size and vital rates, we have used mark-recapture studies relying on physical capture of bears, primarily during the spring. We are currently developing an analytical approach that will allow us to integrate additional types of data (e.g., spatial data, non-invasively collected genetic data) into the modeling process to provide improved assessments of population status. Results of past studies have allowed us to assess the relationships between population vital rates and environmental change, which provides our partners with information needed to inform management decisions.
Health and Energetics
The warming climate has the potential to drive significant changes in the health and energetics of Arctic fauna, particularly those dependent on sea ice habitats like polar bears. An animal’s health and energetic state reflects the interaction between its behavioral choices and the environment. Because of this, measuring changes in health and energetics has potential for revealing important associations between environmental stressors and population dynamics. 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 modulated by climate change, including contaminant and pathogen exposures, changes in food web structure and prey accessibility, and changes in spatial distribution.
Distribution and Movements
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 ice. Over the past 25 years, the summer sea ice melt period has lengthened, and summer sea ice cover has declined by over half a million square miles. In winter, there have been dramatic reductions in the amount of old ice, predominantly in the western Arctic. This loss of stable old ice has catalyzed additional losses of sea ice cover each summer because the thinner younger ice is more easily melted during the recent warmer summers. Research in this focal area seeks to develop a better understanding of how changes in the distribution and characteristics of sea ice habitat are likely to affect polar bear fitness, distribution, and interactions with people. If we know how polar bears respond to changes in ice quantity and quality, we will be able to predict how forecasted changes in the ice may affect future polar bear populations. This will give managers the best chance of adapting strategies to assure the long-term persistence of polar bears in a changing ice environment.
Maternal Denning
Pregnant polar bears enter maternity dens in October or early November, give birth to cubs in December or early January, and exit dens in March or early April. Historically, most polar bears from the Southern Beaufort Sea population constructed maternity dens on the sea ice. However, over the last three decades, as sea ice has become thinner and more prone to fragmentation, there has been a landward shift in the distribution of dens. Based on data collected from radio-tagged adult female bears, maternal denning now occurs at relatively high densities along the central and eastern Arctic coastal plain of Alaska. The availability of denning habitat― mediated by landscape features that facilitate the formation of snow drifts― appears to increase in the eastern portion of the Alaska coastal plain. In the Chukchi Sea, polar bears historically denned primarily on land in both Russia and the Alaska. In recent years as sea ice extent has retreated further north in the fall, Chukchi Sea polar bears have shifted land-based denning northward primarily on Wrangel and Herald Islands in Russia and rarely on the Alaskan coast. Identifying factors influencing the distribution of dens and denning duration will allow us to better monitor reproductive success and mitigate the potential for disturbance of denned bears from anthropogenic activities.
Below are other science projects associated with this project.
Below are data or web applications associated with this project.
Pathogen and Contaminant Exposure Data from Southern Beaufort Sea Polar Bears, 2007-2014
Polar Bear Continuous Time-Correlated Random Walk (CTCRW) Location Data Derived from Satellite Location Data, Southern Beaufort Sea, 1986-2016
Innate Immunity and Stress and Reproductive Hormone Metrics for Southern Beaufort Sea Polar Bears, 2013-2015
Protein and Fat Consumption of Zoo Polar Bears in 14-day Ad Libitum Trials, 2019-2020
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
Cortisol Concentration Data from Polar Bear (Ursus maritimus) Hair Collected in the Bering, Chukchi, and Beaufort seas, Alaska, 1983-1989, 2004-2006, and 2008-2016
Carbon and Nitrogen Isotope Concentrations in Polar Bear Hair and Prey from the Alaska Beaufort and Chukchi Seas, 1978-2019
Fatty Acid Composition of Polar Bear Adipose Tissue and Ringed and Bearded Seal Blubber Collected in the Chukchi Sea, 2008-2017
Serum Urea and Creatinine Levels of Spring-Caught Polar Bears (Ursus maritimus) in the Southern Beaufort and Chukchi Seas
Multistate capture and search data from the southern Beaufort Sea polar bear population in Alaska, 2001-2016
Polar Bear Microsatellite Data Southern Beaufort Sea 2010-2013
Catalogue of Polar Bear (Ursus maritimus) Maternal Den Locations in the Beaufort and Chukchi Seas and Nearby Areas, 1910-2018
Below are multimedia associated with this project.
Polar bear laying down to dry after a swim in the Chukchi sea.
Polar bear laying down to dry after a swim in the Chukchi sea.
Polar bears spend much of their lives in and around water, and they are well adapted for swimming.
Polar bears spend much of their lives in and around water, and they are well adapted for swimming.
This video was edited and compiled from raw footage recorded by a camera equipped radio collar that was put on a female polar bear in the Beaufort Sea during April 2014 by the US Geological Survey. This new type of camera technology was developed by videographer Adam Ravetch with the support of the World Wildlife Fund.
This video was edited and compiled from raw footage recorded by a camera equipped radio collar that was put on a female polar bear in the Beaufort Sea during April 2014 by the US Geological Survey. This new type of camera technology was developed by videographer Adam Ravetch with the support of the World Wildlife Fund.
Large polar bear being weighed by Anthony Pagano and Todd Atwood
Large polar bear being weighed by Anthony Pagano and Todd Atwood
Spring 2014. USGS scientists conduct a health evaluation of a young male polar bear in the Arctic as part of the annual southern Beaufort Sea population survey. The bear is sedated for approximately an hour while the team records a variety of measurements and collects key biological samples.
Spring 2014. USGS scientists conduct a health evaluation of a young male polar bear in the Arctic as part of the annual southern Beaufort Sea population survey. The bear is sedated for approximately an hour while the team records a variety of measurements and collects key biological samples.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An aerial view of sea ice with open water from a helicopter in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
A polar bear is being subjected to the enhanced sampling protocol for suspected alopecic bears. In the photo, we're using the tape measure to demonstrate the size of the area of hair loss on the neck. This photo was taken on the sea ice north of Utqiagvik, Alaska.
A polar bear is being subjected to the enhanced sampling protocol for suspected alopecic bears. In the photo, we're using the tape measure to demonstrate the size of the area of hair loss on the neck. This photo was taken on the sea ice north of Utqiagvik, Alaska.
A polar bear walks across rubble ice in the Alaska portion of the southern Beaufort Sea, April 8, 2011
A polar bear walks across rubble ice in the Alaska portion of the southern Beaufort Sea, April 8, 2011
George Durner and Jennifer Wiley working on an anesthetized polar bear
George Durner and Jennifer Wiley working on an anesthetized polar bear
A view of a pressure ridge in the sea ice in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
A view of a pressure ridge in the sea ice in the Beaufort Sea. Photo taken during Spring Capture of the Polar Bear project.
An adult male polar bear still-hunting at a seal hole on the sea ice of the southern Beaufort Sea.
An adult male polar bear still-hunting at a seal hole on the sea ice of the southern Beaufort Sea.
This image is of a polar bear and their cub.
This image is of a polar bear and their cub.
Polar bears along sea ice in the Arctic Ocean.
Polar bears along sea ice in the Arctic Ocean.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
USGS scientist Karyn Rode takes a blood sample from a polar bear to estimate the diets of wild bears.
Female and two young-of-the-year cubs polar bears on the sea ice
Female and two young-of-the-year cubs polar bears on the sea ice
A view from the inside of a polar bear den in the Chukchi Sea, Alaska
A view from the inside of a polar bear den in the Chukchi Sea, Alaska
Below are publications associated with this project.
Efficacy of bear spray as a deterrent against polar bears
Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985–2040
Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics
Modeling the spatial and temporal dynamics of land-based polar bear denning in Alaska
Comparisons of Coupled Model Intercomparison Project Phase 5 (CMIP5) and Coupled Model Intercomparison Project Phase 6 (CMIP6) sea-ice projections in polar bear (Ursus maritimus) ecoregions during the 21st century
Using in situ/ex situ research collaborations to support polar bear conservation
Evaluating the efficacy of aerial infrared surveys to detect artificial polar bear dens
Intrapopulation differences in polar bear movement and step selection patterns
The role of satellite telemetry data in 21st century conservation of polar bears (Ursus maritimus)
Summer/fall diet and macronutrient assimilation in an Arctic predator
Distinct gut microbiomes in two polar bear subpopulations inhabiting different sea ice ecoregions
Below are news stories associated with this project.
Below are partners associated with this project.