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.
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Ecological change drives a decline in mercury concentrations in southern Beaufort Sea polar bears
Uncertainties in forecasting the response of polar bears to global climate change
Habitat degradation affects the summer activity of polar bears
Using tri-axial accelerometers to identify wild polar bear behaviors
Collar temperature sensor data reveal long-term patterns in southern Beaufort Sea polar bear den distribution on pack ice and land
Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines
Invariant polar bear habitat selection during a period of sea ice loss
Forecasting the relative influence of environmental and anthropogenic stressors on polar bears
Isotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals
Rapid environmental change drives increased land use by an Arctic marine predator
Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions
Validation of mercury tip-switch and accelerometer activity sensors for identifying resting and active behavior in bears
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- Overview
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 CamVideo: Polar Bear Collar CamVideo: About the Polar Bear Research ProgramVideo: About the Polar Bear Research ProgramVideo: Melting Arctic Sea Ice Threatens Polar BearsVideo: Melting Arctic Sea Ice Threatens Polar BearsPopulation 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.
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Filter Total Items: 40No Result Found - Multimedia
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Filter Total Items: 48No results found. - Publications
Below are publications associated with this project.
Filter Total Items: 95Ecological change drives a decline in mercury concentrations in southern Beaufort Sea polar bears
We evaluated total mercury (THg) concentrations and trends in polar bears from the southern Beaufort Sea subpopulation from 2004 to 2011. Hair THg concentrations ranged widely among individuals from 0.6 to 13.3 μg g–1 dry weight (mean: 3.5 ± 0.2 μg g–1). Concentrations differed among sex and age classes: solitary adult females ≈ adult females with cubs ≈ subadults > adult males ≈ yearlings > cubs-AuthorsMelissa A. McKinney, Todd C. Atwood, Sara Pedro, Elizabeth L. PeacockUncertainties in forecasting the response of polar bears to global climate change
Several sources of uncertainty affect how precisely the future status of polar bears (Ursus maritimus) can be forecasted. Foremost are unknowns about the future levels of global greenhouse gas emissions, which could range from an unabated increase to an aggressively mitigated reduction. Uncertainties also arise because different climate models project different amounts and rates of future warmingAuthorsDavid C. Douglas, Todd C. AtwoodHabitat degradation affects the summer activity of polar bears
Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species’ distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of twoAuthorsJasmine V. Ware, Karyn D. Rode, Jeffrey F. Bromaghin, David C. Douglas, Ryan H. Wilson, Eric V. Regehr, Steven C. Amstrup, George M. Durner, Anthony M. Pagano, Jay Olson, Charles T. Robbins, Heiko T JansenUsing tri-axial accelerometers to identify wild polar bear behaviors
Tri-axial accelerometers have been used to remotely identify the behaviors of a wide range of taxa. Assigning behaviors to accelerometer data often involves the use of captive animals or surrogate species, as their accelerometer signatures are generally assumed to be similar to those of their wild counterparts. However, this has rarely been tested. Validated accelerometer data are needed for polarAuthorsAnthony M. Pagano, Karyn D. Rode, A. Cutting, M.A. Owen, S. Jensen, J.V. Ware, C.T. Robbins, George M. Durner, Todd C. Atwood, M.E. Obbard, K.R. Middel, G.W. Thiemann, T.M. WilliamsCollar temperature sensor data reveal long-term patterns in southern Beaufort Sea polar bear den distribution on pack ice and land
In response to a changing climate, many species alter habitat use. Polar bears Ursus maritimus in the southern Beaufort Sea have increasingly used land for maternal denning. To aid in detecting denning behavior, we developed an objective method to identify polar bear denning events using temperature sensor data collected by satellite-linked transmitters deployed on adult females between 1985 and 2AuthorsJay W Olson, Karyn D. Rode, Dennis L. Eggett, T. S. Smith, R. R. Wilson, George M. Durner, Anthony S. Fischbach, Todd C. Atwood, David C. DouglasConservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines
Loss of Arctic sea ice owing to climate change is the primary threat to polar bears throughout their range. We evaluated the potential response of polar bears to sea-ice declines by (i) calculating generation length (GL) for the species, which determines the timeframe for conservation assessments; (ii) developing a standardized sea-ice metric representing important habitat; and (iii) using statistAuthorsEric V. Regehr, Kristin L. Laidre, H. Resit Akçakaya, Steven C. Amstrup, Todd C. Atwood, Nicholas J. Lunn, Martyn E. Obbard, Harry Stern, Gregory W. Thiemann, Øystein WiigInvariant polar bear habitat selection during a period of sea ice loss
Climate change is expected to alter many species' habitat. A species' ability to adjust to these changes is partially determined by their ability to adjust habitat selection preferences to new environmental conditions. Sea ice loss has forced polar bears (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negativeAuthorsRyan H. Wilson, Eric V. Regehr, Karyn D. Rode, Michelle St. MartinForecasting the relative influence of environmental and anthropogenic stressors on polar bears
Effective conservation planning requires understanding and ranking threats to wildlife populations. We developed a Bayesian network model to evaluate the relative influence of environmental and anthropogenic stressors, and their mitigation, on the persistence of polar bears (Ursus maritimus). Overall sea ice conditions, affected by rising global temperatures, were the most influential determinantAuthorsTodd C. Atwood, Bruce G. Marcot, David C. Douglas, Steven C. Amstrup, Karyn D. Rode, George M. Durner, Jeffrey F. BromaghinIsotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals
There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and, alternatively, fast foAuthorsKaryn D. Rode, Craig A. Stricker, Joy Erlenbach, Charles T. Robbins, Seth Cherry, Seth D. Newsome, Amy Cutting, Shannon Jensen, Gordon Stenhouse, Matt Brooks, Amy Hash, Nicole NicassioRapid environmental change drives increased land use by an Arctic marine predator
In the Arctic Ocean’s southern Beaufort Sea (SB), the length of the sea ice melt season (i.e., period between the onset of sea ice break-up in summer and freeze-up in fall) has increased substantially since the late 1990s. Historically, polar bears (Ursus maritimus) of the SB have mostly remained on the sea ice year-round (except for those that came ashore to den), but recent changes in the extentAuthorsTodd C. Atwood, Elizabeth L. Peacock, Melissa A. McKinney, Kate Lillie, Ryan H. Wilson, David C. Douglas, Susanne Miller, Pat TerletzkyIncreased land use by Chukchi Sea polar bears in relation to changing sea ice conditions
Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea bAuthorsKaryn D. Rode, Ryan H. Wilson, Eric V. Regehr, Michelle St. Martin, David C. Douglas, Jay OlsonValidation of mercury tip-switch and accelerometer activity sensors for identifying resting and active behavior in bears
Activity sensors are often included in wildlife transmitters and can provide information on the behavior and activity patterns of animals remotely. However, interpreting activity-sensor data relative to animal behavior can be difficult if animals cannot be continuously observed. In this study, we examined the performance of a mercury tip-switch and a tri-axial accelerometer housed in collars to deAuthorsJasmine Ware, Karyn D. Rode, Anthony M. Pagano, Jeffrey F. Bromaghin, Charles T. Robbins, Joy Erlenbach, Shannon Jensen, Amy Cutting, Nicole Nicassio-Hiskey, Amy Hash, Megan A. Owen, Heiko Jansen - News
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Filter Total Items: 13 - Partners
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