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.
Return to Ecosystems >> Marine Ecosystems >> Polar Bear Research
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.
Effects of declining ice on polar bear behavior and habitat selection
Among all polar bear subpopulations, those occurring in the Beaufort and the Chukchi seas have experienced some of the greatest losses of sea ice in the entire Arctic Ocean. The mechanisms that link habitat to population trend, however, have not been quantitatively described. The role of habitat preference on behavior (i.e., movement and activity) or whether some habitats are important for life history requirements is uncertain. Movements of polar bears are linked to foraging success and energetic costs. Hence, movements, as a proxy for behavior and energetics, may be indicative of habitat value and provide a quantifiable means to elucidate mechanisms of polar bear population response to a changing Arctic. We are using polar bear location data collected by the USGS since 1985 to develop models of polar bear distribution that account for long-term changes in behavior and habitat function. This research will provide products that can be used by managers to mitigate adverse impacts to polar bears and polar bear habitats from anthropogenic activities.
Characterizing the on-shore ecology of Alaska’s polar bears
Polar bear populations have varying strategies for coping with seasonal sea ice formation and recession. In some regions of the Arctic, where sea ice melts completely during summer, bears migrate to on-land refugia where they remain until sea ice returns in the fall. In regions where sea ice persisted year-round, polar bears were able to remain on the pack ice even as it receded from land each summer. However, in Alaska, the progressive decline in sea ice coverage in summer and fall— particularly over the biologically productive continental shelf waters— has led to a novel and increasing trend of land use. The effectiveness of this new behavioral strategy is unknown. Further, there is a lack of information available regarding habitat selection of polar bears while on shore. These data gaps pose a challenge to managers tasked with balancing needs to maintain accessibility to critical habitat with recreational and economic development activities. Our investigations of on-shore ecology will address those data gaps and provide information that can be used to aid in decisions regarding the management of terrestrial habitats.
Factors influencing human-polar bear interactions on Alaska’s North Slope
Loss of sea ice is expected to foster an increase in anthropogenic activities in the Arctic by allowing greater access to the Arctic Ocean, and facilitating the extraction of oil and gas reserves and the opening of new shipping routes. On Alaska’s North Slope, polar bears are regularly observed in close proximity to industrial operations during summer and fall. Because of protections conferred by the Marine Mammal Protection Act (MMPA) and Endangered Species Act (ESA), human activities that result in the harassment, injury, or death of polar bears (considered a “take”) are prohibited. However, activities with the potential to result in “incidental takes” are allowed under a permit that requires permit holders (private, non-federal entities) to take steps to mitigate and minimize risk of harm to polar bears. Objectives of this research include identifying drivers and patterns of human-polar bear interactions, and quantifying and characterizing the types of “incidental take” occurring within industrial areas to begin to understand impacts to both bears and people (including industrial operations). Better knowledge about when and where interactions are likely to occur, and how they are likely to impact polar bears, humans, and industrial activities are needed to inform proactive and reasonable management strategies for minimizing human-polar bear interactions.
Below are other science projects associated with this project.
Polar Bear Research
Polar Bear Maternal Denning
Polar Bear Population Dynamics
Health and Energetics of Polar Bears
Below are publications associated with this project.
Human-polar bear interactions in a changing Arctic: Existing and emerging concerns
Increased Arctic sea ice drift alters adult female polar bear movements and energetics
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
Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes
A model for autumn pelagic distribution of adult female polar bears in the Chukchi Seas, 1987-1994
The use of sea ice habitat by female polar bears in the Beaufort Sea
- Overview
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.
Return to Ecosystems >> Marine Ecosystems >> Polar Bear Research
Sea ice blocks pushed up in a pressure ridge of ice. (Public domain.) 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.
Effects of declining ice on polar bear behavior and habitat selection
Among all polar bear subpopulations, those occurring in the Beaufort and the Chukchi seas have experienced some of the greatest losses of sea ice in the entire Arctic Ocean. The mechanisms that link habitat to population trend, however, have not been quantitatively described. The role of habitat preference on behavior (i.e., movement and activity) or whether some habitats are important for life history requirements is uncertain. Movements of polar bears are linked to foraging success and energetic costs. Hence, movements, as a proxy for behavior and energetics, may be indicative of habitat value and provide a quantifiable means to elucidate mechanisms of polar bear population response to a changing Arctic. We are using polar bear location data collected by the USGS since 1985 to develop models of polar bear distribution that account for long-term changes in behavior and habitat function. This research will provide products that can be used by managers to mitigate adverse impacts to polar bears and polar bear habitats from anthropogenic activities.
Characterizing the on-shore ecology of Alaska’s polar bears
Polar bear populations have varying strategies for coping with seasonal sea ice formation and recession. In some regions of the Arctic, where sea ice melts completely during summer, bears migrate to on-land refugia where they remain until sea ice returns in the fall. In regions where sea ice persisted year-round, polar bears were able to remain on the pack ice even as it receded from land each summer. However, in Alaska, the progressive decline in sea ice coverage in summer and fall— particularly over the biologically productive continental shelf waters— has led to a novel and increasing trend of land use. The effectiveness of this new behavioral strategy is unknown. Further, there is a lack of information available regarding habitat selection of polar bears while on shore. These data gaps pose a challenge to managers tasked with balancing needs to maintain accessibility to critical habitat with recreational and economic development activities. Our investigations of on-shore ecology will address those data gaps and provide information that can be used to aid in decisions regarding the management of terrestrial habitats.
Female and cub polar bear on land near Kaktovik, Alaska. (Public domain.) Factors influencing human-polar bear interactions on Alaska’s North Slope
Loss of sea ice is expected to foster an increase in anthropogenic activities in the Arctic by allowing greater access to the Arctic Ocean, and facilitating the extraction of oil and gas reserves and the opening of new shipping routes. On Alaska’s North Slope, polar bears are regularly observed in close proximity to industrial operations during summer and fall. Because of protections conferred by the Marine Mammal Protection Act (MMPA) and Endangered Species Act (ESA), human activities that result in the harassment, injury, or death of polar bears (considered a “take”) are prohibited. However, activities with the potential to result in “incidental takes” are allowed under a permit that requires permit holders (private, non-federal entities) to take steps to mitigate and minimize risk of harm to polar bears. Objectives of this research include identifying drivers and patterns of human-polar bear interactions, and quantifying and characterizing the types of “incidental take” occurring within industrial areas to begin to understand impacts to both bears and people (including industrial operations). Better knowledge about when and where interactions are likely to occur, and how they are likely to impact polar bears, humans, and industrial activities are needed to inform proactive and reasonable management strategies for minimizing human-polar bear interactions.
- Science
Below are other science projects associated with this project.
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...Polar Bear Maternal Denning
Pregnant polar bears enter maternity dens in October/November, give birth to cubs in December/January, and exit dens in March/April. Historically, most polar bears from the Southern Beaufort Sea (SBS) population constructed maternity dens on the sea ice. Over the last three decades, as sea ice has become thinner and prone to fragmentation, there has been a landward shift in the distribution of...Polar Bear 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...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... - Publications
Below are publications associated with this project.
Human-polar bear interactions in a changing Arctic: Existing and emerging concerns
The behavior and sociality of polar bears (Ursus maritimus) have been shaped by evolved preferences for sea ice habitat and preying on marine mammals. However, human behavior is causing changes to the Arctic marine ecosystem through the influence of greenhouse gas emissions that drive long-term change in ecosystem processes and via the presence of in situ stressors associated with increasing humanAuthorsTodd C. Atwood, Kristin S. Simac, Stewart Breck, Geoff York, James WilderIncreased Arctic sea ice drift alters adult female polar bear movements and energetics
Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences forAuthorsGeorge M. Durner, David C. Douglas, Shannon Albeke, John P. Whiteman, Steven C. Amstrup, Evan Richardson, Ryan H. Wilson, Merav Ben-DavidRapid 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 OlsonLandward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes
Polar bears (Ursus maritimus) in the northern Alaska region den in coastal areas and on offshore drifting ice. We evaluated changes in the distribution of polar bear maternal dens between 1985 and 2005, using satellite telemetry. We determined the distribution of maternal dens occupied by 89 satellite collared female polar bears between 137°W and 167°W longitude. The proportion of dens on pack iceAuthorsAnthony S. Fischbach, Steven C. Amstrup, David C. DouglasA model for autumn pelagic distribution of adult female polar bears in the Chukchi Seas, 1987-1994
We made predictions of polar bear (Ursus maritimus) autumn distribution in the Chukchi Sea with a Resource Selection Function (RSF) developed from 1198 satellite radio-collar locations on 124 adult female polar bears, 1987 – 1994. The RSF was created to assist in an aerial survey design for polar bears proposed by the U.S. Fish and Wildlife Service. The RSF was based on bathymetry and daily sea icAuthorsGeorge M. Durner, David C. Douglas, R. M. Nielson, Steven C. AmstrupThe use of sea ice habitat by female polar bears in the Beaufort Sea
Polar bears (Ursus maritimus) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice composition resulting from climate change. Managers need practical models that explain the distribution of bears in order to assess the impacts of these threats. We used stepwise procedures to create resource seAuthorsGeorge M. Durner, Steven C. Amstrup, Ryan M. Nielson, Trent McDonald