Polar Bear Use of Alaska's Beaufort Sea Coast

Wildlife Biologist, Polar Bears
U.S. Fish and Wildlife Service
Anchorage, Alaska

In recent months much public attention has been given to potential effects of climate change on the world-wide population of polar bears. In January 2007, the U.S. Fish and Wildlife Service (FWS), responsible for polar bear management in the United States, proposed to list the species as “Threatened” under the Endangered Species Act, due to effects of climate change on sea ice. We received over 600,000 public comments, indicative of high public concern regarding polar bears and the Arctic habitat in which they live. In September 2007, the U.S. Geological Survey’s AlaskaScience Center released 9 reports regarding the relationship of sea ice changes and polar bears, including a quantitative assessment of population status projected into the future. Climate change issues are playing an increasingly prominent role in both research and management activities.

One interesting aspect of polar bear life history that we have been monitoring since 2000 is the use of terrestrial habitat along Alaska’s Beaufort Sea coast (between Barrow and the Canadian border) by polar bears. Polar bears in this region historically have spent the majority of their lives at sea, using marine ice as a platform for hunting/feeding, resting, traveling, breeding, and to some extent, for maternal denning. In recent years, however, increasing use of terrestrial habitat has been reported, especially during fall months. This raised concerns because of the potential increase in bear-human conflicts in both coastal villages and oil and gas development areas. The FWS has been monitoring coastal use by polar bears through two studies: 1) aerial surveys to document the distribution and abundance of polar bears using the Beaufort Sea coast prior to winter freeze up; and 2) ground-based observations of polar bears feeding on bowhead whale carcass remains left from Alaska Native subsistence whaling activities. To date, these studies have provided a few interesting findings:

1. In 2000-2005, the number of bears on land increased when sea ice was furthest from shore, indicating that the position of pack ice edge is a primary factor in determining how many bears occur along the coast;
2. The distribution of bears on shore appears to be related to a combination of ringed seal density near shore, as well as to the availability of marine mammal carcasses;
3. Polar bears feeding on marine mammal carcasses were frequently observed feeding side by side in close proximity of each other with minimal conflict among age/sex classes of bears;
4. Brown bears also used marine mammal carcasses and, although much smaller in size than polar bears, tended to be socially dominant and displace polar bears from the feeding site.

At present, the proportion of southern Beaufort Sea polar bears using terrestrial habitat during the fall open water period is pretty low (<10%); however, long term reduction of sea ice could result in an increasing proportion of bears using coastal habitat for a longer period of time. While marine mammal carcasses can provide an alternative food source when bears are waiting for freeze-up, their proximity to human settlements may also result in an increase in problem bear-human interactions and potentially, in increased polar bear mortality. The FWS continues to work with both village residents as well as oil and gas operators to minimize conflicts, e.g. by assisting with polar bear deterrence programs and by providing guidance on reducing bear attractants. Information from these studies is also used for environmental assessment for oil and gas lease sales, exploration and development projects, and oil spill contingency planning. Results from the studies mentioned above are currently being prepared for publication.