Marine Mammals Management
Alaska Region


Polar Bear

Proposed Critical Habitat in Alaska


Distribution of Polar Bear Sea Ice Habitat in the Chukchi and Beaufort Seas, 1989-1992: An Animation

Polar bears in the Chukchi and Beaufort Sea region live mainly on the sea ice, which provides a platform for hunting of ice seals, their primary prey. The Arctic sea ice in this region advances southward in winter and retreats northward in summer. High quality polar bear habitats generally occur around the periphery of the ice pack when the ice is over the continental shelf. Our understanding of sea ice habitats important to polar bears comes from studying the movements of polar bears equipped with satellite radio transmitters.

This animation illustrates how the distribution of polar bear habitat changes as the sea ice retreats and advances with the changing seasons.  Higher quality habitats are depicted with lighter shades of gray. The continental shelf is denoted by a 300-meter depth contour (light-blue line).  Data for this animation are from 1989-1992. Locations of adult female polar bears obtained by U.S. Geological Survey satellite radio-tracking studies are shown as red dots.  Individual polar bears may have been re-located up to 10 times per month.  Because polar bears and the ice pack both move on a daily basis, some spatial disparities between the ice and bear distributions are introduced in the monthly-composited illustrations shown here.  Estimates of habitat quality were derived using resource selection functions (RSFs).  Here, the monthly RSF values of habitat quality throughout the Arctic Ocean were partitioned into 20 equal-area zones, and the top-10 zones were gray-shaded from dark to light.

Source:  U.S. Geological Survey, based on Durner, G.M., D.C. Douglas, R.M. Nielson, S.C. Amstrup, T.L. McDonald, I. Stirling, M. Mauritzen, E.W. Born, O. Wiig, E. DeWeaver, M.C. Serreze, S.E. Belikov, M.M. Holland, J. Maslanlik, J. Aars, D.A. Bailey, and A.E. Derocher. 2009.  Predicting 21st-century polar bear habitat distribution from global climate models. Ecological Monographs 79:25–58.

For further information, contact:

David C. Douglas
U.S. Geological Survey





Last updated: June 29, 2009