Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes

Polar Biology
By: , and 



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 ice declined from 62% in 1985–1994 to 37% in 1998–2004 (P = 0.044) and among pack ice dens fewer occurred in the western Beaufort Sea after 1998. We evaluated whether hunting, attraction to bowhead whale remains, or changes in sea ice could explain changes in den distribution. We concluded that denning distribution changed in response to reductions in stable old ice, increases in unconsolidated ice, and lengthening of the melt season. In consort, these changes have likely reduced the availability and quality of pack ice denning habitat. Further declines in sea ice availability are predicted. Therefore, we expect the proportion of polar bears denning in coastal areas will continue to increase, until such time as the autumn ice retreats far enough from shore that it precludes offshore pregnant females from reaching the Alaska coast in advance of denning.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes
Series title Polar Biology
DOI 10.1007/s00300-007-0300-4
Volume 30
Issue 11
Year Published 2007
Language English
Publisher Springer
Contributing office(s) Alaska Science Center
Description 11 p.
First page 1395
Last page 1405
Country United States
State Alaska
Online Only (Y/N) N
Additional Online Files (Y/N) N
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