Landward 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 satelli...

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Bibliographic Details
Published in:Polar biology 2007-10, Vol.30 (11), p.1395-1405
Main Authors: FISCHBACH, A. S, AMSTRUP, S. C, DOUGLAS, D. C
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Aquatic mammals
Autoecology
Balaena mysticetus
Bears
Biological and medical sciences
Climatology. Bioclimatology. Climate change
Coastal zone
Dens
Earth, ocean, space
Exact sciences and technology
External geophysics
Fundamental and applied biological sciences. Psychology
Mammalia
Meteorology
Pack ice
Polar bears
Sea ice
Telemetry
Ursus maritimus
Vertebrata
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Summary: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.[PUBLICATION ABSTRACT]
ISSN:0722-4060
1432-2056
DOI:10.1007/s00300-007-0300-4