Habitat
Polar bears are closely tied to arctic pack ice. They prefer areas with ice that is periodically active, such as at the interface of landfast ice and drifting pack ice along the arctic coasts or near polynyas. Polar bears, are most commonly observed in or near shore zones where ice is constantly moving, opening up and reconsolidating, rather than pelagic areas which are of lower productivity (Stirling and Smith 1975; Pomeroy 1997; Stirling 1997). Sometimes they wander inland as much as 150 km from the coast. In the Bering and Chukchi Seas, Alaska, where sea ice melts in summer, bears migrate up to 1000 km to remain with the southern ice boundary (Amstrup 2003). Pregnant females remain on or near land in dens through winter while males and non- breeders winter on sea ice (Derocher and Stirling 1990). In Alaska, polar bears den most commonly on offshore islands and associated heavy, stable ice from the mouth of Colville River to Brownlow Point (MacDonald and Cook 2009). Occasionally den on shorefast ice and river bottoms from Kuparuk River to Point Hope (ADF&G 1973).
References
ADF&G. 1973. Alaska’s wildlife and habitat. Anchorage, Alaska. 144 pp. + maps.
Amstrup, S.C. 2003. Polar bear, Ursus maritimus. Chapter 27 (Pp. 587-610) in: Wild mammals of North America: biology, management, and conservation. Edited by G.A. Feldhamer, B.C. Thompson, and J.A. Chapman. John Hopkins University Press, Baltimore, Maryland.
Derocher, A. E. and I. Sterling. 1990. Distribution of polar bears (Ursus maritimus) during the ice-free period in western Hudson Bay. Canadian Journal of Zoology 68:1395-1403.
MacDonald, S. O. and J. A. Cook. 2009. Recent Mammals of Alaska. University of Alaska Press, Fairbanks, AK.
Pomeroy, L. R. 1997. Primary production in the Arctic Ocean estimated from dissolved oxygen. Journal of Marine Systems. 10:1-8.
Stirling, I. 1997. Importance of polynyas, ice edges, and leads to marine mammals and birds. Journal of Marine Systems. 10(1-4):921.
Stirling, I., and T. G. Smith. 1975. Interrelationships of Arctic Ocean mammals in the sea ice habitat. Circumpolar Conference on Northern Ecology. 2:129-136.
