Habitat Preferences of Polar Bears in the Hudson Bay Lowlands during Late Summer and Fall

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From late July through early November, polar bears (Ursus maritimus) in western Hudson Bay are on shore because the annual ice melts. During this period, bears segregate by age and sex classes into different habitats. We investigated habitat selection using the locations of 1,131 captures made from 1966 to 1994. Adult males, the most dominant bears, were found most often in coastal areas, especially on beach ridges. This enables them to keep cool during summer and move little while fasting until freeze-up, thereby conserving stored energy reserves. Lone adult females and females accompanied by dependent young moved inland during the ice-free period and selected riparian, lakeshore, and lichen tundra habitats. We conclude that avoiding adult males, thermoregulation, and suitable denning habitat are the most important factors causing adult females to move to the inland areas and to select habitats once there. Subadult females were distributed through all habitat types while subadult male distribution paralleled adult males. Production of berries, as a potential food source, probably does not influence inland distribution.