Space use by polar bears in and around Auyuittuq National Park, Northwest Territories, during the ice-free period

摘要

We investigated patterns of space use by polar bears (Ursus maritimus) in and around Auyuittuq National Park, Northwest Territories, during the ice-free period in 1991-1995, using satellite telemetry and capture locations. Female polar bears showed general fidelity to the region but no site-specific fidelity. The pattern of sea-ice ablation influenced when and where bears were forced to leave the ice for land, usually at the end of August. While awaiting the return of sea ice, bears conserved energy by reducing movement and activity. Bears left the land after ice formed that was strong enough to support them, usually in mid-November. During the ice-free period, females with cubs of the year were farther inland, closer to fjords, and less likely to use islands than were males. Males found close to females with cubs of the year were thinner than the average male, suggesting that segregation may result from the threat of intraspecific predation. Females with cubs of the year left the ice for land earlier than other classes of bears and rarely used snow shelters. After about 1 week on land, pregnant females entered a maternal den for the winter. Unlike those in other polar bear populations, most females with 1-year-olds entered a shelter after about 3 weeks on land and remained there for about 2 months. Dens and shelters were located at high elevations and far from the coast, and sheltering bears weighed more than nonsheltering bears.