Remote identification of polar bear maternal den habitat in northern Alaska

Polar bears (Ursus maritimus) give birth in dens of ice and snow to protect their altricial young. During the snow-free season, we visited 25 den site s located previously by radiotelemetry and characterized the den site physi ognomy. Seven dens occurred in habitats with minimal relief. Eighteen dens (72%) were in coastal and river banks. These "banks" were identifiable on a erial photographs. We then searched high-resolution aerial photographs (n = 3000) for habitats similar to those of the 18 dens. On aerial photos, we m apped 1782 km of bank habitats suitable for denning. Bank habitats comprise d 0.18% of our study area between the Colville River and the Tamayariak Riv er in northern Alaska. The final map, which correctly identified 88% of ban k denning habitat in this region, will help minimize the potential for disr uptions of maternal dens by winter petroleum exploration activities.