Distribution of grizzly bears in the US Northern Rockies

The current estimated distribution area of grizzly bears (Ursus arctos) in the U.S. Northern Rockies suggests they have recently expanded their distribution in this region. Expansion beyond designated recovery zones has important conservation and land management implications. Using a computer home range program, HOME RANGER, and about 3,000 recorded locations of grizzly bear observations obtained from numerous state and federal agencies, current distribution of grizzly bears was estimated as an aid to recovery efforts. I estimated the distribution area of grizzly bears in the U.S. Northern Rockies at about 102,524 km(2). This is significantly larger than previously reported by other sources, and greatly exceeds the 56,043 km(2) area delimited as grizzly bear recovery zones by the U.S. Fish and Wildlife Service. I suggest there is merit in expanding designated recovery zones. Greater research and management attention must be paid to peripheral areas as range expansion by bears may outpace management response, with potentially negative consequences to both bears and humans.