ROAD AND TRAIL INFLUENCES ON GRIZZLY BEARS AND BLACK BEARS IN

Radio locations from 3 grizzly bears (Ursus arctos) and 26 black bears (U. americanus) in the Cabinet Mountains of northwest Montana were analyzed to determine the effects of roads and trails on seasonal habitat use patterns from 1983 to 1988. Two seasons, spring and fall, were identified based on food habits and habitat use. Distances from radio locations to the nearest open road and trail were compared to distances from random points to the nearest road and trail. Grizzly bears used habitat 0-914 m from open roads less than expected based on availability during spring and fall (P < 0.05). Black bears used habitat 0-274 m from open roads less than expected during spring and used habitat 0-914 m from roads less than expected during fall. Grizzly bears used habitat 0-122 m from trails less than expected during spring and fall. Black bears used habitat 0-122 m from trails less than expected during spring and used habitat 0-305 m from trails less than expected during fall. Habitat availability appeared related to grizzly bearavoidance of trails, and black bearavoidance of roads and trails. Meandistance from grizzly bearradio locationsto a seasonally closed road increased when the road was opened (P < 0.001), though black bear locations did not (P = 0.324). The benefits of road closures in bear management were discussed.