Vegetation and People Influence Where Bears Roam
Grizzly bears and black bears sharing the mountains and forests of British Columbia's upper Columbia river basin keep to different types of vegetation and terrain. Human activity, however, substantially moderates the distribution of habitat amongst the two species in national parks and near roads.
The two competing bear species with analogous diets tend to avoid each other. Compared with grizzlies, black bears frequent lush, gentle valley bottoms, logged landscapes and young tree plantations. Grizzlies are more apt than black bears to use rugged open terrain, productive older forests and recently burned lands. These differences in habitat use reflect different adaptations of the two species.
Despite habitat preferences, grizzlies are less common than black bears in areas that people access or near a highway. In these places, black bears are more likely to be in the types of terrain that grizzlies normally associate with.
Grizzly populations in Glacier and Yoho National Parks are denser than on nearby provincial land and their habitat use also differs. Both bear species are protected in the parks, but hunted outside them. Grizzly bears within parks are more likely to use habitat types that elsewhere are associated with black bears. The authors of this study note that these anomalies in habitat use reflect the relatively greater resilience of black bears to human disturbance.
Clayton D. Apps, Bruce N. McLellan and John G. Woods. 2006. Landscape partitioning and spatial inferences of competition between black and grizzly bears. Ecography. 29(4): 561-572.