The Scandinavian Brown Bear Project Print this page
Abstract:
When exposed to human disturbance, most large carnivores are able to move away from the source with little energetic costs. Bears represent an exception in that during winter, most individuals spend several month in an energy-saving state of hibernation in a den. This implies that disturbance of denning bears has the potential to have a large energetic cost, although data on the subject are rather diffuse. We reviewed the literature on densite selection, denning physiology, and responses to disturbance for the brown bear (Ursus arctos), black bear (U. americanus), and polar bear (U. maritimus). Generally, bears select dens one to 2 km from human activity (roads, habitation, industrial activity) and seemed to tolerate most activities that occurred more than one km from the den. Activity closer that one km and especially within 200m caused variable responses. Some bears tolerate disturbance even inside the den, but bears will abandon dens in response to activity within this zone, especially early in the denning period. Den abandonment by brown and black bear females with cubs of the year can lead to increased cub mortality. Specific excavated or ground dens are rarely reused, whereas natural caves or hollow trees are reused with varying frequency. There is often some distance between an individual bear’s consecutive dens. This indicates that loss of a single denning area following human disturbance will not always lead to deleteroiut effects, if alternative denning areas are available within the home range.
2001, Wildl. Soc. Bull. 28:400-413