Size, body weight and color vary from habitat to habitat. Bears are omnivores . Toward fall, roots and moths clustering in rocky, high-elevation areas are added. Hibernation Bears hibernate because of a decreased food supply, no an inability to stay warm. Dens are used during winter hibernation .
Bears sleep outside in day beds from spring through fall.
May. Males emerge from their dens first each season and females with cubs emerge last. Body temperature drops only a few degrees during denning. Unlike rodents, bears can be easily aroused from their winter sleep. Grizzly bears usually excavate their own dens, while black bears more often locate a natural cavity, such as a rock crevice or hollow tree. Dens are often lined with leaves, grass, spruce or fir boughs, or pine needles.