ALMOST all authorities agree that the two elements that grizzly bears need to survive are space and solitude. The Montana Department of Fish, Wildlife, and Parks says that one grizzly may use as little as a radius of five square miles, but another bear might use 70 times that much. How much land the grizzly needs for foraging and roaming depends largely on how rich the food source is in the area. Grizzlies, although classified as omnivorous, are actually 80 percent vegetarian. Their primary diet comes from wild berries, seasonal grasses, roots, and tubers, as well as vegetation found around stream and river beds. Salmon and an occasional squirrel, mouse, deer, or elk round out the bear's food requirements.
During ``hyperphagia,'' a period of gorging to put on body fat before hibernation, the grizzly eats for as many as 20 hours a day and consumes as many as 20,000 kilocalories. Between July and November, the bear may gain anywhere from 70 to 100 pounds.
Although grizzlies are not territorial and share space with black bears and a variety of other wild animals, they do require solitude. At the top of his food chain, highly intelligent and adaptable, the grizzly competes only with man for land area. Female grizzlies concerned with protecting their cubs especially feel the need for a secure environment. During the two- to three-year period that her cubs remain with her, the female grizzly will share with them all her accumulated knowledge to help ensure their survival.
Both male and female grizzlies prefer avoiding human contact whenever possible.