It ran with amazing speed, resembling a big hog as it noisily left the thicket. Often the bears are nearly fully exposed to the winter weather during their prolonged sleep. They may awaken and become active during a warm spell in midwinter and return to the nest to sleep again when the temperature drops. Their food is extremely varied as reflected by the crushing type of molar teeth. They are known to feed upon nest contents of wild bees, carpenter ants and other insects, manzanita berries, coffee berries, wild cherry, poison oak, apples, pine nuts, acorns, clover, grass, roots, fish, carrion, and garbage about camps.
Occasional animals become killers of livestock and young deer.
The breeding season is in June or July. At birth the young are blind, covered with a sparse growth of fine hair, and almost helpless. They weigh less than 500 g and are about 15 cm long. By the time the mother is ready to leave her winter den they are strong enough to follow. The cubs remain with her until the fall of their second year when they venture forth on their own.