The black bear's fur consists of a dense inner layer of short hairs known as the undercoat, and an outer layer of longer, coarse hairs. This helps to insulate the bear from low temperatures. Its hairs are connected to glands that produce an oily secretion that serves a waterproofing function. In this way, the bear is protected from both cold and rain. The shedding of the bear's winter coat is timed so that his coat is the thinnest during the warmest parts of the summer and thickest when the cold comes. New hairs slowly replace the old, giving the bear a sleek glossy appearance by August.