In summer, the hooves are worn away by travel over hard ground and rocks. Adult bulls generally shed their antlers in November or December, after they have mated. Cows and young animals carry their antlers much longer, often through the winter. The growing antlers have a fuzzy covering, called velvet, which contains blood vessels carrying nutrients for growth. The ability of caribou to use lichens as a primary food distinguishes them from all other large mammals and has enabled them to survive on harsh northern rangeland.
Caribou have an excellent sense of smell, which they use to locate lichens under the snow.
Caribou are very curious and hunters have found that by slowly waving their arms, or bobbing up and down from the waist, they can often attract caribou to close range. A fourth type, the Queen Charlotte Island race, is extinct. The Queen Charlotte Island caribou Rangifer tarandus dawsoni was a small, greyish caribou found only on Graham Island. Little is known of this animal or of the causes for its extinction, but deterioration of habitat due to climate change was probably a more important cause than hunting. The Peary caribou Rangifer tarandus pearyi is a small, light-coloured caribou found only in the islands of the Canadian arctic archipelago.