The wide footpads act like paddles when caribou swim. Caribou eat reindeer moss, lichen growing on trees, fungi, mushrooms, grasses, twigs of birches and willows, wild fruit berries and many other green plants. To ingest calcium, Caribou, along with the many rodents of the North, also gnaw and eat discarded antlers of deer, moose and even other caribou. Caribou are usually quiet but can grunt loudly. When a herd is together, it may sound like grunting pigs.
Caribou are excellent swimmers.
Their long, hollow, buoyant hairs keep a third of their bodies above water as they swim. On land, a caribou can run at nearly 80 km per hour for short bursts. With their long fur, they have trouble with heat. They often lie down on snow drifts left on the north side of a hill in spring, fall or early summer to cool themselves off and avoid insects. During winter, their hollow fur absorbs much heat as they sun themselves.