For many large animals the tundra is only habitable during the summer months and in winter they migrate southwards into the coniferous forests, where conditions are less austere. The largest of these animals is the woolly gigantelope. It differs from equatorial gigantelopes mainly in size and in the possession of a large, fatty hump, which provides it with nourishment during the hungry winter months. It has a long, shaggy winter coat and broad hooves, which prevent it from sinking into soft snow. It uses its enormous horns as snow ploughs to expose the mosses, lichens and herbaceous plants on which it feeds. Its eyes are small to avoid being frostbitten and its nostrils are bordered by blood vessels that warm the air before it reaches the lungs.