Caribou herds migrate different distances. Large herds are more apt to migrate long distances, while smaller herds often migrate shorter distances. For example, the Porcupine caribou herd, which contains about 169,000 animals, migrates between summer and winter ranges that are about 400 miles apart. The Central Arctic herd, which contains about 70,000 animals, migrates between summer and winter ranges that are about 120 miles apart.