The Reindeer (Rangifer tarandus), also known as the caribou in North America, is a species of deer with circumpolar distribution, native to Arctic, sub-Arctic, tundra, boreal, and mountainous regions of northern Europe, Siberia, and North America. This includes both sedentary and migratory populations. Rangifer herd size varies greatly in different geographic regions. Male and female reindeer can grow antlers annually, although the proportion of females that grow antlers varies greatly between population and season. Antlers are typically larger on males.