The North American name for a deer (family Cervidae) that is native to Arctic, sub-Arctic, tundra, and boreal forest regions, with a circumpolar distribution; known as the reindeer in Eurasia. It is unique among deer in that in most populations both males and females grow antlers annually. They graze and browse, and in winter they feed on a lichen, reindeer moss (Cladonia rangiferina). They have been domesticated in Scandinavia and Russia, and kept for meat, skins, antlers, and milk, and used to pull sleds and sleighs (including Santa Claus’s sleigh).