Deer are ruminant mammals and are part of the Cervidae.
Some species include the white-tail deer, roe deer, mule deer, elk, fallow deer and moose, the largest current species of deer. Deer are herbivores and will eat grass, leaves, soft twigs, fungi and fruit. A baby deer is called a fawn or calf depending on which species he/she is, a male is called a buck and the female is called a doe while for some larger species of deer the male can be called a stag, with the largest species having names similar to cattle such as a bull or cow. Nearly all species of male deer except the female reindeer grow antlers. Deer always stay in herds.