Deer live in a variety of biomes, ranging from tundra to the tropical rainforest.. Mule deer are found only on the western great plains, in the rocky mountains, in the southwest united states, and on the west coast of north america.
Deer are primarily herbivorous mammals that constitute cervidae, the second most diverse family of artiodactyls after bovids (family bovidae).. Deer, any of 43 species of hoofed ruminants in the order artiodactyla, notable for having two large and two small hooves on each foot and also for having antlers in the males of most species.