White-tailed deer spend their mornings and evenings grazing for food. They're herbivores, so they eat green plants and nuts. Deer live in small groups -- usually just a mother and her fawns. Males, called bucks, have magnificent antlers and live in small groups of three or four. Both male and female deer are red brown in summer and gray brown in winter. Since none of their predators are still around, deer populations sometimes grow so big that there's not enough food for them to eat. Deer are ruminants, like cattle. This means they have four stomachs and chew on semi-digested food, called cud. This complicated process allows deer to eat things like twigs that most animals can't digest.