Members of the deer family (Cervidae) are cloven-hoofed ungulates that typically have compact torsos with long, slender legs and small tails — and most males have antlers.           

Size & description

Deer species range from very large to very small. The smallest deer is the Southern pudu, according to the ARKive project. It weighs only abbout 20 lbs. (9 kilograms) and gets to be only about 14 inches (36 centimeters) tall when fully grown

Habitat



Cervids are found all over the world, except Australia and Antarctica. While other continents have a wide array of deer, Africa only has one, the Barbary red deer, according to ADW. The Southern pudu is native to Chile and Argentina. The white-tailed deer is common to North and South America.
Deer are found in many different ecosystems. They live in wetlands, deciduous forests, grasslands, rain forests, arid scrublands and mountains. Sometimes, when human civilizations get too close to home, deer will even make themselves comfortable in urban settings.

Habits

Deer are very social and travel in groups called herds. The herd is often led by a dominant male, though with some species the herds are segregated by sex. Sometimes the females will have their own herd and the males will have a separate herd. In other cases, a female herd is watched over by a herd of males. Some caribou herds can have as many as 100,000 members, according to ADW. 
Most deer are active throughout the day, though their most active times are during sunrise and dusk. They spend their days foraging for food.

Diet

Deer are herbivores; they only eat vegetation. For the most part, a deer's diet consists of grass, small shrubs and leaves, though they will forage in trash bins and in gardens if they cannot find the vegetation they need elsewhere. 
Deer have one main stomach and three "false stomachs." Like cows, they chew their cud to fully digest their food.

Offspring

Though not common, some deer are monogamous, such as the European Roe deer. When a deer breeds depends on where it lives. Deer in temperate areas breed during late autumn or early winter. Deer that live in lower latitudes breed from late spring into early summer. Deer that live in tropical climates mate whenever they want, which could be several times per year. 
Deer carry their young for a gestation period of 180 to 240 days. For northern and southern white-tailed deer, gestation is around 193 to 205 days, according to Louisiana State University. Usually, the larger the deer, the longer the mother carries it in her womb. Deer usually only have one to three young at a time and these young are called fawns. Some of the large deer babies are also called calves.
Deer range in color from dark to very light brown, according to ADW, and fawns are born with white spots to help camouflage them from predators. Fawns are weaned at two to five months of age. Deer are unable to fully mature unless they reach a certain size, though how big they need to be varies depending on species. Overall, most deer live 11 to 12 years, though many die long before then due to predators or environmental dangers such as collisions with cars.