A deer is a ruminant mammal belonging to the family Cervidae. A number of broadly similar animals from related families within the order Artiodactyla (even-toed ungulates) are often also called deer. Male deer of all species, except the Chinese water deer, grow and shed new antlers each year, as opposed to horned animals such as antelope—these are in the same order as deer and may bear a superficial resemblance, but they are permanently horned. The Musk deer of Asia and Mouse Deer or Water Chevrotain of tropical African and Asian forests are not true deer and form their own families, "Moschidae" and Tragulidae, respectively. All other animals in Africa resembling deer are antelope.

Etymology

The word deer was originally quite broad in meaning, but became more specific over time. In Middle English, der (O.E. dēor) meant a wild animal of any kind (as opposed to cattle, which meant any domestic livestock). This general sense gave way to the modern sense by the end of the Middle English period, around 1500. The German word Tier, the Dutch word dier and the Scandinavian words djur/dyr/dýr, cognates of English deer, still have the general sense of "animal". The adjective of relation pertaining to deer is cervine.

Depending on their size and species, male deer are called bucks (smallest), stags, or bulls (largest) and females are called does, hinds or cows. Young deer are called kids, fawns or calves. A group of deer is commonly called a herd. Hart, from Old English heorot "deer", is an alternative term for a stag, particularly a Red Deer stag past its fifth year (compare with the modern Dutch word hert meaning deer). The county Hertfordshire is named after a place where deer ford a watercourse. The word hart is not commonly used, but Shakespeare makes several references, punning on the sound-alike "hart" and "heart", for example in Twelfth Night. "The White Hart" and "The Red Hart" are common English pub names. Whinfell Forest once contained a landmark tree called Harthorn. The word "Hart" also exists in Saterfrisian, being a synonym for the Word "Hirsk" which is more similar to the German Word "Hirsch".

Habitat

Deer are widely distributed, and hunted, with indigenous representatives in all continents except Antarctica and Australia, though Africa has only one native species confined to the Atlas Mountains in the northwest of the continent, the Red Deer.

Deer live in a variety of biomes ranging from tundra to the tropical rainforest. While often associated with forests, many deer are ecotone species that live in transitional areas between forests and thickets (for cover) and prairie and savanna (open space). The majority of large deer species inhabit temperate mixed deciduous forest, mountain mixed coniferous forest, tropical seasonal/dry forest, and savanna habitats around the world. Clearing open areas within forests to some extent may actually benefit deer populations by exposing the understory and allowing the types of grasses, weeds, and herbs to grow that deer like to eat. Additionally, access to adjacent croplands may also benefit deer. However, adequate forest or brush cover must still be provided for populations to grow and thrive.