Defined strictly, a deer is a ruminant mammal belonging to the family Cervidae. A number of broadly similar animals, from related families within the order Artiodactyla, are often also called '\'deer''.
Depending on the species, male deer are called stags, bucks or bulls, and females are called hinds, does or cows. Young deer are called fawns or calves. Hart is an old word for a stag, particularly a Red Deer stag; it has a strict meaning of a stag past its fifth year.
Deer are widely distributed, with representatives in all continents except Australia and Africa.
Deer differ from other ruminants in that they have antlers instead of horns. Antlers are bony growths which develop each year (usually in summer) and, in general, it is only male deer that develop them (although there are exceptions).
There are about 43 species of deer worldwide, divided into two broad groups: the old world group includes the subfamilies Muntiacinae and Cervinae; the new world deer the subfamilies Hydropotinae and Capreolinae. Note that the terms indicate the origin of the groups, not their modern distribution: the Water Deer, for example, is a new world species but is found only in China and Korea.
It is thought that the new world group evolved about 5 million years ago in the forests of North America and Siberia, the old world deer in Asia.
Deer are selective feeders. They have small, unspecialised stomachs by herbivore standards, and high nutrition requirememts: ingesting sufficient minerals to grow a new pair of antlers every year is a significant task. Rather than attempt to digest vast quantities of low-grade, fiberous food as, for example, sheep and cattle do, deer select easily digestable shoots, young leaves, fresh grasses, soft twigs, fruit, fungi, and lichens.
Deer have long had economic significance to humans. While they are generally not as easily domesticated as sheep, goats, pigs and even cattle, the association between people and deer is very old. Deer flesh, for which they are hunted and farmed, is called venison.
- SUBORDER RUMINANTIA
- Family Tragulidae: chevrotains
- Family Moschidae: musk deer
- Family Cervidae
- Subfamily Muntiacinae
- Indian Muntjac, Muntiacus muntjak
- Reeves's Muntjac, Muntiacus reevesi
- Hairy-fronted Muntjac, Muntiacus crinifrons
- Fea's Muntjac, Muntiacus feae
- Roosevelt's Muntjac, Muntiacus rooseveltorium
- Gongshan Muntjac, Muntiacus gongshanensis
- Giant Muntjac, Muntiacus vuqangensis
- Tufted Deer, Elaphodus cephalophus
- Subfamily Cervinae
- Fallow Deer, Dama dama
- Chital, Axis axis
- Hog Deer, Axis porcinus
- Kuhl's Deer, Axis kuhlii
- Calamian Deer, Axis calamianensis
- Thorold's Deer, Cervus albirostris
- Swamp Deer, Cervus duvaucelii
- Red Deer, Cervus elaphus
- Wapiti (Elk), Cervus canadensis
- Eld's Deer, Cervus eldii''
- Sika Deer, Cervus nippon
- Rusa Deer, Cervus timorensis
- Sambar, Cervus unicolor
- Pere David's Deer, Elaphurus davidianus
- Subfamily Hydropotinae
- Water Deer, Hydropotes inermis
- Subfamily Capreolinae
- Mule Deer, Odocoileus hermionus
- Black-tailed Deer, Odocoileus hemionus columbianus
- White-tailed Deer, Odocoileus virginianus
- Roe Deer, Capreolus capreolus
- Moose (Elk), Alces alces
- Reindeer (Caribou), Rangifer tarandus''
- Marsh Deer, Blastocerus dichotomus
- Pampas Deer, Ozotoceros bezoarticus
- Chilean Heumul, Hippocamelus bisulcus
- Peruvian Heumul, Hippocamelus antisensis
- Red Brocket, Mazama americana
- Brown Brocket, Mazama gouazoupira
- Little Red Brocket, Mazama rufina
- Dwarf Brocket, Mazama chunyi
- Southern Pudu, Pudu pudu
- Northern Pudu, Pudu mephistophiles
- Family Giraffidae: Giraffe and Okapi
- Family Antilocapridae: Pronghorn
- Family Bovidae: cattle, goats, sheep, and antelope
- In Christmas lore (The Poem Twas The Night Before Christmas), reindeer are believed to pull the sleigh of Santa Claus.
- One famous fictional deer is Bambi.