Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, mule deer such as black-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species (except the Chinese water deer) and also female reindeer grow and shed new antlers each year.
Deer weights generally range from 30 to 300 kilograms, though the smallest species, the Northern Pudú, averages 10 kilograms and the largest, the moose, averages 431 kilograms. They generally have lithe, compact bodies and long, powerful legs suited for rugged woodland terrain. Deer are also excellent jumpers and swimmers. Deer are ruminants, or cud-chewers, and have a four-chambered stomach. The teeth of deer are adapted to feeding on vegetation, and like other ruminants, they lack upper incisors, instead having a tough pad at the front of their upper jaw. Some deer, such as those on the island of Rùm, do consume meat when it is available.
The Chinese water deer, tufted deer, and muntjac have enlarged upper canine teeth forming sharp tusks, while other species often lack upper canines altogether. The cheek teeth of deer have crescent ridges of enamel, which enable them to grind a wide variety of vegetation. Nearly all deer have a facial gland in front of each eye. The gland contains a strongly scented pheromone, used to mark its home range. Bucks of a wide range of species open these glands wide when angry or excited. All deer have a liver without a gallbladder. Deer also have a tapetum lucidum, which gives them sufficiently good night vision.
With the exception of the Chinese Water Deer, which have tusks, all male deer have antlers. Sometimes a female will have a small stub. The only female deer with antlers are reindeer (caribou). Antlers grow as highly vascular spongy tissue covered in a skin called velvet. Before the beginning of a species' mating season, the antlers calcify under the velvet and become hard bone. The velvet is then rubbed off leaving dead bone which forms the hard antlers. After the mating season, the pedicle and the antler base are separated by a layer of softer tissue, and the antler falls off.
During the mating season, bucks use their antlers to fight one another for the opportunity to attract mates in a given herd. The two bucks circle each other, bend back their legs, lower their heads, and charge.
Each species has its own characteristic antler structure – for example white-tailed deer antlers include a series of tines sprouting upward from a forward-curving main beam, while fallow deer and moose antlers are palmate, with a broad central portion. Mule deer and black-tailed deer, species within the same genus as the white-tailed deer, instead have bifurcated (or branched) antlers—that is, the main beam splits into two, each of which may split into two more. Young males of many deer, and the adults of some species, such as brocket deer and pudus, have antlers which are single spikes.
Social and Reproductive
Nearly all cervids are so-called uniparental species: the fawns are only cared for by the mother. A doe generally has one or two fawns at a time (triplets, while not unknown, are uncommon). The gestation period is anywhere up to ten months for the European roe deer. Most fawns are born with their fur covered with white spots, though in many species they lose these spots by the end of their first winter. In the first twenty minutes of a fawn's life, the fawn begins to take its first steps. Its mother licks it clean until it is almost free of scent, so predators will not find it. Its mother leaves often, and the fawn does not like to be left behind. The fawn stays hidden in the grass for one week until it is strong enough to walk with its mother. The fawn and its mother stay together for about one year. A male usually never sees his mother again, but females sometimes come back with their own fawns and form small herds.
Deer are selective feeders. They are usually browsers, and primarily feed on leaves. They have small, unspecialized stomachs by ruminant standards, and high nutrition requirements. Rather than attempt to digest vast quantities of low-grade, fibrous food as, for example, sheep and cattle do, deer select easily digestible shoots, young leaves, fresh grasses, soft twigs, fruit, fungi, and lichens.
The deer family has roughly 62 species. The family Cervidae is organized as follows:
Southern Red Muntjac, Reeves's Muntjac, Hairy-fronted Muntjac, Fea's Muntjac, Bornean Yellow Muntjac, Roosevelt's muntjac, Gongshan muntjac, Giant Muntjac, Truong Son Muntjac, Leaf Muntjac, Sumatran Muntjac, Pu Hoat Muntja
Fallow Deer, Persian Fallow Deer
Père David's Deer
Hog Deer, Calamian Deer, Bawean Deer
Sambar, Sunda Sambar, Philippine Sambar, Philippine Spotted Deer
Red Deer, American Wapiti, Sika Deer, Thorold's Deer
European Roe Deer, Siberian Roe Deer
Chinese water deer
Taruca, South Andean Deer
Red Brocket, Small Red Brocket, Merida Brocket, Dwarf Brocket, Gray Brocket, Pygmy Brocket, Amazonian Brown Brocket, Yucatan Brown Brocket, Little Red Brocket, Central American Red Brocket
Northern Pudú, Southern Pudú
White-tailed deer, Key deer, Mule deer