- This article refers to the sheep genus. For the species commonly referred to simply as "sheep", see Domestic sheep.
Ovis is a genus of mammals, part of the goat-antelope subfamily of the ruminant family Bovidae. Its five or more, highly gregarious species are known as sheep. The domestic sheep is one member of the genus, and is thought to be descended from the wild mouflon of central and southwest Asia.
Female sheep are called ewes, males are called rams (sometimes also called bucks or tups), and young sheep are called lambs. The adjective applying to sheep is ovine, and the collective term for sheep is flock or mob. The term herd is also occasionally used in this sense. Many specialist terms relating to domestic sheep are used.
Sheep are usually stockier than most other bovines, and their horns are usually divergent and curled into a spiral. Sheep have scent glands on their faces and feet. Communication through the scent glands is not well understood, but is thought to be important for sexual signaling. Males can smell females that are fertile and ready to mate, and rams mark their territories by rubbing scent on rocks. Like other ruminants, they have four-chambered stomachs, which play a vital role in digesting food; they eructate, and rechew the cud to increase digestion. Domestic sheep are used for their wool, milk, and meat (which is called mutton or lamb).
Five species and numerous subspecies of sheep are currently recognised, although some subspecies have also been considered full species. These are the main ones:
|Ovis aries aries||Domestic sheep|
|Ovis aries musimon||Mouflon|
|Ovis canadensis||Bighorn sheep|
|Ovis dalli||Dall sheep|
|Ovis nivicola||Snow sheep|
Wild sheep are mostly found in hilly or mountainous habitats. They are fairly small compared to other ungulates; in most species, adults weigh less than 100 kg (220 lb). Their diets consist mainly of grasses, as well as other plants and lichens. Like other bovids, their digestive systems enable them to digest and live on low-quality, rough plant materials. Sheep conserve water well and can live in fairly dry environments. The bodies of wild sheep (and some domestic breeds) are covered by a coat of thick hair to protect them from cold. This coat contains long, stiff hairs, called kemps, over a short, woolly undercoat, which grows in autumn and is shed in spring. This woolly undercoat has been developed in many domestic sheep breeds into a fleece of long wool, with selection against kemp hairs in these breeds. The fleece covers the body (in a few breeds also the face and legs) and is used for fibre.
Sheep are social animals and live in groups, called flocks. This helps them to avoid predators and stay warm in bad weather by huddling together. Flocks of sheep need to keep moving to find new grazing areas and more favourable weather as the seasons change. In each flock, a sheep, usually a mature ram, is folloed by the others.
In wild sheep, both rams and ewes have horns, while in domestic sheep (depending upon breed) horns may be present in both rams and ewes, in rams only, or in neither. Rams' horns may be very large – those of a mature bighorn ram can weigh 14 kg (31 lb) – as much as the bones of the rest of its body put together. Rams use their horns to fight with each other for dominance and the right to mate with females. In most cases, they do not injure each other because they hit each other head to head and their curved horns do not strike each other's bodies. They are also protected by having very thick skin and double-layered skulls.
Wild sheep have very keen senses of sight and hearing. When detecting predators, wild sheep most often flee, usually uphill to higher ground. However, they can also fight back. The Dall sheep has been known to butt wolves off the face of cliffs.
- Grubb, P. (2005). "Order Artiodactyla". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 707–710. ISBN 978-0-8018-8221-0. OCLC 62265494.
- ICZN (International Commission on Zoological Nomenclature) opinion 2027
- Nowak, R. M. and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0-8018-2525-3
- Clutton-Brock, J. 1999. A Natural History of Domesticated Mammals. Cambridge, UK : Cambridge University Press ISBN 0-521-63495-4
- Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing, Inc. ISBN 0-937548-08-1
- Bulanskey, S. 1992. The Covenant of the Wild. New York: William Morrow and Company, Inc. ISBN 0-688-09610-7
- Parker, D. 2001. The Sheep Book. Athens, Ohio, USA : Ohio University Press ISBN 0-8040-1032-3
See also 
- Aries, the Ram (astrological sign)
- Barbary sheep (Ammotragus lervia), another type of goat antelope, not closely related to Ovis sheep
- Blue sheep or bharal (Pseodois), two species of goat antelopes, not closely related to Ovis
- List of sheep breeds
- Sheep husbandry
- Miller, S. 1998. "Sheep and Goats". United States Department of Agriculture, Foreign Agricultural Service
- Oklahoma State University (OSU). 2003 Breeds of Livestock: Sheep Retrieved January 13, 2007
- Huffman, B. 2006. The Ultimate Ungulate Page Website Retrieved January 13, 2007