''Ovis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of mammals, part of the

Caprinae The subfamily Caprinae, also sometimes referred to as the tribe Caprini, is part of the ruminant family Bovidae, and consists of mostly medium-sized bovids. A member of this subfamily is called a caprine, or, more informally, a goat-antelope (a ...

subfamily of the

ruminant Ruminants (suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The ...

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Bovidae The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, t ...

. Its seven highly sociable

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

are known as sheep or ovines.

Domestic sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticated ...

are members of the genus, and are thought to be descended from the wild

mouflon The mouflon (''Ovis gmelini'') is a wild sheep native to Cyprus, the Caspian region from eastern Turkey, Armenia, Azerbaijan, and Iran. It is thought to be the ancestor of all modern domestic sheep breeds. Taxonomy ''Ovis gmelini'' was the sc ...

of central and

southwest Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...

Terminology

Female sheep are called ''ewes'', males are called ''rams'' or less frequently ''bucks'' or ''tups'', neutered males are called ''wethers'', 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, generally for large flocks. Many specialist terms relating to domestic sheep are used.

Characteristics

Sheep are fairly small compared to other

ungulates Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ca ...

; in most species, adults weigh less than .Nowak, R. M. and J. L. Paradiso. 1983. ''Walker's Mammals of the World''. Baltimore, Maryland: The Johns Hopkins University Press. Males are usually heavier than females by a significant amount. Wild sheep are mostly found in hilly or mountainous habitats. Their diets consist mainly of

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

es, as well as other plants and lichens. Like other

s, they have four-chambered

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

s, which play a vital role in digesting food; they eructate, and rechew the cud to 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.Clutton-Brock, J. 1999. ''A Natural History of Domesticated Mammals''. Cambridge, UK : Cambridge University Press This woolly undercoat has been developed in many domestic sheep breeds into a fleece of long

wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal 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. Domestic sheep are also reared for their

milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modula ...

and meat (which is called lamb or mutton depending on the age of the animal). 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 – 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.Voelker, W. 1986. ''The Natural History of Living Mammals''. Medford, New Jersey: Plexus Publishing, Inc. Wild sheep have very keen senses of

sight Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflecte ...

and

hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is audit ...

. When detecting predators, wild sheep most often flee, usually to higher ground, but they can also fight back. The Dall sheep has been known to butt

wolves The wolf (''Canis lupus''; : wolves), also known as the gray wolf or grey wolf, is a large canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, and gray wolves, as popularly un ...

off the face of cliffs. Sheep have

scent gland Scent gland are exocrine glands found in most mammals. They produce semi-viscous secretions which contain pheromones and other semiochemical compounds. These odor-messengers indicate information such as status, territorial marking, mood, and s ...

s 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 in

estrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous ...

, and rams mark their territories by rubbing scent on rocks.

Species

Seven species (and numerous subspecies) of sheep are currently recognized. The main recognized divisions are:

Behaviour

Sheep are social animals and live in groups, called flocks. This helps them to avoid

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s and stay warm in cold 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 followed by the others. This "leader to follower" relationship can be both a positive and negative for flocks of ''Ovis aries''. Although there is safety in numbers, it has been reported that the following of one mature ram can bring flocks to slaughter in many situations where the mature ram misguides the flock.

Mating

Mating in sheep is characterized by males competing for females in estrus. Social rank in rams is established by male-male competition, known as the rut. Females select from dominant males based on sexually selected characteristics such as body size and horn size, as those traits are desirable in offspring. Females typically are separated from males outside the rut, but during the rut, females and males are found together. Females that are oestrous isolate themselves from other ewes, and may be less mobile. The rut is also linked with different ewe behaviour than during nonrutting periods. These changes are characterized by decreased feeding, increased time observing their surroundings, and increased behaviour changes. Ewes are also predicted to be slightly receptive to the displays of the rams.

References

*Bulanskey, S. 1992. ''The Covenant of the Wild''. New York: William Morrow and Company, Inc. *Parker, D. 2001. ''The Sheep Book''. Athens, Ohio, USA : Swallow Press / Ohio University Press

External links

Miller, S. 1998. "Sheep and Goats". United States Department of Agriculture, Foreign Agricultural Service
{{Authority control Sheep Mammal genera Taxa named by Carl Linnaeus