''Ovis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s, 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 In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

of the

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

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

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, ...

. 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 sh ...

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 Sea, 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'' ...

central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

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 Anat ...

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 A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called ''herding''. These animals are known as gregarious animals. The term ''herd'' is ...

'' 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, cam ...

; 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 an ...

es, as well as other plants and

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.ruminant Ruminants (suborder Ruminantia) are ungulate, hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principally ...

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 Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...

food; they eructate, and rechew the

cud Cud is a portion of food that returns from a ruminant's stomach to the mouth to be chewed for the second time. More precisely, it is a bolus of semi-degraded food regurgitated from the reticulorumen of a ruminant. Cud is produced during the phy ...

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 Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and f ...

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. As ...

, 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 Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...

. 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 digestion, digest solid food. Immune factors and immune ...

and

meat Meat is animal flesh that is eaten as food. Humans have hunted, farmed, and scavenged animals for meat since prehistoric times. The establishment of settlements in the Neolithic Revolution allowed the domestication of animals such as chic ...

(which is called lamb or mutton depending on the age of the animal). In wild sheep, both rams and ewes have

horn Horn most often refers to: *Horn (acoustic), a conical or bell shaped aperture used to guide sound ** Horn (instrument), collective name for tube-shaped wind musical instruments *Horn (anatomy), a pointed, bony projection on the head of various ...

s, while in domestic sheep (depending upon

breed A breed is a specific group of domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist several slig ...

) 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 A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of stimuli. (For example, in the human body, the brain which is part of the central nervous system rec ...

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

and

hearing Hearing, or auditory perception, is the ability to perceive sounds In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psycholog ...

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

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 sexu ...

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 p ...

, 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 A social class is a grouping of people into a set of hierarchical social categories, the most common being the upper, middle and lower classes. Membership in a social class can for example be dependent on education, wealth, occupation, incom ...

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