Ovis aries vignei

Geographic Range

Urial sheep are widely distributed in Asia minor. They are found from southwestern Kazakhstan through Turkmenistan, Uzbekistan, Tajikistan, Afgahnistan, Pakistan, and into the Kashmir region of India. They range eastward into Iran, and some are found in Oman, although that population is thought to have been introduced.

• Biogeographic Regions
• palearctic palearctic
  • native native
• oriental oriental
  • native native

Habitat

Urial sheep inhabit steep to undulating grassy terrain, to an elevation of 6,000 m. Their habitat tends to be moderately to very arid. They may also be found in agricultural fields and sometimes enter partly wooded areas.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• forest forest
• mountains mountains

• Other Habitat Features
• agricultural agricultural

Physical Description

Males of this species may weigh up to 90 kg and have a shoulder height up to 1m. Overall, they are brown colored with a lighter coat in summer than in winter. They have a distinct white rump patch below the base of the tail and along the back of the hind quarters. Urial sheep have a black and white saddle patch. Males have a black neck ruff which is restricted to the front of the neck and brisket.

Males are reported to have massive horns, whereas female horns are much smaller. Horn shape may be variable, but tends to be in a supracervical arangement. The greatest horn length recorded was 990.6 mm and greatest basal circumference was 304.8 mm.

Urial sheep have antelope-like features, characterized by sinewy bodies and long legs.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• ornamentation ornamentation

Reproduction

Urial sheep males are polygynous, but males do not accumulate a harem. Males approach females slowly in a stretched posture. The female reacts by squatting and urinating. The males then smells the female's urine to determine chemically whether she is in estrus. Females in estrus are claimed by the dominant male. After copulation, the dominant male gaurds female from other males until she is no longer in estrous. Once the female is no longer receptive, the male will leave in search of another female in estrus.

• Mating System
• polygynous polygynous

Reproductive patterns of Urial sheep may be inferred from those of relatives. Moufloniforms are monoestrous and breed during rutt between November and December. Ewes become sexually mature at 1.5 years of age, and may bear their first young at 2 years of age. Estrous lasts for 1-2 days. Copulation is speedy, lasting a mere 2-3 seconds. Gestation is long, lasting 150-160 days.

Ewes give birth to one lamb per pregnancy until they are above 3 years old. Older ewes may give birth to 2 or 3 lambs. The probability of twinning in ewes over 4 years old is 0.50. At birth, lambs weigh between 6 and 10 pounds. In a well nourished population all ewes of breeding age will bear young. Lambs nurse for 5-6 months, although they may nibble on vegetation within 1 month after birth. The life span of this species ranges from 8 to 12 years.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Ewes segregate themselves from the herd prior to giving birth. After giving birth, females and their young remain apart from the herd for 3 to 7 days. During this time the lamb gains strength and both the mother and her offspring learn to recognize each other by smell. The ewes and lambs then return to the herd. Moufloniforms do not form nursery bands.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
• post-independence association with parents
• extended period of juvenile learning

Lifespan/Longevity

Lifespan of urial sheep ranges from 8 to 12 years.

Behavior

These sheep are mainly diurnal, and spend most of their day foraging. They move throughout a range, but do not maintain territories (Valdez, 1982).

Urial sheep are gregarious and form herds of related individuals. Herds usually are comprised of females, lambs, and juveniles. Adult rams form separate all-male groups. Seperation of herds eliminates competition for forage and reduces female harassment. Herds have a social structure in whch dominance is based on body size. Dominance relationships are especially evident in ram herds, where dominance is largely based on horn size--the larger the horns, the higher the dominance rank (Nowak, 1999; Valdez, 1982).

Dominant males act as a stabalizing force in sheep society by preventing younger rams from harassing females. Young males are more aggressive and bullying towards ewes thn are older males. Agressive encounters between similar-sized individuals usually include head twists and front kicks. Urial sheep do not rise on to back legs before clashing (Valdez, 1982).

• Key Behaviors
• cursorial
• terricolous
• diurnal diurnal
• motile motile
• nomadic nomadic
• social social
• dominance hierarchies dominance hierarchies

Communication and Perception

Details regarding communication in this species are lacking. However, it is known that males have aggressive physical encounters by which they establish and communicate dominance relationships. Tactile communication seems likely. Females communicate their estrous status to adult males via chemical cues in their urine. Also, mothers and infant recognize one another based on scent, so olfactory communication plays an important role in this species. Based upon the vocalizations of domestic sheep, probably domesticated from a common ancestor (Nowak, 1999), it would seem likely that there is also some amount of acoustic communication, although this is reportedly not common. (Nowak, 1999; Valdez, 1982).

• Communication Channels
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Ovis vignei is herbivorous. It consumes a variety of unspecified plants, presumably grasses and shrubs. It will also eat grains.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• wood, bark, or stems
• seeds, grains, and nuts

Predation

Predation has not been specifically reported for these animals. They are agile climbers, and their antelope-like features may help them to evade predators. It is likely that large eagles, canids, and large felids, where present, could take young sheep.

Ecosystem Roles

Urial sheep have the capability to influence vegetative composition in their habitat through grazing.

Economic Importance for Humans: Positive

Urial sheep provide recreational value as a game species.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

Urial sheep may be a potential pest on agricultural fields.

• Negative Impacts
• crop pest

Conservation Status

Ovis vignei is a CITES Appendix I subspecies. It is listed by the IUCN as vulnerable as part of O. orientalis (see additional comments below). It is clear that populations are decreasing, regardless of the taxonomy used. Expansion of agriclture into wild sheep habitat, other human habitat modifications, and indiscriminant hunting for trophies has led to a serious decline (Nowak, 1999). Ovis vignei is considered especially vulnerable because it inhabits the low, open country where people commonly graze their livestock (Nowak, 1999). This makes these animals especially susceptible to competition from domestic livestock for food resources. Two of the subspecies hardest hit, according to Nowak (1999) are O. v. vignei and O. v. punjabiensis , each with an estimated remaining population around 2,000 individuals.

Other Comments

The taxonomy of the genus Ovis is controversial. Various authorities have lumped O. aries (domestic sheep) with O. orientalis (mouflon) as members of the same species. Others recognize the two as distinct species, but claim that O. orientalis is the ancestral species from which domestic sheep were derived. Some consider populations of sheep on the islands of Corsica and Sardinia as subspecies of O. orientalis , whereas others separate them as a distinct species. In north India, populations of O. ammon and O. vignei occur near one another, and some think they represent a single species. There are also those who consider O. orientalis and O. vignei conspecific.

Complicating matters further, the genus Ovis has also been considered by some to be synonymous with the genus Capra (goats) because of fertile hybrids produced between C. hircus (domestic goats) and O. aries (domestic sheep).

All wild species of sheep are allopatric, however, hybridization can, and does, occur (Nowak, 1999). Urial sheep represent a chromosomal, geographic and morphological extreme amongst the wild sheep of Iran. Urial sheep (2N=58) hybridize with Ovis orientalis (2N=54), producing a 150 kilometer zone of hybridization. Hybrids in the hybridization zone display variable pelage and chromosome number (54-58). (Valdez et al., 1978) .

Additional Links

Encyclopedia of Life

Contributors

Andrew Hagen (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.

References

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.

Valdez, R., C. Nadler, T. Bunch. March 1978. Evolution of Wild Sheep in Iran. Evolution , 32: 56-72.

Valdez, R. 1982. The Wild Sheep of the World . Mesilla, New Mexico, USA: The Wild Goat and Sheep International.