The onager (/ˈɒnədʒər/;[3]Equus hemionus/ˈɛkwəshɪˈmaɪənəs/),[4][5] also known as hemione or Asiatic wild ass,[6] is a species of the family Equidae native to Asia. A member of the subgenus Asinus, the onager was described and given its binomial name by German zoologist Peter Simon Pallas in 1775. Six subspecies have been recognized, two of which are extinct.
The Asiatic wild ass weighs about 200–260kg (440–570lb)[7] and reaches about 2.1m (6.9ft) head-body length. They are reddish-brown or yellowish-brown in color and have broad dorsal stripe on the middle of the back. Unlike most horses and donkeys, onagers have never been domesticated. They are among the fastest mammals, as they can run as fast as 64km/h (40mph) to 70km/h (43mph). The onager is closely related to the African wild ass, as they both shared the same ancestor. The kiang, formerly considered a subspecies of Equus hemionus, is generally considered a distinct species,[8] however, this has been questioned, with some genomic studies finding the kiang to be nested within the diversity of Equus hemionus.[9]
The specific name is from the Ancient Greekἡμίονος, hēmíonos, from ἡμι-, hēmi-, 'half', and ὄνος, ónos, 'donkey'; thus, 'half-donkey' or mule. The term onager comes from the ancient Greek ὄναγρος, again from ὄνος, ónos, 'donkey', and ἄγριος, ágrios, 'wild'.
The species was commonly known as Asian wild ass, in which case the term onager was reserved for the E.h.onager subspecies,[6] more specifically known as the Persian onager. Until this day, the species share the same name, onager.
The Asiatic wild ass, among Old World equids, existed for more than 4 million years. The oldest divergence of Equus was the onager followed by the zebras and onwards.[11] A new species called the kiang (E.kiang), a Tibetan relative, was previously considered to be a subspecies of the onager as E.hemionus kiang, but recent molecular studies indicate it to be a distinct species, having diverged from the closest relative of the Mongolian wild ass's ancestor less than 500,000 years ago.[8]
One of the largest subspecies of onager. It is 200–250cm (79–98in) long, 100–140cm (39–55in) tall at the withers, and weighs 200–240kg (440–530lb). Male onagers are larger than the females.
Formerly thought to be a distinct species, shown to be a subspecies of Onager by genetic studies in 2017.[9]
Europe, Western Asia
A sixth possible subspecies, the Gobi khulan (E.h.luteus,[1] also called the chigetai[12] or dziggetai) has been proposed, but may be synonymous with E.h.hemionus.
Debates over the taxonomic identity of the onager occurred until 1980. As of 2015[update], four living subspecies and one extinct subspecies of the Asiatic wild ass have been recognized. The Persian onager was formerly known as Equus onager, as it was thought to be a distinct species.
Characteristics
A Turkmenian kulanThe skeleton
Onagers are the most horse-like of wild asses. They are short-legged compared with horses, and their coloring varies depending on the season. They are generally reddish-brown in color during the summer, becoming yellowish-brown or grayish-brown in the winter. They have a black stripe bordered in white that extends down the middle of the back. The belly, the rump, and the muzzle are white in most onagers, except for the Mongolian wild ass that has a broad black dorsal stripe bordered with white.
Onagers are larger than donkeys at about 200 to 260kg (440 to 570lb) in size and 2.1 to 2.5m (6.9 to 8.2ft) in head-body length. Male onagers are usually larger than females.
The genus Equus, which includes all extant equines, is believed to have evolved from Dinohippus via the intermediate form Plesippus. One of the oldest species is Equus simplicidens, described as zebra-like with a donkey-shaped head. The oldest fossil to date is about 3.5 million years old from Idaho, USA. The genus appears to have spread quickly into the Old World, with the similarly aged Equus livenzovensis documented from western Europe and Russia.[13]
Molecular phylogenies indicate the most recent common ancestor of all modern equids (members of the genus Equus) lived around 5.6 (3.9–7.8) million years ago (Mya). Direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a more recent 4.07Mya for the most recent common ancestor within the range of 4.0 to 4.5Mya.[14] The oldest divergencies are the Asian hemiones (subgenus E. (Asinus), including the kulan, onager, and kiang), followed by the African zebras (subgenera E. (Dolichohippus), and E. (Hippotigris)). All other modern forms including the domesticated horse (and many fossil Pliocene and Pleistocene forms) belong to the subgenus E. (Equus) which diverged about 4.8 (3.2–6.5) Mya.[11]
The onagers' favored habitats consist of desert plains, semideserts, oases, arid grasslands, savannahs, shrublands, steppes, mountainous steppes, and mountain ranges. The Turkmenian kulan and Mongolian wild asses are known to live in hot and colder deserts. The IUCN estimates about 28,000 mature individuals in total remain in the wild.[1]
During the late Pleistocene era around 40,000 years ago, the Asiatic wild ass ranged widely across Europe and in southwestern to northeastern Asia. The onager has been regionally extinct in Israel, Saudi Arabia, Iraq, Jordan, Syria, and southern regions of Siberia.
Onagers at Wadi Lotz, Negev Mountains, Israel
The Mongolian wild ass lives in deserts, mountains, and grasslands of Mongolia and Inner Mongolian region of northern China. A few live in northern Xinjiang region of northwestern China, most of which live mainly in Kalamaili Nature Reserve. It is the most common subspecies, but its populations have drastically decreased to a few thousand due to years of poaching and habitat loss in East Asia. The Gobi Desert is the onager's main stronghold. It is regionally extinct in eastern Kazakhstan, southern Siberia, and the Manchurian region of China.
The Indian wild ass was once found throughout the arid parts and desert steppes of northwest India and Pakistan, but about 4,500 of them are found in a few very hot wildlife sanctuaries of Gujarat. The Persian onager is found in two subpopulations in southern and northern Iran. The larger population is found at Khar Turan National Park. However, it is extirpated from Afghanistan. The Turkmenian kulan used to be widespread in central to north Asia. However, it is now found in Turkmenistan and has been reintroduced in southern Kazakhstan and Uzbekistan.
Asiatic wild asses are mostly active at dawn and dusk, even during the intense heat.
Social structure
A group of onagersA group of khurs
Like most equids, onagers are social animals. Stallions are either solitary or live in groups of two or three. The males have been observed holding harems of females, but in other studies, the dominant stallions defend territories that attract females. Differences in behaviour and social structure likely are the result of changes in climate, vegetation cover, predation, and hunting.
The social behavior of the Asian wild ass can vary widely, depending on different habitats and ranges, and on threats by predators including humans. In Mongolia and Central Asia (E.h.hemionus and E.h.kulan), an onager stallion can adopt harem-type social groups, with several mares and foals in large home areas in the southwest, or in territory-based social groups in the south and southeast. Also, annual large hikes occur, covering 4.5km2 (1.7sqmi) to 40km2 (15sqmi), where hiking[clarification needed] in summer is more limited than in the winter. Onagers also occasionally form large group associations of 450 to 1,200 individuals, but this usually only occurs in places with food or water sources. As these larger groups dissolve again within a day, no overarching hierarchy apart from the ranking of the individual herds seems to exist. Young male onagers also frequently form "bachelor groups" during the winter. Such a lifestyle is also seen in the wild horse, the plains zebras (E.quagga) and mountain zebras (E.zebra).
Southern populations of onagers in the Middle East and South Asia tend to have a purely territorial life, where areas partly overlap. Dominant stallions have home ranges of 9km2 (3.5sqmi), but they can also be significantly larger. These territories include food and rest stops and permanent or periodic water sources. The waters are usually at the edge of a coalfield[clarification needed] and not in the center. Mares with foals sometimes find themselves in small groups, in areas up to 20km2 (7.7sqmi), which overlap with those of the other groups and dominant stallions. Such features are also seen among Grévy's zebras (E.grevyi) and the African wild asses.
Reproduction
The Asian wild ass is sexually mature at two years old, and the first mating usually takes place at three to four years old.
Breeding is seasonal, and the gestation period of onagers is 11 months; the birth lasts a little more than 10 minutes. Mating and births occur from April to September, with an accumulation from June to July. The mating season in India is in the rainy season. The foal can stand and starts to nurse within 15 to 20 minutes. Females with young tend to form groups of up to five females. During rearing, a foal and dam remain close, but other animals and her own older offspring are displaced by the dam. Occasionally, stallions in territorial wild populations expel the young to mate with the mare again. Wild Asian wild asses reach an age of 14 years, but in captivity, they can live up to 26 years.
Diet
Indian wild ass herd feeding on grass
Like all equids, onagers are herbivorous mammals. They eat grasses, herbs, leaves, fruits, and saline vegetation when available, but browse on shrubs and trees in drier habitats. They have also been seen feeding on seed pods such as Prosopis and breaking up woody vegetation with their hooves to get at more succulent herbs growing at the base of woody plants.
During the winter, onagers also eat snow as a substitute for water. When natural water sources are unavailable, the onager digs holes in dry riverbeds to reach subsurface water. The water holes dug by the onagers are often subsequently visited by domestic livestock, as well as other wild animals. Water is also found in the plants on which the onagers feed.
During spring and summer in Mongolia, the succulent plants of the Zygophyllaceae form an important component of the diet of the Mongolian wild ass.
Predation
An Asiatic lion attacking an onager (Roman, c.AD 150)
The onager is preyed upon by predators such as Persian leopards and striped hyenas. A few cases of onager deaths due to predation by leopards have been recorded in Iran. Though leopards do not usually feed on equids as in Africa, this may be because Persian leopards are larger and strong enough to prey on Asiatic wild asses.[15][16]
Currently, the main predator for onagers are gray wolves. However, like most equids, they are known to have antipredator behaviour. Groups of stallions cooperate and try to chase off predators. If threatened, onagers defend themselves and violently kick at the incoming predator.[citation needed]
The greatest threat facing the onager is poaching for meat and hides, and in some areas for use in traditional medicine. The extreme isolation of many subpopulations also threatens the species, as genetic problems can result from inbreeding. Overgrazing by livestock reduces food availability, and herders also reduce the availability of water at springs. The cutting down of nutritious shrubs and bushes exacerbates the problem. Furthermore, a series of drought years could have devastating effects on this beleaguered species.
Habitat loss and fragmentation are also major threats to the onager, a particular concern in Mongolia as a result of the increasingly dense network of roads, railway lines, and fences required to support mining activities.
The Asiatic wild ass is also vulnerable to diseases. A disease known as the "South African horse sickness" caused a major decline to the Indian wild ass population in the 1960s. However, the subspecies is no longer under threat to such disease and is continuously increasing in number.
Conservation
A Persian onager in Augsburg Zoo
Various breeding programs have been started for the onager subspecies in captivity and in the wild, which increases their numbers to save the endangered species. The species is legally protected in many of the countries in which it occurs. The priority for future conservation measures is to ensure the protection of this species in particularly vulnerable parts of its range, to encourage the involvement of local people in the conservation of the onager, and to conduct further research into the behavior, ecology, and taxonomy of the species.
Two onager subspecies, the Persian onager and the Turkmenian kulan are being reintroduced to their former ranges, including in other regions the Syrian wild ass used to occur in the Middle East. The two subspecies have been reintroduced to the wild of Israel since 1982, and had been breeding hybrids there,[17] whilst the Persian onager alone has been reintroduced to Jordan and the deserts of Saudi Arabia.
Relationship with humans
Quadriga consists of a chariot and a charioteer with four onagers. From Tell Agrab, Iraq. Early Dynastic period, 2600–2370 BCE. Iraq Museum. This is the oldest known model of a quadriga drawn by onagers.
Onagers are notoriously difficult to tame. Equids were used in ancient Sumer to pull wagons c.2600 BC, and then chariots on the Standard of Ur, c.2550 BC. Clutton-Brock (1992) suggests that these were donkeys rather than onagers on the basis of a "shoulder stripe".[18] However, close examination of the animals (equids, sheep and cattle) on both sides of the piece indicate that what appears to be a stripe may well be a harness, a trapping, or a joint in the inlay.[19][20] Genetic testing of skeletons from that era shows that they were kungas, a cross between an onager and a donkey.
In literature
In the Hebrew Bible there is a reference to the onager in Job 39:5:
Who freed the wild donkey, loosed the ropes of the onager?
A short poem by Ogden Nash also features the onager:
Have you ever harked to the jackass wild, which scientists call the onager? It sounds like the laugh of an idiot child, or a hepcat on a harmonager.
But do not laugh at the jackass wild, for there is method in his he-haw: for with maidenly blush, and accent mild, the jenny-ass answers "She-haw".
Related Research Articles
Equidae is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. The family evolved around 50 million years ago from a small, multi-toed ungulate into larger, single-toed animals. All extant species are in the genus Equus, which originated in North America. Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
Perissodactyla is an order of ungulates. The order includes about 17 living species divided into three families: Equidae, Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, artiodactyls bear most of their weight equally on four or two of the five toes: their third and fourth toes. Another difference between the two is that perissodactyls digest plant cellulose in their intestines, rather than in one or more stomach chambers as artiodactyls, with the exception of Suina, do.
The donkey is a domesticated equine. It derives from the African wild ass, Equus africanus, and may be classified either as a subspecies thereof, Equus africanus asinus, or as a separate species, Equus asinus. It was domesticated in Africa some 5000–7000 years ago, and has been used mainly as a working animal since that time.
Equus is a genus of mammals in the family Equidae, which includes horses, asses, and zebras. Within the Equidae, Equus is the only recognized extant genus, comprising seven living species. Like Equidae more broadly, Equus has numerous extinct species known only from fossils. The genus most likely originated in North America and spread quickly to the Old World. Equines are odd-toed ungulates with slender legs, long heads, relatively long necks, manes, and long tails. All species are herbivorous, and mostly grazers, with simpler digestive systems than ruminants but able to subsist on lower-quality vegetation.
The kiang is the largest of the Asinus subgenus. It is native to the Tibetan Plateau in Ladakh, northern Pakistan, Tajikistan, China and northern Nepal. It inhabits montane grasslands and shrublands. Other common names for this species include Tibetan wild ass, khyang and gorkhar.
The wild asses (Asinus) are a subgenus of single toed grazing ungulates. Its species are:
The Mongolian wild ass, also known as Mongolian khulan, is the nominate subspecies of the onager. It is found in southern Mongolia and northern China. It was previously found in eastern Kazakhstan and southern Siberia before being extirpated there through hunting. As of 2015, the Mongolian wild ass is listed as Near Threatened by the IUCN. Current population estimates are approximately 42,000 individuals in Mongolia and around 5,000 individuals in Northern China.
The African wild ass or African wild donkey is a wild member of the horse family, Equidae. This species is thought to be the ancestor of the domestic donkey, which is sometimes placed within the same species. They live in the deserts and other arid areas of the Horn of Africa, in Eritrea, Ethiopia and Somalia. It formerly had a wider range north and west into Sudan, Egypt, and Libya. It is Critically Endangered, with about 570 existing in the wild.
Grant's zebra is the smallest of the seven subspecies of the plains zebra. This subspecies represents the zebra form of the Serengeti-Mara ecosystem and others across central Africa.
The European wild ass or hydruntine is an extinct equine from the Middle Pleistocene to Late Holocene of Europe and West Asia, and possibly North Africa. It is a member of the subgenus Asinus, and closely related to the living Asiatic wild ass. The specific epithet, hydruntinus, means from Otranto.
Asinus is a subgenus of Equus that encompasses several subspecies of the Equidae commonly known as wild asses, characterized by long ears, a lean, straight-backed build, lack of a true withers, a coarse mane and tail, and a reputation for considerable toughness and endurance.
The Yotvata Hai-Bar Nature Reserve is a 3,000-acre (12 km2) breeding and reacclimation center administered by the Israel Nature Reserves & National Parks Authority, situated in the Southern Arava near Yotvata.
The Syrian wild ass, less commonly known as a hemippe, an achdari, or a Mesopotamian or Syrian onager, is an extinct subspecies of onager native to the Arabian peninsula and surrounding areas. It ranged across present-day Iraq, Palestine, Israel, Iran, Jordan, Saudi Arabia, Syria, and Turkey.
The Indian wild ass, also called the Indian onager or, in the local Gujarati language, Ghudkhur and Khur, is a subspecies of the onager native to South Asia.
Primitive markings are a group of hair coat markings and qualities seen in several equine species, including horses, donkeys, and asses. In horses, they are associated with primitive breeds, though not limited to such breeds. The markings are particularly associated with the dun coat color family. All dun horses possess at least the dorsal stripe, but the presence of the other primitive markings varies. Other common markings may include horizontal striping on the legs, transverse striping across the shoulders, and lighter guard hairs along the edges of a dark mane and tail.
The Badhyz State Nature Reserve is a protected area (zapovednik) in south-western Turkmenistan that was established in 1941 and extends over 877 km2 (339 sq mi) in the Mary and Akhal Provinces. It is located south of the Karakum Desert, and the Tejen River forms its western border.
The Turkmenian kulan, also called Transcaspian wild ass, Turkmenistani onager or simply the kulan, is a subspecies of onager native to Central Asia. It was declared Endangered in 2016.
The Persian onager, also called the Persian wild ass or Persian zebra, is a subspecies of onager native to Iran (Persia). It is listed as Endangered, with no more than 600 individuals left in the wild and only 30 individuals living within North American institutions.
↑ Crees, Jennifer J.; Turvey, Samuel T. (2014). "Holocene extinction dynamics of Equus hydruntinus, a late-surviving European megafaunal mammal". Quaternary Science Reviews. 91: 16–29. Bibcode:2014QSRv...91...16C. doi:10.1016/j.quascirev.2014.03.003.
↑ Clutton-Brock, Juliet (1992). Horse Power: A History of the Horse and the Donkey in Human Societies. Boston, Massachusetts, US: Harvard University Press. ISBN978-0-674-40646-9.
↑ Heimpel, Wolfgang (1968). Tierbilder in der Sumerische Literatur. Italy: Studia Pohl 2.
↑ Maekawa, K. (1979). "The Ass and the Onager in Sumer in the Late Third Millennium B.C.". Acta Sumerologica. I. Hiroshima: 35–62.
Duncan, P., ed. (1992). Zebras, Asses, and Horses: An Action Plan for the Conservation of Wild Equids. Gland, Switzerland: IUCN/SSC Equid Specialist Group. ISBN9782831700526. OCLC468402451.
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