The onager (; ''Equus hemionus'' ), A new species called the
kiang
The kiang (''Equus kiang'') is the largest of the '' Asinus'' subgenus. It is native to the Tibetan Plateau, where it inhabits montane and alpine grasslands. Its current range is restricted to the plains of the Tibetan plateau; Ladakh; and nort ...
(''E. kiang''), a
Tibet
Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa, Taman ...
an 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.
Subspecies
Five widely recognized subspecies of the onager include:
A sixth possible subspecies, the Gobi khulan (''E. h. luteus'',
[ also called the ''chigetai''] or ''dziggetai'') has been proposed, but may be synonymous with ''E. h. hemionus''.
Debates over the taxonomic identity of the onager occurred until 1980. , 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
Onagers are the most horse-like of wild asses. They are short-legged compared to 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
The domestic donkey is a hoofed mammal in the family Equidae, the same family as the horse. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as a ...
at about in size and in head-body length. Male onagers are usually larger than females.
Evolution
The genus ''Equus'', which includes all extant equines, is believed to have evolved from ''Dinohippus
''Dinohippus'' (Greek: "Terrible horse") is an extinct equid which was endemic to North America from the late Hemphillian stage of the Miocene through the Zanclean stage of the Pliocene (10.3—3.6 mya) and in existence for approximately . Foss ...
'' via the intermediate form ''Plesippus
''Plesippus'' is a genus of extinct horse from the Pleistocene of North America. Although commonly seen as a subgenus of ''Equus'' recent cladistic analysis considers it a distinct genus.
Species
Two species are recognized by Barron et al. (201 ...
''. One of the oldest species is ''Equus simplicidens
The Hagerman horse (''Equus simplicidens''), also called the Hagerman zebra or the American zebra, was a North American species of equid from the Pliocene epoch and the Pleistocene epoch. It was one of the oldest horses of the genus ''Equus'' and ...
'', 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.
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 4.07 Mya for the most recent common ancestor within the range of 4.0 to 4.5 Mya. The oldest divergencies are the Asian hemiones (subgenus ''E. (Asinus
''Asinus'' is a subgenus of '' Equus'' (single-toed (hooved) grazing animal) 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, ...
)'', including the kulan, onager, and kiang
The kiang (''Equus kiang'') is the largest of the '' Asinus'' subgenus. It is native to the Tibetan Plateau, where it inhabits montane and alpine grasslands. Its current range is restricted to the plains of the Tibetan plateau; Ladakh; and nort ...
), followed by the African zebras (subgenera ''E. ( Dolichohippus)'', and ''E. (Hippotigris
Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: the Grévy's zebra (''Equus grevyi''), plains zebra (''E. quagga''), and the mountain zebra (''E. zeb ...
)''). All other modern forms including the domesticated horse (and many fossil Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58[Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...](_blank)
forms) belong to the subgenus ''E. ( Equus)'' which diverged about 4.8 (3.2–6.5) Mya.
Distribution and habitat
The onagers' favored habitats consist of desert plains, semideserts, oases, arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ...
grasslands, savannahs, shrublands, steppes, mountainous steppes, and mountain range
A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
s. 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.[
During the late ]Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
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 Palestine, Saudi Arabia
Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...
, Iraq
Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to the north, Iran to the east, the Persian Gulf and K ...
, Jordan
Jordan ( ar, الأردن; tr. ' ), officially the Hashemite Kingdom of Jordan,; tr. ' is a country in Western Asia. It is situated at the crossroads of Asia, Africa, and Europe, within the Levant region, on the East Bank of the Jordan Rive ...
, Syria, and southern regions of Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive region, geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a ...
.
The Mongolian wild ass
The Mongolian wild ass (''Equus hemionus hemionus''), 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 Siberi ...
lives in deserts, mountains, and grasslands of Mongolia and Inner Mongolia
Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...
n region of northern China. A few live in northern Xinjiang region of northwestern China, most of which live mainly in Kalamaili Nature Reserve
Mountain Kalamaili Ungulate Nature Reserve (''Kalamaili'' means "black earth" in Kazakh, ), also spelled Kalamely Nature Reserve, is a nature reserve in Xinjiang Autonomous Region of China, targeting in preserving the wildlife and natural vegeta ...
. 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
East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...
. The Gobi Desert is the onager's main stronghold. It is regionally extinct in eastern Kazakhstan, southern Siberia, and the Manchuria
Manchuria is an exonym (derived from the endo demonym " Manchu") for a historical and geographic region in Northeast Asia encompassing the entirety of present-day Northeast China (Inner Manchuria) and parts of the Russian Far East (Outer M ...
n region of China.
The Indian wild ass
The Indian wild ass (''Equus hemionus khur''), also called the Indian onager or, in the local Gujarati language, Ghudkhur and Khur, is a subspecies of the onager native to South Asia.
It is currently listed as Near Threatened by IUCN. The prev ...
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
The Persian onager (''Equus hemionus onager''), also called the Persian wild ass or Persian zebra, is a subspecies of onager (Asiatic wild ass) native to Iran (Persia). It is listed as Endangered, with no more than 600 individuals left in the wil ...
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
The Turkmenian kulan (''Equus hemionus kulan''), also called Transcaspian wild ass, Turkmenistani onager or simply the ', is a subspecies of onager (Asiatic wild ass) native to Central Asia. It was declared Endangered in 2016.
The species's popu ...
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.
Biology and behavior
Asiatic wild asses are mostly active at dawn and dusk, even during the intense heat.
Social structure
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 harem
Harem ( Persian: حرمسرا ''haramsarā'', ar, حَرِيمٌ ''ḥarīm'', "a sacred inviolable place; harem; female members of the family") refers to domestic spaces that are reserved for the women of the house in a Muslim family. A har ...
s 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
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
and Central Asia
Central Asia, also known as Middle Asia, is a subregion, region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes t ...
(''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 to , where hiking 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 zebra
The plains zebra (''Equus quagga'', formerly ''Equus burchellii''), also known as the common zebra, is the most common and geographically widespread species of zebra. Its range is fragmented, but spans much of southern and eastern Africa south o ...
s (''E. quagga'') and mountain zebra
The mountain zebra (''Equus zebra'') is a zebra species in the family Equidae, native to southwestern Africa. There are two subspecies, the Cape mountain zebra (''E. z. zebra'') found in South Africa and Hartmann's mountain zebra (''E. z. hartman ...
s (''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 , 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 and not in the center. Mares with foals sometimes find themselves in small groups, in areas up to , 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
Like all equids, onagers are herbivorous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...
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
''Prosopis'' is a genus of flowering plants in the family Fabaceae. It contains around 45 species of spiny trees and shrubs found in subtropical and tropical regions of the Americas, Africa, Western Asia, and South Asia. They often thrive in ari ...
'' 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
Zygophyllaceae is a family of flowering plants that contains the bean-caper and caltrop. The family includes around 285 species in 22 genera.
Plants in the family Zygophyllaceae may be trees, shrubs, or herbs. They are often found in dry habit ...
form an important component of the diet of the Mongolian wild ass.
Predation
The onager is preyed upon by predators such as Persian leopard
''Panthera pardus tulliana'' is a leopard subspecies native to the Iranian Plateau and surrounding areas encompassing Turkey, the Caucasus, Azerbaijan, Georgia, Armenia, Iraq, Iran, Turkmenistan, Afghanistan and possibly Pakistan. Since 2016, ...
s and striped hyenas. A few cases of onager deaths due to predation by leopards were recorded in Iran. Though leopards do not usually feed on equids as in Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, this may be because Persian leopards are larger and strong enough to prey on Asiatic wild asses.
In the Middle East and the Indian subcontinent, Asiatic lion
The Asiatic lion is a population of '' Panthera leo leo'' that today survives in the wild only in India. Since the turn of the 20th century, its range has been restricted to Gir National Park and the surrounding areas in the Indian state of Gujar ...
s and tiger
The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on ...
s were the main predators of onagers. They were also formerly preyed upon by dhole
The dhole (''Cuon alpinus''; ) is a canid native to Central, South, East and Southeast Asia. Other English names for the species include Asian wild dog, Asiatic wild dog, Indian wild dog, whistling dog, red dog, red wolf, and mountain wolf. It ...
s, Asiatic cheetahs, and possibly bears, though they may have mostly preyed only on onager foals. In India, mugger crocodile
The mugger crocodile (''Crocodylus palustris'') is a medium-sized broad- snouted crocodile, also known as mugger and marsh crocodile. It is native to freshwater habitats from southern Iran to the Indian subcontinent, where it inhabits marshes ...
s can be great threats to onagers during migratory river crossings.
Currently, the main predator for onagers are gray 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 ...
. 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.
Threats
The greatest threat facing the onager is poaching for meat and hides, and in some areas for use in traditional medicine. It is one of the highest threats for the Mongolian wild ass. The extreme isolation of many subpopulations also threatens the species, as genetic problems can result from inbreeding. Overgrazing
Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...
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
A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...
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
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, whilst the Persian onager alone has been reintroduced to Jordan and the deserts of Saudi Arabia.
Relationship with humans
Onagers are notoriously difficult to tame. Equids were used in ancient Sumer to pull wagons , and then chariots on the Standard of Ur, . Clutton-Brock (1992) suggests that these were donkeys rather than onagers on the basis of a "shoulder stripe". However, close examination of the animals (equids, 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 ...
and cattle
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult ma ...
) 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. 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
The Hebrew Bible or Tanakh (;["Tanach"](_blank)
'' Honoré de Balzac
Honoré de Balzac ( , more commonly , ; born Honoré Balzac;Jean-Louis Dega, La vie prodigieuse de Bernard-François Balssa, père d'Honoré de Balzac : Aux sources historiques de La Comédie humaine, Rodez, Subervie, 1998, 665 p. 20 May 179 ...
, the onager is identified as the animal from which comes the ass' skin or shagreen
Shagreen is a type of rawhide consisting of rough untanned skin, historically from a horse's or onager's back, or from shark or ray.
Etymology
The word derives from the French ''chagrin'' and is related to Italian ''zigrino'' and Venetian '' ...
of the title.
A short poem by Ogden Nash
Frederic Ogden Nash (August 19, 1902 – May 19, 1971) was an American poet well known for his light verse, of which he wrote over 500 pieces. With his unconventional rhyming schemes, he was declared by ''The New York Times'' the country's bes ...
also features the onager:
References
*
External links
"Ass"
''Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various t ...
''
''Equus hemionus'' bibliography
at The Biodiversity Heritage Library
{{Authority control
EDGE species
Asinus
Extant Pliocene first appearances
Fauna of the Middle East
Fauna of Iran
Fauna of Iraq
Fauna of Western Asia
Mammals described in 1775
Mammals of Afghanistan
Mammals of Central Asia
Mammals of Mongolia
Mammals of Pakistan
Near threatened biota of Asia