Mammals

14. Onager (Equus onager) CR
The onager is one of the larger species of Asiatic wild ass. It is the swiftest of all the equids, and has been recorded running at speeds of up to 70 km/h. The species occurs in flat semi-desert regions which are hot during the day and cool at night, with little rainfall. Once common in most of the central and southern plains of Iran, onagers are now found in just two protected areas. The animals are at risk from poachers even within these areas, and constant conservation attention is required to secure the species’ future.
Urgent Conservation Actions
Further research into behaviour and ecology so that the two populations can be managed more effectively, and facilitation of interbreeding between individuals from the two populations to prevent inbreeding.
Distribution
Occurs only in Iran.
 
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Evolutionary Distinctiveness
Order: Perissodactyla
Family: Equidae
Horses are perissodactyls (odd-toed ungulates), a group of herbivores that also includes rhinoceroses and tapirs. The first horses appeared in the early Eocene of North America, around 56 million years ago. They were the size of small dogs and had several toes on each foot, unlike the single hooves of modern horses. These early horses closely resembled the ancestors of rhinos and tapirs. They were browsers, and lived in forests and savannas. During the Miocene (25-8 mya) climate change led to a reduction in the amount of forest cover and an increase in grasslands. This was a time of great evolutionary change for the early equids, with many groups evolving larger body sizes and adapting to a grazing lifestyle. Horse diversity peaked in the mid-Miocene (11-9.5 mya), with more than a dozen different genera evolving in many different sizes. Since that time horse diversity has gradually decreased, with all forms becoming extinct with the exception of the modern horse genus, Equus. This genus first evolved during the North American Pliocene (4.5 to 1.8 million years ago). Members of this successful genus spread throughout Asia, Europe, Africa and South America during the first major glaciations of the late Pliocene (2.6 mya). However, in the late Pleistocene (around 12,000 years ago) all of the New World horse species became extinct, along with most other large mammals in North and South America. Today, wild horses are found only in parts of Africa and Asia. They are classified into four main groups within the genus Equus: Asiatic Wild Asses
Kulan and Onager (Equus hemionus)
Kiang (Equus kiang)

African Wild Asses
African Wild Ass (Equus asinus/africanus)

Caballine (True) Horses
Przewalski's Horse (Equus caballus)

Zebras
Grevy's Zebra (Equus grevyi)
Burchell's Zebra (Equus burchelli)
Mountain Zebra (Equus zebra)

There is some debate over the taxonomic identity of the onager. Bennett (1980) regarded Equus onager as a distinct species. However, many experts now regard it as a subspecies of the Asian wild ass (E. hemionus onager). According to this classification, there are five living and one extinct subspecies of Asian wild ass: E. h. onager (onager), E. h. hemippus (Syrian wild ass – now extinct), E. h. kulan (kulan), E. h. kuhr (Indian wild ass), E. h. luteus (Gobi kulan), and E. h. hemionus (Mongolian wild ass).
Description
Size: 
Head and body length: 200-250 cm
Shoulder height: 100-142 cm
Tail length: 30-49 cm
Weight: 200-260 kg
Slightly larger than other Asiatic wild asses, the onager has a pale sandy-red coloured coat with a distinctive dark brown stripe running along the backbone. The flanks, back and underside of the animal are white. During the winter, the reddish fur is replaced with a dense coat of long grey fur. The species has a black mane of short bristly hair and a short tail with a tuft of very long hairs at the tip. The legs are short and thin compared with those of other wild equines. Males are slightly larger than females.
Ecology
Onagers eat grasses when available, but will also browse on herbs, shrubs and trees. They are thought to be most active at dawn and dusk, when temperatures are cooler. Although they obtain most of their water from food, they are almost always seen within 30 km of a water source. Lactating females in particular need to visit water frequently. The social structure of this species appears to be relatively fluid, with females and their offspring forming small, temporary aggregations of around 2-5 individuals. Descriptions of male breeding strategies vary, but it seems likely that males defend resources rather than the females themselves. Dominant males are thought to defend territories close to a permanent water source during the breeding season. This means that they have exclusive access to visiting females and can mate with all of the females within their territory. This is not a harem-based mating system because some females remain in a single territory throughout the breeding season, while others move freely between territories. This indicates that female movement is dependent on resource availability as well as mate preference. Females give birth to a single foal after a gestation period of approximately one year. Foals remain with their mothers for the first two years.
Habitat
Occurs in flat semi-desert regions which are hot during the day and cool at night, with little rainfall. The animals are always found within 30 km of a water source.
Distribution
The onager was once common in most of the central and southern plains of Iran. However, today its distribution is limited to just two protected areas – the Touran Protected Area in Semnan province and Bahram-e-Goor Protected Area in Fars Province.
Population Estimate
The population is estimated to number 471 animals at Touran and 96 at Bahram-e-Goor. The estimated total number of mature individuals is currently 144 (IUCN Red List 2004).
Population Trend
Although Critically Endangered, the population seems to be relatively stable.
Status
Classified as Critically Endangered (CR C1) on the 2006 IUCN Red List of Threatened Species.
Threats
Despite the fact that they occur in protected areas, the two remaining onager populations are at risk from poachers, who hunt the animals illegally for their meat. Overgrazing by domestic animals and the intensive use of springs by herders reduces the availability of food and water, and forces the species to compete with livestock for these essential resources. The removal of shrubs and bushes by woodcutters further reduces food availability. The geographic isolation of the two populations poses a problem for their viability, as genetic problems can result from inbreeding. Disease and/or drought pose constant threat to the two small populations.

The greatest threat facing the onager is poaching for meat. Overgrazing by livestock reduces the amount of food available and forces the species to compete for other resources, such as water. The removal of shrubs and bushes further reduces food availability. Geographic isolation of the two small populations is another threat as genetic problems can result from inbreeding. The diversion of rivers for crop irrigation has resulted in the desert habitat becoming even more dry and barren. Disease and periods of drought may have a devastating effect on the two small populations.
Conservation Underway
The onager is protected by law, and there are a number of conservation actions in place to protect the two populations. The reserves are patrolled daily and a $55,000 penalty has been introduced for killing an onager. In both reserves the number of domestic animals has been reduced so that the species has greater access to food and water. In the Touran Protected Area artificial watering holes have been created and hay is supplied for the animals to eat.

Hunting of the onager is illegal under Iranian law, and heavy fines are imposed for poaching. The two surviving populations are protected within reserves. Local farmers are allocated land outside the reserves as compensation for the removal of their livestock. The IUCN/SSC Equid Specialist Group supports several research programmes which aim to study the behaviour and ecology of the species so that it may be effectively conserved.

The species is listed on Appendix II of CITES. Some animals are kept in captivity (including at Whipsnade Wild Animal Park).
Conservation Proposed
The IUCN/SSC Equid Specialist Group has written an Action Plan for the Asiatic Wild Ass, which includes recommendations for the two onager populations. These include further research into behaviour and ecology, and prevention of inbreeding by allowing animals from the two populations to interbreed.
Links
References
IUCN/SSC Equid Specialist Group

Goyal, S.P., Reading, R., Rowen, M., Shah, N. and Feh, C. 2002. Status and Action Plan for the Asiatic Wild Ass (Equus hemionus). In: Moehlman, P.D. Ed. Equids: Zebras, Asses, and Horses: Status Survey and Conservation Action Plan. IUCN/SCC Equid Specialist Group, IUCN (The World Conservation Union), Gland, Switzerland and Cambridge, England.

Moehlman, P. & Feh, C. 2002. Equus hemionus ssp. onager. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. Downloaded on 09 August 2006.

Nowak, R. M. 1999. Walker’s Mammals of the World. Sixth edition. The Johns Hopkins University Press. Baltimore and London.

Distribution map based on data provided by the IUCN Global Mammal Assessment.

if you can provide new information to update this species account or to correct any errors, please email us at info@edgeofexistence.org


Forum comments

  1. saudiya
    Member

    Who is working at the moment from the EDGE sponsored project base in Iran on onager? Do you have any local Iranian involvement?

    The major PA's for this critically endangered species are Touran/Dasht-e-Kavir and Bahram e-Gour and there is a promising captive-breeding project inbetween (near Shiraz I believe).

    Posted 1 year ago #

  2. Anonymous
    Unregistered

    i thought onagers were walruses

    Posted 1 year ago #

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