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ass, hoofed, herbivorous mammal of the genus Equus, closely related to the horse. It is distinguished from the horse by its small size, large head, long ears, and small hooves. There are three living species: Equus hemonius, the Asian wild ass; E. kiang, the Tibetan wild ass; and E. asinus, the African wild ass. The last species includes the domesticated variety, E. asinus asinus, commonly known as the donkey. A male ass is called a jackass and a female, a jenny. Wild asses are swift desert animals that may attain speeds of up to 40 mi (60 km) per hr. They can live in herds of up to 1,000 animals, though in most subspecies populations are now much reduced.

Asian Wild Ass

The Asian wild ass, also known as the onager (a term also used historically for one of its subspecies), typically has a sandy-colored coat with lighter-colored legs and belly, a short erect black mane, a black spinal stripe, and a black tail tuft. Its neigh is shrill. Different subspecies of this ass vary in size, with the largest reaching about 55 in. (140 cm) in shoulder height. They were once widely distributed across Asia, but they have been crowded out of their grazing lands by domestic livestock and have been hunted for their flesh and hides. Each subspecies is now restricted to a very limited territory within their former range. Among them are the Persian wild ass, or onager, of Iran, Afghanistan, and Pakistan; the Turkmenian kulan of Central Asia; the Mongolian wild ass, or Mongolian khulan, of E Kazakhstan and NE Asia; and the Indian ass, or ghudkhur, of S Asia. All are considered endangered, and the continued survival of the Persian and Mongolian subspecies is particularly threatened. The Syrian wild ass, formerly found in SW Asia, is extinct, but some of the other subspecies have been introduced into a few areas of its range.

Tibetan Wild Ass

The Tibetan wild ass, or kiang, presently the most numerous wild ass in Asia, is found on the steppe and alpine grasslands of the Tibetan Plateau in China and neighboring areas of India and Nepal. Formerly classified as a subspecies of the Asian wild ass, it is considered to have western, southern, and eastern subspecies. The kiang can reach 56 in. (142 cm) in shoulder height, and has a chestnut-colored coat with whitish legs and belly and a dark brown spinal stripe and tail tuft.

African Wild Ass and the Donkey

The two wild subspecies of the African wild ass, called Nubian and Somali wild asses, are becoming rare. They are found in the mountains and deserts of NE Africa. The African wild ass averages about 53 in. (135 cm) in shoulder height; it is grayish in color, with longer ears and mane than the Asian ass, and with a characteristic loud, harsh bray. Its descendant, the donkey, is the oldest domestic beast of burden; it is believed to have been domesticated in Egypt by c.4000 B.C. A variety of the Asian wild ass was used in ancient Mesopotamia but did not survive as a domestic animal; all modern domestic donkeys are descended from the African species.

The donkey is still used as a pack and draft animal. Although not as swift or powerful as the horse, it is strong for its size and has great powers of endurance. Donkeys are more surefooted than horses in mountainous country and are cheaper to maintain, as they feed on dry scrub. They may live up to 47 years, about twice as long as a horse. In some regions the donkey is crossbred with the horse to produce a mule.

The donkey was once widely used in Mexico and the SW United States, where it was known by its Spanish name of burro. A large population of feral donkeys (wild descendants of domesticated animals) now exists in the deserts of that region. Feral donkeys are also found in the Old World, where they have given rise to some confusion about the number of true wild asses left in existence.


Asses are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Perissodactyla, family Equidae.
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(vertebrate zoology)
A small donkey used as a pack animal.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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