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Science EncyclopediaScience & Philosophy: A-series and B-series to Ballistic Missiles - Categories Of Ballistic Missile

Asses include three of the seven genera that make up the family Equidae, which also includes horses and zebras. Wild asses are completely wary and apt to run swiftly away, so they have been difficult to study. Asses can survive in poor habitat such as scrub and near desert regions. Asses have loud voices, most notable in the raucous bray of the domestic burro and a keen sense of hearing. Male asses (stallions) tend to leave the herd and live solitary lives except during the mating season in late summer. Female asses tend to stay in the herd, especially when caring for their young. All of the species of wild asses are endangered.

The Asiatic wild ass (Equus hemionus) was formerly distributed in Asia from China to the Middle East.

The largest species of the kiang ass (E. kiang) lives in the high steppes of Tibet and China. This spieces is about 4.5 ft (1.4 m) tall at the shoulder, weighs up to 880 lbs (400 kg) with a red-brown to black back, and white sides and belly. The coat becomes thicker during the cold Tibetan winters.

The other Asiatic asses are smaller than the kiang, with narrower heads and longer ears. The onager of Iran was perhaps the first member of the horse family to be domesticated. These wild asses once lived in large herds in the deserts and grasslands of Asia, but now are limited to a few very small areas and may even be extinct in the wild, though their exact status is uncertain. The kulan is a small wild ass found in the Mongolian Desert which can run at speeds of up to 40 MPH (64 km/h). The khur, or Indian onager and the dziggetai of Mongolia are both endangered and probably exist today only in wildlife reserves. The small Syrian onager is the wild ass of the Bible, stands only slightly more than 3 ft (1 m) high at the shoulder, has not been seen since 1927, and is probably extinct in the wild.

The African wild ass (E. africanus), is the ancestor of the domesticated donkey, and is represented by a few thousand individuals in Ethiopia, Somalia, and the Sudan. The domesticated donkey is sometimes given a separate name, E. asinus. The African wild ass has hooves that are higher and narrower than those of other equids, allowing sure footing in its dry, hilly home. Like many desert living animals, these wild asses need little water, can withstand dehydration, even in temperatures of 125°F (52°C), and can survive two or three days without drinking.

There are two varieties of African wild ass. The Somali wild ass of Somalia and Ethiopia has a dark stripe along its back, light stripes on its legs, dark tips on its ears, and a dark, short mane. The animal's base coat color may turn yellowish or tan during the summer. The Somali wild ass is an endangered species, while the slightly smaller Nubian wild ass, which lacks stripes on its legs, is probably already extinct in the wild.

Domesticated asses are known as donkeys, jackasses, or burros. Their size varies from the tiny 2-ft (less than a meter) burro of Sicily to the Spanish donkey that stands more than 5 ft (2 m) at the shoulder. Numerous feral (wild, formerly domestic) burros live in the western United States, which are regularly rounded up and sold as pets. These sure-footed animals carry tourists on the steep narrow paths leading down into the Grand Canyon.

The hybrid offspring produced when a horse mare mates with a donkey stallion are called mules, which are as sure-footed as burros, and are even stronger than horses. However, mules, being hybrids, are almost always sterile. The offspring hybrid produced by the mating of a horse stallion with a donkey mare is called a hinny. Hinnies tend to resemble a horse more than a mule but are relatively rare because female donkeys do not easily become pregnant.



Duncan, P., ed. Zebras, Horses and Asses: An Action Plan for the Conservation of Wild Equids. Washington, DC: Island Press, 1992.

Knight, Linsay. The Sierra Club Book of Great Mammals. San Francisco: Sierra Club Books for Children, 1992.

Patent, Dorothy Hinshaw. Horses and Their Wild Relatives. New York: Holiday House, 1981.

Special Publications Division. National Geographic Book of Mammals. Vol. 1 & 2. Washington, DC: National Geographic Society, 1981.

Stidworthy, John. Mammals: The Large Plant-Eaters. Encyclopedia of the Animal World. New York: Facts On File, 1988.

Wild Horses. Zoobooks series. San Diego: Wildlife Education, 1987.

Jean F. Blashfield


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—Any member of family Equidae, including horses, zebras, and asses.


—This refers to a non-native, often domesticated species that is able to maintain a viable, breeding population in a place that is not part of its natural range, but to which it has been introduced by humans.

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