Donkey (Equus asinus): Facts, Behavior, Bray and Lifespan

What is a donkey and where does it come from?

Donkeys belong to the family Equidae, together with horses and zebras. All living members of the family are placed in a single genus, Equus. The donkey’s wild ancestor is the African wild ass (Equus africanus), and the two are so closely related that some scientists treat the donkey as a subspecies, Equus africanus asinus. Both names are in use.

The animal goes by several names. “Ass” is the old English word, “donkey” spread from the late 18th century, and “burro” is Spanish and Portuguese for donkey, used in the United States mainly for the feral donkeys of the West. An adult male is a jack, an adult female is a jenny or jennet, and a youngster of either sex is a foal.

Where and when were donkeys domesticated?

Donkeys were domesticated in northeast Africa, probably by pastoral peoples in the region of Nubia and the Horn of Africa. A large genetic study led by Evelyn Todd and published in Science in 2022 concluded that all modern donkeys trace back to a single domestication in East Africa around 5000 BCE, after which they spread into Asia and Europe.

Archaeology tells a similar story. Bones of domestic donkeys from the fourth millennium BCE have been found at Maadi in Lower Egypt, and ten donkeys were buried in a royal tomb at Abydos from around the time of the first pharaohs. Donkeys made long-distance trade possible across the deserts of Egypt and the Near East, reached Europe by the second millennium BCE and arrived in the Americas with Spanish ships in 1495.

The wild ancestor is now in serious trouble. The African wild ass is listed as Critically Endangered by the IUCN, with only a few hundred animals at most left in the deserts of Eritrea and Ethiopia, threatened by hunting, competition with livestock and interbreeding with domestic donkeys.

Appearance

A donkey has a large head, very long ears, a short upright mane, slender legs and small, narrow, tough hooves. The tail is cow-like, with short hair along most of its length and a tuft of long hair at the end, unlike the full, flowing tail of a horse.

Gray-brown, often called gray dun, is the classic donkey color, but donkeys can also be brown, black, white, reddish or spotted. Most donkeys have a dark stripe along the spine crossed by a stripe over the shoulders, forming the famous “cross” on the back. Many also have pale “light points”: a pale muzzle, pale rings around the eyes and a light belly. Some show faint zebra-like bands on the legs, a trait inherited from the wild ass.

The long ears do two jobs. They pick up distant sounds, which helps animals that live spread out across open country, and their many blood vessels help shed heat in hot climates.

How big is a donkey?

Donkeys vary in size more than most people expect, because breeds have been developed for very different jobs.

The African wild ass stands about 1.2 m (4 ft) at the shoulder and weighs roughly 230–275 kg (500–600 lb), so an average donkey is a little smaller than its ancestor. Jacks and jennies are similar in size. For comparison with its biggest relative, see the horse, which is usually much heavier.

Habitat and range

The donkey’s ancestors lived in rocky deserts and dry scrub, and the domestic donkey is still at its best in hot, dry country. Today it lives wherever people keep it, from the Sahel and the Ethiopian highlands to the Andes, India, China and Mexico. FAO statistics give a world population of roughly 50 million, and the great majority live in Africa and Asia, where they remain essential working animals.

Donkeys are less suited to cold, wet climates. Their coat is built for dry heat and does not shed rain as well as a horse’s coat, so donkeys in northern Europe and similar climates rely on shelter in wet weather.

Diet and feeding

Donkeys are grazers and browsers that eat grasses, herbs, shrubs, thistles and bark, including tough, dry plants that many other livestock avoid. In dry regions they spend more than half of each day feeding, moving slowly between scattered plants.

Like horses, donkeys digest fiber in a large hindgut, where microbes break down plant material. They are more efficient than horses, getting more out of poor-quality forage and needing less food for their size. They can also cope with dehydration better than most domestic animals, losing a large share of their body water and then drinking it back quickly when they reach water.

Behavior and communication

Wild and feral donkeys in very dry areas live more spread out than horses. Adult males often hold large territories that they mark with dung piles, and females with foals move through these areas. In greener places with more food, feral donkeys form more stable groups. Domestic donkeys form strong friendships with companions and can become distressed if separated from a bonded partner.

The donkey’s best-known signal is the bray, the loud “hee-haw” made while breathing in and out. A bray can last around 20 seconds and carry more than 3 km (about 2 miles), which suits animals that live far apart in open desert. Read more in Why do donkeys bray?. Donkeys also communicate with ear positions, tail swishes, touch and scent.

Faced with something new or frightening, a donkey is more likely to stop and assess it than to bolt the way a horse might. It can also defend itself by biting, striking with the front hooves and kicking with the hind legs. This boldness is why donkeys are used in the United States, Canada and Australia as livestock guardians that chase coyotes and dogs away from sheep and goats.

Reproduction and life cycle

A jenny is pregnant for about 12 months, with a normal range of about 11 to 14 months, and usually gives birth to a single foal. Twins are rare. The foal weighs about 20–34 kg (44–75 lb) at birth, can stand within an hour and is usually weaned at about six to eight months. Because of the long pregnancy and slow return to breeding, a jenny produces fewer than one foal a year on average.

Donkeys can breed with horses and zebras. A jack and a mare (female horse) produce a mule, while a stallion and a jenny produce the rarer hinny. These hybrids are almost always sterile, as explained in Can mules have babies?, and the differences between the two animals are set out in donkey vs mule.

How long do donkeys live?

Donkeys are long-lived for their size. Well-kept donkeys commonly live 25–35 years, and some pass 40. Animal Diversity Web lists recorded maximum ages of about 47–50 years in captivity. Working donkeys in the poorest regions often live only 12–15 years because of overwork, poor feeding and disease. The full picture is in How long do donkeys live?.

Donkeys and people

After human muscle, the donkey is the cheapest source of power on many farms in developing countries. Donkeys carry water, firewood and goods to market, pull carts, plow and turn mills. In richer countries they are kept mainly for breeding mules, guarding livestock, giving rides and as companions, and their milk is sold in small quantities, often for cosmetics.

Some breeds are famous in their own right. The shaggy Baudet du Poitou of western France and the American Mammoth Jack were bred large to sire strong mules, and both nearly disappeared when tractors replaced draft animals. Welfare charities such as The Donkey Sanctuary in England run rescue centers and support working donkeys in Africa, Asia and Latin America.

A newer threat is the trade in donkey hides, which are boiled to make ejiao, a gelatin used in traditional Chinese medicine. Demand has led to large-scale slaughter and theft of donkeys in parts of Africa and Asia, and several African countries have restricted the trade.

Feral donkeys and burros

Where donkeys escaped or were turned loose, they have gone wild. In the US Southwest, burros left behind by miners and prospectors in the 1800s founded herds that still roam the deserts of Arizona, Nevada and California. They are protected on federal land under the Wild Free-Roaming Horses and Burros Act of 1971 and managed by the Bureau of Land Management.

Australia has the world’s largest feral donkey population, possibly numbering in the millions, where they are treated as an invasive species that damages vegetation and water holes. Smaller feral groups include the white donkeys of Asinara Island off Sardinia and the donkeys of St. John in the US Virgin Islands.

Myths and facts

Myth: donkeys are stupid and stubborn. Formal research on donkey cognition is still limited, but donkeys learn well and remember places and companions. Their “stubbornness” is mostly caution: a donkey that refuses to move has usually judged something unsafe.

Myth: a mule is just a big donkey. A mule is a hybrid with a donkey father and a horse mother. It usually has a horse-like body and a donkey-like head and ears, and it cannot normally breed.

Fact: donkeys are related to zebras. The cross on a donkey’s back and the faint bands on some donkeys’ legs are reminders of a shared ancestry with striped relatives such as the plains zebra.