The donkey or ass, Equus africanus asinus, is a domesticated member of the Equidae or horse family. The wild ancestor of the donkey is the African Wild Ass, E. africanus. In the western United States, a small donkey is sometimes called a burro (from the Spanish word for the animal).

A male donkey or ass is called a jack, a female a jenny, and offspring less than one year old, a foal (male: colt, female filly).

While different species of the Equidae family can interbreed, offspring are almost always sterile. Nonetheless, horse/donkey hybrids are popular for their durability and vigor. A mule is the offspring of a jack (male donkey) and a mare (female horse). The much rarer successful mating of a male horse and a female donkey produces a hinny.

Asses were first domesticated around 3000 BC, approximately the same time as the horse, and have spread around the world. They continue to fill important roles in many places today and domesticated species are increasing in numbers, but the African wild ass and another relative, the Onager, are endangered. As "beasts of burden" and companions, asses and donkeys have worked together with humans for millennia.

Characteristics
Donkeys vary considerably in size, depending on breed and management. Most domestic donkeys range from 9 to 14.2 hands (36 to 58 inches, 91 to 147 cm), though the Mammoth Jack breed is taller, and the Andalucian-Cordobesan breed of southern Spain can reach up to 15.2 hands (62 inches, 157 cm)high. Donkeys have a lifespan of 30 to 50 years.

Donkeys are adapted to marginal desert lands, and have many traits that are unique to the species as a result. Wild donkeys live separated from each other, unlike tight wild horse and feral horse herds. Donkeys have developed very loud vocalizations, which help keep in contact with other donkeys over the wide spaces of the desert. The best-known call is referred to as a "bray," which can be heard for over three kilometers. Donkeys have larger ears than horses. Their longer ears may pick up more distant sounds,[citation needed] and may help cool the donkey's blood. Donkeys in the wild can defend themselves with a powerful kick of their hind legs as well as by biting and striking with their front hooves.

Communication
Satirical use of braying in a political cartoonBraying is the characteristic sound made by an ass, donkey, and most mules. Donkeys use this sound to communicate and will bray more frequently when a new donkey is encountered. The sound typically lasts for twenty seconds. The sound may be rendered onomatapoeically as "eeyore" and so this was used as the name of the donkey in Winnie-the-Pooh. Donkeys may be trained to bray or not to bray upon command. This may be used as a form of mockery. Braying may be considered a simile for loud and foolish speech. For example, There are braying men in the world as well as braying asses; for what's loud and senseless talking and swearing, any other than braying
—Sir Roger L'Estrange

Etymology of the name
Until recently the synonym ass was the more common term for Equus asinus (as in jackass, meaning "male donkey"). The first written use of donkey is as recent as 1785. While the word ass has cognates in most other Indo-European languages, donkey is an etymologically obscure word for which no credible cognate has been identified. Hypotheses on its derivation include the following:

Perhaps a diminutive of dun (dull grayish-brown), a typical donkey colour.
Perhaps from the name Duncan.
Perhaps of imitative origin.
The homonymity in the United States with a vulgar term ass for "buttocks" might have influenced its gradual replacement by donkey there, though this does not account for the parallel change in Britain and Australia.

The ancestors of the modern donkey are the Nubian and Somalian subspecies of African wild ass. The African Wild Ass was domesticated around 4000 BC. The donkey became an important pack animal for people living in the Egyptian and Nubian regions as they can easily carry 20% to 30% of their own body weight and can also be used as a farming and dairy animal. By 1800 BC, the ass had reached the Middle East, where the trading city of Damascus was referred to as the "City of Asses" in cuneiform texts. Syria produced at least three breeds of donkeys, including a saddle breed with a graceful, easy gait. These were favored by women.

For the Greeks, the donkey was associated with Dionysus, the god of wine. The Romans also valued the ass and would use it as a sacrificial animal[citation needed]

Equines had become extinct in the Western Hemisphere at the end of the last Ice Age. However, horses and donkeys were brought back to the Americas by the Conquistadors. In 1495,[citation needed]the ass first appeared in the New World when Christopher Columbus brought four jacks and two jennys. It is from this bloodline that many of the mules which the Conquistadors used while they explored the Americas were produced.[citation needed] Shortly after the United States became independent, President George Washington imported the first mammoth jack stock into the country. Because the existing Jack donkeys in the New World at the time lacked the size and strength he sought to produce quality work mules, he imported donkeys from Spain and France, some standing over 1.63 m tall. One of the donkeys Washington received from the Marquis de Lafayette, named "Knight of Malta", stood 1.43 m and thus was regarded as a great disappointment. Viewing this donkey as unfit for producing mules, Washington instead bred Knight of Malta to his jennys and, in doing so, created an American line of Mammoth Jacks (a breed name that includes both males and females).

Despite these early appearances of donkeys in America, the donkey did not find widespread distribution in America until it was found useful as a pack animal by miners, particularly the gold prospectors, of the mid-19th century. Miners preferred this animal due to its ability to carry tools, supplies, and ore. Their sociable disposition and adaptation to human companionship allowed many miners to lead their donkeys without ropes. They simply followed behind their owner. As mining became less an occupation of the individual prospector and more of an industrial underground operation, the miners' donkeys lost their jobs, and many were simply turned loose into the American deserts. Descendants of these donkeys, now feral, can still be seen roaming the Southwest today.

By the early 20th century, donkeys began to be used less as working animals and instead kept as pets in the United States and other wealthier nations, while remaining an important work animal in many poorer regions. The increased popularity of the donkey as a pet was seen in the appearance of the miniature donkey in 1929. Robert Green imported miniature donkeys to the United States and was a lifetime advocate of the breed. Mr. Green is perhaps best quoted when he said, "Miniature donkeys possess the affectionate nature of a Newfoundland, the resignation of a cow, the durability of a mule, the courage of a tiger, and the intellectual capability only slightly inferior to man's." Standing only 32-40 inches, many families recognized the potential of miniature donkeys as pets and companions for their children.

Although the donkey faded from public notice and became viewed as a comical, stubborn beast which was considered "cute" at best, the donkey has recently regained some popularity in North America as a mount, for pulling wagons, and even as a guard animal. Some standard species are ideal for guarding herds of sheep against predators, since most donkeys have a natural wariness toward coyotes and other canines, and will keep them away from the herd.

Donkeys in warfare
Donkeys have been used throughout history for transportation of supplies, pulling wagons, and, in a few cases, as riding animals. During World War I a British stretcher bearer, John Simpson Kirkpatrick, serving with the Australian and New Zealand Army Corps, used a donkey named Duffy to rescue wounded soldiers, carrying them to safety in Gallipoli. There is a statue of John Simpson Kirkpatrick and his donkey in his home town, South Shields.

According to British food writer Matthew Fort, donkeys were, until recently, used in the Italian Army. The Mountain Fusiliers each had a donkey to carry their gear, and in extreme circumstances the animal could be eaten. In 2006, security forces in Afghanistan prevented a man from entering a town in Zabul Province with a donkey which he had laden with 30 kg (66 lbs.) of explosives and a number of landmines, which the man had planned to set off with a remote controlled detonator.