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Grevy's zebra

Class: Mammalia
Order: Perissodactyla
Family: Equidae
Genus and Species: Equus grevyi
  • Two large hoofed animals with bold black and white stripes
  • Closeup of the heads of two horselike animals with black and white stripes
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Grevy's zebra

The largest of the zebra species, Grevy’s zebra have thicker stripes and bigger ears than other zebras. They are also the most threatened: fewer than 2,500 Grevy’s zebras may remain in the wild.

Physical Description

Most famously, zebras have black and white stripes. Grevy's are the largest of all zebras, and they have long necks with prominent, erect manes. They have the largest ears of any zebra species, and their long, narrow heads give them a mule-like appearance.

The two major characteristics that set zebras apart from their two closest relatives are their very distinct black and white stripes and their untamable wild nature. The black and white stripes appear all over the zebra's body, even on their mane and ears. While their coat is black and white, their skin is dark brown or black. Grevy's zebra have about 80 stripes in all.

Grevy's zebras have many other adaptations that are common to all zebras. They have long, slender legs and hoofed feet that allow them to run quickly in an effort to avoid fast-moving predators. Grevy's zebras also have very keen eyesight. Their large eyes are set far back on their heads, which provides a wide field of vision and the ability to spot movement at great distances.

Grevy's zebras' teeth are well adapted for grazing. They use their upper and lower incisors to clip vegetation and high-crowned, ridged molars for grinding. All of their teeth are elongated and covered with thick enamel to allow them to chew tough, abrasive grass constantly. Males have four more teeth than females: short, pointed canines used for fighting.

Size

Grevy's zebras are the largest of all zebra species. They stand 4 to 5 feet (1.2 to 1.5 meters) tall at the shoulder, can reach a length of 7.5 feet (2.3 meters) and typically weigh between 770 and 950 pounds (348.8 to 430.4 kilograms).

Native Habitat

Populations of Grevy's zebra live in Ethiopia and northern Kenya, with a small introduced population in southern Kenya. Fewer than 100 remain in Ethiopia and fewer than 2,400 in Kenya. Grevy's zebra have been extirpated from Eritrea, Djibouti and Somalia. Grevy's zebras live in semi-arid scrub and grasslands and prefer hot, dry regions. They can often be seen on the open plains mingling with other grazing animals such as wildebeest, ostriches and antelopes.

Fossils found in China and Uzbekistan, as well as a two million-year-old fossil found in South Africa, suggest that ancestral forms of Grevy's zebras were once widespread in Africa and Eurasia. More recent fossils show that, during the Neolithic period (about 6,000 years ago), Grevy's zebras had a range that extended as far north as Egypt.

Food/Eating Habits

Grevy's zebras feed mainly on grasses but they will also consume bark, fruit and leaves. Poor nutrient content requires a high volume of intake, so they spend about 60 percent of their day eating. In drier times when food is scarce, eating can occupy up to 80 percent of their time. Zebras are beneficial to other wild grazers because they clear off the tops of coarse grasses that are difficult for other herbivores to digest.

To provide the proper amount of roughage in the diet, the Smithsonian's National Zoo feeds a balanced ratio of a manufactured pellet diet and hay. Typically, a nutrient composition of hay is variable. In contrast, manufactured pellet diets provide a consistent supply of nutrients. Grevy's zebras are also given leaf eater biscuits while training and offered salt licks.

Social Structure

Unlike all other species of zebras, Grevy's zebras do not form permanent herds or permanent social bonds between adults. Mares and their latest foals make up the basis for Grevy social structure. These mare-foal units can combine together with other mares and foals. These "herds" do not have hierarchies and are subject to change. These female herds usually include fewer than ten mares, but much larger groups can be seen together around water sources in the dry season. Meanwhile, male zebras also form loose bachelor herds—usually between two to six stallions. These groups have no apparent leader or dominance hierarchy and constantly change as more zebras enter or leave the herd.

Many adult male Grevy's zebras live alone and occupy large territories. Males without territories usually form bachelor herds. These free-ranging groups often wander into areas occupied by a resident male. Territorial males tolerate other males and often will seek out their company unless there is a female in estrus nearby. In this case, the resident male will chase off all other males and try to mate with the female and keep her from leaving his area. Two males will compete for a territory by having pushing contests, rearing and biting. Females have a dominance hierarchy, as well, but engage in mutual grooming to establish relationships with each other. Females with young may form loose nursery herds.

Reproduction and Development

Sexual maturity for Grevy's zebras is two to three years for mares and six years for stallions.

Females will usually give birth to a single foal after a gestation period of 390 days, the longest of any equid. The mother will leave the herd to give birth in heavy brush. The mother drives away other zebras during the first two days of life before rejoining the nursery group. Newborns orient on their mother's rump and tail pattern. Young are weaned at nine months.

Grevy's females become independent of their mother at 13 to 18 months of age. Young males remain with their mother for at least three years. Independent adolescents move freely from herd to herd.

Lifespan

In the wild, Grevy's zebras live to between 20 and 25 years. In human care, they live to between 25 and 30 years.

Grevy's zebras are endangered. Now confined to northern Kenya and southern and eastern Ethiopia, Grevy's zebras have faced one of the greatest range reductions of any African mammal. They no longer live in Somalia, Eritrea and Djibouti, and may be gone from Sudan as well. There may be fewer than 2,500 Grevy's zebras in the wild.

Historically, Grevy's zebras have been hunted for their meat and attractive skins, which are used to make consumer items such as coats, rugs, and bags. To help increase the number of Grevy's zebras, Kenya banned all hunting of zebras in May of 1977 and all trading of wildlife products in March of 1978. Ethiopia has also legally protected this species.

Habitat loss continues to be a problem. Grevy's zebras must compete with an increasing number of domestic livestock for water and food. Badly managed tourism, like off-road driving, can limit their access to breeding and watering sitesareas essential for their survival.

A male Grevy’s zebras named Moyo lives at the Cheetah Conservation Station.