Our Animals - Grevy Zebra
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Grévy's Zebra (Equus grevyi), also known as the Imperial Zebra, is the largest species of zebra. It is found in the wild in Kenya and Ethiopia. Compared to other zebras, it is tall, has large ears, and its stripes are narrower. The species is named after Jules Grévy, a president of France, who, in the 1880s, was given one by the government of Abyssinia. In certain regions of Kenya, the Plains Zebras and Grévy's Zebras coexist.
The Grevy’s zebra is the only living species of the subgenus Dolichohippus. The Plains Zebra and Mountain Zebra belong to Hippotigris. Fossils of Dolichohippus zebras have been found throughout Africa and Asia in the Pliocene and Pleistocene deposits. Notable examples include E. sanmeniensis from China, E. cautleyi’’ from India, E. valeriani from central Asia and E. oldowayensis from East Africa. The latter, in particular is very similar to the Grevy’s Zebra and may have been its ancestor. The modern Grevy’s zebra arose in the early Plesistocene.
Grévy's Zebra differs from the other two zebras in its primitive characteristics and different behavior. It was the first living zebra to emerge as a species. In many respects, it is more akin to the asses. Nevertheless, DNA and molecular data show that zebras do indeed have monophyletic origins.
Grévy's Zebra is the largest of all wild equines. It is 2.5--2.75 m (8--9 ft) from head to tail with a 38--75 cm (15--30 in) tail, and stands 1.45--1.60 m (4'7"--5'3") high at the shoulder. These zebras weigh 350--450 kg (770-990 lb). The stripes are narrow and close-set, being broader on the neck, and they extend to the hooves. The belly and the area around the base of the tail lack stripes. With all of the stripes closer together and thinner than most of the other zebras, it is easier to make a good escape and to hide from predators. The ears are very large, rounded, and conical. The head is large, long, and narrow, particularly mule-like in appearance. The mane is tall and erect; juveniles having a mane extending the length of the back.
Ecology and behavior
The Grevy’s zebra once ranged though most of Kenya, Eritrea, Ethiopia and Somalia. Today they now largely inhabit northern Kenya with some isolated populations in southern Ethiopia. This zebra fills an ecological niche between the more arid living African wild ass and the more water dependant plains zebra. It has adapted to the barren plains of the Acacia-Commiphora bushlands and thickets. It does however require well watered highlands during the dry season. During droughts the zebra will dig water holes and defend them.
Grévy's Zebra feed mostly on grasses but they will also eat fruit, shrubs, roots, leaves, buds, and bark. They may spend 60-80% of their days eating, depending on the availability of food. Their well adapted digestive system allows them to subsist on diets of lower nutritional quality than that necessary for herbivores.
Grévy's Zebra is similar to the donkey in many ways. Behaviorally, for example, it has a social system characterized by small groups of adults associated for short time periods of a few months. Adult males spend their time mostly alone in territories of 2-12 am², which is considerably smaller than the territories of the wild asses. Individuals may assimilate together with no strict dominance hierarchies
Grévy's Zebra at the Henry Doorly Zoo The territories are marked by dung piles and females who wander within the territory mate solely with the resident male. Small bachelor herds are known. Like all zebras and asses, males fight amongst themselves over territory and females. The species is vocal during fights (an asinine characteristic), braying loudly. However unlike other zebras, territory holding Grévy's Zebra males will tolerate other males who wander in their territory possibly because non-resident males do not try to mate with the resident male's females nor interfere in his breeding activities. Territorial males will even peacefully communicate with bachelors and other territorial males during the non-breeding seasons.
Grévy's Zebras mate year-round. Gestation of the zebra lasts 350--400 days, with a single foal being born. A newborn zebra will follow anything that moves and thus new mothers are highly aggressive towards other mares a few hours after they give birth. This prevents the foal from imprinting another female as its mother. Mare may leave their foals unguarded while searching for water. The foals will not hide so they are vulnerable to predators. Lone foals may gather in kindergartens until their mothers return.
To adapt to an arid lifestyle, Grévy's Zebra foals take longer intervals between suckling bouts and do not drink water until they are 3 months old. Foals are weaned after nine month but continue to stay with their mothers. Females reach become independence when they are three years old. This is when they reach estrous and is driven away from her mother by stallions. Males may stay with their mothers even longer.