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| - The Grévy's zebra (Equus grevyi), also known as the imperial zebra, is the largest extant wild equid and the largest and most threatened of the three species of zebra, the other two being the plains zebra and the mountain zebra. Named after Jules Grévy, it is the sole extant member of the subgenus Dolichohippus. The Grévy's zebra is found in Kenya and Ethiopia. Compared with other zebras, it is tall, has large ears, and its stripes are narrower. The Grévy's zebra lives in semi-arid grasslands where it feeds on grasses, legumes, and browse; it can survive up to five days without water. It differs from the other zebra species in that it does not live in harems and has few long-lasting social bonds. Male territoriality and mother–foal relationships form the basis of the social system of the Grévy's zebra. This zebra is considered to be endangered. Its population has declined from 15,000 to 3,000 since the 1970s. However, as of 2008, the population is stable. The Grévy's zebra is the largest of all wild equines. It is 2.5–2.75 m (8.2–9.0 ft) from head to tail with a 55–75 cm (22–30 in) tail, and stands 1.45–1.6 m (4.8–5.2 ft) high at the shoulder. These zebras weigh 350–450 kg (770–990 lb). Grévy's zebra differs from the other two zebras in its more primitive characteristics. It is particularly mule-like in appearance; the head is large, long, and narrow with elongated nostril openings; the ears are very large, rounded, and conical and the neck is short but thick. The zebra's muzzle is ash-grey to black in colour with the lips having whiskers. The mane is tall and erect; juveniles have a mane that extends to the length of the back and shortens as they reach adulthood. As with all zebra species, the Grevy's zebra's pelage has a black and white striping pattern. 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 which is unique to the Grevy's zebra. Foals are born with brown and white striping, with the brown stripes darkening as they grow older.[12] Embryological evidence has shown that the zebra's background colour is dark and the white is an addition. The stripes of the zebra may serve to make it look bigger than it actually is or disrupt its outline. It appears that a stationary zebra can be inconspicuous at night or in shade. Experiments have suggested that the stripes polarize light in such a way that it discourages biting horse-flies in a manner not shown with other coat patterns. Other studies suggest that, when moving, the stripes may confuse observers, such as mammalian predators and biting insects, via two visual illusions, the wagon wheel effect, where the perceived motion is inverted, and the barber pole illusion, where the perceived motion is in a wrong direction. The Grévy’s zebra largely inhabits northern Kenya, with some isolated populations in Ethiopia. It was extirpated from Somalia and Djibouti and its status in South Sudan is uncertain. It lives in Acacia-Commiphora bushlands and barren plains. Ecologically, this species is intermediate between the arid-living African wild ass and the water-dependent plains zebra. Lactating females and non-territorial males use areas with green, short grass and medium, dense bush more often than non-lactating females and territorial males. Grévy's zebras rely on grasses, legumes, and browse for nutrition. They commonly browse when grasses are not plentiful. Their hindgut fermentation digestive system allows them to subsist on diets of lower nutritional quality than that necessary for ruminant herbivores. Grevy's zebras can survive up to five days without water, but will drink daily when it is plentiful. They often migrate to better watered highlands during the dry season. Females require significantly more water when they are lactating. During droughts, the zebras will dig water holes and defend them. Grévy's zebras are preyed on by lions, hyenas, wild dogs, cheetahs and leopards. In addition, they are susceptible to various gastro-intestinal parasites, notably of the Trichostrongylus genus. Adult males mostly live in territories during the wet seasons but some may stay in them year round if there's enough water left. Stallions that are unable to establish territories are free-ranging and are known as bachelors. Females, young and non-territorial males wander through large home ranges. The females will wander from territory to territory preferring the ones with the highest-quality food and water sources. Up to nine males may compete for a female outside of a territory. Territorial stallions will tolerate other stallions who wander in their territory, however when an oestrous female is present the territorial stallion keeps other males at bay. Non-territorial males may avoid territorial ones because of harassment. When females are not around, a territorial stallion will seek the company of other stallions. The stallion shows his dominance with an arched neck and a high-stepping gait and the least dominant stallions submit by extending their tail, lowering their heads and nuzzling their superior's chest or groin. The call of the Grévy's zebra has been described as "something like a hippo's grunt combined with a donkey's wheeze". To get rid of flies or parasites, they roll in dust, water or mud or, in the case of flies, twitch their skin. They also rub against trees, rocks and other objects to get rid of irritations like itchy skin, hair or parasites. Although Grévy's zebras do not perform mutual grooming, they do sometimes rub against a conspecific.
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