Grévy's zebra (''Equus grevyi''), also known as the imperial zebra, is the largest living wild equid and the most threatened of the three species of zebra, the other two being the plains zebra and the

mountain zebra The mountain zebra (''Equus zebra'') is a zebra species in the family Equidae, native to southwestern Africa. There are two subspecies, the Cape mountain zebra (''E. z. zebra'') found in South Africa and Hartmann's mountain zebra (''E. z. hartman ...

. Named after Jules Grévy, it is found in parts of

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

Somalia Somalia, , Osmanya script: 𐒈𐒝𐒑𐒛𐒐𐒘𐒕𐒖; ar, الصومال, aṣ-Ṣūmāl officially the Federal Republic of SomaliaThe ''Federal Republic of Somalia'' is the country's name per Article 1 of thProvisional Constitut ...

and

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

. Superficially, Grévy's zebras’ physical features can help to identify it from the other zebra species; their overall appearance is slightly closer to that of a mule, compared to the more “equine” (horse) appearance of the plains and mountain zebras. Compared to other zebra species, Grévy’s are the tallest; they have mule-like, larger ears, and have the tightest stripes of all zebras. They have distinctively erect manes, and more slender snouts. The Grévy's zebra live in semi-arid savanna, where they feed on grasses,

legumes A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock for ...

, and

browse Browsing is a kind of orienting strategy. It is supposed to identify something of relevance for the browsing organism. When used about human beings it is a metaphor taken from the animal kingdom. It is used, for example, about people browsing o ...

, such as

acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus nam ...

; they can survive up to five days without water. They differ from the other zebra species in that they do not live in a harem, and they maintain few long-lasting social bonds. Stallion territoriality and mother–foal relationships form the basis of the social system of the Grévy's zebra. Despite a handful of zoos and animal parks around the world having had successful captive-breeding programs, in its native home this zebra is listed by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

. Its population has declined from 15,000 to 2,000 since the 1970s. In 2016, the population was reported to be “stable”; however, as of 2020, the wild numbers are still estimated at only around 2,250 animals, in part due to anthrax outbreaks in eastern Africa.

Taxonomy and naming

The Grévy's zebra was first described by French naturalist Émile Oustalet in 1882. He named it after Jules Grévy, then

president of France The president of France, officially the president of the French Republic (french: Président de la République française), is the executive head of state of France, and the commander-in-chief of the French Armed Forces. As the presidency i ...

, who, in the 1880s, was given one by the government of

Abyssinia The Ethiopian Empire (), also formerly known by the exonym Abyssinia, or just simply known as Ethiopia (; Amharic and Tigrinya: ኢትዮጵያ , , Oromo: Itoophiyaa, Somali: Itoobiya, Afar: ''Itiyoophiyaa''), was an empire that historica ...

. Traditionally, this species was classified in the subgenus ''Dolichohippus'' with plains zebra and

in ''Hippotigris''. Groves and Bell (2004) place all three species in the subgenus ''Hippotigris''. Fossils of zebra-like equids have been found throughout Africa and Asia in the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

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 Grévy's zebra and may have been its ancestor. The modern Grévy's zebra arose in the Middle Pleistocene. Zebras appear to be a monophyletic lineage and recent (2013) phylogenies have placed Grevy's zebra in a

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

with the plains zebra. In areas where Grévy's zebras are sympatric with plains zebras, the two may gather in same herds and fertile hybrids do occur.

Description

The Grévy's zebra is the largest of all wild equines. It is in head-body with a tail, and stands high at the withers. These zebras weigh . 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 Vibrissae (; singular: vibrissa; ), more generally called Whiskers, are a type of stiff, functional hair used by mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarse ...

. 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 and are just white in color, 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.

Range and ecology

The Grévy's zebra largely inhabits northern

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

, with some isolated populations in

. It was extirpated from

and

Djibouti Djibouti, ar, جيبوتي ', french: link=no, Djibouti, so, Jabuuti officially the Republic of Djibouti, is a country in the Horn of Africa, bordered by Somalia to the south, Ethiopia to the southwest, Eritrea in the north, and the Red ...

and its status in

South Sudan South Sudan (; din, Paguot Thudän), officially the Republic of South Sudan ( din, Paankɔc Cuëny Thudän), is a landlocked country in East Africa. It is bordered by Ethiopia, Sudan, Central African Republic, Democratic Republic of th ...

is uncertain. Database entry includes a brief justification of why this species is endangered. It lives in ''

Acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus nam ...

''-'' Commiphora'' bushlands and barren plains. Ecologically, this species is intermediate between the arid-living African wild ass and the water-dependent plains zebra. Lactating mares and non-territorial stallions use areas with green, short grass and medium, dense bush more often than non-lactating mares and territorial stallions. Grévy's zebras rely on

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...

es, legumes, and

for nutrition. They commonly browse when grasses are not plentiful. Their

hindgut fermentation Hindgut fermentation is a digestive process seen in monogastric herbivores, animals with a simple, single-chambered stomach. Cellulose is digested with the aid of symbiotic bacteria.ruminant herbivores. Grevy's zebras can survive up to a week without water, but will drink daily when it is plentiful. They often migrate to better watered highlands during the dry season. Mares require significantly more water when they are lactating. During droughts, the zebras will dig water holes and defend them. The Grévy's zebra's main predator is the

lion The lion (''Panthera leo'') is a large cat of the genus '' Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphic; adu ...

, but adults can be hunted by spotted hyenas. African hunting dogs, cheetahs and

leopard The leopard (''Panthera pardus'') is one of the five extant species in the genus '' Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, ...

s almost never attack adults, even in desperate times, but sometimes prey on young animals, although mares are fiercely protective of their young. In addition, they are susceptible to various gastro-intestinal parasites, notably of the genus '' Trichostrongylus''.

Behaviour and life history

Adult stallions 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. Mares, young and non-territorial stallions wander through large home ranges. The mares will wander from territory to territory preferring the ones with the highest-quality food and water sources. Up to nine stallions may compete for a mare outside of a territory. Territorial stallions will tolerate other stallions who wander in their territory. However, when an oestrous mare is present the territorial stallion keeps other stallions at bay. Non-territorial stallions might avoid territorial ones because of harassment. When mares 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. Zebras produce numerous sounds and vocalisations. When alarmed, they produce deep, hoarse grunts. Whistles and squeals are also made when alarmed, during fights, when scared or in pain. Snorts may be produced when scared or as a warning. A stallion will bray in defense of his territory, when driving mares, or keeping other stallions at bay. Barks may be made during copulation and distressed foals will squeal. The call of the Grévy's zebra has been described as "something like a hippo's grunt combined with a

donkey The domestic donkey is a hoofed mammal in the family Equidae, the same family as the horse. It derives from the African wild ass, ''Equus africanus'', and may be classified either as a subspecies thereof, ''Equus africanus asinus'', or as ...

's wheeze". To get rid of flies or parasites, they roll in dust, water or mud or, in the case of flies, they twitch their skin. They also rub against trees, rocks and other objects to get rid of irritations such as itchy skin, hair or parasites. Although Grévy's zebras do not perform

mutual grooming Social grooming is a behavior in which social animals, including humans, clean or maintain one another's body or appearance. A related term, allogrooming, indicates social grooming between members of the same species. Grooming is a major socia ...

, they do sometimes rub against a conspecific.

Reproduction

Grévy's zebras can mate and give birth year round, but most mating takes place in the early rainy seasons and births mostly take place in August or September after the long rains. An oestrous mare may visit as many as four territories a day and will mate with the stallions in them. Among territorial stallions, the most dominant ones control territories near water sources, which mostly attract mares with dependant foals, while more subordinate stallions control territories away from water with greater amounts of vegetation, which mostly attract mares without dependant foals.Rubenstein, D. I. (2010
"Ecology, social behavior, and conservation in zebras"
pp. 231–58. In: ''Advances in the Study Behavior: Behavioral Ecology of Tropical Animals'', Vol. 42. R. Macedo, ed. Elsevier Press. Zebre grevy

The resident stallions of territories will try to subdue the entering mares with dominance rituals and then continue with courtship and copulation. Grévy's zebra stallions have large

testicles A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testosteron ...

and can ejaculate a large amount of

semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...

to replace the sperm of other males. This is a useful adaptation for a species whose mares mate polyandrously. Bachelors or outside territorial stallions sometimes "sneak" copulation of mares in another stallion's territory. While mare associations with individual stallions are brief and mating is promiscuous, mares who have just given birth will reside with one stallion for long periods and mate exclusively with that stallion. Lactating females are harassed by stallions more often than non-lactating ones and thus associating with one male and his territory provides an advantage as he will guard against other males. Gestation of the Grévy's zebra normally lasts 390 days, with a single foal being born. A new-born zebra will follow anything that moves, so new mothers prevent other mares from approaching their foals while imprinting their own striping pattern, scent and vocalisation on them. Mares with young foals may gather into small groups. Mares may leave their foals in "kindergartens" while searching for water. The foals will not hide, so they can be vulnerable to predators. However, kindergartens tend to be protected by an adult, usually a territorial stallion. A mare with a foal stays with one dominant territorial stallion who has exclusive mating rights to her. While the foal may not be his, the stallion will look after it to ensure that the mare stays in his territory. To adapt to a semi-arid environment, Grévy's zebra foals have longer nursing intervals and wait until they are three months old before they start drinking water. Although offspring become less dependent on their mothers after half a year, associations with them continue for up to three years.

Relationship with humans

The Grévy's zebra was known to the Europeans in

antiquity Antiquity or Antiquities may refer to: Historical objects or periods Artifacts *Antiquities, objects or artifacts surviving from ancient cultures Eras Any period before the European Middle Ages (5th to 15th centuries) but still within the histo ...

and was used by the Romans in

circuses A circus is a company of performers who put on diverse entertainment shows that may include clowns, acrobats, trained animals, trapeze acts, musicians, dancers, hoopers, tightrope walkers, jugglers, magicians, ventriloquists, and unicycli ...

. It was subsequently forgotten in the Western world for a thousand years. In the seventeenth century, the king of

Shoa SHOA or Servicio Hidrográfico y Oceanográfico de la Armada de Chile (Spanish for Hydrographic and Oceanographic Service of the Chilean Navy) is an agency of the Chilean Navy managing situations dealing with hydrography and oceanography, includin ...

(now central Ethiopia) exported two zebras; one to the Sultan of Turkey and another to the Dutch governor of

Jakarta Jakarta (; , bew, Jakarte), officially the Special Capital Region of Jakarta ( id, Daerah Khusus Ibukota Jakarta) is the capital city, capital and list of Indonesian cities by population, largest city of Indonesia. Lying on the northwest coa ...

. A century later, in 1882, the government of

sent one to French president Jules Grévy. It was at that time that the animal was recognised as its own species and named in Grévy's honour.

Status and conservation

The Grévy's zebra is considered

. Its population was estimated to be 15,000 in the 1970s and by the early 21st century the population was lower than 3,500, a 75% decline. In 2008 it was estimated that there are less than 2,500 Grévy's zebras still living in the wild, further declining to fewer than 2,000 mature individulas in 2016. Nonetheless, the Grévy's zebra population trend was considered stable as of 2016. There are also an estimated 600 Grévy's zebras in captivity. Captive herds have been known to thrive, like at

White Oak Conservation White Oak Conservation, which is part of Walter Conservation, is a conservation center in northeastern Florida. It has long been dedicated to the conservation and care of endangered and threatened species, including rhinoceros, okapi, bongo a ...

in Yulee, Florida, United States, where more than 70 foals have been born. There, research is underway in partnership with the Conservation Centers for Species Survival on semen collection and freezing and on artificial insemination. The Grévy's zebra is legally protected in Ethiopia. In Kenya, it is protected by the hunting ban of 1977. In the past, Grévy's zebras were threatened mainly by hunting for their skins which fetched a high price on the world market. However, hunting has declined and the main threat to the zebra is habitat loss and competition with livestock. Cattle gather around watering holes and the Grévy's zebras are fenced from those areas. Community-based conservation efforts have shown to be the most effective in preserving Grévy's zebras and their habitat. Less than 0.5% of the range of the Grévy's zebra is in protected areas. In Ethiopia, the protected areas include Alledeghi Wildlife Reserve, Yabelo Wildlife Sanctuary, Borana National Park, and Chelbi Sanctuary. In Kenya, important protected areas include the Buffalo Springs, Samburu and Shaba National Reserves and the private and community land wildlife conservancies in

Isiolo Isiolo is a town in Isiolo County, of which it is the capital. It is located in the upper eastern region of Kenya and geographically considered the centre of the country Kenya. It lies 285 kilometres north of the capital Nairobi. The town grew a ...

, Samburu and the Laikipia Plateau. The mesquite plant was introduced into Ethiopia around 1997 and is endangering the zebra's food supply. An invasive species, it is replacing the two grass species, ''

Cenchrus ciliaris ''Cenchrus ciliaris'' (buffel-grass or African foxtail grass; syn. ''Pennisetum ciliare'' (L.) Link) is a species of grass native to most of Africa, southern Asia (east to India), southern Iran, and the extreme south of Europe (Sicily). Other na ...

'' and '' Chrysopogon plumulosus,'' which the zebras eat for most of their food.

References

External links

"Wildlife Grévy's Zebra"
– summary from the African Wildlife Foundation
Images and footage of Grévy's zebra
from ARKive.org
"To Catch a Zebra"
by Brian Jackman – story of catching endangered Grévy's zebra for relocation

– Rich Blundell reports from Kenya
Grevy's Zebra Trust
– a Kenyan organization dedicated to preserving the Grévy's zebra {{Good article EDGE species Grévy's zebra Mammals of Kenya Mammals of Ethiopia Mammals of South Sudan Fauna of East Africa Fauna of the Horn of Africa Grévy's zebra