Animal Diversity Web

Ge­o­graphic Range

Grevy's ze­bras live in north­ern Kenya and a few small areas of south­ern Ethiopia. His­tor­i­cally, Grevy's ze­bras in­hab­ited So­ma­lia, Ethiopia, Er­itrea, Dji­bouti, and Kenya in East Africa. The last sur­vey in Kenya in 2000 re­sulted in an es­ti­mated pop­u­la­tion of 2,571. Cur­rent es­ti­mates place the num­ber of Grevy's ze­bras in Kenya be­tween 1,838 and 2,319. In Ethiopia, the cur­rent pop­u­la­tion es­ti­mate is 126, over a 90% de­crease from the es­ti­mated 1,900 in 1980. The east­ern dis­tri­b­u­tion is north of the Tana River east of Garissa and the Lo­rian Swamp. In the west, they are found east and north of a line from Mount Kenya to Donyo Nyiro, and east of Lake Turkana to Ethiopia. In Ethiopia, they are found east of the Omo River north to Lake Zwai, south­east to Lake Stephanie and to Marsabit in Kenya. ("Grevy's Zebra", 2004; "Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 2004; Churcher, 1993; "Grevy's Zebra", 1999; "Equus Grevyi", 2003)

• Biogeographic Regions
• ethiopian
  • native

Habi­tat

Grevy's ze­bras in­habit semi-arid grass­lands, fill­ing a niche dis­tinct from that of other mem­bers of the genus Equus that live within the same ge­o­graph­i­cal range, such as wild asses (which pre­fer arid habi­tats) and plains ze­bras (which are more de­pen­dent on water than Grevy's ze­bras). They usu­ally pre­fer arid grass­lands or aca­cia sa­van­nas. The most suit­able areas have a per­ma­nent water source. In re­cent years, Grevy's ze­bras have be­come in­creas­ingly con­cen­trated in the south of their range due to habi­tat loss in the north. Dur­ing the dry sea­son, when lo­ca­tion near a per­ma­nent water source is es­pe­cially im­por­tant, ze­bras tend to be­come more con­cen­trated in ter­ri­to­ries with per­ma­nent water sources. In rainy sea­sons, they are more dis­persed. Areas with green, short grass and medium-dense bush are used by lac­tat­ing fe­males and bach­e­lors more fre­quently than non-lac­tat­ing fe­males or ter­ri­to­r­ial males. Lac­tat­ing fe­males may trade off for­age quan­tity and safety to ac­cess nu­tri­ents in grow­ing grass. ("Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 2004; Cord­ing­ley, et al., 2009; "Grevy's Zebra", 1999; Sun­dare­san, et al., 2008)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• savanna or grassland

• Range elevation

  300 to 600 m

  984.25 to 1968.50 ft

• Average elevation

  500 m

  1640.42 ft

Phys­i­cal De­scrip­tion

Grevy's ze­bras have large heads, large and rounded ears, and thick, erect manes. The muz­zle is brown. The neck is thicker and more ro­bust than in other zebra species. These qual­i­ties make it ap­pear more mule-like than other ze­bras. The coat has black and white nar­row stripes, shaped like chevrons, that wrap around each other in a con­cen­tric pat­tern and are bi­sected by a black dor­sal stripe. The chevron pat­tern is es­pe­cially dis­tinct on the limbs, where the point of the chevron points dor­sally, be­com­ing more acute the fur­ther up the limb they climb; they reach a final peak at the shoul­ders and the with­ers. On the cra­nium, chevrons ex­tend dor­sally to the cheek, where the pat­tern be­comes more lin­ear. The belly of this zebra is com­pletely white, un­like other ze­bras. Grevy's ze­bras are also the largest of all the wild equids and only do­mes­tic horses are larger. Grevy's ze­bras ex­hibit slight sex­ual di­mor­phism; males are usu­ally about 10 per­cent larger than fe­males. Grevy's zebra foals are born with a coat that has red­dish-brown or rus­set stripes in­stead of the black of adults. This grad­u­ally dark­ens to black as the zebra ages. A dor­sal mane that ex­tends from the top of the head to the base of the tail is pre­sent in all young ze­bras. This mane is erect when an an­i­mal is ex­cited and flat when it is re­laxed. Adult den­tal for­mula is 3/3, 1/1, 4/4, 3/3. ("Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 2004; Churcher, 1993; "Grevy's Zebra", 1999)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  349 to 451 kg

  768.72 to 993.39 lb

• Range length

  125 to 150 cm

  49.21 to 59.06 in

• Average length

  135 cm

  53.15 in

Re­pro­duc­tion

A male mates with any fe­males that come into his ter­ri­tory if they are in es­trous. Mares are usu­ally polyan­drous and mate with one male be­fore switch­ing ter­ri­to­ries and mat­ing with an­other, al­though some­times mares be­come mo­nan­drous. When a mare stays in a sin­gle ter­ri­tory, usu­ally be­cause she de­sires the re­sources that are pre­sent in that ter­ri­tory, she will stay with a sin­gle male and mate only with him. (Churcher, 1993; Gins­berg and Ruben­stein, 1990)

• Mating System
• polygynous

Grevy's ze­bras can mate year round, but the ma­jor­ity of breed­ing oc­curs from July to Au­gust and Sep­tem­ber to Oc­to­ber. Foals are born after a 13 month ges­ta­tion pe­riod, usu­ally within the rainy months of the year. Peaks usu­ally occur in May and June, the pe­riod of long rains, and in No­vem­ber and De­cem­ber, the pe­riod of short rains. As birth ap­proaches, fe­males iso­late them­selves from the herd. Birth nor­mally takes place lying down, with the young's hoofs ap­pear­ing first, and full emer­gence in 7 to 8 min­utes. If birth be­gins with the mother stand­ing, it is com­pleted lying down. The new­born frees it­self from the am­ni­otic mem­branes and crawls to­wards its mother's head. The mother licks it clean and in­gests the mem­branes and some am­ni­otic fluid, which may be im­por­tant in ini­ti­at­ing lac­ta­tion or the ma­ter­nal bond. Ze­bras take an av­er­age of 275 days to be weaned. Once weaned, they con­tinue to stay with their mother. Fe­males dis­perse sooner than males, fe­males dis­perse at 13 to 18 months and males often stay with their mother for up to 3 years. A new­born Grevy's zebra foal is rus­set-col­ored with a long hair crest down its back and belly. At this stage, im­print­ing oc­curs. Fe­male ze­bras keep other ze­bras at a dis­tance so that the foal can bond with its mother. New­born foals can walk just 20 min­utes after being born and run after an hour, which is a very im­por­tant sur­vival adap­ta­tion for this cur­so­r­ial, mi­grat­ing species. Foals nurse heav­ily for half a year and may take as long as three years to be com­pletely weaned. Fe­males achieve sex­ual ma­tu­rity around 3 years of age and males achieve sex­ual ma­tu­rity around 6 years of age. Fe­males tend to con­ceive once every two years. ("Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 2004; Churcher, 1993; "Grevy's Zebra", 1999)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Female Grevy's zebras breed about once every two years.

• Breeding season

  Grevy's zebras can mate year round, but most breeding occurs July through August and October through November.

• Range number of offspring

  1 to 1

• Average number of offspring

  1

  AnAge

• Range gestation period

  358 to 438 days

• Average gestation period

  390 days

• Average weaning age

  275 days

• Range time to independence

  1 to 3 years

• Range age at sexual or reproductive maturity (female)

  3 to 4 years

• Average age at sexual or reproductive maturity (female)

  3 years

• Range age at sexual or reproductive maturity (male)

  1 to 7 years

• Average age at sexual or reproductive maturity (male)

  6 years

Males play lit­tle to no role in car­ing for the young, fe­males are solely re­spon­si­ble for car­ing for the young. Im­me­di­ately after child­birth, the foal im­prints on the mother and can rec­og­nize her dis­tinct scent, ap­pear­ance, and vo­cal­iza­tions. An im­printed foal will di­rectly fol­low its mother and can rec­og­nize the shape of the stripes on its mother's back­side. Until it is weaned, a foal will fol­low its mother and learn to mimic all of her be­hav­ior. Fe­male foals be­come in­de­pen­dent from their moth­ers sooner than male foals, even though both gen­ders are weaned at around the same time. Males often re­main with their birth herd until they reach three years of age and fe­males have been known to sep­a­rate at just 13 months of age.

• Parental Investment
• precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female
• post-independence association with parents

Lifes­pan/Longevity

Like most other species the lifes­pan of Equus grevyi is longer in cap­tiv­ity than in the wild. In cap­tiv­ity, Equus grevyi usu­ally lives be­tween 22 and 30 years. In the wild, the me­dian age is closer to 12 or 13, al­though an 18 year old an­i­mal has been re­ported. (Churcher, 1993)

• Range lifespan
  Status: wild

  18 (high) years

• Range lifespan
  Status: captivity

  30 (high) years

• Typical lifespan
  Status: wild

  18 (high) years

• Average lifespan
  Status: wild

  12-13 years

• Typical lifespan
  Status: captivity

  22 to 30 years

Be­hav­ior

Grevy's ze­bras are dif­fer­ent from most other mem­bers of the genus Equus in that they do not have con­crete so­cial struc­ture. They are loosely so­cial an­i­mals; herd com­po­si­tion can vary on a daily basis as new mem­bers enter a dom­i­nant male's ter­ri­tory and old mem­bers leave. The two most sta­ble re­la­tion­ships that Grevy's ze­bras have are a stal­lion's at­tach­ment to his ter­ri­tory and a mare's at­tach­ment to her young. There is not a rig­or­ously ob­served hi­er­ar­chy of dom­i­nance within a group of Grevy's ze­bras, al­though a dom­i­nance struc­ture is pre­sent. A ter­ri­to­r­ial male has the right to breed­ing fe­males in that ter­ri­tory. In the ab­sence of fe­males, males will as­so­ci­ate in bach­e­lor herds with a loose dom­i­nance struc­ture. Males are ter­ri­to­r­ial and claim prime wa­ter­ing and graz­ing areas. These ter­ri­to­ries can get up to 6 square kilo­me­ters in size. Males mark their ter­ri­to­ries with piles of dung, called "mid­dens," and emit loud vo­cal­iza­tions that let other ze­bras know they're pre­sent. A ter­ri­to­r­ial male may re­tain his ter­ri­tory for a pe­riod of 7 years be­fore a younger, stronger male chal­lenges him for it. Grevy's zebra males are soli­tary in their ter­ri­to­ries, ex­cept when fe­males ar­rive in breed­ing sea­son. Bach­e­lor males, or non-ter­ri­to­r­ial males, travel to­gether in groups of 2 to 6. This so­cial sys­tem is dif­fer­ent from other ze­bras, which form fe­male harems in a sin­gle male's ter­ri­tory all year. Dur­ing droughts, some Grevy's ze­bras mi­grate to moun­tain pas­tures where food sources are more abun­dant, but ter­ri­to­r­ial males often re­main on their ter­ri­to­ries year-round.

Lac­tat­ing fe­males have dif­fer­ent re­source re­quire­ments than non-lac­tat­ing fe­males. When fe­males are lac­tat­ing, they need water at least every other day, so male ze­bras in ter­ri­to­ries with large, safe bod­ies of water in them usu­ally get the op­por­tu­nity to mate with more fe­males. Lac­tat­ing fe­males have more re­stricted move­ments and fewer male as­so­ci­ates than non-lac­tat­ing fe­males. It is pos­si­ble that male ha­rass­ment also in­flu­ences fe­male dis­tri­b­u­tion and as­so­ci­a­tions with males. Lac­tat­ing fe­males ex­pe­ri­ence higher ha­rass­ment rates from males than non-lac­tat­ing fe­males and tend to move faster dur­ing ha­rass­ment pe­ri­ods ("Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 2004; "Grevy's Zebra", 1999; Sun­dare­san, et al., 2007)

• Key Behaviors
• cursorial
• diurnal
• motile
• nomadic
• solitary
• territorial
• social
• dominance hierarchies

• Range territory size

  2 to 12 km^2

• Average territory size

  6 km^2

Home Range

Ter­ri­to­r­ial males have ter­ri­to­ries of as lit­tle as 2 square kilo­me­ters and as much as 12 square kilo­me­ters, al­though the av­er­age ter­ri­tory is 6 square kilo­me­ters. The home range size of non-ter­ri­to­r­ial ze­bras is some­times as great as 10,000 square kilo­me­ters. Grevy's ze­bras are ex­tremely mo­bile and some in­di­vid­u­als have been known to move dis­tances of greater than 80 kilo­me­ters. ("Grevy's Zebra", 2004; Sun­dare­san, et al., 2007)

Com­mu­ni­ca­tion and Per­cep­tion

No two ze­bras have the same stripe pat­tern. Each in­di­vid­ual zebra's stripe pat­tern acts as a type of fin­ger­print that al­lows it to be iden­ti­fied ac­cu­rately by human re­searchers up to 90% of the time. This, along with scent and in­di­vid­ual vo­cal­iza­tions, allow in­di­vid­u­als to be rec­og­nized by con­specifics.

Scent mark­ing, es­pe­cially by fe­males, plays a sig­nif­i­cant role in breed­ing. Males often sniff the leav­ings of a fe­male in order to de­ter­mine if she is in es­trous. Males use dung and urine in order to mark their ter­ri­tory.

Males use sounds and vi­sual cues to as­sert their dom­i­nance. They may do this by bar­ing their teeth, flat­ten­ing their ears, kick­ing, or bit­ing other males. Ter­ri­to­r­ial males often ha­rass fe­males into breed­ing with them using these same tech­niques.

Grevy's ze­bras are very vocal, though not quite as vocal as plains ze­bras. Their vo­cab­u­lary in­cludes sev­eral dis­tinct pitches. In­di­vid­u­als often emit these pitches when they are es­cap­ing preda­tors or when they are fight­ing. ("Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 2004; Churcher, 1993)

• Communication Channels
• visual
• tactile
• acoustic

• Other Communication Modes
• scent marks

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Grevy's ze­bras are her­bi­vores and graz­ers with oc­ca­sional brows­ing ten­den­cies. They pri­mar­ily eat tough grasses and forbs but, in the dry sea­son when grasses are not as abun­dant, leaves can con­sti­tute up to 30 per­cent of their diet. Grevy's ze­bras can di­gest many dif­fer­ent types and parts of plants that cat­tle can­not. Grevy's ze­bras are water de­pen­dent and will often mi­grate to grass­lands within daily reach of water. Most Grevy's ze­bras can sur­vive with­out water for up to five days, but lac­tat­ing fe­males must drink at least every other day in order to main­tain healthy milk pro­duc­tion. ("Grevy's Zebra Trust: En­dan­gered Species", 2007; "Grevy's Zebra", 1999)

• Primary Diet
• herbivore
  • folivore

• Plant Foods
• leaves

Pre­da­tion

The stripes of Grevy's ze­bras may act as cam­ou­flauge, es­pe­cially at night. Ze­bras are often hard to spot from large dis­tances at night. The stripes also help to break up the out­line of the an­i­mal to preda­tors and may help to cam­ou­flage them in tall grass. When in the same ter­ri­tory, Grevy's ze­bras band to­gether in tem­po­rary so­cial groups to pro­vide pro­tec­tion from preda­tors. ("Grevy's Zebra Trust: En­dan­gered Species", 2007; Churcher, 1993)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • lions (Panthera leo)
  • cheetahs (Acinonyx jubatus)
  • striped hyenas (Hyaena hyaena)
  • African wild dogs (Lycaon pictus)
  • leopards (Panthera pardus)

Ecosys­tem Roles

Grevy's ze­bras are large, graz­ing un­gu­lates that feed on grasses and serve as prey for a num­ber of large preda­tors. They fill a niche left open be­tween arid-habi­tat lov­ing wild asses and wa­ter-de­pen­dent plains ze­bras. ("Grevy's Zebra", 2004; Churcher, 1993)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Grevy's ze­bras have a dis­tinct ap­pear­ance and are a source of eco­tourism in­ter­est. Grevy's ze­bras have been used as food and a source of pelts in the past.

• Positive Impacts
• body parts are source of valuable material
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Equus grevyi may some­times com­pete with do­mes­ti­cated cat­tle for re­sources on graz­ing lands.

Con­ser­va­tion Sta­tus

A 5-year con­ser­va­tion plan of the Kenya Wildlife Ser­vices (KWS) was launched on June 25, 2008. This con­ser­va­tion plan aims to re­cover the pop­u­la­tion of Grevy's ze­bras, which de­clined from 15,000 in the 1970s to just over 2,500 in 2009. The plan sug­gests the need for a mon­i­tor­ing sys­tem to es­ti­mate the pop­u­la­tion size of Equus grevyi, to as­sess its con­di­tion, to track move­ments, and to de­ter­mine the causes of mor­tal­ity. In ad­di­tion to this, local com­mu­ni­ties in Kenya are get­ting more in­volved in the con­ser­va­tion of Equus grevyi and Ethiopa has held two work­shops re­gard­ing sta­tus and con­ser­va­tion. Equus grevyi was pre­vi­ously listed as a game an­i­mal in Kenya and is now being up­graded to a pro­tected an­i­mal. It is also listed as pro­tected in Ethiopia, al­though of­fi­cial pro­tec­tion has been lim­ited. (Low, et al., 2009; Moehlman, et al., 2009; Muo­ria, et al., 2009)

• IUCN Red List

  Endangered
  More information

• IUCN Red List

  Endangered
  More information

• US Federal List

  Threatened

• CITES

  Appendix I

• State of Michigan List

  No special status

Other Com­ments

Equus grevyi in­di­vid­u­als can run at speeds of up to 40 mph (64 kph). ("Grevy's Zebra", 2004)

Con­trib­u­tors

Alexis J. Holling­shead (au­thor), Case West­ern Re­serve Uni­ver­sity, Darin Croft (ed­i­tor, in­struc­tor), Case West­ern Re­serve Uni­ver­sity, Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Ref­er­ences

The Wild Class­room. 2003. "Equus Grevyi" (On-line). Bio­mes of the World. Ac­cessed No­vem­ber 15, 2009 at http://​www.​thewildclassroom.​com/​biomes/​speciesprofile/​savanna/​grevyszebra.​html.

2007. "Grevy's Zebra Trust: En­dan­gered Species" (On-line). Grevy's Zebra Trust. Ac­cessed No­vem­ber 15, 2009 at http://​www.​grevyszebratrust.​org/​.

Amer­i­can Wildlife Foun­da­tion. 2004. "Grevy's Zebra" (On-line). Amer­i­can Wildlife Foun­da­tion. Ac­cessed No­vem­ber 15, 2009 at http://​www.​awf.​org/​content/​wildlife/​detail/​grevyszebra.

Friends of the Na­tional Zoo. 1999. "Grevy's Zebra" (On-line). Smith­son­ian Na­tional Zo­o­log­i­cal Park. Ac­cessed No­vem­ber 15, 2009 at http://​nationalzoo.​si.​edu/​Animals/​AfricanSavanna/​fact-gzebra.​cfm.

Churcher, C. 1993. Mam­malian Species. Amer­i­can So­ci­ety of Mam­mal­o­gists, 453: 1-9. Ac­cessed No­vem­ber 10, 2009 at http://​www.​jstor.​org/​stable/​3504222.

Cord­ing­ley, J., S. Sun­dare­san, I. Fis­chhoff, B. Shapiro, J. Ruskey. 2009. Is the en­dan­gered Grevy's zebra threat­ened by hy­bridiza­tion?. An­i­mal Con­ser­va­tion, Vol. 12 Issue 6: 505-513. Ac­cessed De­cem­ber 01, 2009 at http://​search.​ebscohost.​com/​login.​aspx?​direct=true&​db=a9h&​AN=45231153&​site=ehost-live.

Gins­berg, J., D. Ruben­stein. 1990. Sperm Com­pe­ti­tion and Vari­a­tion in Zebra Mat­ing Be­hav­ior. Be­hav­ioral Ecol­ogy and So­cio­bi­ol­ogy, Vol. 26: 427-434. Ac­cessed No­vem­ber 10, 2009 at http://​www.​jstor.​org/​stable/​4600432.

Low, B., S. Sun­dare­san, I. Fis­chhoff, D. Ruben­stein. 2009. Part­ner­ing with local com­mu­ni­ties to iden­tify con­ser­va­tion pri­or­i­ties for en­dan­gered Grevy’s zebra. Bi­o­log­i­cal Con­ser­va­tion, Vol. 142 Issue 7: 1548-1555. Ac­cessed No­vem­ber 10, 2009 at http://​search.​ebscohost.​com/​login.​aspx?​direct=true&​db=a9h&​AN=38806267&​site=ehost-live.

Moehlman, P., D. Ruben­stein, F. Kebede. 2009. "IUCN Redlist of Threat­ened Species" (On-line). IUCN Redlist. Ac­cessed No­vem­ber 23, 2009 at www.​iucnredlist.​org.

Muo­ria, P., P. Mu­ruthi, P. Omondi, C. Mutua, J. Bernard, N. Oguge, J. King. 2009. Kenya launches na­tional strat­egy to con­serve Grevy's zebra.. Oryx, Vol. 43 Issue 2: 271-272. Ac­cessed No­vem­ber 10, 2009 at http://​search.​ebscohost.​com/​login.​aspx?​direct=true&​db=a9h&​AN=39795368&​site=ehost-live.

Sun­dare­san, S., I. Fis­chhoff, H. Har­tung, P. Ak­i­long, D. Ruben­stein. 2008. Habi­tat choice of Grevy’s ze­bras ( Equus grevyi) in Laikipia, Kenya.. African Jour­nal of Ecol­ogy, Vol. 46 Issue 3: 359-364. Ac­cessed No­vem­ber 10, 2009 at http://​search.​ebscohost.​com/​login.​aspx?​direct=true&​db=a9h&​AN=34038297&​site=ehost-live.

Sun­dare­san, S., I. Fis­chhoff, D. Ruben­stein. 2007. Male ha­rass­ment in­flu­ences fe­male move­ments and as­so­ci­a­tions in Grevys zebra (Equus grevyi).. Be­hav­ioral Ecol­ogy, Vol. 18 Issue 5: 860. Ac­cessed No­vem­ber 10, 2009 at http://​search.​ebscohost.​com/​login.​aspx?​direct=true&​db=a9h&​AN=26420265&​site=ehost-live.