Table of Contents
Overview
Brief Summary
Biology
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Comprehensive Description
Description
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Distribution
Range Description
Yalden et al. (1996) recorded them to 1,600 m in Ethiopia.
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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.
Biogeographic Regions: ethiopian (Native )
- 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.
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Kenya, Ethiopia, Somalia
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Range
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Physical Description
Morphology
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.
Range mass: 349 to 451 kg.
Range length: 125 to 150 cm.
Average length: 135 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
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Ecology
Habitat
Habitat and Ecology
Systems
- Terrestrial
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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.
Range elevation: 300 to 600 m.
Average elevation: 500 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland
- 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.
- 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.
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Trophic Strategy
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.
Plant Foods: leaves
Primary Diet: herbivore (Folivore )
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Associations
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.
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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.
Known Predators:
- lions (Panthera leo)
- cheetahs (Acinonyx jubatus)
- striped hyenas (Hyaena hyaena)
- African wild dogs (Lycaon pictus)
- leopards (Panthera pardus)
Anti-predator Adaptations: cryptic
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Life History and Behavior
Behavior
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.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: scent marks
Perception Channels: visual ; acoustic
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Life Expectancy
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.
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.
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Lifespan, longevity, and ageing
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Reproduction
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.
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.
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.
Range gestation period: 358 to 438 days.
Average gestation period: 390 days.
Average birth mass: 40 kg.
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.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average birth mass: 40000 g.
Average number of offspring: 1.
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
- 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.
- 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.
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Molecular Biology and Genetics
Molecular Biology
Statistics of barcoding coverage: Equus grevyi
Public Records: 0
Species: 1
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
History
- 1996Endangered
- 1994Endangered(Groombridge 1994)
- 1990Endangered(IUCN 1990)
- 1988Endangered(IUCN Conservation Monitoring Centre 1988)
- 1986Endangered(IUCN Conservation Monitoring Centre 1986)
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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.
US Federal List: threatened
CITES: appendix i
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
- 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.
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Status: Threatened
Date Listed: 09/20/1979
Lead Region: Foreign (Region 10)
Where Listed:
Population detail:
Population location: entire
Listing status: T
For most current information and documents related to the conservation status and management of Equus grevyi , see its USFWS Species Profile
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Status
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Trends
Population
In Kenya, the Grevy’s Zebra population declined from an estimated 4,276 in 1988 (KREMU 1989) to 2435-2707 in 2000 (Nelson and Williams 2003) to 1567-1976 in 2004 (B. Low pers.comm.) to an estimated population size of 1468-2135 in 2006 (B. Low pers. comm. 2007). In 2007, the population estimate of 1838-2319 indicates that either more individuals were being accurately observed or that the population is stabilizing and increasing (Mwasi and Mwangi 2007). The trend from 1988 to 2006 (18 years) is a decline of 50 to 66%. The data for 2007 indicates a potential increase in the population in Kenya.
In Ethiopia, Grevy’s Zebra declined from an estimated 1,900 in 1980 to 577 in 1995 (Rowen and Ginsberg 1992, F. Kebede pers. comm. 2007), to 106 in 2003 (Williams et al. 2003). In 2006, the population in Ethiopia was estimated to be 128 (F. Kebede pers. comm. 2007). The trend from 1980 to 2003 (23 years) is a decline of roughly 94%. The data for 2006 indicates a potential increase in the population in Ethiopia.
The density and area of occupancy of Grevy’s Zebras fluctuates seasonally as animals move in their search for resources. During the dry season, when they are dependent on permanent water, animals tend to be more concentrated. However, given that they can move up to 35 km from water even during the dry season, their densities are never high. They are most abundant and most easily observed in the southern portion of their range in southern Samburu and the Laikipia Plateau.
Population Trend
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Threats
Threats
In Kenya, hunting for skins in the late 1970s may have contributed to the observed decline, although recent data suggest that the continuing decline in this country is attributable to low recruitment due to low juvenile survival. This is a result of competition for resources – both food and access to water – with pastoral people and domestic livestock (Williams 1998). However, a low level of hunting of Grevy’s Zebra for food and, in some areas, medicinal uses continues (Williams 2002, in press). Furthermore, the water supply in critical perennial rivers has declined, most notably in the Ewaso Ng’iro River where over-abstraction of water for irrigation schemes has reduced dry season river flow by 90% over the past three decades (Williams 2002, in press).
In Ethiopia, killing of Grevy’s Zebra is the primary cause of the decline (F. Kebede pers. comm. 2007).
Recently, Muoria et al. (in press) recorded an outbreak of anthrax in the Wamba area of southern Samburu, Kenya, during which more than 50 animals succumbed to the disease.
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Threats
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Management
Conservation Actions
At present, protected areas form less than 0.5% of the range of Grevy’s Zebra. In Ethiopia, the protected areas are nominal (Alledeghi Wildlife Reserve, Yabello Sanctuary, Borana Controlled Hunting Area and Chalbi Sanctuary). In Kenya, the Buffalo Springs, Samburu, Shaba N.R. complex and the private and community land wildlife conservancies in Isiolo, Samburu and the Laikipia Plateau provide a core and crucial protection of Kenya’s southern population of Grevy’s Zebra (Williams 2002). On the Laikipia Plateau, protection and reduced competition with domestic livestock, have seen Grevy's Zebra numbers increasing since they first expanded into this area in the early 1970s (Williams 2002, in press).
Kenya has recently taken steps to develop a national conservation strategy for Grevy’s Zebras. Ethiopia has held two workshops on the status and conservation of the Grevy’s Zebra. Research and community-based conservation is on-going in the three known population areas.
Williams (2002) highlights several other conservation actions focused on wild populations, involving: 1. Protection of water supplies; 2. Management of protected areas; 3. Community conservation; and 4. Monitoring of numbers in the wild.
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Conservation
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Negative
Equus grevyi may sometimes compete with domesticated cattle for resources on grazing lands.
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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
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Wikipedia
Grévy's zebra
The Grévy's zebra (Equus grevyi), also known as the imperial zebra, is the largest extant wild equid and the largest and most endangered 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.[2] Compared with other zebras, it is tall, has large ears, and its stripes are narrower. It is more ass-like in appearance as compared to other zebras, which are more horse-like.
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.[1]
Contents |
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, who, in the 1880s, was given one by the government of Abyssinia. It is the only extant 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.[3] Notable examples include E. sanmeniensis from China, E. cautleyi from India, E. valeriani from central Asia and E. oldowayensis from East Africa.[3] The latter, in particular is very similar to the Grévy's zebra and may have been its ancestor.[3] The modern Grévy's zebra arose in the early Pleistocene.[3] Recent phylogenetic evidence suggests that Grevy's zebras are with asses and donkeys in a lineage separate from plains zebras, but perhaps not from mountain zebras.[4] In areas where Grévy's zebras are sympatric with plains zebras, the two may gather in same herds[5] and fertile hybrids do occur.[6]
Description
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).[5] Grévy's zebra differs from the other two zebras in its more primitive characteristics.[7]:147 It is particularly mule-like in appearance; the head is large, long, and narrow with elongated nostril openings;[7]:147 the ears are very large, rounded, and conical and the neck is short but thick.[8]
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.[8] The belly and the area around the base of the tail lack stripes. Foals are born with brown and white striping, with the brown stripes darkening as they grow older. 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.[8] Its muzzle is ash-grey to black in color 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.
Range and ecology
The Grévy’s zebra once ranged though most of Kenya, Eritrea, Ethiopia and Somalia. Today it now largely inhabits northern Kenya, with some isolated populations in Ethiopia.[7]:147[8] Its status in Sudan is uncertain.[1] It lives in Acacia-Commiphora bushlands and barren plains.[5] Ecologically, this species is intermediate between the arid-living African wild ass and the water-dependent plains zebra.[7]:147[5] 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.[9]
Grévy's zebras rely on grasses, legumes, and browse for nutrition.[8] They commonly browse when grasses are not plentiful.[5][10] 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.[11] They often migrate to better watered highlands during the dry season.[5] Females require significantly more water when they are lactating.[12] During droughts, the zebras will dig water holes and defend them.[5] Grévy's zebras are preyed on by lions, hyenas, wild dogs, cheetahs and leopards.[8] In addition, they are susceptible to various gastro-intestinal parasites, notably of the Trichostrongylus genus.[13]
Behavior
Behaviourally, the Grévy's zebra differs from the other two zebra species as it does not live in harems.[14] The basic social units of the species are adult females or mares with their immature offspring or foals. Numerous groups of females and young often gather into herds which are open and fluid and have no strict dominance hierarchies.[5] Adult males or stallions will establish territories that average 5.75 km²,[7]:152[14] through vocalizations and by marking them with dung piles.[5][7]:151 They mostly live in territories during the wet seasons but some may stay in them year round if there's enough water left.[5] Stallions that are unable to establish territories are free-ranging[7]:151 and are known as bachelors. Females, young and non-territorial males wander though large home ranges. The females will wander from territory to territory preferring the ones with the highest-quality food and water sources.[15] Up to nine males may compete for a female outside of a territory.[8]
Territorial stallions will tolerate other stallions who wander in their territory, however when an estrous female is present the territorial stallion keeps other males at bay.[5][7]:151 Non-territorial males may avoid territorial ones because of harassment.[9] When females are not around, a territorial stallion will seek the company of other stallions. The stallion show 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.[7]:151 The call of the Grévy's zebra has been described as "something like a hippo's grunt combined with a donkey's wheeze".[5] 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.[8] Although Grévy's zebras do not perform mutual grooming, they do sometimes rub against a conspecific.[8]
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.[8] An estrous mare may visit though as many as four territories a day[15] 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,[16] while more subordinate stallions control territories away from water with greater amounts of vegatation, which mostly attract mares without dependant foals.[16] The resident stallions of territories will try to subdue the entering mares with dominance rituals and then continue with courtship and copulation.[5] Grévy's zebra stallions have large testicles and can ejaculate a large amount of semen to replace the sperm of other males.[15] This is a useful adaptation for a species whose females mate polyandrously. Bachelors or outside territorial stallions sometimes "sneak" copulation of mares in another stallion’s territory.[15] While female associations with individual males are brief and mating is promiscuous, females who have just given birth will reside with one male for long periods and mate exclusively with that male.[15] Lactating females are harassed by males 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.[17]
Gestation of the Grévy's zebra normally lasts 390 days,[8] with a single foal being born. A newborn zebra will follow anything that moves, so new mothers prevent other mares from approaching their foals while imprinting their own striping pattern, scent and vocalization on them.[8] Females with young foals may gather into small groups.[12] Mares may leave their foals in "kindergartens" while searching for water.[12] The foals will not hide, so they can be vulnerable to predators.[5] However, kindergartens tend to be protected by an adult, usually a territorial male.[12] A female with a foal stays with one dominant territorial male who has exclusive mating rights to her. While the foal will not likely be his, the stallion will look after it to ensure that the female stays in his territory.[18] To adapt to a semi-arid environment, Grévy's zebra foals have longer nursing intervals and wait until they are 3 months of age before they start drinking water.[12] Although foals became less dependant on their mothers after half a year, associations with them continue for up to three years.[5]
Relationship with humans
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The Grévy's zebra was known to the Europeans in antiquity and was used by the Romans in circuses.[3] It was subsequently forgotten in the Western world for a thousand years.[3] In the seventeenth century, the king of Shoa (now central Ethiopia) exported two zebras; one to the Sultan of Turkey and another to the Dutch governor of Jakarta.[3] A century later in 1882, the government of Abyssinia sent one to French president Jules Grévy. It was at that time that the animal was recognized as its own species named in Grévy’s honor.[3]
Status and conservation
The Grévy's zebra is considered endangered.[1] 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.[19]:11 It is estimated that there are less than 2,500 Grévy's zebras still living in the wild.[1] There are also an estimated 600 Grévy's zebras in captivity.[19]:20 The Grévy's zebra population trend is considered stable as of 2008.[1]
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.[19]:17 Community-based conservation efforts have shown to 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.[1] In Ethiopia, the protected areas include Alledeghi Wildlife Reserve, Yabelo Wildlife Sanctuary, Borana Controlled Hunting Area and Chalbi 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, Samburu and the Laikipia Plateau.
References
- ^ a b c d e f g Moehlman, P.D., Rubenstein, D.I. & Kebede, F. (2008). Equus grevyi. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 10 April 2009. Database entry includes a brief justification of why this species is endangered.
- ^ Grubb, Peter (16 November 2005). "Order Perissodactyla (pp. 629-636)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). p. 631–632. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14100019.
- ^ a b c d e f g h Prothero D.R, Schoch R. M (2003). Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals'. Johns Hopkins University Press. pp. 216–18. ISBN 0-801-87135-2. http://books.google.co.uk/books?id=kWpQX-sfsLgC&printsec=frontcover&dq=Horns,+Tusks,+and+Flippers:+The+Evolution+of+Hoofed+Mammals&hl=en&ei=nFtdTbv2EIO0hAeQ5-GqCA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CC8Q6AEwAA.
- ^ Orlando, Ludovic; et al. (2009). "Revising the recent evolutionary history of equids using ancient DNA". PNAS 106: 21754–21759. doi:10.1073/pnas.0903672106.
- ^ a b c d e f g h i j k l m n o Estes, R. (1991). The Behavior Guide to African Mammals. University of California Press. pp. 240–242. ISBN 0-520-08085-8.
- ^ J. E. Cordingley, S. R. Sundaresan, I. R. Fischhoff, B. Shapiro, J. Ruskey, D. I. Rubenstein (2009). "Is the endangered Grevy's zebra threatened by hybridization?". Animal Conservation 12 (6): 505–13. doi:10.1111/j.1469-1795.2009.00294.x. http://www.princeton.edu/~dir/pdf_dir/2009_Cordingley_AnimConser.pdf.
- ^ a b c d e f g h i Kingdon, J. (1988). East African Mammals: An Atlas of Evolution in Africa, Volume 3, Part B: Large Mammals. University of Chicago Press. pp. 147–61. ISBN 9780226437224.
- ^ a b c d e f g h i j k l Churcher, C.S. 1993. Equus grevyi. Mammalian Species. 453:1–9.
- ^ a b 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 46 (3): 359–64. doi:10.1111/j.1365-2028.2007.00848.x. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2028.2007.00848.x/pdf.
- ^ Bauer, I. E., McMorrow, J. and Yalden, D. W. (1994). "The Historic Ranges of Three Equid Species in North-East Africa: A Quantitative Comparison of Environmental Tolerances". Journal of Biogeography 21 (2): 169–182. JSTOR 2845470.
- ^ Youth, H. (2004). Thin Stripes on a Thin Line. ZooGoer. 33(6).
- ^ a b c d e Becker, C. D.; Ginsberg, J. R. (1990). "Mother-infant Behaviour of Wild Grevy's Zebra". Animal Behavior 40 (6): 1111–1118. doi:10.1016/S0003-3472(05)80177-0.
- ^ Muoria. P. K., Muruthi. P, Rubenstein. D, Oguge N. O, Munene E. (2005). "Cross-sectional survey of gastro-intestinal parasites of Grevy's zebras in southern Samburu, Kenya". African Journal of Ecology 43 (4): 392–95. doi:10.1111/j.1365-2028.2005.00588.x. http://www.princeton.edu/~dir/pdf_dir/2005_Muoria_Grevy_parasites_AJZ.pdf.
- ^ a b Klingel, H. (1972). "Social behavior of African equidae." Zoologica Africana 7(1): 175–185
- ^ a b c d e Ginsberg, R., D. I. Rubenstein (1990). "Sperm competition and variation in zebra mating behavior". Behavioral Ecology and Sociobiology 26 (6): 427–34. doi:10.1007/BF00170901. http://www.princeton.edu/~dir/pdf_dir/1990_Ginsberg&dir_BehEcolSo.pdf.
- ^ a b 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. ISBN 0123808944
- ^ Sundaresan, S., I. Fischhoff, D. Rubenstein. (2007). "Male harassment influences female movements and associations in Grevys zebra (Equus grevyi)". Behavioral Ecology 18 (5): 860–65. doi:10.1093/beheco/arm055. http://www.princeton.edu/~equids/images/sundaresan_grevys_harassment.pdf.
- ^ Rubenstein, D. I. (1986) "Ecology and sociality in horses and zebras". Pp. 282-302. In: Ecological Aspects of Social Evolution. D. I. Rubenstein & R. W. Wrangham, (eds.). Princeton University Press, ISBN 0691084394
- ^ a b c Moelman, P.D (2002). "Status and Action Plan for the Grévy's Zebra (Equus grevyi) by Stuart D. Williams". Equids. Zebras, Assess and Horses. Status Survey and Conservation Action Plan'. IUCN/SSC Equid Specialist Group. pp. 11–27. ISBN 2-831-70647-5.
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