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Equus grevyi 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Perissodactyla Equidae

Scientific Name: Equus grevyi
Species Authority: Oustalet, 1882
Common Name(s):
English Grevy's Zebra
French Zèbre de Grévy
Spanish Cebra de Grévy
Taxonomic Notes: Groves (2002) provisionally listed two subspecies of Grevy's Zebra. However, Groves and Bell (2004) concluded that the species is indeed monotypic. Reviewed by Churcher (1993).

Assessment Information [top]

Red List Category & Criteria: Endangered A2acd ver 3.1
Year Published: 2016
Date Assessed: 2016-08-25
Assessor(s): Rubenstein, D., Low Mackey, B., Davidson, ZD, Kebede, F. & King, S.R.B.
Reviewer(s): Ginsberg, J., Woodfine, T., King, J. & Moehlman, P.D.
Justification:
Grevy's Zebra has been assessed as Endangered under criterion A2acd. There was a population reduction of 54% over the past three generations (30 years) from an estimated 5,800 in the late 1980s to a current population of about 2,680 individuals. The species also qualifies as Vulnerable under Criterion C1+2a(i) as there are <2,000 mature individuals. This number consists of approximately 2,350 individuals in Kenya (1,716 mature animals) in 2016 and about 230 individuals in Ethiopia (168 mature animals) in 2011. There is an estimated continuing decline of 10% over the next three generations if the population in Ethiopia declines severely, and additionally the largest subpopulation of Grevy's Zebra has <1,000 mature individuals.

The population has been roughly stable over the past 10 years. It is considered stable or increasing in Kenya, but may be stable or declining in Ethiopia. In Kenya the proportion of foals and juveniles in the population has grown (Kenya Wildlife Service 2016). If this trend continues, it bodes well for the population in this country. In Ethiopia, estimates based on transect counts and some ‘sight-resight’ analyses suggest that in 2009-2010 the total population size was 228 +/- 53 (F. Kebede pers. comm. 2012), with the largest population numbering 196 individuals.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Grevy's zebra is only found in the Horn of Africa, specifically Ethiopia and Kenya. Grevy's Zebras have undergone substantial reductions in range. Historically, they ranged east of the Rift Valley in Kenya to southwestern Somalia, and in northern Ethiopia from the Alledeghi Plain through the Awash Valley, the Ogaden, and north-east of Lake Turkana in Ethiopia to north of Mt. Kenya and southeast down the Tana River in Kenya (Bauer et al. 1994). Currently, Grevy’s Zebra have a discontinuous range, and are found from the eastern side of the Rift Valley in Kenya to the Tana River. Currently there is a small, isolated population in the Alledeghi Plains northeast of Awash National Park (N.P.) in Ethiopia. From Lake Ch’ew Bahir in southern Ethiopia, the population extends to just north of Mt. Kenya although a few animals are found further southeast along the Tana River. A small introduced population survives in and around Tsavo East N.P. in Kenya.

Grevy's Zebra are considered to be extirpated from Somalia, where the last confirmed sightings date to 1973. There are no confirmed records that the species ever occurred in Eritrea or Djibouti (Bauer et al. 1994, Yalden et al. 1986). Sightings in South Sudan are questionable and need to be verified (Williams 2002, 2013).
Countries occurrence:
Native:
Ethiopia; Kenya
Regionally extinct:
Somalia; Sudan
Additional data:
Estimated area of occupancy (AOO) - km2:89260Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:270999
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):300
Upper elevation limit (metres):2300
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Grevy's Zebra suffered a severe population reduction between the late 1970s/early 1980s and the early 2000s, declining from a global population of around 15,600 individuals in the late 1970s/early 1980s (Williams 2002) to around 2,000 individuals in 2004. Since then there have been some signs of population recovery, with the population remaining roughly stable over the last 10 years. Over the last three generations (a generation is approximately 10 years) there has been a population reduction of about 54% from an estimated 5,800 Grevy's Zebra in the 1980s to ~2,680 animals currently.

The most recent estimates put the total population of Grevy's Zebra remaining in the wild in Kenya and Ethiopia at less than 2,000 mature individuals, based on 73% adults in well studied populations (Rubenstein and Brown pers. obs. 2014). This number consists of approximately 2,350 individuals in Kenya (1,716 mature animals) in 2016 and about 230 individuals in Ethiopia (168 mature animals) in 2012. The largest regional population numbering around 1,300 individuals (949 mature) is in the centre of the Samburu region of central Kenya.

In Kenya, the Grevy’s Zebra population declined from around 13,700 in 1977 (Dirschl and Wetmore 1978) to 4,300 in 1988 (KREMU 1989). They then declined further to 2,400-2,700 in 2000 (Nelson and Williams 2003) and 1,570-1,980 in 2004 (KWS 2012), to an estimated population size of 1,470-2,140 in 2006 (B. Low pers. comm. 2007); a decline of 85-90% over 29 years. In 2008, the population was estimated to consist of 2,400 individuals, indicating that either counting techniques had improved or that the population had stabilized or even increased, or a combination of the two (Mwasi and Mwangi 2007, KWS 2012). An assessment of all existing counts carried out by Kenya’s Grevy’s Zebra Technical Committee in 2012 estimated that by 2011 the population in Kenya was approximately 2,500. In January 2016 a comprehensive census of Grevy's zebra in five counties in Kenya was conducted (“The Great Grevy’s Rally”). The census comprised of 350 people (members of the public, conservancy members, rangers and scouts from conservancies and National Parks and Reserves, and scientists) driving over 25,000 km² recording Grevy's zebras using GPS enabled cameras. Over 40,000 photos of Grevy's Zebra were taken. The photographs were sent to the US-based IBEIS team to process the images, identifying unique individuals seen on days 1 and 2 as well as the number seen on day 1 that were re-sighted on day 2. From these three values population size estimates could be computed. In the future, such analyses will be performed by Kenyan scientists once the software is made publicly available. From the sight-resight analysis the population was estimated to be 2,250 individuals (95% CI of +/- 93; KWS 2016). For the first time, Laikipia county has the highest number of Grevy’s Zebras (supporting over half of Kenya's Grevy's Zebra population), surpassing Samburu and Isiolo counties, the traditional heartland of the species. An additional 80-100 animals were estimated in Tsavo, Oserian, Meru National Park, and the Laisamas area - areas that were too dangerous or inaccessible to survey during the census period (KWS 2016). The total Kenya population in 2016 is therefore estimated to be ~2,350 individuals. The population will be re-censused in August 2017. It is expected that the Kenyan population of Grevy's Zebra will remain stable, or may increase due to conservation efforts.

In Ethiopia, Grevy’s Zebra declined from an estimated 1,500 (or a possible maximum of 1,900) in 1980 to approximately 600 in 1995 (Rowen and Ginsberg 1992, F. Kebede pers. comm. 2007), to approximately 100 in 2003 (Williams et al. 2003). In 2006, the population in Ethiopia was estimated to be approximately 130 (F. Kebede pers. comm. 2007). The trend from 1980 to 2003 (23 years) suggests a decline of roughly 94%. Counts and ‘sight-resight’ population analyses of the largest population suggest that by 2011 Ethiopia’s population had increased to approximately 230 individuals (Kebede et al. 2012, Kebede pers. comm. 2014). However this population is mainly in the Alledghi Wildlife Reserve (196 +/- 53 animals, declined from 600 in 1970) and very few individuals remain in Chew Bahir (22 animals, declined from 1,500 in 1970) and Borana (10 animals) (Williams 2002, Kebede pers. comm. 2014).  The population in Ethiopia is expected to at best stay stable, and is likely to decline.


The density and area of occupancy of Grevy’s Zebra 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 Laikipia counties, Kenya.
Current Population Trend:Stable
Additional data:
Number of mature individuals:1956Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:12Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:Grevy’s Zebras live in arid and semi-arid grass/shrubland where they can gain access to permanent water (Klingel 1974; Rubenstein 1986; Rowen and Ginsberg 1992; Williams 2002, 2013; Kebede 2013). They are predominantly grazers, although browse can comprise up to 30% of their diet during times of drought or in those areas that have been highly transformed through overgrazing (Kartzinel et al. 2015). Breeding males defend resource territories (water and food being the key resources) of 2–12 km²; the home range size of non-territorial individuals can be as large as 10,000 km² (Williams 2013). They are extremely mobile and individuals have been recorded to move distances of greater than 80 km, with movements determined by the availability of resources; lactating females, for example, can only tolerate one or two days away from water (Klingel 1974; Rubenstein 1986; Rowen and Ginsberg 1992; Williams 2002, 2013). Hence when pastoral livestock monopolize water, Grevy’s Zebras suffer. They often mill around watering points in the late afternoon waiting to drink, thus reducing foraging time. By drinking predictably at night they are prone to predation by lions and in some areas when co-habiting with plains Zebras, they are preferentially attacked (Rubenstein 2010). During the dry season, when they are dependent on permanent water, Grevy’s Zebra may stay nearer to water and tend to be more concentrated. However, in the Alledeghi Wildlife Reserve in Ethiopia, they are more concentrated during the wet season in order to avoid the pastoralists and livestock that move into the area during that season (Kebede et al. 2012).

Between 2010 and 2014 the population of Grevy’s Zebras inhabiting the Mpala, Ol Jogi and Pyramid Conservancies in central Laikipia County, was monitored three times per year. During this period on average the population consisted of: 33% adult males of which 17% were territorial and 16% were bachelors; 40% adult females; 8% juveniles, half males and half females; and 19% infants of which 8% were males, 8% were females and 3% were of undetermined sex (Rubenstein and Brown pers. obs.). Therefore 33% adult males + 40% adult females gives 73% of the population as mature. Given that population projection models show population stability is maintained when the percentage of recruits (juveniles and foals) reach 30% (Rubenstein 2010), the Laikipia Grev’s Zebra population appears to be in relatively good demographic health (between 2004 and 2014). A decade of data on sightings of Grevy's Zebra numbers as well as age and sex class from scouts in the Meibae, Westgate, Sessia, Laisamas, Ngili West and Kalama Conservancies show an that the percentage of recruits (foals and juveniles) has increased from 9% to 22% of the population, with the 2016 Great Grevy's Rally showing a Kenya-wide age structure of 28% recruits. This indicates that this population is approaching sustainability.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):10
Movement patterns:Nomadic
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade: In Kenya, Grevy’s Zebras are only hunted at subsistence level for meat and medicinal uses; commercial trading of skins has ceased. In Ethiopia, killing of Grevy’s Zebra for meat and medicine is the primary cause of the decline (Kebede 2013).

Threats [top]

Major Threat(s): Kenya’s Grevy’s Zebra Technical Committee recently assessed and ranked the threats to Grevy’s Zebras. In decreasing order they include: 1) Habitat degradation and loss induced by extremely heavy grazing by livestock (Rubenstein 2010, Low et al. 2009); 2) Competition with livestock, especially over access to water and high quality rangeland (Rowen and Ginsberg 1992; Williams 2002, 2013); 3) Local hunting for meat as well as medicinal and cultural purpose; 4) Disease from contact with unvaccinated livestock, especially with respect to anthrax and babesiosis (Hawkins et al. 2015); 5) Hybridization with plains Zebras, although genes currently only flow from Grevy’s to plains Zebras (Cordingley et al. 2009); 6) Predation (Rubenstein 2010); 7) Anticipated land conversion for resort development and other large-scale initiatives for economic expansion.

In Kenya, hunting for skins in the late 1970s was the likely cause of the initial precipitous decline in numbers. Recent data suggest that numbers continued to decline because recruitment was limited by low levels of infant and juvenile survival. This was a result of competition for resources – both food and water – with pastoral people and their domestic livestock (Williams 1998). However, a low level of hunting of Grevy’s Zebra for food and, in some areas, medicinal uses continues (Williams pers. comm. 2002). Furthermore, access to existing water sources continues to decline in some regions and the water supply in critical perennial rivers has been reduced, 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 pers. comm. 2002).

In Ethiopia, the Grevy’s Zebra population was in a declining trend during the last 30 years, due to habitat loss/fragmentation, drought, poaching and potential competition with livestock. Habitat loss, drought and poaching were considered to be the major threats. Illegal killing of Grevy’s Zebra was the primary cause of the decline (Kebede 2013). The Alledeghi Wildlife Reserve population is small and genetically isolated. Initial population genetics research on the mtDNA control region revealed two new haplotypes that so far are not found in any other Grevy’s Zebra populations. The nucleotide diversity levels for both the Alledeghi and the southern Ethiopian populations were extremely low (Kebede et al. 2014).

Recently, Muoria et al. (2007) recorded an outbreak of anthrax in the Wamba area of southern Samburu, Kenya, during which more than 50 animals succumbed to the disease. Further research on disease prevalence is revealing that Grevy’s Zebra are a reservoir for Theileria and Babesia (tick borne disease), and the first case of West Nile Virus has been found in one individual; the first detected in a wild equid (Hawkins et al. 2015). Disease represents a significant potential threat to fragmented and small populations of endangered species.

Conservation Actions [top]

Conservation Actions: Listed on CITES Appendix I. Grevy's Zebra are legally protected in both Kenya and Ethiopia, although in the latter, official protection has been limited. Changing attitudes of local pastoralist populations towards the species has had dramatic effects on improving the ranging, foraging and drinking capabilities of Grevy’s Zebras. Scout programs in which community members participate in gathering essential data on the ecology and behaviour of their populations not only generates income, it transforms the scouts into Grevy’s Zebra champions which in turn helps change community attitudes and gather essential information when populations are at risk (Low et al. 2009). In addition, in Kenya Grevy’s Zebras have been protected by a hunting ban since 1977. While under the Wildlife Conservation and Management Act No 376 of 1976 (Part II of the First Schedule), Grevy’s Zebra was listed as a ‘Game Animal’ (Williams 2002); there is a chance that they will be up-listed to a legally ‘Protected Animal’ in Kenya.

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, Borena Controlled Hunting Area and Chew Bahir/Chalbi Wildlife Reserve). 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, 2013). In addition, changing attitudes in Samburu county, the centre of its distribution, has enabled Grevy’s Zebra to share resources more equitably with livestock, thus increasing the proportion of infants and juveniles (Low et al. 2009).

Habitat restoration through grass re-seeding and planned livestock grazing is targeting core habitat areas in Grevy’s Zebra range. Close monitoring of Grevy’s Zebra body condition during prolonged droughts is carried out by scouts and additional water provision made to ensure continued access to declining water sources (http://www.grevysZebratrust.org/water-management.html). In addition, supplementary feeding of Grevy’s Zebra during extreme drought is being piloted in Kenya (Grevy’s Zebra Disease Response Committee, 2013), and appears to have prevented a population decline during the 2011 drought in the conservancies of central Samburu County (Low and Rubenstein pers. obs).

Kenya has completed its second conservation strategy for Grevy’s Zebra (KWS 2012). It has 5 strategic objectives: 1) Coordination and implementation of the conservation and management strategy; 2) Enhancement of stakeholder partnership in Grevy’s Zebra conservation; 3) Enhancement of Grevy’s Zebra conservation and habitat management; 4) Establishment of a program for monitoring and managing Grevy’s Zebra population health; and 5) Enhancement of transboundary Grevy’s Zebra conservation.

In September 2016  a workshop involving Grevy’s zebra biologists, conservationists and the governors of the five counties where Grevy’s zebras live will be convened by Kitili Mbathi, the Director General of the Kenya Wildlife Service, at the Mpala Reseach Center. The workshop will explore options that will move the populations from ‘ sustainable’ to increasing’ and identify actions that the governors can commit to that will help make this happen. Future actions to increase numbers might include: restoration of grasslands, improved water access, addressing high lion predation rates in Meru County, and developing local capacity and supporting citizen science monitoring. 

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 Alledeghi Wildlife Reserve. The Ethiopian Wildlife Conservation Authority in collaboration with the IUCN/SSC Equid Specialist Group will be developing a national species action plan in the near future.

Citation: Rubenstein, D., Low Mackey, B., Davidson, ZD, Kebede, F. & King, S.R.B. 2016. Equus grevyi. The IUCN Red List of Threatened Species 2016: e.T7950A89624491. . Downloaded on 09 December 2016.
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