Grevy's Zebra
They also known as the imperial zebra. It is 2.5–2.75 m from head to tail, it has a 55–75 cm tail and stands 1.45–1.6 m high at the withers. They can weigh 350–450 kg. It is particularly mule-like in appearance; the head is large, long, and narrow with elongated nostril openings; the ears are very large, rounded, and conical and the neck is short but thick. The zebra's muzzle is ash-grey to black in colour with the lips having whiskers. The mane is tall and erect; juveniles have a mane that extends to the length of the back and shortens as they reach adulthood.
Habitat
The Grévy's zebra largely inhabits northern Kenya, with some isolated populations in Ethiopia. It was extirpated from Somalia and Djibouti and its status in South Sudan is uncertain. It lives in Acacia-Commiphora bushlands and barren plains. Ecologically, this species is intermediate between the arid-living African wild ass and the water-dependent plains zebra. Lactating mares and non-territorial stallions use areas with green, short grass and medium, dense bush more often than non-lactating mares and territorial stallions.
Diet
Grévy's zebras rely on grasses, legumes, and browse for nutrition. They commonly browse when grasses are not plentiful. Their hindgut fermentation digestive system allows them to subsist on diets of lower nutritional quality than that necessary for ruminant herbivores. Grevy's zebras can survive up to 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 zebras main predator is the lion, but adults can be hunted by spotted hyenas. African hunting dogs, cheetahs and leopards 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,
Breeding
They 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 though 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. 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 and can ejaculate a large amount of semen 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 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 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 dependant on their mothers after half a year, associations with them continue for up to three years.
Population
Grevy's Zebra suffered a severe population reduction between the late 1970s to early 1980s and the early 2000s, declining from a global population of around 15,600 individuals in the late 1970s/early 1980s 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.
Threats
n 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. However, a low level of hunting of Grevy’s Zebra for food and, in some areas, medicinal uses continues. 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.
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. 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.
Recently, there was 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. Disease represents a significant potential threat to fragmented and small populations of endangered species.
Conservation
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. 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, Grevy’s Zebra was listed as a Game Animal; 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. 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. 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.
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. 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.
Kenya has completed its second conservation strategy for Grevy’s Zebra. 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.