What's the difference between a Grevy's zebra and plains zebra?

The Grevy's zebra is the largest wild equine - weighing between 350-450 kgs - and was the first of the zebra species to evolve after asses. It is taller than the plains zebra, with narrower stripes, a white belly, a black dorsal stripe, large rounded ears and a brown muzzle. It is highly adapted to semi-arid and arid habitats, while the plains zebra is more suited to lusher habitat with abundant water. These two species overlap in the southern range of Grevy's zebra and the northern range of plains zebra.

                                                                                                                                                                                    Plains zebra (left) and Grevy's zebras (right)

                                                                                                                                                                                    Plains zebra (left) and Grevy's zebras (right)

Conservation Status

Grevy's zebra is listed as Endangered A1a, 2c by the IUCN/SSC Equid Specialist Group. Grevy's zebra is also listed on Appendix I of the Convention on International Trade of Endangered Species of Flora and Fauna (CITES) which offers them the highest protection against illegal trading. They are legally protected in Ethiopia and since 1977 they have been protected by a hunting ban in Kenya. 

In the 1970's, the global population of Grevy's zebra was estimated to be approximately 15,000 individuals. However in 2008, an estimate 2,800 animals remain in the wild. 

Habitat

Grevy's zebra occupy the niche between the water-dependent plains zebra, and the arid-adapted wild ass. Its home range now primarily consists of northern Kenya and parts of southern and north-eastern Ethiopia. They are predominantly grazers, and can survive off poor quality grass much better than their plains zebra cousins, however during extremely dry periods they also browse. Grevy's zebra can go without water for up to five days, but females with young foals must drink at least every other day. With land degradation worsening each year, the distance between available grazing and water increases. This means that Grevy's zebra mothers have to make long and more frequent journeys, resulting in high foal mortality, which is one of the major threats to the survival of the species.

Behaviour

Breeding stallions reign over territories of up to 10 square kilometres, which they establish based on water availability and grazing. Depending on her breeding condition, a female has different resource requirements. When she is lactating, she needs to be closer to water and therefore those males who have water within their territory will be more successful at breeding. Grevy's zebra males who haven't yet reached breeding age hang out in bachelor groups. Only if females are not in breeding season within a territory, will the bachelors be tolerated by the dominant territorial male. A territorial male can keep his territory for up to seven years before he will be defeated by a younger, stronger bachelor male. Males mark the boundaries of their territories known by vocalising loudly and by creating dung piles which they mark regularly to let everyone know they are present.

Gestation in Grevy's lasts for 13 months. Births are usually timed with the onset of rains, with peaks observed in May/June (long rains) and November/December (short rains). When resources become scarce with a resulting drop in body condition, females may not come into oestrus.