Plains Zebra, Equus quagga
The plains zebra (Equus quagga) is native to Africa, and is the most common zebra found. Its range extends from southern Ethiopia to East Africa, with a southern range including Angola and eastern South Africa. Its other common names include Burchell’s zebra and the common zebra. The plains zebra holds six recognized subspecies including Grant’s zebra and the maneless zebra.
The plains zebra and the mountain zebra are classified in the subgenus Hippotigris and appear to be more horse-like than Grevy’s zebra, classified as the only species in the subgenus Dolichohippus, which is more ass-like in appearance. Recent studies have suggested, however, that the mountain zebra and Grevy’s zebra are actually more closely related to asses and donkeys than the plains zebra, placing them in distinct lineages. Plains zebras will intermingle with Grevy’s zebras and as a result fertile hybrids have occurred. Plains zebras have also produced hybrids in captivity with mountain zebras, and these foals favored the plains zebra in appearance, but lacked a dewclaw and the typical long ears and hindquarters of the plains zebra.
The plains zebra is relatively smaller than the other two species of zebra, reaching an average weight between 390 to 850 pounds and an average height of up to 4.8 feet at the shoulder. Typically, males can weigh up to ten percent more than females. The body length of an adult zebra can reach up to 8.2 feet, and this does not include the twenty-inch tail.
As is typical to zebra species, the plains zebra is marked with black and white stripes and no two zebras bear the same markings. Young zebras are brown with white and brown stripes that will fade into black and white as they age. All plains zebras bear black or dark colored noses and horizontal stripes on the hindquarters, but stripes can vary slightly in color depending on location. Zebras located in the southern portion of the range bear brown “shadow” stripes between the white and black markings, while northern populations bear narrow stripes that are more defined.
The stripes of the plains zebra are thought to be used to camouflage the zebras within the trees, bushes, and tall grasses of their habitats. Although this defense mechanism is similar to that of the kudu and bushbuck, plains zebras are not timid and quiet, and will not remain if a threat is present. Another likely reason for the striping of zebras is the ability it gives them to confuse their predators, although studies have shown that this is not effective. It is thought that the most likely reason for the zebra’s stripes is for social purposes. Zebras have shown the ability to recognize each other by their distinctive markings, and these stripes may serve as grooming cues. When moving as a herd, the stripes may help the entire herd to stay together.
The plains zebra prefers a habitat within savanna woodlands and grasslands that lack trees. It can, however, be seen in other places including tropical and temperate areas. They do not live in thick rainforests, deserts, or perpetual wetlands. These zebras can live at elevations between sea level and 2.6 miles, as high as Mount Kenya. The plains zebra depends heavily on rainfall for food and water resources, and will migrate up to 700 miles with a rainstorm. They will not wander farther than 18.6 miles from a water source.
The plains zebra will form small familial groups called harems, comprised of one male, several females, and their young and these individuals can remain with each other for years. Young males will form their own groups known as bachelor groups, which contain up to fifteen males. A bachelor group is maintained by an age-based hierarchy, and each member of the group will prepare for adulthood in harem groups by play fighting and participating in fake challenges and meetings. Many groups of harem and bachelor groups will gather to form large herds, a trait that is not typical to harem forming species.
New harem groups are formed when stallions steal mares from their natal harem groups. The lead stallion of this birth group, typically the mare’s father, will fight to protect the mare from being captured and even when the mare is no longer with her birth group, the fight to keep her will continue until she is no longer in estrous. Typically, mares are not kept by an abductor for very long, unless the stallion succeeds in breeding, in which case the mare will remain in the new harem group.
When a stallion must defend his harem, he will first warn the offending zebra by rubbing shoulders or noses with him. If the intruder does not leave, a fight will occur that involves biting of the legs, neck, and back, as well as wrestling and even kicking. Some males may act as though they are surrendering in order to gain the upper hand. Typically, fighting only occurs over young females that are in estrous, and as long as a stallion is healthy and strong, there is little risk of fights occurring.
Within a harem group of plains zebras, mares are placed in their own hierarchy, with the lead mare holding the right to breed with the stallion first. Mares are aggressive towards new female members, so the stallion must protect her until she is accepted into the hierarchy. Mares do drop in rank if they are weak or sick, and may even leave the group altogether. If a stallion dies, mares will maintain their hierarchy even when a new male takes over. Grooming is highly important in a harem groups’ social structure. Mothers and their young will groom most often, followed by siblings.
When reproducing, a stallion will mate with all of the mares in his harem, beginning with the lead mare. Most births occur during the rainy seasons, and mares are able to produce one foal each year. Because stallions do not tolerate foals, mares will keep them away from him and other members of the group until they are old enough to bond. Stallions have been known to practice infanticide and feticide, although this usually occurs with individuals in captivity.
As is typical to equids, young zebras are able to stand, move about, and suckle not long after birth and they will hold the same status within the hierarchy as their mother. Although every member of the group will defend the foals, up to fifty percent will perish due to starvation, disease, and predation.
Young male plains zebras will leave their natal group to form bachelor groups, but this is not due to sexual maturity or aggression from stallions. After a while, a mother and a male foal will lose their bond when she produces another foal. Being social creatures, they will leave their birth groups to gain the company of other young males.
The plains zebra is able to make six different types of vocalizations. One call consists of a series of noises that sound like “kwa-ha, kaw-ha, ha, ha” or “a-ha, a-ha, a-ha”. When a predator is near, the zebra will emit a two-part alarm call. When traveling through cover and a threat is spotted, the zebras will make a short snorting noise. Young zebras will emit a wail when distressed. When the zebras are content, they will emit a longer snort. Plains zebras are also know to make facial expressions to communicate, including a friendly greeting where the ears are erect and placed in a forward direction.
The main diet of the plains zebra consists mainly of grasses, but may also contain shrubs and herbs. There is no preference for shorter grasses, as is typical to migratory animals, but they do prefer to consume young grasses when possible, and are also able to eat leaves and shrubs. This allows the zebras to have an extended range that even extends into woodland areas. Because they are able to eat more types of food than other grazers are, they pave the way for more specialized grazers to feed after they have moved on.
The plains zebra does fall prey to many animals, but particularly spotted hyenas and lions. When crossing rivers during migration, Nile crocodiles are a common threat. Young zebras are mainly hunted by cheetahs, leopards, and wild dogs, and occasionally may fall prey to baboons. When hunted by small ground predators, the plains zebra is able to defend itself by kicking a biting, but will attempt to outrun larger predators like lions.
In order to avoid predators or threats, the plains zebra will sleep and rest in open areas. These areas must have clear visibility because zebras are diurnal and must rest at night. When facing the threat of small land predators, like hyenas, mares will group together to protect the weaker members of the harem and the foals. Stallions will attempt to directly attack the hyena, although it will try to avoid the stallion if possible. Because larger predators tend to be slower, zebras will turn to their speed and endurance to escape.
Because of its large range and populous numbers, the plains zebra is not threatened by extinction. Many areas of its range occur in protected regions such as the Serengeti National Park in Tanzania and Etosha National Park in Namibia. These zebras are important for overall tourism within their range, and are even represented in human culture. They appear in the coat of arms of Botswana as well as in the totem for the Dube tribe in South Africa. Many African cultures revere the zebra as a symbol of beauty, and in Uganda, the Karamojong tribe women will paint themselves with stripes and act like zebras.
Although the populations of the plains zebra are stable, civil war in much of their range does pose a problem. In Burundi, the plains zebra has become extinct and the subspecies called the quagga has also become extinct. In Tanzania, the populations have decreased by as much as twenty percent between the 1990’s and the 2000’s. Threats include hunting, poaching, habitat destruction, and competition for food. The plains zebra is listed on the IUCN Red List with a conservation status of “Least Concern”.
Image Caption: A Plains Zebra, Equus quagga in the Ngorongoro Crater in Tanzania. Credit: Muhammad Mahdi Karim /Wikipedia