Learning Their Lines
The Types and Stripes of Zebras
BY Peggy Scott
Photography by Ken Bohn
According to Namibian folklore, the zebra was once all white. It was only after getting into an argument with a baboon about a waterhole that the zebra lost his balance, tripped over the monkey’s fire, and ended up with scorch marks from the logs. From then on, zebras have sported stripes. While the truth about these spirited, sturdy wild equines isn’t quite as colorful as that tale, the world of the zebra is not quite black and white.
A Study of Stripes
The most common question about zebras is a matter of perspective: are they white with black stripes or black with white stripes? For a long time, the general consensus sided with the white-with-black-stripes opinion. How are the lines drawn these days? “It can always be said that they are black-and-white striped,” says Steve Metzler, Henshaw curator of mammals at the San Diego Zoo Safari Park. “There’s an evolutionary method that says zebras evolved from prehistoric equid ancestors that were brown with white spots, and these white areas changed to the stripes zebras have today. From that theory, they are black with white stripes.”
Beyond the origin and arrangement of stripes, one thing is definitely true: you can judge a zebra by its cover. Zebra stripes are unique to each animal, much like human fingerprints. Researchers have used zebras’ individual stripe patterns for identification. Stripes also serve as camouflage for zebras by making them harder to spot from a distance at night and breaking up the outline of the animals’ shape. If you were a predator (like a lion, leopard, cheetah, or hyena) looking at a herd of zebras with stripes going every which way, it would be harder to single out one animal to pursue for a meal. Another theory contends that striping helps cool the body by creating micro currents across the body. The black-and-white bands may even help make zebras less attractive to flies—that certainly gives a whole new meaning to “avoiding the lines.”
A (Wild) Horse Is a Horse
Of course, as members of the same Equidae family, different zebra species share many similar characteristics. The basic form of wild equids—large head, sturdy neck, long legs, a dorsal stripe along the spine and down a tasseled tail, and a bristly mane—is universal. While it may seem that a zebra is a zebra, there are three species: plains zebra, mountain zebra, and the Grevy’s zebra. The different zebra species have different types of stripes, from narrow to wide, and it seems to be connected to geography: the farther south on the African plains the zebra lives, the farther apart the stripes!
The plains zebra Equus quagga is the most abundant and the smallest of the three zebra species, topping out at around 800 pounds at adulthood. Plains zebras occupy the largest area of the zebra species—their range runs from the south of Ethiopia through East Africa, and as far south as Botswana and eastern South Africa. They live in small family groups consisting of a stallion (an adult male), several mares (adult females), and their young. These families may combine with other groups to form huge herds of thousands, but family members remain close within the herd. Plains zebras spend most of their day eating, mostly grazing on grass, but also eating leaves and stems. And, as with all zebras, back teeth continue to grow throughout their lives. It takes good teeth to grind up all those greens!
Some subspecies have a stripe pattern different from all others: brownish “shadow” stripes between the black stripes on their coat. Among the seven subspecies of plains zebras is the Grant’s zebra E. q. boehmi, which you can see at the San Diego Zoo. Zari, an eight-year-old female Grant’s zebra, is part of the Zoo’s popular Animals in Action program. She is an ambassador, and a favorite with visitors and keepers alike. Zebras can be quite feisty and unpredictable, but Zari seems to be a horse of a different color in that regard. She came to the Zoo as a two-month-old filly and was hand raised.
There are two subspecies of mountain zebra: Hartmann’s mountain zebra E. zebra hartmannae, and the Cape mountain zebra E. zebra zebra. Native to southwestern Angola, Namibia, and South Africa, mountain zebras weigh up to 820 pounds when full grown and top out at a height of 4 feet, 11 inches at the withers (shoulders). They have vertical stripes on the neck and torso, which graduate to wider—and fewer—horizontal bars on the haunches. There is a distinctive gridiron pattern on the rump, and a mountain zebra’s white underside has a dark stripe that runs the length of the belly. A mountain zebra also has a distinctive dewlap on the throat that looks a bit like an Adam’s apple. Its name offers a hint at this striped steed’s preferred home: mountainous and hilly habitats, where they graze on tufted grass. Not enough grass underfoot? In a pinch, they’ll eat twigs, buds, fruit, roots, leaves, and even bark.
Hanging on to the Horn
Favoring semi-arid grassland that allows access to a permanent water source, Grevy’s zebras Equus grevyi once inhabited Somalia, Ethiopia, Eritrea, Djibouti, and Kenya in East Africa. As their numbers have shrunk (over 50 percent in the last 30 years), so has their range, which is now basically the Horn of Africa—primarily southern Ethiopia and northern Kenya.
The largest of zebras, Grevy’s weigh as much as 990 pounds, and measure up to 5 feet at the shoulder. Its thick neck and large, round ears give the Grevy’s zebra an almost mule-like appearance. The Grevy’s zebra also has the thinnest stripes, extending all the way down to their white belly; on the hindquarters the stripes are vertical until above the hind legs. The Zoo is home to a Grevy’s zebra and the Park is home to a breeding herd, two males and nine females.
A Number of Concerns
Even though zebras are fairly swift of hoof (hitting up to 40 miles per hour), there are some threats—loss of habitat, poaching, disease—they can’t outrun. The situation is rapidly approaching “code red” for these black-and-white creatures. Mountain zebras are classified as endangered; the Grevy’s is critically so, with wild populations estimated at as few as 2,250. San Diego Zoo Global is a member of the Grevy’s Zebra Trust, and our researchers are working with other conservation groups to help preserve the population.
Part of this effort is, of course, in educating visitors about these striking striped steeds. At the Park, you can view the herd of Grevy’s zebras from the Africa Tram Safari. Come check them out, read between the lines, and discover the more colorful aspects of these black-and-white equines.