Zebra (Equus quagga) represents several species of African wild horses that are part of the Equus genus and also members of the Equidae family.
Zebras can be found today in a variety of habitats such as savannas, grasslands, woodlands, coastal hills and mountains, and also thorny scrublands.
Zebras along with horses and asses (members of the Equidae family) have evolved from a smaller ancestor (an animal about the size of a dog) about 55 million years ago and spread into a large number of species during the Tertiary period.
Some of the members of Equidae family have crossed the Bering Strait and they have discovered the Old World where they have become full grazers.
Within the last 4.5 million years, zebras have evolved from the Old World horses and as an adaptation to their habitat they have developed distinctive black and white striped coats.
I already mentioned that zebras have evolved about 4.5 million years ago from the Old World horses and today there are three extant species from which two species have eight subspecies (seven are extant).
1. Plains Zebra (Equus quagga) also known as Burchell’s zebra or the common zebra is part of the Hippotigris genus and is the most known species of zebra that lives today in Southern Ethiopia (Eastern Africa), and also in South Botswana (South East Africa).
There are seven subspecies of Plains Zebra (one being extinct today).
- Burchell’s zebra (Equus quagga burchellii), is a southern subspecies of plains zebra also known as Zululand zebra or Damara zebra, and received its name after William John Burchell (a British explorer and naturalist).
- Quagga (Equus quagga quagga), is the extinct subspecies of plains zebra that lived in South Africa and is extinct since the 19th century.
- Grant’s zebra (Equus quagga boehmi), is the smallest subspecies of plains zebra and can be found today in the Serengeti-Mara ecosystem.
- Selous’ zebra (Equus quagga selousi), is another subspecies of plains zebra that lives today in southeastern Africa (mostly Mozambique), but is considered critically endangered by the IUCN Red List.
- Maneless zebra (Equus quagga borensis), is a subspecies of plains zebra that lives today in the North side of Eastern Africa.
- Crawshay’s zebra (Equus quagga crawshayi), is a subspecies of plains zebra that is distinctive from other subspecies of plains zebra due to its lower incisors that lack of infundibulum (a funnel-like tunnel of the tooth that is filled with cementum).
Crawshay’s zebra also features very narrow black and white stripes that are different from other subspecies of plains zebra.
- Chapman’s zebra (Equus quagga chapmani), lives today in the South African savannah (the northeast side), in north of Zimbabwe, west of Botswana, southern Angola and the Caprivi Strip in Namibia.
Their stripes are pretty distinctive with the stripes of the Burchell’s zebra.
2. Mountain zebra (Equus zebra) is a zebra that lives today in southwestern Angola, Namibia and South Africa.
Is a threatened species of zebra considered vulnerable by the IUCN Red List.
Mountain zebra consists of two subspecies.
- Cape mountain zebra (Equus zebra zebra), being a mountain zebra, is the smallest among all subspecies of zebra, and can be found today in the Eastern and Western Cape provinces of South Africa.
- Hartmann’s mountain zebra (Equus zebra hartmannae), is another mountain subspecies of zebra that lives today in western Namibia and southwestern Angola.
3. Grévy’s zebra (Equus grevyi) is part of the subgenus Dolichohippusis and is the largest known species of zebra.
This species of zebra is also known as the Imperial zebra, and received its name after Jules Grévy (a President of the French Third Republic).
Even being the largest species of zebra, it is considered the most threatened zebra on the planet and is listed as endangered by the IUCN Red List.
Grévy’s zebra is a tall zebra with large ears and narrow stripes that lives today in countries like Ethiopia and Kenya.
Plains zebra, which is the common zebra has a height at the shoulder of 47 to 51 in (1.2 – 1.3 meters) and a body length between 6.6 and 8.5 ft (2 – 2.6 meters).
Males that are slightly larger than females and can weigh up to 770 lbs (350 kg).
However, Grévy’s zebra being the largest known zebra reaches a shoulder height between 4.8 and 5.2 ft (1.45 – 1.6 meters), a body length between 8.2 and 9 ft (2.5 and 2.75 meters), and a weight (males) of up to 990 lbs. (450 kg).
Mountain zebras are the smallest zebras known today having a shoulder height between 1.16 and 1.5 meters, a body length between 2.1 and 2.6 meters and a weight between 450 and 820 lbs. (204 and 372 kg).
Cape mountain zebras feature an interesting sexual dimorphism (females are larger than males).
The black and white stripes of the zebras are vertical on the head, neck, main body and forequarters, and horizontally on the rear and on the legs.
Several hypotheses have suggested that the black and white stripes have a role in camouflaging the animal in the grass of the savannah by creating a motion dazzle that makes the predators to see them as a large mass of flickering stripes (a group of zebras standing or moving together).
The stripping patterns of the zebra are unique to each individual and beside camouflaging the animal from predators in its natural habitat, they have the role of confusing horseflies because a smaller number of tabanid horseflies are attacking them.
The black and white stripes have also the role of cooling the zebras because the air moves quickly over the black stripes and slowly over the white stripes, which creates convection currents around these animals to cool them in the hot days.
Zebra Behavior and Social Organization
Zebras being members of the Equidae family are very social animals that live in small or larger groups.
Mountain zebras live in groups called “harems” consisting of one stallion and up to six mares and their foals.
Younger zebra males live alone or in bachelor groups, and they wait until they are ready to challenge a breeding stallion to take over the harem.
When sleeping, zebras sleep while standing, but they sleep only if they have neighbors around that will warn them of predators.
Female zebras become mature earlier than males and they can give birth at their first foal at the age of three.
Pregnancy period takes about one year (an average of 375 days) at zebras, and moms will stay with their foal up to the age of a year.
At birth, the coat of the zebra foal is brown and white and becomes black and white with the age.
Zebra foals are protected not only by their mother, but also by the stallion and also by the other mares in the harem.
When attacked by predators like hyenas and wild dogs, the foals will be moved to the center of the group surrounded by mares and the stallion will try to ward them off.
Zebras populations decrease due to habitat loss and due to hunting and poaching (for meat and skin).
A century ago, Cape mountain zebras were hunted almost to extinction, but conservation efforts increased their number from less than 100 individuals to about 700 today.
Both mountain zebras (Hartmann’s mountain zebra and the Cape mountain zebra) are endangered even today, even if they are currently protected in several national parks in Africa.
The largest zebra species (Grévy’s zebra or the Imperial zebra) is also endangered due to hunting, poaching and habitat loss (human farms expansion).
Plains zebras are more numerous, but their populations are also decreasing due to hunting, poaching and again loss of habitat (farming affects not only the zebras but several other animal and bird species in Africa).