CULTURAL NEWS –
Saturday, September 1, 2007
– Excellent eyesight, great hearing
ZEBRAS, horses and wild asses are all equids, long-lived animals that move quickly for their large size and have teeth built for grinding and cropping grass.
Zebras have horselike bodies, but their manes are made of short, erect hair, their tails are tufted at the tip and their coats are striped.
Three species of zebra still occur in Africa, two of which are found in East Africa. The most numerous and widespread species in the east is Burchell’s, also known as the common or plains zebra. The other is the Grevy, a president of France in the 1880s who received one from Abyssinia as a gift, and now found mostly in northern Kenya. (The third species, Equus zebra, is the mountain zebra, found in southern and south-eastern Africa).
The Burchell’s zebra is built like a stocky pony. Its coat pattern can vary greatly in number and width of stripes. The stripes are a form of disruptive coloration which breaks up the outline of the body. At dawn or in the evening, when their predators are most active, zebras look indistinct and may confuse predators by distorting distance. Their shiny coats dissipate over 70 per cent of incoming heat.
Zebras are black with white stripes and their bellies have large blotch for camouflage purposes.
The stripes are typically vertical on the head, neck, forequarters, and main body, with horizontal stripes at the rear and on the legs of the animal. The “zebra crossing” is named after the zebra’s white and black stripes.
Zoologists believe that the stripes act a camouflage mechanism.
Stripes are also believed to play a role in social interactions, with slight variations of the pattern allowing the animals to distinguish between individuals.
Burchell’s zebras inhabit savannas, from treeless grasslands to open woodlands; they sometimes occur in tens of thousands in migratory herds on the Serengeti plains. Grevy’s zebras are now mainly restricted to parts of northern Kenya. Although they are adapted to semi-arid conditions and require less water than other zebra species, these zebras compete with domestic livestock for water and have suffered heavy poaching for their meat and skins.
The Burchell’s zebra’s social system is based on a harems by abducting fillies advertise their condition with a peculiar stance – straddled legs with raised tail and lowered head. All the stallions in the area will fight for a filly in this condition, as she will permanently stay with whichever stallion succeeds in mating with her. The newest female in a harem assumes lowest social status, and is often received with hostility by the other females. Once a female has bonded to a stallion, she will no longer advertise herself when in estrus.
When a foal is born the mother keeps all other zebras (even the members of her family) away from it for two or three days, until it learns to recognize her by sight, voice and smell.
While all foals have a close association with their mothers, the male foals are also close to their fathers. They leave their group of their own accord between the ages of one and four years to join an all-male bachelor group until they are strong enough to head a family.
The zebra, though water dependent, is a very adaptable grazer, able to eat both short, young roots and long flowering grasses. It is often a pioneer in the grassland community – the first to enter tall or wet pastures. Wildebeests and gazelle follow once the zebras have trampled and clipped the vegetation shorter.
Like horses, zebras walk, trot, canter and gallop. They are generally slower than horses but their great stamina helps them outpace predators; especially lions which get tired quickly. When chased, a zebra will zig-zag from side to side making it more difficult for the predator. When cornered the zebra will rear up and kick its attacker. A kick from a zebra can be fatal. Zebras will bite their attackers as well.
Zebras have excellent eyesight with binocular-like vision. It is believed that they can see in colour. Like most ungulates the zebra has its eyes on the sides of its head, giving it a wide field of view. Zebras also have night vision although it’s not as advanced as that of most their predators.
Ears and hearing
Zebras have great hearing, and tend to have larger and rounder ears than horses. Like horses and other ungulates, zebra can turn their ears in almost any direction toward and listen for sounds. Zebra ear movement can also signify the zebra’s mood. When a zebra is in a calm or friendly mood, its ears stand erect. When it is frightened, its ears are pulled forward. When angry, the ears are pulled backward.
In addition to eyesight and hearing, zebras have an acute sense of smell and taste.
Predators and threats
Zebras are important prey for lions and hyenas and, to a lesser extent, for hunting dogs, leopards and cheetahs. When a family group is attacked, the members form a semicircle, face the predator and watch it, ready to bite or strike should the attack continue. If one of the family is injured the rest will often encircle it to protect it from further attack.
Like many species of East Africa’s grazing animals, the Burchell’s zebra is most in danger of habitat loss and competition for water with livestock.
Did you know?
● Romans called Grevy’s zebras ‘hippotigris’ and trained them to pull two-wheeled carts for exhibition in circuses.
● At first glance zebras in a herd might all look alike, but their stripe patterns are as distinctive as fingerprints are in man. Scientist can identify individual zebras by comparing patterns, stripe widths, colour and scars.
The Mirror - Saturday, September 1, 2007 Page: 35