The Grant’s zebra is one of the most nomadic of grazers, ceaselessly in search of green pastures. It can subsist on coarse dry grass, but dependence on water keeps it within 20 miles of water holes during the dry season.
One of the most interesting characteristic of the zebra is its harem system, which may consist of a stallion, up to six mares and all of their immature offspring. To acquire a harem, a stallion must first abduct a filly from her herd, usually fighting her father and then fending off other rival stallions. Females remain permanently in the herd where they first become pregnant and foal.
When a mare is about to give birth the stallion moves the rest of the herd away. If the stallion communicates danger to the mare she can delay the birth up to 18 hours. She gives birth lying down and guards her newborn from other members of her herd, giving the baby time to learn her stripe pattern. Foals weigh about 65 pounds at birth and have a longer, softer coat with brown stripes. They are up and walking within 30 minutes of birth and can run usually after an hour. The mortality rate of foals is high in the first year due to predation. Within the herd, females establish a dominance hierarchy. During travel, the herd is led by the dominant female and her foal, followed by other females in their order of dominance. The stallion usually brings up the rear or walks to the side. Zebra herds will join enormous herds of wildebeest during the migration for increased mutual protection from predators. But even then they maintain their close family bond and stay together. When a predator approaches a herd that has a young colt, the mother hides it behind her family members. By staying close together instead of bolting and leaving behind a weak or sick animal, the whole herd cooperates to protect any threatened member. However, it is the stallion that actively defends his herd and does not hesitate to attack hyenas. This defense is so effective that only hyenas hunting in large packs have much luck with zebras. The stallion will go looking for missing members of his herd. Zebras can run up to 40 mph but when attacked the herd bunches up and flees at about half that speed so the group can keep tightly together.
Whether the zebra’s stripes help to disguise them from predators, regulate body temperature or identify individuals within a group, no two animals look exactly alike. One theory is that the black and white stripes break up the animals shape and make it harder to recognizable as prey. Another is that the stripes of a herd exploding in all directions make it difficult for a predator to focus on one animal. At Fossil Rim, photographs of each side of an individual zebra are taken and used for identification
Zebras have an acute sense of sight, smell and hearing which benefits the other animals that associate with them. Their night vision is thought to be about as good as that of cats or owls. They have long jaws, so that when they are grazing their eyes are still high enough to watch for predators. With eyes located on the side of their head, they have a wide field of vision. |
