Kenya's Tana River divides the range of East Africa's two types of oryx the beisa oryx (Oryx gazella beisa) and the fringe-eared oryx (Oryx g. callotis). The fringe-eared oryx ranges from Kenya to central Tanzania. The beisa oryx ranges from Ethiopia through Somalia into northeastern Uganda and Kenya.
The oryx, a large antelope with long, spear-like horns, is a true desert animal. It has a thick, horse-like neck with a short mane and a compact, muscular body. A defined pattern of black markings that contrast with the white face and fawn-colored body are prominently displayed in dominance rituals to emphasize the length of horns and strength of the shoulder.
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Originally, various oryx species were found in all of Africa's arid regions. One species that occurred on the Arabian Peninsula was exterminated recently but has now been reintroduced into the wild from captive stock. Well adapted to the conditions of their hot, arid habitats, oryx can live as long as 20 years.
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The social system of the oryx is unusual in that nonterritorial males live in mixed groups with females, or with females and their young. Males that dominate are territorial to a degree, marking their areas with dung deposits.
The dominance hierarchy among oryx is based on age and size. As they grow, calves assess one another in tests of strength that look like games. As the hierarchy becomes established, the need to fight is reduced. Ritual displays replace actual contact, except when evenly matched individuals may have to fight to establish their rank. Along with lateral displays, oryx perform a slow, prancing walk and sometimes break into a gallop. When several males are making these displays, they may clash horns.
A female leaves the herd to give birth and hides the calf for 2 or 3 weeks, visiting a few times a day to nurse it. The newborn is an inconspicuous brown color. The black markings begin to appear when the calf is ready to return to herd with its mother. Calves are suckled for 6 to 9 months and reach maturity at 18 to 24 months. Most young males migrate out of their natal group to join other groups.
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Oryx typically feed in early morning and late afternoon. Their diet mainly consists of coarse grasses and browse from thorny shrubs. In desert areas they consume thick leaved plants, wild melons, and roots and tubers they dig out of the ground. Plants collect dew, which is gradually released during the hotter parts of the day. Some plants increase their water content by 25 to 40 percent, so when oryx feed late at night or early in the morning, they maximize both food and water sources.
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The tribesmen of Lake Turkana hunt oryx for their meat and hides. In many cultures, the horns of the oryx are sought after as charms; even in medieval England they were marketed as unicorn horns.
Did You Know?
- The oryx is a good example of an antelope that has successfully adapted to the harsh conditions of dispersed food, intense heat and little or no water.
- The female comes into heat soon after giving birth. The more frequent estrus cycles enable females to produce calves at 9-month intervals.
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