 The ostrich, Struthio camelus, is the largest living bird. It may stand 3 m (10 ft) tall and weigh more than 150 kg (330 lb). Although flightless, the ostrich is able to take 3.5-m (12-ft) strides and to run at a sustained speed of 50 km/h (30 mph) for 15 minutes or more. In short bursts it may reach 70 km/h (43 mph) when escaping from predators. If cornered, it can also kick dangerously with the two clawed toes on each of its long, featherless legs. Its long neck is sparsely covered with hairlike feathers; the head is small, with large eyes and a short, flat bill. Its body is covered with large, soft, loosely structured feathers, and its wings and tail are many-feathered and plumelike. The female is an almost uniform grayish brown; the male is black, with white wings and tail. Ostriches are the only living birds that eliminate their urine separately from their feces.
Ostriches live in arid, open country, where they feed on succulent plants, fruits, grasses, and leaves as well as occasional insects and lizards, birds, and mice. The birds can go for long periods without water but ultimately need a water supply. They commonly live in small, loosely organized flocks. Sometimes, due to food or water conditions, flocks may temporarily join to form a group of several hundred birds.
The most common mating pattern is one male and three females in a family unit. The male usually makes a nest by scraping out a depression in sandy ground. All the females lay their eggs in the same nest, and both sexes incubate the eggs. Usually only the dominant female will sit on the nest, however. She incubates during the day, when her gray brown coloration is more concealing; the male incubates from late afternoon to early morning. A family of females may lay from 15 to 30 eggs, but not all hatch. The eggs are larger than those of any other living bird, and each may be 150 mm (6 in) long and 127 mm (5 in) wide, have a shell 1.97 mm (5/64 in) thick, and weigh up to 1,600 g (3.5 lb). The young hatch in 42 days and are able to run almost immediately. Both young and adult ostriches hide by sitting with their heads and necks stretched out on the ground, which may have given rise to the erroneous belief that ostriches bury their heads in the sand. Ostriches reach full size in about 6 months but do not attain sexual maturity until 3 or 4 years of age. They may live for 30 years.
The ostrich is the only living species in the family Struthionidae and in the order Struthioniformes. It originated in the Asiatic steppes during the Eocene Epoch, 40 million to 50 million years ago, and once ranged through Asia, Europe, and Africa. Its natural range is now limited to Africa, where it is separated into four subspecies. In the 19th century ostrich feathers were in demand as decorations and accessories, and wild ostriches were in danger of extinction until the development of ostrich farms. The first South African ostrich farm was established in 1838. Most of the world's ostrich farming still takes place in South Africa. A few farmers in the southern United States have begun to raise ostriches. |
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