Ostrich: Struthionidae

Ostriches are diurnal, meaning they are most active during the day. They are sometimes active on moonlit nights. They live in flocks, families and alone. The flocks can range in size from five to fifty birds and are usually found grazing with other herbivores, including antelope and zebras. During the breeding season, flocks occupy territories of 0.8 to 6 square miles (2 to 15 square kilometers). Flocks often gather together, forming large groups of hundreds of birds. Outside the breeding season, flocks are usually much smaller, generally two to five birds but sometimes up to ten birds. Male ostriches are called cocks and females are hens.

Ostriches take frequent sand baths, especially during dry periods, laying together in large sandy depressions where they stir up the sand with powerful wing beats. They also like to take water baths, and do so frequently during the wet season when pools of water are more plentiful.

The normal walking pace of ostriches is 2.5 miles per hour (4 kilometers per hour). When ostriches sense danger or are threatened, they can run at speeds of up to 45 miles per hour (70 kilometers per hour) for a few minutes and can maintain a steady speed of about 31 miles per hour (50 kilometers per hour) for thirty minutes. Ostrich strides can be 10 to 16 feet (3 to 5 meters). When running, ostriches hold their wings out for balance, especially when making sudden turns. Ostriches prefer to outrun their predators but when cornered, they will use their long and thick legs as weapons. An ostrich's kick is so powerful, it has been known to kill lions.

Ostriches have a wide variety of vocal sounds, including whistles, snorts, and grunts. They have a loud booming call used to announce their territory.

Ostriches are territorial, meaning they are protective of an area they consider home and claim exclusively for themselves. Each family has its own territory, which is established by the dominant male. The family also has a dominant female and several other females, called minor hens. During the mating season, a male will show its dominance by stretching its head high and lifting its wing and tail feathers. Ostriches of both sexes show submission by holding their heads, wings, and tails towards the ground.

When ostriches are not breeding, they usually form flocks of two to ten birds. (© Nigel Dennis/Photo Researchers, Inc. Reproduced by permission.)

Males and females are polygamous (puh-LIH-guh-mus), meaning they have more than one mate at the same time. Following mating, the dominant male will build a nest by scraping the ground or sand with his feet several times, making a shallow depression. A number of females will lay their eggs in a single nest. The dominant hen is the first to lay eggs. She will lay up to twelve eggs in the center of the nest over a three-week period. The minor hens will then lay their eggs around the dominant hen's eggs. Ostrich nests usually contain thirteen to twenty eggs but can contain up to sixty eggs. On average, one egg is 6 inches (15 centimeters) long and 5 inches (13 centimeters) wide and weighs 3 pounds (1.4 kilograms). Often, after all the eggs are deposited, the dominant female will discard some of the eggs laid by the minor hens. The dominant male sits on the eggs at night and the dominant female during the day. The eggs take about forty-two days to hatch. About 10 percent of the eggs will hatch and on average only one chick per nest will survive to adulthood. The average lifespan of an ostrich is thirty to forty years but can be up to fifty years, both in the wild and in captivity.