Ostrich

## Description

The Common ostrich (Struthio camelus), or simply ostrich, is a species of flightless bird native to certain large areas of Africa and is the largest living bird species. It is one of two extant species of ostriches, the only living members of the genus Struthio in the ratite order of birds. The other is the Somali ostrich (Struthio molybdophanes), which was recognized as a distinct species. The ostrich is distinctive in its appearance and can run for a long time at a speed of 55 km/h (34 mph) with short bursts up to about 70 km/h (40 mph), the fastest land speed of any bird. It is the largest living species of bird and the largest living dinosaur. It lays the largest eggs of any living bird (the extinct elephant birds of Madagascar and the giant moa of New Zealand laid larger eggs).

## Appearance

The feathers of adult males are mostly black, with white primaries and a white tail. However, the tail of one subspecies is buff. Females and young males are grayish-brown and white. The head and neck of both male and female ostriches are nearly bare, with a thin layer of down. The skin of the female's neck and thighs is pinkish gray, while the male's is gray or pink dependent on the subspecies. The long neck and legs keep the head of these birds up to 2.8 m (9 ft 2 in) above the ground, and their eyes are said to be the largest of any land vertebrate - 50 mm (2 in) in diameter - helping them to see predators at a great distance. The eyes are shaded from sunlight from above. Their skin varies in color depending on the subspecies, with some having light or dark gray skin and others having pinkish or even reddish skin. The strong legs of the common ostrich are unfeathered and show bare skin, with the tarsus (the lowest upright part of the leg) being covered in scales: red in the male, black in the female. The tarsus of the common ostrich is the largest of any living bird, measuring 39 to 53 cm (15+1⁄2 to 21 in) in length. The bird is didactyl, having just two toes on each foot (most birds have four), with the nail on the larger, inner toe resembling a hoof. The outer toe has no nail. The reduced number of toes is an adaptation that appears to aid in running, useful for getting away from predators. New chicks are fawn in color, with dark brown spots. After three months they start to gain their juvenile plumage, which is steadily replaced by adult-like plumage during their second year. At four or five months old, they are already about half the size of an adult bird, and after a year they reach adult height, but not till they are 18 months old will they be fully as heavy as their parents.

## Distribution

Ostriches live in the wild in western and eastern Africa, as well as South Africa. Once they roamed all over Africa, Asia, and the Arabian Peninsula. Ostriches farmed in Australia, New Mexico, and Israel have established feral populations. These birds inhabit open land and are native to the savannas and Sahel of Africa, both north and south of the equatorial forest zone. In southwest Africa, they inhabit the semi-desert or true desert. They can also be found in dry grasslands, scrubby areas, and pasturelands.

## Lifestyle

Ostriches live in flocks numbering 5 to 50 and are normally found alongside grazing animals such as antelope and zebras. During the breeding season, of about 5 months, flocks will occupy territories extending 2-15 sq km. Outside the breeding season, smaller, looser flocks of 2-5 members form. Ostriches have a lifestyle that is nomadic and mostly diurnal, being active early in the day as well as late. Males are territorial, defending their territory aggressively. These birds like water and frequently take baths, if given the opportunity, and are good swimmers. Sometimes, to escape detection, they lie down with their necks outstretched, which probably was the origin of the myth that an ostrich buries its head in the sand. They use posture to threaten a rival or predator, fluffing up the feathers of their wings and hissing loudly. These birds are fast runners and usually will comfortably outrun their predators. Ostriches are very vocal, and their sounds include whistling, booming, snorting, and hissing.

## Diet

Ostriches are mainly herbivores (granivores, graminivores, folivores), they eat buds, leaves, seeds, and flowers, and sometimes lizards, grasshoppers, and animal remains that carnivorous predators have left.

## Reproduction

Ostriches are polygynous, each male having three to five hens, with a “major” hen and several “minor” hens. Dominant males defend their territory and mate with their major hen and other hens within the area. The major hen is given more careful consideration, getting the first choice of nesting ground. She lays her eggs first, then allows the others in the flock to produce theirs. The major hen will know which are her eggs and protects her clutch by pushing away other hens’ eggs. The mating season starts in March or April, running until September. The male will scrape out a nest, which is just a depression in the ground, then attracts the hens by dancing, fluffing up his feathers and flapping his wings, as well as swinging his head while going down on his knees. Females lay 2 to 11 creamy eggs in the communal nest. Only the dominant male and major female guard the nest. The eggs are incubated for about 6 weeks. The female is on the nest during daylight hours, and the male at night. Within the first three days, the chicks leave the nest. They fledge when they are 4 to 5 months old, and by about 18 months they are fully grown, reaching maturity at 2 to 4 years.

## Population

### Population threats

Although not considered globally threatened and still relatively abundant, in recent times, ostrich numbers have decreased, as has their range. Their feathers and eggs have been used by humans for a long time, almost causing their extermination in northern and southern Africa. Overgrazing has caused habitat destruction and greatly reduced their range, this currently being the main threat.

### Population number

The IUCN Red List and other sources don’t provide the number of the Common ostrich total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List, but its numbers today are decreasing.

## Fun Facts

The ostrich is unique amongst birds in having two toes on each of its feet. All other birds possess three or four toes.

"Strothio camelus", the ostrich’s scientific name, means camel-like.

The feathers of the ostrich are unusual because they don’t have the usual tiny hooks that keep the feather together, leaving the barbs or ‘branches’ loose, and giving the feathers a very soft, smooth feel.

Males change color during the breeding season, their skin turning bright red, signaling to the hens that they are ready to mate.

One ostrich egg weighs as much as 24 or so chicken eggs.

Ostriches peck curiously at small, shiny objects, being attracted to them.

In Nairobi National Park, one communal ostrich nest had 78 eggs from different females.

Lacking teeth, ostriches ingest pebbles in order to grind their food, with an adult ostrich carrying in its stomach about 1 kg of stones.

Contrary to popular belief, ostriches do not bury their heads in the sand to avoid danger. This may have been a misunderstanding of their sticking their heads in the sand to swallow sand and pebbles to help digest their fibrous food, or, as National Geographic suggests, of the defensive behavior of lying low, so that they may appear from a distance to have their head buried. Another possible origin for the myth lies in the fact that ostriches keep their eggs in holes in the sand instead of nests, and must rotate them using their beaks during incubation; digging the hole, placing the eggs, and rotating them might each be mistaken for an attempt to bury their heads in the sand.