The Ostrich (Struthio camelus) is a flightless bird native to Africa. It is the only living species of its family, Struthionidae, and its genus, Struthio. It is distinctive in its appearance, with a long neck and legs and the ability to run at speeds of about 65 km/h (40 mph), the top landspeed of any bird.
Ostriches are the largest living species of bird and are farmed
in many areas all over the world. The scientific name for the
Ostrich is from the Greek for "camel sparrow" in allusion to its
Ostriches usually weigh from 93 to 130 kg (200 to 285 pounds), although some male ostriches have been recorded with weights of up to 155 kg (340 pounds). The feathers of adult males are mostly black, with some white on the wings and tail. It is often said that their eyes are larger than their brains.
Females and young males are greyish-brown and white. The small vestigial wings are used by males in mating displays. They can also provide shade for chicks. The feathers are soft and serve as insulation, and are quite different from the stiff airfoil feathers of flying birds. There are claws on two of the wings' fingers.
The strong legs of the Ostrich lack feathers. The bird stands on two toes, with the bigger one resembling a hoof. This is an adaptation unique to Ostriches that appears to aid in running.
At sexual maturity (two to four years old), male Ostriches can be between 1.8 m and 2.7 m (6 feet and 9 feet) in height, while female Ostriches range from 1.7 m to 2 m (5.5 ft to 6.5 ft). During the first year of life, chicks grow about 25 cm (10 inches) per month. At one year, ostriches weigh around 45 kg (100 pounds). An Ostrich can live up to 75 years.
The ostrich belong to the Struthioniformes order of (ratites). Other members include rheas, emus, cassowaries and the largest bird ever, the now-extinct Aepyornis. However, the classification of the ratites as a single order has always being questioned, with the alternative classification restricting the Struthioniformes to the ostrich lineage and elevating the other groups. Presently, molecular evidence is equivocal while paleobiogeographical and paleontological considerations are slightly in favor of the multi-order arrangement.
Ostriches are native to savannas and the Sahel of Africa, both north and south of the equatorial forest zone. Five subspecies are recognized:
Also called the 'North African Ostrich. They are the most widespread
subspecies, ranging from Ethiopia and Sudan in the east.
Analyses indicate that the Somali Ostrich may be better considered a full species. mtDNA haplotype comparisons suggest that it diverged from the other Ostriches not quite 4 mya due to formation of the Great Rift Valley. Subsequently, hybridization with the subspecies that evolved southwestwards of its range, S. c. massaicus, has apparently been prevented from occurring on a significant scale by ecological separation, the Somali Ostrich preferring bushland where it browses middle-height vegetation for food while the Masai Ostrich is, like the other subspecies, a grazing bird of the open savanna and miombo habitat (Freitag & Robinson, 1993).
The population from Río de Oro was once separated as Struthio camelus spatzi because its eggshell pores were shaped like a teardrop and not round, but as there is considerable variation of this character and there were no other differences between these birds and adjacent populations of S. c. camelus, it is no longer considered valid. This population disappeared in the later half of the 20th century. In addition, there have been 19th century reports of the existence of small ostriches in North Africa; these have been referred to as Levaillant's Ostrich (Struthio bidactylus) but remain a hypothetical form not supported by material evidence (Fuller, 2000). Given the persistence of savanna wildlife in a few mountaineous regions of the Sahara (such as the Tagant Plateau and the Ennedi Plateau), it is not at all unlikely that ostriches too were able to persist in some numbers until recent times after the drying-up of the Sahara.
The earliest fossil of ostrich-like birds is the Central European Palaeotis from the Middle Eocene, a middle-sized flightless bird that was originally believed to be a bustard. Apart from this enigmatic bird, the fossil record of the ostriches continues with several species of the modern genus Struthio which are known from the Early Miocene onwards. While the relationship of the African species is comparatively straightforward, a large number of Asian species of ostrich have been described from very fragmentary remains, and their interrelationships and how they relate to the African ostriches is very confusing. In China, ostriches are known to have become extinct only around or even after the end of the last ice age; images of ostriches have been found there on prehistoric pottery and as petroglyphs. There are also records in maritime history of ostriches being sighted way out at sea in the Indian Ocean and when discovered on the island of Madagascar the sailors of the 18th century referred to them as Sea Ostriches, although this has never been confirmed.
Ostriches live in nomadic groups of 5 to 50 birds that often
travel together with other grazing animals, such as zebras or
antelopes. They mainly feed on seeds and other plant matter;
occasionally they also eat insects such as locusts. Lacking
teeth, they swallow pebbles that help as gastroliths to grind
the swallowed foodstuff in the gizzard. An adult ostrich
typically carries about 1 kg of stones in its stomach. Ostriches
can go without water for a long time, exclusively living off the
moisture in the ingested plants. However, they enjoy water and
frequently take baths.
With their acute eyesight and hearing, they can sense predators such as lions from far away. When being pursued by a predator, Ostriches have been known to reach speeds in excess of 70 km per hour (45 miles per hour), and can maintain a steady speed of 50 km per hour (30 miles per hour).
Ostriches are known to eat almost anything (dietary indiscretion), particularly in captivity where opportunity is increased.
Ostriches can tolerate a wide range of temperatures. In much of its habitat, temperature differences of 40°C between night- and daytime can be encountered. Their temperature control mechanism is more complex than in other birds and mammals, utilizing the naked skin of the upper legs and flanks which can be covered by the wing feathers or bared according to whether the bird wants to retain or lose body heat.
When lying down and hiding from predators, the birds lay their head and neck flat on the ground, making them appear as a mound of earth from a distance. This even works for the males, as they hold their wings and tail low so that the heat haze of the hot, dry air that often occurs in their habitat aids in making them appear as a nondescript dark lump. When threatened, Ostriches run away, but they can cause serious injury and death with kicks from their powerful legs.
The most unique behavior occurs when a pair of ostrich bearing the young meets another pair. The parents will fight and the winning pairs will be parents of both pairs' offspring. It has been reported that the biggest group of ostriches contains 300 offspring.
Ostriches become sexually mature when 2 to 4 years old; females mature about six months earlier than males. The species is iteroparous, with the mating season beginning in March or April and ending sometime before September. The mating process differs in different geographical regions. Territorial males will typically use hisses and other sounds to fight for a harem of 2 to 5 females (which are called hens). The winner of these fights will breed with all the females in an area but only form a pair bond with one, the dominant female. The female crouches on the ground and is mounted from behind by the male.
Ostriches are oviparous. The females will lay their fertilized eggs in a single communal nest, a simple pit scraped in the ground and 30 to 60 cm deep. Ostrich eggs can weigh 1.3 kg and are the largest of all eggs, though they are actually the smallest eggs relative to the size of the bird. The nest may contain 15 to 60 eggs, with an average egg being 15 cm (6 inches) long, 13 cm (5 inches) wide, and weigh 1.4 kg (3 pounds). They are shiny and whitish in color. The eggs are incubated by the females by day and by the male by night, making use of the different colors of the two sexes to escape detection. The gestation period is 35 to 45 days. Typically, the male will defend the hatchlings, and teach them how and on what to feed.
The life span of an Ostrich is from 30 to 70 years, with 50 being typical.
This Ostrich Page is Copyright The Animal Web Guide © 2004 - 2009 Chuck Ayoub