Ostriches are flightless birds, with their great body size and reduced wing size rendering them incapable of flying. They have a long neck, long bare legs and two toes. Their strong legs allow them to run up to 70 km per hour when necessary, with strides of up to 8 m. Neck and thigh muscles are well developed and unfeathered.
Since ancient times, ostriches have aroused people's interest. Apart from being hunted for their flesh and plumes, ostriches were kept in captivity, tamed and semidomesticated by the early Egyptians, Greeks and Romans. Egyptians and Roman women of noble birth rode ostriches on ceremonial occasions. There are descriptions in Tutankhamen's tomb of the king hunting the birds with a bow and arrow; a privilege that apparently was kept for the Pharaohs. In the Arabian Peninsula, ostriches were hunted for their meat, while their skin was used to make protective clothing. Unlike those of other birds' feathers, the barbs of the ostrich feather are equally long on both sides of the central shaft. This is why the ostrich feather was adopted in ancient Egypt as a symbol of justice and truth. Formerly found in Syria and Saudi Arabia until the middle of the present century, wild ostriches are now confined to Africa (Siegfried, 1984).
The species name Struthio camelus comes from Latin. The word camelus is based on the similarities ostriches have with camels, such as their prominent eyes and eyelashes, their large size and their remarkable tolerance to the desert habitat.
Commercial ostrich farming
The first commercial ostrich farm was established in South Africa in about 1860 solely for harvesting the feathers every six to eight months. Ostrich farms began to spread gradually to other countries, particularly Egypt, Australia, New Zealand, the United States and Argentina, until the total number of ostriches raised commercially reached over 1 million by 1913. With the First and Second World Wars, however, the ostrich feather market crashed and the number of ostrich farms dropped significantly. The industry, nonetheless, managed to survive on a much smaller scale in South Africa. By keeping ostriches not only for their feathers but also for their meat and hides, it grew steadily thereafter. In 1986, just before the economic sanctions were imposed, South Africa exported a record high of 90 000 ostrich hides to the United States alone (Vyver, 1992). The shortage of ostrich skins after 1986 caused prices to rise. This made ostrich farming an attractive proposition and a number of farms were established in Europe and more in the United States in an attempt to fill part of the ever-increasing international demand. The world ostrich industry had finally begun and continues to grow steadily.
Characteristics and behaviour
The ostrich is very adaptable and thrives under extreme conditions. Among the many ways of regulating its body temperature, it controls heat loss during cold weather by covering its thighs with its wings, and during hot weather, by lifting and moving its wings, it creates a gentle breeze. The feathers are excellent insulators, minimizing heat gain from direct solar radiation, as well as reducing heat loss during cold desert nights.
It has a remarkable tolerance to heat, withstanding air temperatures of 56°C without undue stress. Heat is lost by panting via the well-developed air sac system that avoids overventilation of the lungs and consequent dangerous water loss (Jones, 1982). Adaptations of the blood circulatory system permit its body to heat up to a greater extent than those of other warm-blooded animals while still keeping the head at a safe temperature (Crawford and Schmidt-Nielsen, 1967). Ostriches rarely seek shade, as most desert animals regularly do. Furthermore, the ostrich's urine contains uric acid carried in a mucus-like substance that helps to minimize water loss (Levy et al., 1990; Yagil et al., 1990).
Ostriches may be found in a variety of open habitats. They normally avoid areas of thick bush or heavy tree cover, and inhabit wooded grasslands and other open country. Semi-arid, open and short-grass plains are usually associated with the highest ostrich densities. They are also able to thrive in very poorly vegetated areas.
Behaviour of the ostrich
Ostriches are completely diurnal. They are on their feet for most of the daylight hours, except when dust-bathing, resting or nesting. They invariably sit down at dusk and remain virtually inactive throughout the night unless disturbed (Degen, Kam and Rosenstrauch, 1989).
The chicks and juveniles are strictly gregarious and always remain in compact groups. Adults are semi gregarious and tend to be attracted to each other for short periods. Like camels, ostriches can travel for long distances in search of food and water.
In addition to temperature control, ostriches use their wings for a variety of display purposes, including courting, protecting eggs and young and submission (Sauer, 1966).
The ostrich's posture communicates information to other birds. A more confident and aggressive bird will hold its head and neck high, with the front of the body tilted upwards and the tail up, while a submissive bird will hold its head low and its tail down (Bertram, 1992).
Ostrich farmers battle as drought cripples Karoo- South Africa
Sexual characteristics
The wild ostrich is sexually mature at four to five years of age, while the domesticated ostrich is mature at two to three years; the female matures slightly earlier than the male. Male ostriches attain the black-and-white plumage when mature. Females and immature birds have a much duller colouring, with grayish-brown plumage. The young have spiky, black-tipped buff-coloured plumage until they are about four months of age. The plumage of the cock is brighter during the breeding/mating season, while the skin, usually light blue, becomes bright red (scarlet) over the beak, forehead and around the eyes, and the leg scales and toes become pink.
Male and female chicks are very similar in appearance and their sex can only be determined by examining their sexual organs. This is difficult as the penis of the male is still tiny and easily confused with the clitoris of the female (Gandini and Keffen, 1985; Samour, Markham end Nieva, 1984). From about seven to eight months of age, the sex can be determined when the bird urinates or defecates, as the penis emerges at these times. It is interesting to note that, unlike most birds, the male ostrich has a penis and that micturition and defecation are separate acts, although one normally follows the other almost immediately.
Full distinction between sexes is reached at about two years of age. The wing quills are pure white in the male, while they are ringed with grey or black in the female. The tail feathers of the male are white or yellowish brown and those of the female are mottled light and dark grey. The thighs of the adult ostrich are almost devoid of feathers.
It is important to note that the scarlet coloration of the male is dependent on the presence of mature testes, while its black plumage is dependent on the absence of ovaries. A castrated cock never acquires scarlet coloration, but its feathers are the normal black of the cock. Removal of the testes after sexual maturity has little effect on the bird's sexual instincts, and it continues the mating procedure (Osterhoff, 1979, 1984).
The breeding season
Ostriches are seasonal breeders, breeding only during particular seasons of the year. On average, the breeding/mating season lasts from six to eight months every year, although the timing and duration of breeding can vary with latitude and altitude (Shanawany, 1994a). In the northern hemisphere, breeding commences during March and ends around August/September (Leuthold, 1977), while in the southern hemisphere it begins around July/August and finishes by the end of March (Jarvis, Jarvis and Keffen, 1985).
