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Ratites - The Ostrich

By Edited Sep 25, 2016 0 0

Flightless Birds

The Ostrich

The ostrich belongs to a group of birds known as the ratites. Ratites are unable to fly as they have a flat sternum which has no keel and thus there is nowhere for the wing muscles to attach.

There are four groups of ratites besides the ostrich – the rhea of South America, the Australian emu, the cassowary of Australia and New Guinea and the kiwi of New Zealand. Extinct ratites include the moa and the elephant bird.

The ostrich has the scientific name of Struthio camelus and is endemic to the savannahs and deserts of Africa. It is the only living species of the family and genus. There are five subspecies.

  • Struthio camelus australis or Southern ostrich from southern Africa and found south of the Zambezi and Cunene rivers.
  • S.c.camelus – North African ostrich or red-necked ostrich. Historically the most widespread but now only in 6 of its original 18 countries. This is the largest of the subspecies.
  • S.c.massaicus – Masai ostrich from East Africa. Limited to southern Kenya, eastern Tanzania, Ethiopia and parts of southern Somalia.
  • S.c.syriacus – Arabian ostrich or Middle Eastern ostrich became extinct around 1966.
  • S.c.molyhdophanes – Somali ostrich from southern Ethiopia, north-eastern Kenya and Somalia. Its range overlaps the Masai ostrich.

An ostrich pair

The ostrich is the tallest and heaviest of all living birds and reaches up to 2.75 metres in height and around 63 to 130kg in weight with some males exceeding this figure. It has a distinctive appearance. The legs and neck are long and it can reach speeds of over 70kms per hour and maintain this speed for up to 30 minutes. It has a stride of 4.9 metres when in full flight.

The feathers are soft and fluffy. Adult males are mostly black with a white tail and white primaries. One subspecies has a buff tail. Females and young stock are greyish-brown and white. The head is bare with only a thin layer of down covering the skin. The beak is flat and broad and the tip is rounded. The wings span 2 metres and are used during courtship displays and to shade chicks.

Depending on the subspecies, the skin on the males's thighs and neck may be blue-grey, grey or pink. Females have skin of a pinkish grey colour. In most subspecies the skin of the neck and thighs of the males becomes brighter during the mating season.

There is no feathering on the legs and the lowest part of the legs, the tarsometatarsus, is covered in red scales (males) or black scales (females). Whereas most birds have four toes, the ostrich has two. The larger inner toe has a nail resembling a hoof but the outer toe has no nail.

Ostriches have a few unique traits. They pass urine separately from faeces. The pubic bones are fused to hold the gut. Males have a copulatory organ which is retractable and 8 inches long.

The winter months are spent in pairs or alone. During the breeding season they travel in nomadic groups of between 5 and 50 birds, led by the dominant hen. They are diurnal and most active at sunrise and sunset. They may be active on moonlit nights.

Its diet consists mainly of vegetable matter although it also eats invertebrates. Its water requirements are obtained mostly from the plants they eat.

The ostrich often travels along with grazing animals such as zebras and wildebeest. The animals stir up insects for the ostriches while the birds help keep an eye out for predators. Their hearing and eyesight are acute.

Its defences include its speed and its strong feet and legs. It may lie on the ground to hide, stretching its neck along the ground. Its plumage blends with the sandy soil and this fact gave rise to the fallacy of the ostrich 'hiding its head in the sand'. It will also flee from attackers. If cornered, it will kick with enough force to kill a lion. Territorial males will fight by slamming their heads against each other.

Under natural conditions, males compete for control of a small group of females. A herd will consist of about twelve birds and includes a dominant male and female.

Males may mate with a number of females but only forms a pair bond with the dominant hen. They perform a pair dance before mating.

Ostrich egg

All hens lay in the nest of the dominant female. Her eggs are laid in the centre of the nest where they are best protected and she and her mate incubate all the eggs. There may be 15 to 60 eggs, each 15cm long and 1.5kg in weight. Incubation lasts about 40 days. The glossy creamy eggs have thick shells covered in small pits. An ostrich egg would take 40 minutes to hard-boil.

Ostrich Chick

The chicks hatch fully feathered with stiff, pointy down and leave the nest within days. They are sexually mature at three to four years of age. The life span of an ostrich is 30 to 40 years with some individuals living much longer. Like the emu, the ostrich has a booming call which is produced by the expansion of the loose skin on its neck. They also whistle and snort.

Ostriches are farmed throughout the world. The decorative plumes have always been held in high regard and are still made into hats and boas as well as feather dusters. The Kalahari bushmen use punctured ostrich eggs are water canteens. The discovery of engraved eggs suggests that ostriches formed part of human culture and civilisation from very early days.

Ostriches were in danger of extinction by the nineteenth century because of the demand for their plumage. Fortunately it was discovered that the bird could be plucked without needing to kill it. They are also relatively docile and will breed in captivity. The skins are tanned for leather and the meat is eaten. The meat is a dark red when it is raw. It has a similar taste to lean beef and is low in fat and cholesterol and high in iron, calcium and protein.

The practice of racing ostriches is common in Africa with the birds being harnessed with special saddles, bridles and bits. They are then ridden just like horses but have a reputation as being harder to manage. Ostrich racing is also held at quite a few localities in the USA.

The ostrich is incredibly adaptable and has been farmed from South Africa to Alaska.

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