Common ostrich

The common ostrich (Struthio camelus), or simply ostrich, is a species of flightless bird native to certain areas of Africa (and historically, Arabia) and is the largest living species of bird. The common ostrich is one of two extant species of ostriches, the only living members of the genus Struthio in the ratite group of birds. The other is the Somali ostrich (Struthio molybdophanes), which has been recognised as a distinct species by BirdLife International since 2014, having been previously considered a distinctive subspecies of ostrich.

The common ostrich belongs to the order Struthioniformes. Struthioniformes previously contained all the ratites, such as the kiwis, emus, rheas, and cassowaries. However, a recent genetic analysis has found that the group is not monophyletic, as it is paraphyletic with respect to the tinamous, so the ostriches are now classified as the only members of the order. Phylogenetic studies have shown that it is the sister group to all other members of Palaeognathae, and thus the flighted tinamous are the sister group to the extinct moa. It is distinctive in its appearance, with a long neck and legs, and can run for a long time at a speed of with short bursts up to about , While exceptional male ostriches (in the nominate subspecies) can weigh up to , some specimens in South Africa can only weigh between . New chicks are fawn-coloured, with dark brown spots. The reduced number of toes is an adaptation that appears to aid in running, useful for getting away from predators. Common ostriches can run at a speed over and can cover in a single stride. The wings reach a span of about , and the wing chord measurement of is around the same size as for the largest flying birds. They have 50–60 tail feathers, and their wings have 16 primary, four alular, and 20–23 secondary feathers.

Taxonomy

The common ostrich was originally described by Carl Linnaeus from Sweden in his 18th-century work, Systema Naturae under its current binomial name. the "camel" term referring to its dry habitat. It is the largest subspecies, at in height and up to in weight. it became extinct around 1966.

Western Asia: Iran, Iraq, Israel, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, Syria, the United Arab Emirates, and Yemen

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{| class="wikitable"

|+ Somali ostrich

! Species !! Description !! Image

|Somali ostrich (S. molybdophanes), also known as the blue-necked ostrich || Found in southern Ethiopia, northeastern Kenya, and Somalia. Mitochondrial DNA haplotype comparisons suggest that it diverged from the other ostriches around 4 mya due to the formation of the East African Rift. Hybridisation with the subspecies that evolved southwestward of its range, S. c. massaicus, has apparently been prevented from occurring on a significant scale by ecological separation; the Somali ostrich prefers 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. This population disappeared in the latter half of the 20th century. There were 19th-century reports of the existence of small ostriches in North Africa; these are referred to as Levaillant's ostrich (Struthio bidactylus) but remain a hypothetical form not supported by material evidence. The Arabian ostriches in the Near and Middle East were hunted to extinction by the middle of the 20th century. Attempts to reintroduce the common ostrich into Israel have failed.

Ostriches were introduced to Australia for farming, and a large feral population now exists in the Australian outback.

Behaviour and ecology

thumb|Two birds "dancing"|alt=Pair "dancing"

thumb|Sleeping, with [[rapid eye movement sleep|REM sleep and slow-wave sleep phases]]

Common ostriches normally spend the winter months in pairs or alone. Only 16 percent of common ostrich sightings were of more than two birds. and can maintain a steady speed of , which makes the common ostrich the fastest bipedal animal. When lying down and hiding from predators, the birds lay their heads and necks flat on the ground, making them appear like a mound of earth from a distance, aided by the heat haze in their hot, dry habitat.

Feeding

They mainly feed on seeds, shrubs, grass, fruit, and flowers;

Due to predation pressure, common ostriches have many antipredator tactics. Though they can deliver formidable kicks, they use their great eyesight and speed to run from most of their predators. In non-native areas, especially on ostrich farms in North America, adult ostriches have no known enemies due to their large size, intimidating presence, and behaviour similar to that of overgrown guard dogs, with instances of them attacking and decapitating coyotes on one occasion.

Usually, ostrich hunting is done by male cheetah coalitions in the Kalahari region during the night, when ostrich's vigilance is less effective. Cheetahs in other regions rarely hunt ostriches, but an exceptional coalition composed of three East African cheetahs has been reported in Kenya. Similarly, lions hunt ostriches mainly in the Kalahari region and not in other regions, or take ostriches as only a small percentage of their prey. Despite parental care, 90% is typical for chick mortality, most of it caused by predation. The tidal volume is seen to double resulting in a 16-fold increase in ventilation.

Common ostriches develop via intussusceptive angiogenesis, a mechanism of blood vessel formation, characterising many organs. of vessels to meet physiological requirements. Moreover, similarities also include a larger right atrium volume and a thicker left ventricle to fulfil the systemic circuit. The Purkinje cells are mostly found within both the endocardium and the sub-endocardium. The blood oxygen affinity, known as P50, is higher than that of both humans and similar avian species. This subtype increases oxygen affinity in order to transport oxygen across the allantoic membrane of the embryo. Hot, arid habitats pose osmotic stress, such as dehydration, which triggers the common ostrich's homeostatic response to osmoregulate.

System overview

The common ostrich is well-adapted to hot, arid environments through specialisation of excretory organs. The common ostrich has an extremely long and well-developed colon, a length of approximately between the coprodeum and the paired caeca, which are around long.

Common ostrich kidneys are fairly large and so are able to hold significant amounts of solutes. Hence, common ostriches drink relatively large volumes of water daily and excrete generous quantities of highly concentrated urine. It is when drinking water is unavailable or withdrawn that the urine becomes highly concentrated with uric acid and urates. on the flow rate (Poiseuille's Law) and composition of the ureteral urine in the ostrich, knowledge of renal function has been based on samples of cloacal urine, and samples or quantitative collections of voided urine. However, the common ostrich shows no nasal glandular function in regard to this homeostatic process. The common ostrich also experiences an increase in haematocrit, resulting in a hypovolemic state. Total evaporative water loss (TEWL) is statistically lower in the common ostrich than in membering ratites. The ostrich will also expose the thermal windows of their unfeathered skin to enhance convective and radiative loss in times of heat stress. At higher ambient temperatures lower appendage temperature increases to difference from ambient temperature. These feather-heavy areas such as the body, thighs, and wings do not usually vary much from ambient temperatures due to this behavioural controls.

:Metabolic rate = 70M0.75

where M is body mass, and metabolic rate is measured in kcal per day.

In common ostriches, a BMR (mL O2 g−1 h−1) = 389 kg0.73, describing a line parallel to the intercept with only about 60% in relation to other non-passerine birds.]]

The wild common ostrich population has declined drastically in the last 200 years, with most surviving birds in reserves or on farms.

"Head in the sand" misconception

Contrary to a popular assumption, ostriches do not bury their heads in sand to avoid danger. This misconception gave rise to the term "ostrich effect" for avoiding negative information.

Economic use

thumb|left|Fashion accessories, Amsterdam, 1919|alt=Fashion accessories made from feathers, Amsterdam, 1919

thumb|Being moved between camps in preparation for filming a movie in South Africa

In Roman times, there was a demand for common ostriches to use in venatio games, cooking, or medicine. They have been hunted and farmed for their feathers, which at various times have been popular for ornamentation in fashionable clothing (such as hats during the 19th century). Their skins are valued for their leather. In the 18th century they were almost hunted to extinction; farming for feathers began in the 19th century. At the start of the 20th century there were over 700,000 birds in captivity. Feathers are still commercially harvested. It is claimed that common ostriches produce the strongest commercial leather. Uncooked, it is dark red or cherry red, a little darker than beef. This may include tours of the farmlands, souvenirs, or even ostrich rides.

Attacks

Common ostriches typically avoid humans in the wild, since they correctly assess humans as potential predators. If approached, they often run away, but sometimes ostriches can be very aggressive when threatened, especially if cornered, and may also attack if they feel the need to defend their territories or offspring. Similar behaviour is noted in captive or domesticated common ostriches, which retain the same natural instincts and can occasionally respond aggressively to stress. When attacking a person, common ostriches deliver slashing kicks with their powerful feet, armed with long claws, with which they can disembowel or kill a person with a single blow. In one study of common ostrich attacks, it was estimated that two to three attacks that result in serious injury or death occur each year in the area of Oudtshoorn, South Africa, where a large number of common ostrich farms are set next to both feral and wild common ostrich populations, making them statistically, the world's most dangerous bird.

Racing

thumb|right|upright|[[Jacksonville, Florida, |alt=Ostrich-drawn cart carrying a man, circa 1911, Jacksonville, Florida]]

In some countries, people race each other on the backs of common ostriches. The practice is common in Africa

thumb|left|upright|1933, The Netherlands|alt=Racing, 1933, The Netherlands

The racing is also a part of modern South African culture. Chandler, Arizona, hosts the annual "Ostrich Festival", which features common ostrich races.

Notes

References

External links

(Common) Ostrich – Species text in The Atlas of Southern African Birds.
British Domesticated Ostrich Association
Index for various ostrich studies and papers