The flightless Ostrich (Struthio camelus) is the only species in the genus Struthio and in the family Struthionidae. The Ostrich is the tallest and heaviest living bird. Males are 2.1 to 2.75 m tall and weigh 100 to 130 (or even 150) kg; females are around 1.75 to 1.9 m tall and weigh 90 to 110 kg. The eyes are the largest of any terrestrial vertebrate, with a diameter of 5 cm. Its long, stout legs allow an Ostrich to cover a lot of ground quickly and can also serve as powerful weapons; each foot has a 10 cm sturdy flattened claw on the thick inner toe (uniquely among living birds, there are only two toes on each foot). The Ostrich is the fastest runner among birds. It can maintain a speed of 50 km/h for around half an hour and can sprint to 70 km/h with strides of 3.5 m, using its wings for balance at high speeds.
The male Ostrich is mostly pitch black, but the wings and tail are a sharply contrasting pure white; females are notably drabber. The Ostrich is one of the relatively few bird species that has a penis, which the male displays prominently during courtship.
Ostriches are found across much of the Sahel and eastern and southern Africa in a range of open habitats, from savanna to desert (in southern Australia there are some small populations of feral Ostriches from abandoned Ostrich farming operations). Ostriches do not require drinking water since they obtain sufficient water mainly from succulent plants. On hot days, they can allow their body temperature to rise to 42 C, reducing water loss through transpiration.
Outside the breeding season, Ostriches tend to live in small groups (although hundreds of Ostriches may congregate around water sources in the dry season). During the breeding season, birds form pairs or small harems. Males are territorial and engage in conspicuous courtship rituals. Multiple females may lay eggs in a single nest; a single nest may contain dozens of eggs, although only around two dozen can be incubated. Both the male and female incubate, with the more conspicuous male taking the night shift. Each egg weighs around 1.5 kg--enormous in absolute terms, but only around 1.5% of the adult female's weight. Eggs hatch together after around six weeks.
The idea that an Ostrich will bury its head in the sand in the face of danger is a myth, although when it feels trapped an Ostrich may sit down motionless with head and neck stretched on the ground in front of it in an apparent attempt to remain inconspicuous.
Ostriches produce many vocal and non-vocal sounds. They are omnivorous, but generally feed largely on plant material. The 14 m intestines allow them to eat many foods rejected by many other animals not equipped to extract enough of value from less desirable food items.
Ostriches have long been exploited by humans for their feathers, eggs, meat, and skin. At one time the Ostrich was common in most of Africa and southwestern Asia. Today, the range is considerably reduced and the subspecies that used to occur from the Syrian desert to the Arabian Peninsula was virtually extinct by 1941, having declined rapidly after World War I, with the last known record being a drowning individual in Jordan in 1966. There have been some efforts to reintroduce Ostriches to the Middle East.
(Folch 1992 and references therein)
- Folch, A. 1992. Family Struthionidae (Ostrich). Pp. 76-83 in: del Hoyo, J., Elliott, A., and Sargatal, J., eds. Handbook of the Birds of the World. Volume 1. Ostrich to Ducks. Lynx Edicions, Barcelona.
Molecular Biology and Genetics
Statistics of barcoding coverage
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Species[edit source | edit]
There are ten known species from this genus, of which eight are extinct. There are five more possible species of which trace fossils have been found. They are:
- †Struthio coppensi (Early Miocene of Elizabethfeld, Namibia)
- †Struthio linxiaensis (Liushu Late Miocene of Yangwapuzijifang, China)
- †Struthio orlovi (Late Miocene of Moldavia)
- †Struthio karingarabensis (Late Miocene - Early Pliocene of SW and CE Africa) - oospecies(?)
- †Struthio kakesiensis (Laetolil Early Pliocene of Laetoli, Tanzania) - oospecies
- †Struthio wimani (Early Pliocene of China and Mongolia)
- †Struthio daberasensis (Early - Middle Pliocene of Namibia) - oospecies
- †Struthio brachydactylus (Pliocene of Ukraine)
- †Struthio chersonensis (Pliocene of SE Europe to WC Asia) - oospecies
- †Struthio asiaticus, Asian Ostrich (Early Pliocene - Late Pleistocene of Central Asia to China ?and Morocco)
- †Struthio dmanisensis, Giant Ostrich (Late Pliocene/Early Pleistocene of Dmanisi, Georgia)
- †Struthio oldawayi (Early Pleistocene of Tanzania) - probably subspecies of S. camelus
- †Struthio anderssoni - oospecies(?)
- Struthio camelus, Common Ostrich
- Struthio camelus molybdophanes, Somali Ostrich
Fossil records and egg shell fragments show that the ancestors of this genus originated about 40-58 million years ago (mya) in the Asiatic steppes as small flightless birds. The earliest fossils from this genus are from the early Miocene (20-25mya), and are from Africa, so it is proposed that they originated there. Then by the middle to late Miocene (5-13mya) they had spread to Eurasia. By about 12 mya they had evolved into the larger size of which we are familiar. By this time they had spread to Mongolia and, later, South Africa.
Evolution[edit source | edit]
The genus Struthio used to include the Emu, Rhea, and also the Cassowary, until they each were placed in their own genera. The Somali Ostrich, Struthio molybdophanes, has recently become recognized as a separate species by some authorities, while others are still reviewing the information.
Footnotes[edit source | edit]
- Gray, G.R. (1855)
- Hou, L. et al. (2005)
- Davies, S.J.J.F. (2003)
- Gil, F. & Donsker D. (2012)
- Birdlife International (2012)
References[edit source | edit]
- BirdLife International (2012). "The BirdLife checklist of the birds of the world, with conservation status and taxonomic sources." (xls). Retrieved 16 Jun 2012.
- Brands, Sheila (14 Aug 2008). "Taxon: Genus Struthio". Project: The Taxonomicon. Retrieved 12 Jun 2012.
- Davies, S. J. J. F. (2003). Ostriches. In Hutchins, Michael. "Birds I Tinamous and Ratites to Hoatzins". Grzimek's Animal Life Encyclopedia 8 (2nd ed.). Farmington Hills, MI: Gale Group. p. 99. ISBN 0-7876-5784-0.
- Gill, F.; Donsker, D (2012). "Ratites". IOC World Bird List. WorldBirdNames.org. Retrieved 13 Jun 2012.
- Gray, George Robert (1855). Catalogue of the Genera and Subgenera of Birds contained in the British Museum. London, UK: Taylor and Francis. p. 109.