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| South African ostrich | |||
|---|---|---|---|
%2c_cabo_de_Buena_Esparanza%2c_Sud%25C3%25A1frica%2c_2018-07-23%2c_DD_86.jpg) | |||
| Male atCape of Good Hope, South Africa | |||
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| Female atEtosha National Park, Namibia | |||
Scientific classification | |||
| Kingdom: | Animalia | ||
| Phylum: | Chordata | ||
| Class: | Aves | ||
| Infraclass: | Palaeognathae | ||
| Order: | Struthioniformes | ||
| Family: | Struthionidae | ||
| Genus: | Struthio | ||
| Species: | |||
| Subspecies: | S. c. australis | ||
| Trinomial name | |||
| Struthio camelus australis | |||
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Struthio camelus distribution map
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TheSouth African ostrich (Struthio camelus australis), also known as theblack-necked ostrich,Cape ostrich orsouthern ostrich is a subspecies of thecommon ostrich endemic toSouthern Africa. It is widely farmed for its meat, eggs and feathers.
The South African ostrich known as wilde volstruis inAfrikaans, is a large flightless bird with long, bare legs and neck, a thick body, and a small head.[1] The South African ostrich has grey-colored legs and neck. The ostrich is adidactyl species, meaning each foot has two toes, both ending in a sharp claw. They stand at a height of 1.2-2m tall and can weigh between 60–80 kg.[2]
There issexual dimorphism between males and females. Males have mostly black feathers covering their body, except for the tips of theprimary feathers andrectrices, which are white. The male's tail feathers are often stained a chestnut colour. Females and immature individuals have almost entirely grey-brown feathers covering their body. Juveniles have tan/dark brown banded plumage. They possess a similar appearance as a small long-leggedgamebird.[2]
In 1868, Gurney came up with the nameStruthio australis for the South African ostrich.[3] The full scientific name isStruthio camelus australis. The nameStruthio signifies "ostrich",camelus stands for "camel", andaustralis means "southern".[4] The South African ostrich is a subspecies of thecommon ostrich (Struthio camelus). Other subspecies of the common ostrich include theNorth African ostrich (Struthio camelus camelus),Masai ostrich (Struthio camelus massaicus), and theArabian ostrich (Struthio camelus syriacus). TheSomali ostrich (Struthio molybdophanes) is the other modern species of ostrich.[5]
The South African ostrich belongs to the group of flightless birds known asratites, which are part of thetaxonomic groupPalaeognathae. The living ratites include five orders:kiwis,cassowaries,emus,rheas andostriches.[6]
South African ostriches are often found in semi-arid andarid environments, such assavannas,deserts, and openplains, which provide ample space for running andforaging.[2][7] Thesenomadic birds tend to travel in groups, known asflocks. Their flocks typically consist of adominant male, several females, and their chicks.[7]
Most common ostriches inSouth Africa were partly derived from theSomali ostrich asdomesticated hybrids bred for the feather industry.[2] Today, the South African ostrich is found inSouth Africa,Namibia,Malawi,Zambia,Zimbabwe,Angola andBotswana.[8] It lives in south of the riversZambezi andCunene. The subspecies ranges from southern and southwestern Angola east to Zimbabwe and Botswana, southernMozambique, and south to western and northern South Africa.[5] It was formerly found throughout Zambia and was once more widespread across South Africa. They have been introduced inEswatini and not present inLesotho.[9]
It is farmed for itseggs, meat,leather and feathers in theLittle Karoo area ofCape Province.
Feral South African ostriches roam theAustralian outback after having escaped from farms in the 20th century.[10] The extent of their range in Australia is not known.
The South African ostrich comes across as a timid, calm yet vigilant when around other groups of mammals and birds. They try to avoid other species only frequenting the same areas when necessary, such as for food and water. In the presence oforyx,kudu,Burchell's zebra andspringbok the South African ostrich often remained impartial.[11] This species is described as jumpy, seen many times fleeing from harmless animals after the smallest disruption. During the dry season, a flock of ostriches may be composed of individuals with varying sexes and ages. Water holes act as social gathering sites. Young males, females and families regularly pass through from many different areas. These meetings will create a temporary social spot.[12]
Acommensalistic relationship is often brief and formed through a random encounter and not from any deliberate actions.[11] In 1969, Sauer observed ostriches directing their tension from another species, towards a flock member. The ostrich is very capable of defending itself. With strong legs, the ostrich can administer powerful kicks. When given the choice, they would prefer to quickly run away. After fleeing from danger, the ostrich will hastily find their flock members.[12]
The South African ostrich emits a variety of sounds described as booming or lion-like.[2] Similar to the reproductive stance, the male ostrich will stand tall and make "booming" calls to assert his dominance or deter predators from the young. He can make a wide range of threatening calls which sound almost like a snort, hiss or low boo. The "boo boo boohoo'hoo" as described in Sauer & Sauer (1966) is a vocalization heard on nest sites during thepre-copulatorycourtship. Once a nesting site is established the male makes similar "booming" calls directed towards rivals in theirterritory.[12] The ostrich will be heard more often calling in the early morning and late afternoon, sometimes until midnight or late into the night.[2][12]
The South African ostrich is aherbivorous species adapted for eating several different food items. They eat grass and forage on trees and bushes. Ostriches do not have acrop, meaning the food passes from theesophagus to thestomach.[13] They do not develop anyteeth. They are able to break up their food using theirgizzard. The gizzard has a few small pebbles which will help grind the food.
Nearing the end of thedry season. The female South African ostrich will signal her fitness to a potential mate by performing a courtship dance or display. To attract a male, the female may even producefeces andurinate. The female will even chase off other females from her potential partner's territory.[12]
As the males approach the reproductively ready female, their face, neck and shins turn red. The males perform a dance or ceremonial rivalries in front of the females to get their attention. He kneels down, moving his head and wings from side to side. The male will chase the females while standing tall, almost on "tippy toes" and display quick tiny steps while his neck and wings are pointed upwards. Dominant males will remain erect and vocalize to passing by males. They are capable of keeping this position for many hours without eating.[12]
Nests are chosen by the male or by the breeding individuals. Most commonly, they will formpolygamous units composed of onecock and threehens, with one taking on a more dominant role (major hen). The South African ostrich chooses a nest site away from communal grounds and watering holes. They construct a nest in dry sandy locations by pushing thesediment. These nests average three meters in diameter. The "major hen" will start laying first, followed by the "minor hens" who starts laying after the "major hen" lays her second egg. This synchronized process of laying eggs lasts 11 days. During this time the male guards the nest.[12]
In the study done by Sauer & Sauer (1966), the South African Ostrich laid aclutch of eight eggs maximum. The "minor hens" laid three or four eggs. The weight of these eggs ranged from 1,221g to 1,752g with the average being 1,346g. The length of the eggs measured 12.2 cm to 15.6 cm and the width measured 11.2 cm to 13.0 cm. With an average length and width of 14.3 cm and 12.1 cm, respectively.[14] When theincubation period starts, the male and females will rotate the task of sitting on the eggs.[12] The ideal temperature for ostrich egg incubation falls within 35 °C to 36 °C and the relative humidity is between 40% to 42%.[15]
This subspecies of ostrich found in the wild is scarce. Most populations are located onreserves and wilderness areas.[2]
