Salvadoran crow
| Salvadoran crow | ||||||||||||
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Salvadoran crow |
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| Corvus orru | ||||||||||||
| Bonaparte , 1850 |
The Salvadoran crow ( Corvus orru ), also known as the torres crow , is a bird belonging to the raven and crows ( Corvus ) genus . It occurs from Wallacea through New Guinea to Australia.
Salvadoran crows utilize a wide variety of food sources and are very adaptable. The IUCN classifies its stock situation as safe ( least concern ). There are three subspecies.
features
Build and color
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Between the sexes of Salvadorikrähe is neither in the plumage coloration still in Build a dimorphism , the same applies to young and adult birds. It reaches a body length of 46 to 51 cm. The beak is 57.6–61.9 mm long. The Salvadoran crow has a wing length of 337–354.9 mm, its tail measures 18.8–20 mm. The weight is between 440 and 670 g. It is about as big as the New Holland crow , the most widespread Corvus species in Australia .
The plumage of the Salvadoran crow appears uniformly black. The plumage on the head, neck, upper side of the body, breast, flanks and the plumage of the under tail-coverts shine black. The shimmer ranges from a metallic green on the ear covers to a blue-violet shimmer on the other parts of the body. The intensity of the shimmer strongly depends on the incidence of light. The underside of the body is matt black.
The feathers have a white feather base, the feathers are black only from the middle. In living birds, this feather base is visible when strong winds blow the feathers apart.
The beak is black, the rear third of the upper beak including the nostrils is covered by bristle feathers. In adult birds, the iris is whitish with a light blue inner ring. The legs and feet are black.
Fledglings
Young birds are slightly smaller than the adult birds. Their beak is even shorter. The plumage is not as shiny as in the adult birds and looks a bit brownish. Their beak is still dark gray, the iris is blue-gray. The iris begins to change color when the birds are around 22 months old.
Possible confusion
In Australia, come Corvus TYPES society Crow , Neuhollandkrähe , Tasmankrähe and Bennett Crow ago that are difficult to distinguish in field observations of the Tasmankrähe. However, the Salvadoran crow lacks the elongated neck feathers that are typical of the society crows, the New Holland crows and the Tasman crows. The most reliable distinguishing feature is reputation.
Distribution area and habitat
The northern limit of distribution of the Salvadoran crow is the Wallacea , which represents the transition area between Asian and Australian fauna and thus lies between Orientalis and Australis . From there the distribution area extends over the north of the Moluccas, the east of the Lesser Sunda Island and the lowlands of New Guinea to Australia, where the Salvadoran crow is a widespread species in the northern half of mainland Australia.
The Salvadoran crow populates a number of different forest types, all of which are comparatively dry and have sparse trees. She has a particular preference for eucalyptus forests. In addition, it also occurs on agricultural land, provided that there are still some trees. It can also be found wherever there is a rich supply of food. The Salvadoran crow can be seen regularly along roadsides and on garbage dumps.
In the southeast of the Australian state of Queensland , the number of Salvadoran crows has increased noticeably since the 1970s. The cause is the increased grain cultivation in this region.
The migratory movements of the Salvadoran crows have not yet been finally investigated. It is generally assumed that couples occupy a territory all year round. Subadult and non-breeding Salvadoran crows, on the other hand, roam a larger area.
Way of life
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Salvadoran crows live solitary, in pairs or in small flocks of up to 20 birds. In exceptional cases, groups of this type are observed, which include up to 150 individuals.
food
Salvadoran crows are opportunistic omnivores. A large part of the food requirement is covered by insects, especially beetles and caterpillars. In addition, seeds, including cereals and fruits, play a major role. Salvadoran crows also eat small vertebrates, including small birds as well as nestlings and eggs from various bird species. For example, it has been proven that the spectacled pelican and cattle egret eat eggs . They also eat carrion. The food composition depends on the season and the availability of individual food components. They find most of their food on the ground. Several individuals can often be found on larger carcasses, on harvested fields or on extensive garbage dumps. They are also more often associated with white-cheeked herons , masked lapwings , hunter's lairs , bell-chattering birds ( Manorina melanophrys ), stilt monarchs , garden fan tails , black-faced caterpillars and ground caterpillars ( Coracina maxima ) while foraging. The Salvadoran crow is one of the native Australian species of animals that can overwhelm and kill the Aga toad .
Reproduction
Salvadoran crows are sexually mature from the second year, but usually only breed when they are at least three years old. The breeding pair defends a territory and does not tolerate any conspecifics near the nest. They are not tied to any specific breeding season, nests with clutches are found in all calendar months. The nest is built in a fork in a high tree. Mostly these are eucalyptus trees. The nest is built from branches and twigs and the nest hollow is laid out with grass, roots, bark, horse hair and wool. The clutch comprises one to six eggs, the typical clutch size is five eggs. The laying interval is one to two days. It only breeds the female while the male brings food to the nest. The breeding season is 19 days. The nestlings fledge after about 41 days.
literature
- PJ Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7: Boatbill to Starlings. Part A: Boatbill to Larks . Oxford University Press, Melbourne 2006, ISBN 0-19-555884-7 .
Web links
- Videos, photos and sound recordings of Corvus orru in the Internet Bird Collection
Individual evidence
- ↑ a b Torresian Crow (Corvus orru). In: Handbook of the Birds of the World. accessed on May 11, 2017.
- ^ PJ Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 768.
- ↑ a b c P. J. Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 757.
- ↑ a b c P. J. Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 763.
- ^ PJ Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 758.
- ↑ a b P. J. Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 760.
- ↑ a b P. J. Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 761.
- ↑ Daniel Lingenhöhl: Crows outsmart poison toads . In: Spektrum.de from February 2, 2018.
- ↑ D. Donato, R. Potts: Culturally transmitted predation and consumption techniques by Torresian crows Corvus orru on Cane Toads Bufo marinus. In: Australian Field Ornithology. 21, 2004, pp. 125-126.
- ^ PJ Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 765.
- ↑ a b P. J. Higgins, JM Peter, SJ Cowling: Handbook of Australian, New Zealand & Antarctic Birds. Volume 7, Part A, p. 766.