Black-throated crow's shrike
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Black-throated crow's shrike ( Cracticus nigrogularis ) |
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| ( Gould , 1837) |
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The black-throated crow's shrike ( Cracticus nigrogularis ), also known as the black-throated crow's star , is a bird belonging to the genus of the black-throated crows ( Cracticus ). It occurs exclusively in Australia and some offshore islands.
The IUCN classifies its stock situation as safe ( least concern ). There are two subspecies.
features
Build and color
The black-throated crow's shrike reaches a body length of around 28 to 32 cm, of which 16.2 to 19 cm is on the tail. The beak is 40 to 49.7 mm long. The black-throated crow's shrike has a wing length of 160-190 mm and a wingspan of an average of 51 centimeters. The weight is between 97 and 159 g. The gender dimorphism is not very pronounced.
male
In the male, the head, neck and front chest are black. The rest of the underside of the body is white. A wide white band runs in the neck and separates the black head plumage from the also black coat, back and the black wing-covers. On the lower back, the black plumage turns gray and then the white of the upper tail-coverts. The tail plumage is black on top with a wide white tip. On the underside, the black part of the tail plumage is almost completely covered by the white under-tail covers and only the white tips of the tail feathers are visible.
The beak is pale blue-gray with a black tip. The iris is dark reddish brown. The legs and feet are dark gray.
Females and young birds
Some adult females are indistinguishable from the males. However, some of the females have black-brown head and back plumage. The ring that separates the head plumage from the back plumage is usually light gray.
The plumage of young birds is significantly more brown, even if the color distribution superficially resembles that of adult birds. The crown of the head and the back neck are dark brown and form a cap because the sides of the head are pale yellowish brown. Their chin and throat are still cream-colored and turn into a darker yellow-brown on the upper throat.
voice
The calls of the black-throated crow's shrike are perceived as pleasant because of their flute-like sound. They usually call during the day, but especially in the morning. Their calls can also be heard on moonlit nights.
Possible confusion
In most of its range, the black-throated crow's shrike is the only species of crow's shrike in which the adult birds have black and white plumage. The black-backed crow's shrike , which is similar to the black-throated crow's shrike, shares its distribution area with this species only on the Cape York Peninsula . The gray-backed crow's shrike has predominantly gray body plumage. The flute bird , on the other hand, is black on the underside of the body. The stilt monarch, on the other hand, has a black and white head.
Distribution area and habitat
The black-throated crow's shrike occurs exclusively on the Australian continent. It is widespread in the Australian states of Queensland and Northern Territory and is only absent in the far north of the Cape York Peninsula. It is also widespread in the Australian state of New South Wales and is only absent in the extreme southeast. In Victoria, however, it occurs predominantly in the valley of the Murray River and its tributaries. It is comparatively rare in South Australia, but common in West Australia. It is a resident bird in its entire range . Ringing data prove this local loyalty: almost 99 percent of the black-throated crow's shrike caught or found had moved less than 10 kilometers from the original ringing location.
In West Australia, the black-throated crow's shrike has been able to expand its range since the end of the 19th century, after forests were increasingly cleared in favor of agricultural land. On the other hand, it has become rare around the city of Darwin in the Northern Territory, after the suburban areas have expanded further and further.
The habitat of the black-throated crow's shrike are light eucalyptus and acacia forests and bushland. It is also found in sparse forests along rivers. It also occurs on agricultural land, in parks and gardens, if these have sparse trees. In arid and semi-arid areas it is mostly found near rivers. It is occasionally seen in monsoon forests and, less often, in mangrove forests.
Way of life
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Black-throated crows shrike live solitary or in pairs. Smaller groups of them are only observed sporadically, presumably these are family groups. Basically it is a trusting bird, but it aggressively defends the immediate vicinity of its nest. Black-throated crow's shrike are often found exposed in perch, mostly branches, but also on fence posts and wires. The flight is quick and straight.
food
Black-throated crow's shrike meet most of their food needs with invertebrates, but they also eat smaller vertebrates and, less often, fruits, seeds and nectar. They find most of their food on the ground. There is evidence that they eat other bird species: a black-throated crow shrike that was observed first ate the young birds of a garden fan tail and then also killed one of the parent birds that tried to defend its nestlings. He has also been seen catching and eating a drinking ringel deer.
Occasionally he follows Australian tree hawks as they hunt small bird species. Try from this scared bird species such as Star and Rostkehl honeyeater ( Conopophila rufogularis ) to catch fleeing into the undergrowth before the hawks. Conversely, the Australian tree falcon catches the birds that the black-throated crow's shrike chased up from the undergrowth.
Reproduction
The reproductive biology of the black-throated crow's shrike has not yet been conclusively investigated. However, he is considered a bird that enters into a monogamous couple relationship. In Brisbane, the area occupied by a pair ranged from 13 to 22 acres and was occupied by the breeding pair year-round. But there are also reports of black-throated crow shrike in which two breeding pairs had their nests in the same tree.
The black-throated crow's shrike is also one of the species in which brood helpers have been observed. The number of helping birds varied between three and 15 birds. Breeding helpers took part in feeding the nestlings and still dependent young birds and also defended the nest. At least in some of the observed cases, one is certain that the hatching helpers are not yet sexually mature offspring of the parent birds from the previous breeding season.
The breeding season falls from July to December with a peak in September to November. The nest is usually built high up in the treetops. It is an open bowl nest made of twigs and twigs, and occasionally leaves, bark and grass. The inside of the nest is laid out with small roots, branches, grass, wool and feathers. The clutch consists of two to four eggs, which the female lays two days apart. The brood begins with the laying of the first egg, the incubation period is 20 days. The nestlings can fledge after 29 to 31 days.
Life expectancy
One male ringed as an adult bird was found dead 7 years and 7 months after being ringed. Another male, also ringed adult, lived 8 years and 8 months after being ringed.
Black-throated crow shrike and human
Due to the European settlement of the Australian continent, the black-throated crow's shrike has been able to expand its range where forests have been cut down in favor of agricultural land. It is considered a useful bird in Australia as it eats mice and grasshoppers. He becomes comparatively trusting when he is fed regularly in gardens or parks and becomes so tame that he takes food out of his hand. As an ornamental bird, however, it is very rarely kept.
Trivia
The to the foliage birds belonging to drop Laubenvogel and spotted bowerbird imitate the calls for several species of birds that know them as predators. This also includes the reputation of the black-throated crow's shrike.
literature
- PJ Higgins, JM Peter and 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 978-0-195-55884-5 .
Web links
- Videos, photos and sound recordings of Cracticus nigrogularis in the Internet Bird Collection
Individual evidence
- ↑ a b Handbook of the Birds of the World on Black-throated Crow Shrike , accessed May 8, 2017
- ^ A b Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 527.
- ^ Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 516.
- ^ Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 517.
- ↑ a b c Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 519.
- ↑ a b c Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 520.
- ↑ a b c Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 521.
- ^ Higgins, Peter & Cowling: Handbook of Australian, New Zealand & Antarctic Birds: Volume 7 Boatbill to Starlings, Part A: Boatbill to Larks . P. 524.
- ↑ Clifford B. Frith, Dawn. W. Frith: The Bowerbirds - Ptilonorhynchidae . Oxford University Press, Oxford 2004, ISBN 0-19-854844-3 . P. 419.
- ↑ Clifford B. Frith, Dawn. W. Frith: The Bowerbirds - Ptilonorhynchidae . Oxford University Press, Oxford 2004, ISBN 0-19-854844-3 . P. 407.