Yellow-naped bowerbird
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Yellow-naped bowerbird ( Sericulus chrysocephalus ), male, Queensland, Australia |
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| ( Lewin , 1808) |
The yellow-naped bower bird or velvet gold bird ( Sericulus chrysocephalus ) is a species from the family of bower birds (Ptilonorhynchidae). While the other species of the genus Sericulus occur in New Guinea, the yellow- naped bowerbird is a representative of the avifrauna of Australia . Its distribution area is on the Australian east coast.
The yellow-naped bower bird is a relatively small bower bird with a body length of around 25 centimeters and is one of the species of this genus whose courtship behavior includes the construction of an arbor by the male. As is typical for bowerbirds, there is a striking sexual dimorphism . The distinction between two subspecies has since been abandoned, the species is considered monotypical.
The IUCN classifies the population of the yellow-naped bowerbird as harmless ( least concern ).
description
The males of the gold-naped bowerbird reach a body length of up to 24 centimeters, of which between 8.2 and 9.1 centimeters are on the tail. The females become slightly larger with a body length of up to 25 centimeters. With them fall between 9.6 and 11.1 centimeters on the tail plumage. The beak length of the males is between 2.9 and 3.2 centimeters and of the females between 2.9 and 3.1 centimeters. Males weigh between 76 and 110 grams, females weigh between 91 and 138 grams. There is a pronounced dimorphism between the sexes .
Appearance of the male
In the male, the reins, crown, neck and upper back are orange-yellow. In a number of individuals, the front part of the crown is also washed out orange-red to crimson-red. The feathers on the forehead and crown are short, very dense and velvety, which has led to the alternative German name Samtgoldvogel. A black, wide and slightly wedge-shaped line also runs over the eye.
The rest of the top of the body is black with a purple sheen. The two outermost wings of the hand and all wing covers are matt black. Otherwise, the arm and hand wings are golden yellow with wide to narrow feather tips and black edges on the outer flags. The control feathers of most adult males are pure black. However, some individuals end the control pens with fine yellow tips. Other individuals have yellow components on the outside flags of some control feathers.
The legs are black-brown. The iris is bright yellow, the beak is orange-yellow.
Appearance of the female
The adult female is far more inconspicuous in color than the male.
The head and neck are dirty whitish to brown-gray to an individually different extent and have fine dark-gray to black dashes and spots. There is a soot-black stain on the top. In some - possibly older - females, this spot is narrowly lined with yellow feathers at its rear end. In addition, an individually variable, wide and soot-black collar runs in the neck, which can be very pronounced in individual females.
The coat is olive, the back and rump are lighter. All feathers on the coat, back and rump have whitish to gray ends, which gives the female a speckled appearance on the upper side of the body. The wings and the tail plumage are gray, the arm and hand wings also have paler tips. A few females, again probably older, have yellow patches of color on the wings of the hand.
The underside of the body is dirty whitish to cream-colored. The feathers on the throat are matt soot black in the middle, the breast feathers are lined with black-brown and cross-banded. The beak is black, very rarely some females have a pale spot on the upper beak. The legs and feet are blackish. The iris is yellow.
Young, sexually mature females are more densely and conspicuously scaled and transversely banded than older females. The black spot on the top of the head is lined with a narrow dark gray.
Appearance of the young birds
The male juveniles initially resemble the female and have only individual feathers that correspond to the plumage of the male. Young birds of both sexes initially have a longer tail plumage than the adult birds. From the age of three, females have plumage that corresponds to that of adults. The plumage of the males corresponds to that of the adult male in the fifth year of life. From the second to the fourth year the beak and iris become increasingly lighter. By the age of six, males have completely yellow eyes and an orange beak.
distribution and habitat
The yellow-naped bower bird occurs in the far east of Australia . The range, which lies along the east coast, begins north of Sydney and extends to Queensland. The northern limit of distribution of this species is in southeast Queensland along the course of the Connors and Clark Rivers . There is a distribution gap near Rockhampton in the valley of the Fitzroy River . Individual yellow-naped bowerbirds and occasionally even smaller flocks are also observed within the Sydney metropolitan area.
The altitude distribution ranges from the lowlands to altitudes of 900 meters. The habitat are subtropical rainforests and moist hard-leaved forests . They are also looking for more open habitats and can be observed on agricultural areas and in gardens in the suburbs, especially in the winter months. In Lamington National Park , southeast Queensland, flocks of yellow-naped bowerbirds regularly migrate from the higher mountain forests to the low-lying coastal forests of the Gympie region in the winter months .
Subspecies
Traditionally, two subspecies were distinguished.
- S. c. chrysocephalus - Lewin, 1808
- S. c. rothschildi - Mathews, 1912. This subspecies has a more crimson-colored front parting
Clifford B. Frith and Dawn. W. Frith pointed out as early as 2004 that the difference in the color of the front part of the head was not pronounced or even non-existent and therefore do not consider the distinction between two subspecies to be justified. Genetic studies have meanwhile confirmed that the yellow-naped bower bird is monotypical.
Way of life
Adult male yellow-naped bowerbirds are very shy but get used to the presence of observers at feeding grounds. Females, on the other hand, are much more trusting. They occasionally form mixed flocks with silkworm birds and thick-billed strangler crows .
Yellow-naped bowerbirds first sunbathe at the start of the day and regularly sit in the treetops that protrude from the closed crown area of the forests. Occasionally, however, they come on the ground to sunbathe.
food
Yellow-naped bowerbirds are omnivores, but fruits dominate the nutritional composition. They eat a very wide range of different fruits, as well as flowers, nectar and animal protein. In a long-term study over 33 months in the area of the Sarabah National Park , the food of the yellow-naped bowerbirds observed consisted of 72% fruit, of which 19 percentage points are figs . 14 percent came from flowers, buds and nectar. Leaves made up two percent and animal protein made up 12 percent. The composition of the food shifts over the course of the year. Leaves are usually eaten outside of the breeding season. The leaves of passion flowers ( Passflora subpeltata ) are particularly frequently eaten. An animal food Gold neck foliage birds eat predominantly Huatflügler with a body length of less than 5 millimeters and leafhoppers . Usually they peck them from the leaves.
Most of the fruits eaten are yellow-red or blue-black. Yellow-naped bowerbirds typically peck the fruit directly from the branches. Small fruits are occasionally picked from branches by standing in front of the branches shaking in the air. Large fruits are torn apart on the spot. Yellow-naped bowerbirds tolerate other fruit-eating bird species, but other bowerbirds are usually driven away by them. They can almost always prevail against silky arborebirds and drive away most of the green arboreal birds and often also golden-eared honeyeater . Crested fruit pigeons , on the other hand, are more assertive than gold-naped bowerbirds.
The females of the yellow-naped bowerbirds usually also chase away the somewhat smaller males at suitable feeding places. They approach the males with closed but raised wings and open beak. At artificial feeding places there is also antagonistic behavior between the females. Usually the female who first shows an aggressive behavior pattern is also the one that prevails.
Reproduction
Yellow-naped bowerbirds are polygamous. The adult males build an arbor that lasts for a short time and, if possible, mate with several females in their courtship area. The female raises the offspring alone.
Construction of the arbor
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The male searches the ground to erect an arbor and perform his courtship ritual. Due to the way its arbors are built, the yellow-naped bower bird is one of the "avenue farmers". The arbors are usually well hidden in the vicinity of thickets of climbing plants in places where the surrounding trees have not yet reached too great a height and the canopy is not tightly closed. The arbors usually face north-south. As a rule, it is only sexually mature, adult males that erect complete arbors. Subadult males that are not yet sexually mature "practice" building arbours from around three years of age, but usually do not finish the arbors. The fact that males raised individually in captivity only build incomplete arbors suggests that they partially copy the arboreal hoof in older males.
The male first builds an elongated platform out of twigs and fibers, which he presses down with his beak. As soon as this platform has a height of about 1.5 centimeters, he erects the walls on the sides by sticking branches with a diameter of one to one and a half millimeters vertically into the earth. They are not intertwined by the male. Small branches that touch each other are often intertwined by a whitish fungus that naturally settles in the humid climate.
The two walls to the left and right of the arcade can reach a height of up to 30 centimeters. However, the majority of the built-in branches are no longer than 10 to 15 centimeters. Only very rarely do they come together like a roof. The walls are so far apart that the bird can just walk in the avenue without being cramped. The finished avenue is about 36 centimeters long and 25 centimeters wide. In eight arbors examined in more detail, an average of 432 branches were built, which together weighed 182 grams. In the most elaborate arbor, the number of built-in twigs was 686, which together weighed 274 grams.
Decorating the arbor
Yellow-naped bowerbirds are among the bowerbirds that decorate their arbor with objects and paint parts of the arbor with crushed plants and fruits.
In the arcade and occasionally at the entrance to the arcade, the male places various objects as jewelry, including leaves, berries, snail shells but also objects such as pieces of metal, glass or plastic parts. In the 33 fully erected arbors in the Sarabah region, the arbors were decorated with an average of 10 objects. The most decorated arbor contained 23 objects. Of the total of 341 objects that were used for decoration, 14% were human-made objects such as plastic parts. The most common decorative objects were green leaves, the paper coverings of the fruits of Rhodosphaera rhodanthema , snail shells and pieces of blue plastic. Clifford and Dawn Frith point out that yellow-naped bowerbirds have a preference for blue decorative objects, but these are very rare in the wild and therefore human-made objects can be found comparatively often in the arbors of the yellow-naped bowerbird.
Not all of the arbors are painted. To paint, the male chews leaves and / or fruits and leaves them on the ground. He then returns to this pile of paint several times and then uses his beak to apply the chewed plant material to the inner walls of his arcade by pecking or wiping sideways. Red and yellow-brown colors are preferred. All leaves and other loose objects are removed from a circular area around the arbor.
Construction time and inventory
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It takes a yellow-naped bower bird about three hours to build a rudimentary arbor. According to observations in Sarabah, the males spend only about 3% of their day in the direct vicinity of the arbor. 23 percent of this is accounted for by building the arbor and 39 percent for maintaining the arbor. Maintenance includes redecorating the decorative objects, removing leaves, removing damage and painting the arbor. 37 percent are allotted to times when the male is sitting or courting quietly near the arbor.
The arbors of the yellow-naped bowerbirds usually only exist for a few days. If an arbor is destroyed or even discovered by a rival male, the male gives up his arbor and builds a new one elsewhere. A male that gives up his arbor usually destroys it himself. One percent of the time a male spends near arbor is therefore the time it takes if the males destroy their arbor after a competing male has discovered it. Usually afterwards it builds a new arbor nearby. Of the 33 completed arbors of the yellow-naped bowerbird in the Sarabah region , twenty had existed for a period of no more than 10 days. Only five were used by the male for more than 25 days.
Courtship
In front of and in such an arbor, the male performs courtship and mates with the female. During the courtship ritual, the male unfolds his wings to bring out his bright colors even better. There are panting and panting hissing noises. Occasionally there are also fights between rival males. The male attracts females with his courtship and song. However, it can take several weeks for a female to bond with the male because the female chooses the male after the arbor or the courtship dance. Mating takes place in the arbor. After mating, the female immediately leaves the arbor to build a nest. The male mates for several weeks in the hope of finding new partners.
Rearing the young birds
The rearing of the young birds is the responsibility of the female. The females build a bowl-shaped nest out of twigs on a forest tree. The clutch usually consists of two white or mottled gray eggs that are speckled yellow, reddish or black-violet. The young birds hatch after 19 to 24 days. After three weeks, the young birds leave the nest.
Yellow-naped bowerbirds and humans
The yellow-naped bowerbird was a more common captive bird for several decades, both in Australia and outside. Yellow-naped bowerbirds were kept in Great Britain as early as 1867, the London Zoo kept this species of bowerbird as early as 1905/1906. It was first bred in captivity in 1905. The yellow-naped arborvitae is currently being bred regularly in Australian zoos. Bred yellow nack bowerbirds are still occasionally offered in the bird trade in Australia today. A pair, both of which have been shown to have been bred in captivity, were offered in Sydney in 2000 for 1500 Australian dollars.
In captivity, despite the polygamy of the species, it is not possible to keep a male with more than one female. Females are aggressive towards the male and just as they hunt a male out of a fruit-bearing tree in the wild, in captivity it can happen that a female keeps the male away from the food or even wounds or kills it through attacks. The male must therefore be removed from the aviary as soon as the female has laid eggs. The females have to be offered a lot of insect food during the rearing of the young birds, as they hardly feed the nestlings any fruit.
literature
- Clifford B. Frith, Dawn. W. Frith: The Bowerbirds - Ptilonorhynchidae . Oxford University Press, Oxford 2004, ISBN 0-19-854844-3 .
- Bernhard Grzimek: Grzimeks animal life. Volume 7-9 birds , Deutscher Taschenbuchverlag GmbH & Co. KG, Munich 1993
- Gottfried Mauersberger, Wilhelm Meise: Urania Tierreich, 7 vols., Birds , Urania, Stuttgart 1995
- David Attenborough: The Secret Life of Birds . Verlag Scherz, 1999
Web links
- Sericulus chrysocephalus in the endangered Red List species the IUCN 2011. Posted by: BirdLife International, 2009. Accessed November 13, 2011th
Individual evidence
- ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae . P. 349.
- ↑ Sericulus chrysocephalus in the endangered Red List species the IUCN 2016 Posted by: BirdLife International, 2016. Retrieved on April 1, 2017th
- ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae . P. 347.
- ↑ a b Handbook of the Birds of the World zum Goldaubenvogel , accessed April 1, 2017
- ↑ a b c Frith: The Bowerbirds - Ptilonorhynchidae . P. 348.
- ↑ a b c Frith: The Bowerbirds - Ptilonorhynchidae . P. 350.
- ↑ a b c d e f Frith: The Bowerbirds - Ptilonorhynchidae . P. 351.
- ↑ a b c d e Frith: The Bowerbirds - Ptilonorhynchidae . P. 352.
- ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 353.
- ↑ KRL Hall: Tool-using performances as indicators of behavioral adaptability [1]
- ^ AH Chisholm: The use by birds of "tools" or "instruments". Ibis Volume 96, Issue 3, pages 380–383, July 1954 [2]
- ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae . P. 354.
- ↑ a b c Frith: The Bowerbirds - Ptilonorhynchidae . P. 360.
- ↑ W. Grummt, H. Strehlow (Ed.): Zoo animal keeping birds . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1636-2 , p. 748