Gold birds
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Yellow-naped bowerbird ( Sericulus chrysocephalus ), male, Queensland, Australia |
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| Swainson , 1825 |
The golden birds ( Sericulus ) are a genus of bower birds . There are three or four species in this genus. It is not yet clear whether the flaming arborebird ( Sericulus ardens ) is classified as a subspecies of the golden arborebird or as an independent species. All species occur in New Guinea or Australia. The species found in New Guinea colonize mountain rainforests, while the yellow-naped bowerbird, native to Australia, occurs in subtropical forests in Eastern Australia and can also be found in forests on the lowlands. Its distribution area extends from the north of Sydney to the southeast of Queensland .
The IUCN classifies the population of the red-crowned bowerbird as potentially endangered ( near threatened ). The red-crowned bowerbird is endemic to the secluded and inaccessible Adelbert Mountains of Papua New Guinea , where it inhabits an area of around 570 square kilometers. Wherever the red-crowned bowerbird finds suitable habitats, it is relatively common. Due to the small distribution area, the IUCN assumes fewer than 10,000 sexually mature individuals. The inaccessibility of the mountains helps protect the bird. The IUCN also sees no decreasing population trend for this species. The other species are classified by the IUCN as not endangered ( least concern ).
Of the species in the genus, only the yellow-naped bowerbird found in eastern Australia has been studied more extensively.
Position within the bowerbird family
The golden birds are closely related to the silkworm bird , the only representative of the genus Ptilonorhynchus , and the species of the genus Chlamydera . All types of these three genera build arbors and that of the " Allee " type .
The skull of the Sericulus species has features that can also be found in Ptilonorhynchus and Chlamydera . However, they also share features with the skulls of Amblyornis and Archboldia .
Characteristics of the genus
The golden birds are comparatively small bower birds with a body size of up to 27 centimeters. The beak is slender and either the same or slightly longer than the head. All species show a very pronounced sexual dimorphism . The tail plumage is comparatively short in relation to the length of the body, especially in males. The wings are short and rounded. They have 12 to 13 arm swings . The legs correspond in length to 29 percent of the wing length, which is long compared to the species within the bowerbird family. But they are less strongly built than in the other genera of this family.
All species show a pronounced sexual dimorphism. The males have a shiny metallic black plumage with yellow, yellow-red or orange feathers that stand out from the rest of the body's plumage. These characteristics are also reflected in the German names for the individual species. The females, on the other hand, are much less conspicuous in color. On the upper side of the body, they are olive-colored to gray-brown, the side of the body is somewhat lighter and often appears scaly due to darker feather edges. In the well-studied yellow-naped bowerbirds, it has been found that some females develop features of the male's plumage to a small extent. This includes, in particular, the development of a yellow feather border on the black apex and yellow feather areas on the wings of the hand . With them, the beak also partially brightens. It is believed that these traits are only developed by very old females.
species
A maximum of four types are distinguished, which are now classified as monotypical:
- Yellow-naped bower bird or velvet gold bird ( Sericulus chrysocephalus )
- Flame arborebird ( Sericulus ardens )
- Golden arboreal bird or golden papua bird ( Sericulus aureus )
- Red-crowned bowerbird ( Sericulus bakeri )
For the yellow-naped bower bird, two subspecies were distinguished until a few years ago. 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.
food
The diet consists of fruits, leaves, buds, nectar and, to a lesser extent, invertebrates. The young birds are mainly fed animal protein.
Reproduction
All species are polygamous. The male mates with several females. The female takes care of nest building, incubation and rearing of the young alone. The nest is a shallow, bowl-like nest made of twigs on trees. The clutch consists of one to three eggs. The incubation period is between 19 and 24 days.
Arbor construction
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The golden birds belong to the bower birds that erect arbors for courtship, which are adorned with objects that the males often collect according to their color. This courtship behavior is so unique in the bird world that the American ornithologist Ernest Thomas Gilliard stated that the order of birds can actually be divided into two groups: bowerbirds and all other bird species.
The details of the arbor is the worst studied of the golden bird species found in New Guinea. For example, at the end of the 1960s, Ernest Thomas Gilliard and numerous assistants searched in vain for such an arbor of the red-headed bowerbird for several weeks, so that for almost two decades it was assumed that this type of bowerbird was one of those that did not have this elaborate courtship behavior demonstrate. The first arbors of this type were only discovered in September 1986.
All arbors that are erected by golden bird species belong to the so-called avenue type. In an avenue type, the male erects two parallel walls made of small branches along a slightly raised platform. The yellow-naped bower bird partially paints the inner walls of the arcade with crushed plant pulp. To what extent this also occurs with the other species cannot yet be conclusively stated.
It takes a yellow-naped bower bird about three hours to build a rudimentary arbor. The finished avenue is about 36 centimeters long and 25 centimeters wide. In eight arbors of this type 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. According to observations in the Sarabah region , the males only spend about 3% of their day in close proximity to 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 last only a few days, at least in the case of the yellow-naped bowerbird. They are destroyed by rival males, the yellow-naped bower bird also destroys its arbor itself if it was discovered by a competing male. Of 33 completed yellow-naped bowerbird arbors in the Sarabah region , twenty had been in existence for a period of no more than 10 days. Only five were used by the male for more than 25 days.
Golden birds and people
Of the golden bird species, only the yellow-naped bower bird plays a role in captivity. 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. The first breeding in captivity was successful in 1905. The yellow-naped bowerbird is currently being bred regularly in Australian zoos. Bred yellow-naped bowerbirds are still occasionally offered in the bird trade in Australia today. A pair known to have come from captivity was offered in Sydney in 2000 for 1500 Australian dollars.
literature
- Clifford B. Frith, Dawn. W. Frith: The Bowerbirds - Ptilonorhynchidae . Oxford University Press, Oxford 2004, ISBN 0-19-854844-3 .
Single receipts
- ↑ Handbook of the Birds of the World zum Goldlaubenvogel , accessed April 1, 2017
- ↑ a b Sericulus bakeri in the Red List of Threatened Species of the IUCN 2016.3. Posted by: BirdLife International, 2016. Retrieved April 1, 2017.
- ↑ Sericulus chrysocephalus in the Red List of Threatened Species of the IUCN 2016.3. Posted by: BirdLife International, 2016. Retrieved April 1, 2017.
- ↑ a b c Frith: The Bowerbirds - Ptilonorhynchidae . P. 332.
- ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 347.
- ^ IOC World Bird List 6.4 . In: IOC World Bird List Datasets . September. doi : 10.14344 / ioc.ml.6.4 .
- ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 348.
- ↑ Handbook of the Birds of the World zum Goldlaubenvogel , accessed April 1, 2017
- ↑ W. Grummt, H. Strehlow (Ed.): Zoo animal keeping birds . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1636-2 , p. 746.
- ↑ Jennifer Ackerman: The Genius of Birds . Corsair, London 2016, ISBN 978-1-59420-521-7 , p. 159.
- ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 345.
- ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae . P. 352.
- ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 351.
- ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 354.
- ↑ a b 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
