Bowerbirds

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Bowerbirds
Male silkworm bird (Ptilonorhynchus violaceus)

Male silkworm bird ( Ptilonorhynchus violaceus )

Systematics
without rank: Neornithes
Subclass : New-jawed birds (Neognathae)
Order : Passerines (Passeriformes)
without rank: Eupasseres
Subordination : Songbirds (passeri)
Family : Bowerbirds
Scientific name
Ptilonorhynchidae
Gray , 1841

The bower birds (Ptilonorhynchidae) are a family in the order of the passerine birds (Passeriformes), which occur exclusively in Australia and New Guinea. The name of the family is the arbor building, the courtship place of the males with which they try to attract a female. These arbors are built by 17 of the 20 species in the family and decorated with objects that the males often collect according to their color. This courtship behavior is so unique in the bird world that the ornithologist Ernest Thomas Gilliard stated that the order of birds could actually be divided into two groups: bower birds and all other bird species. Bowerbirds are often counted among the most intelligent species among birds. Their brains are very large in relation to their body weight, they are comparatively old and it takes several years to reach sexual maturity. Most species are polygamous .

The silky bowerbird, native to eastern Australia, is considered to be the best-researched and best-known bowerbird . It was already kept as a cage bird in Australia in the second half of the 19th century. In contrast, the bowerbirds found in remote mountain regions of New Guinea have not been well researched. For example, the diet and reproduction details in the red-crested gardener are still unclear. The yellow-crowned gardener was scientifically described in 1895 on the basis of some bird hides, but living individuals were not observed until 1982 in the Foja Mountains . It was not until 2005 that some individuals were also able to be photographed.

There is a close relationship to the birds of paradise . Like these, the bowerbirds occur in New Guinea , the neighboring islands and in Australia .

features

With a body length between 23 and 36 centimeters, bowerbirds are medium-sized, very differently colored feathered songbirds. With them, the back toe is always a little shorter than the middle toe. The males of this family are not as brightly colored as the closely related birds of paradise, but some species have a feather bonnet or elongated head feathers. In a number of species, the males have feathers that have a metallic sheen and bright highlights when the light falls. A sexual dimorphism is present in several of the species. In the species of the genus Chlamydera , on the other hand, there is little or no sexual dimorphism.

voice

Column gardener, male
( Prionodura newtoniana )

Numerous species of bowerbirds are excellent scoffers, imitating bird calls and sounds from the environment. The imitation of the human voice has even been described for the brown-bellied bowerbird . It also mimics the sounds of its surroundings such as fast flowing water, the neighing of horses and the hoof noises of shod horses. A three-speed bower mimicked the sound of water running quickly over gravel, the squeaking of pigs, the sound of a chainsaw, and hammering. Archbold bowerbirds also mimic the rustling sound that dead screw tree leaves make when they rub against each other in the wind and the sound when such a leaf falls from the tree to the ground.

Imitated songbirds

Bowerbirds also imitate the calls of numerous bird species in their environment. When inter alia on the Cape York Peninsula occurring Brown abdominal Laubenvogel are the among other noisy friarbird that Balzlaute of silk leaves bird , the voice of the Reinwardt chicken and Sulfur-crested cockatoo . The column gardener's reputation repertoire is even more extensive. Among other things, imitation of the calls of the white-breasted pigeon , Banks black cockatoo , yellow -crested cockatoo and king parakeet were proven . Pennant parakeet , Lärmpitta , yellow Kehl-Sernicornis ( Sericornis citreogularis ) and Fahlburg end-Sericornis ( Sericornis magnirostris ) Grauwangengerogyne ( Gerygone mouki ), stained beak-Honigfresser ( Lichenostomus Ferrand ), slaty-Dickkopf ( Colluricincla boweri ) Glasses Monarch , Pied Currawong , Victoria bird of paradise , black-eared bower bird and silk arbor bird. In addition to at least 44 different species of birds, the toothed arbor bird also imitates the sounds of fruit bats , frogs and cicadas.

Teeth bower birds often react opportunistically and react, for example, to flocks of pennant parakeets or yellow-crested cockatoos flying past by imitating their calls. Often they call alternately with the imitated bird species, that is, they answer, for example, to the calls of the fern flycatcher , which in turn responds to their calls. Neighboring males also follow each other's calls and also imitate their bird's voice imitation.

Imitation of predators when threatened

Both breeding females of the gray bower and the males of this species near their arbor imitate the calls of predators. Among other things , there is evidence of the imitation of the calls of the wedge-tailed harrier ( Haliastur sphenurus ), Papuan harrier ( Aviceda subcristata ) and black kite . A female with two newly hatched cubs flew up, took cover in the bushes and imitated the calls of the Jägerliest and the blue-eared honey eater , known for reacting to predators with hatred when someone approached the nest. There is also other evidence for the targeted use of imitation sounds: A gray bower bird perched on a branch above a sleeping cat observed it and imitated meowing until the cat left the area. Something similar has been described for the column gardener and the spotted arborebird . Spotted arborebirds then mainly imitate the calls of the wedge-tailed harlequin. However, imitations of the calls of the wedge-tailed eagle , gray-headed saber ( Pomatostomus temporalis ), New Holland crows , flute birds , hooded birds , gray-backed crows , black-throated crows and jays , all of which eat young birds and eggs, have also been proven. A female of the column gardener, who tried to seduce a predator from her nestling, initially imitated the calls of various nest robbers such as the mangrove heron , the hooded heron , the black-backed crow's shrike and later, when the situation relaxed again, let the calls of the garden fan-tail be heard.

Way of life

Spotted arborebird
( Chlamydera maculata )

Bowerbirds spend a lot of time on the ground. The trees are brooded. They look for their food on the ground and on trees and bushes. They have a strong beak and strong legs. In the plumage color, the females are mostly brown or gray. In the inconspicuously colored males there are some species in which the male has a conspicuous hood hidden in the head feathers, which is only put up for a short time during courtship.

Instead of the 9-10 armwings typical of songbirds, including umbrella feathers, bowerbirds have 11-14. The brain, especially that of arboriculture species, is also larger than that of other songbirds in the region. The life expectancy of these species is between 20 and 30 years, but the polygamous species need seven years to develop their adult plumage.

Arbor construction

In 17 species of bowerbirds, the males use elaborately built and decorated mating places to win the favor of a female.

The male does not take part in the breeding or rearing of the young birds. Nor does he defend any territory. The female chooses her partner solely on the basis of the quality of the arbor and the mating dance shown. The arbors of the males are in some species no more than 100 meters apart, so that the female has the choice between several males. Some males manage to attract a large number of females with their arbor construction. Very successful males of the silk arborist mate with twenty to thirty females. Other males, however, remain unsuccessful and do not mate. The construction of arbors accordingly plays a major role in the life of the males.

Arbor types

Male of the drop arborebird building the arbor

The arbor construction varies from species to species. The more inconspicuous a male is colored, the more magnificent the arbor is. Since the females mate with the builders of the most beautiful arbors, the ability to build such burrows can be seen as a " secondary sexual characteristic ". Building arbors as an "alternative strategy" to sexual selection - compared to colorful plumage - has the advantage that the males are less noticeable to the predators. The arbors are built on a free, level place in the thicket.

Jared Diamond , as he explains in his book The Third Chimpanzee , sees the arbor construction as a very effective feature for sexual selection , as this enables females to assess many properties of the potential mating partner - including those of their arbor before being destroyed by one Preserve rivals.

Basically, the individuals of a species build the same type of arbor. In one case, an arbor of the gray bower bird was found, which deviated from the basic principle and in its shape was reminiscent of the complex arbors of the three- aisle bowerbird , as the central aisle was short and two more walls were built at the end of the central aisle. If the two walls had been connected, they would have framed the arcade center aisle in a semicircle. This arbor has so far represented the greatest deviation from the respective species-specific construction that has so far been found in arborebirds. The burrows of the bower birds can be divided into three types: courtyard or threshing floor, maypole or avenue.

Arbor type threshing floor

Tennenbauer among the bower birds is the name given to the species that first clean a larger area of ​​the forest floor and then cover it with leaves. The toothed bower bird is one of the best-known species that show this behavior . He lays out leaves on the cleaned surface, turning them so that their paler underside is facing up. The threshing floors are located closer to each other. The biologist Hansell therefore speaks of a Lek-like behavior. In biology, a lek is a courtship place where several males courtship together around a female. The term is mainly used in ornithology , as this form of courtship occurs in a number of species of different bird families.

Deciduous type maypole

Depiction of the hut gardener's arbor from 1921

A total of five species of bowerbirds build an arbor in the maypole type. It is a construction in which branches are joined around a thinner tree trunk or a tree fern. The resulting column of twigs around this trunk is the essential characteristic of this type of arbor.

The golden hood gardener builds the simplest form of this arbor . The maypole is only two or three times the height of the male and consists of a few hundred, finely interwoven branches in the center of an otherwise unadorned moss platform. The yellow-crowned gardener's arbor is similar, but here the area is adorned with small heaps of yellow, green and blue fruits. The arbor of the column gardener is much more elaborate . The most complicated form of this type of arbor is built by the cottage gardener. Over the so-called “maypole”, the hut gardener erects a roof that extends to the ground and opens up to a threshing floor in front of the maypole.

Arbor type avenue

The avenue-building gray bower bird in its arbor
Arbor of the drop arborebird

An avenue usually consists of two parallel walls made of small branches. The most well-known species that erects such arbors is the silk arborebird . The avenue farmers also include the species of the genus Chlamydera and Sericulus .

The most complex type of such "avenue" type arbors is built by the three-flight arborebird . Its arbor has four walls instead of two. The walls of the middle corridor face outwards, while other avenue builders among the bowerbirds either incline their walls inwards or build them vertically. The middle avenue is based on a thick platform made of branches and grass, which extends at both ends of the avenue. At both ends of the platform there is another wall across the main avenue. The arbor thus has a central aisle and two cross aisles. Finished arbors have a length of 71 to 97 centimeters, are 48 to 66 centimeters wide and 36 to 64 centimeters high. The middle corridor is 6 to 8 centimeters wide and 17 to 32 centimeters long. Including the small pebbles and fruits that the males use to decorate the arbors, the construction weighs between 3 and 7.5 kilograms. In a particularly large arbor of the three-flight bower bird, more than 3000 branches were built, more than 1000 blades of grass were laid down and decorated with more than 1000 stones with a total weight of almost 4.5 kilograms.

In the brown-bellied bower bird , the male can be observed near his bower for about eight months a year. In experiments in which a male occupying an arbor was removed, the arbor space was immediately occupied by other males. The male occupying a new arbor space immediately destroyed the existing arbor and built it again. As a rule, the arbor was then smaller. According to Clifford and Dawn Frith, the rapidity with which abandoned arbor spaces are filled indicates that there are more males than suitable places for erecting an arbor.

The males steal the blue decorative material from each other in the silk arboreal birds that also build avenues. The arbors of the males are about 100 meters apart and are therefore out of sight of the individual males. The ability of the males to seek out the arbors of other males is evidence that the males have a mental map of their surroundings. A male looking for the arbor of a neighboring silky arborebird flies noiselessly near it and observes the surroundings from a viewing point. If the arbor owner is not nearby, it will approach the arbor. Some of the males limit themselves not only to stealing decorative material from the arbors of their competitors, but also destroy their arbors with quick movements within a few minutes.

Decorating the arbor

Decorated arbor of the gray bower bird

In a majority of the species, the males decorate their arbors with colored objects. For many species, arbors were also found, which the male painted with fruit or vegetable pulp in certain places. When it comes to decorative objects, the males show a preference for certain colors. The silky arborebird, for example, prefers to decorate its arbors with blue objects - a color that is comparatively rare in the wild - while the drip arborebird shows a preference for whitish objects.

Decorative objects are often seed pods, snail shells, flowers, pebbles or bleached small bone fragments. Decorative objects made by humans are also often used, such as glass fragments, plastic parts and so-called pull tabs from tinplate cans and ammunition cases. The silk arborebird with its predilection for blue objects, for example, often removes blue plastic caps from bottles on its arbors. The number of decorative objects attached can be very high. There are always arbors found with more than 1000 decorative objects attached. In an arbor of the drip arborebird examined near Alice Springs , the male used 1,427 bone objects, 174 snail shells and numerous pebbles and glass and metal fragments. In total, the attached decoration material weighed 7.4 kilograms. More than 1,350 small bones were found in one arbor of the spotted arborviar , and around 1,900 snail shells in another.

To paint the arbor, for example, the male of the yellow-naped bowerbird chews leaves and / or fruits and leaves them on the ground. He then returns to this pile of paint several times and, with the help of his beak, applies the chewed plant material to the inner walls of his arcade by pecking or wiping sideways. Red and yellow-brown colors are preferred.

Learning to build arbours

Brown-bellied bowerbird with twigs in its beak

It has been shown in several species that building an arbor is a learning achievement in which the example of other, older birds is important: The fact that male yellow-naped bowerbirds raised individually in captivity only build incomplete arbors indicates this suggest that they partially copy the arbor construction in older males. The male fledglings of the silk arborist spend a lot of time learning how to build arbors, the perfecting of which largely determines their reproductive success. Young males of this species initially build very inadequate arbors. They typically choose twigs to build the arbor walls that are too thick, too different in length, and have not yet mastered the skill that allows them to build symmetrical walls. The first buildings are pure practice arbors, on which several young birds are often working. They don't work cooperatively on this - a single young bird, for example, builds individual branches, the next young bird destroys the existing structure and starts over, a third adds further branches.

Young birds perfect their technique by imitating older birds. They regularly visit the arbors of older silk arboretists and help out there. They also learn courtship behavior by approaching the arbor similar to a female and watching the male perform his courtship dance and song. The older males tolerate this because they also benefit from the exercise in front of a fellow watching.

Bowerbirds and people

attitude

Several species of bowerbirds are shown in zoos. More commonly kept birds are the species of the genus Ailuroedus , which are monogamous and do not build arbors. With them, the offspring succeed regularly. The white-eared bowerbird in particular was successfully bred from this genus in several zoological gardens. Successful breeders in Germany are the Weltvogelpark Walsrode , Wilhelmina , Heidelberg Zoo and Krefeld . It was also successfully bred from 1998 to 2001 in the Berlin Zoo and in 2007 in the Berlin Zoo. Offspring are also bred at Chester Zoo in Great Britain, the Hong Kong Zoological and Botanical Gardens , the San Diego Zoo and the Los Angeles Zoo . Important findings on reproductive biology were gained in particular at the Krefeld Zoo.

Although most of the arboriculture species kept in captivity build arbors and also courtship, only a few species have so far been successfully bred in captivity. The silkworm bird was bred as early as 1912. There is evidence that it was regularly kept as a cage bird as early as 1860. Already at the beginning of the 20th century it was therefore clear that the male alone builds arbors and that it takes several years for a male to show adult plumage. The brown-bellied bowerbird raised offspring at Cologne Zoo in 2008.

The yellow-naped bowerbird was a commonly kept 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, both of which are known to have been captive-bred, were offered for sale in Sydney in 2000 for A $ 1,500.

Conflicts

Both in the specialist literature and in popular scientific writings there are numerous reports that silky arborebirds and spotted arborebirds remove jewelry, keys and the like from houses, vehicles and tents.

During the winter months, when silkworm birds mainly feed on saplings and occur in larger flocks also in more open terrain, they pose a problem for fruit and vegetable growers, as they eat both cultivated fruit and young leafy vegetables during this time. They also have a particular fondness for maize as it ripens . The green arboreal bird also visits gardens and plantations more often to eat the fruit grown there. He is still shot occasionally for this reason.

Bowerbirds as hunting game

The green arboreal bird was hunted for a long time because its meat was considered delicate. It was mostly shot during hunts aimed at pigeons.

Genera and species

Spotted arborebird
( Chlamydera maculata )
Gray dove bird
( Chlamydera nuchalis )
Yellow-naped Bowerbird , male
( Sericulus chrysocephalus )

Natural hybrids

Natural hybrids occasionally occur where the range of individual species overlaps. The distribution area of ​​the spotted arborebird overlaps to a small extent along the Cape River with the gray bowerbird . Various natural hybrids have been observed between the two species.

literature

  • Jennifer Ackerman: The Genius of Birds. Corsair, London 2016, ISBN 978-1-59420-521-7 .
  • Bruce M. Beehler, Thane K. Pratt: Birds of New Guinea; Distribution, Taxonomy, and Systematics. Princeton University Press, Princeton 2016, ISBN 978-0-691-16424-3 .
  • Jared Diamond: The third chimpanzee . S. Fischer Verlag, Frankfurt am Main 1994, ISBN 3-596-17215-2 .
  • Clifford B. Frith, Dawn. W. Frith: The Bowerbirds - Ptilonorhynchidae. Oxford University Press, Oxford 2004, ISBN 0-19-854844-3 .
  • Mike Hansell: Bird nests and construction behavior. illustrated by Raith Overhill, Cambridge University Press, ISBN 0-521-01764-5 .
  • Laura Kelly, John Endler: Illusions Promote Mating Success at Great Bowerbirds. In: Science Magazine . January 20, 2012, pp. 335-338.
  • Peter Rowlalnd: Bowerbirds. Csiro Publishing, Collingwood 2008, ISBN 978-0-643-09420-8 .

Web links

Commons : Bowerbirds (Ptilonorhynchidae)  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Ackerman: The Genius of Birds. 2016, p. 159.
  2. ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae. P. 365.
  3. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 287.
  4. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 297.
  5. ↑ First photo of the yellow-crowned gardener from 2005 , accessed on April 18, 2017.
  6. ↑ a b W. Grummt, H. Strehlow (Ed.): Zoo animal keeping birds . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1636-2 . P. 748
  7. ↑ a b c d e Frith: The Bowerbirds - Ptilonorhynchidae. P. 398.
  8. ↑ a b c d Frith: The Bowerbirds - Ptilonorhynchidae. P. 391.
  9. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 303.
  10. ↑ Rowlalnd: Bowerbirds. P. 100.
  11. ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 317.
  12. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 262.
  13. ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae. P. 263.
  14. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 427.
  15. ↑ Frith: The Bowerbirds - Ptilonorhynchidae . P. 407.
  16. ↑ a b c Ackerman: The Genius of Birds. P. 165.
  17. ↑ It's all a question of perspective. In: Frankfurter Allgemeine Sonntagszeitung . January 2, 2012, p. 57.
  18. ↑ Jared Diamond: The Third Chimpanzee. Fischer Taschenbuch Verlag, Frankfurt am Main 2000, ISBN 3-10-013912-7 , Chapter 9 “How art arose from the animal kingdom” p. 217 ff., Reference on p. 223.
  19. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 429.
  20. ^ A b c d Hansell: Bird nests and construction behavior. P. 195.
  21. ^ Hansell: Bird nests and construction behavior. P. 196.
  22. ^ KRL Hall: Tool-using performances as indicators of behavioral adaptability. In: Current Anthropology Volume 4, No. 5, 1963 ( abstract ).
  23. ↑ AH Chisholm: The use of birds of "tools" or "instruments". In: Ibis. Volume 96, No. 3, 1954, pp. 380-383, doi: 10.1111 / j.1474-919X.1954.tb02331.x .
  24. ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae. P. 408.
  25. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 420.
  26. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 353.
  27. ^ KRL Hall: Tool-using performances as indicators of behavioral adaptability. ( online )
  28. ^ AH Chisholm: The use by birds of "tools" or "instruments". In: Ibis. Volume 96, No. 3, July 1954, pp. 380-383 ( online ).
  29. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 352.
  30. ↑ a b Ackerman: The Genius of Birds. P. 169.
  31. ↑ Ackerman: The Genius of Birds. P. 170.
  32. ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae. P. 256.
  33. ↑ a b W. Grummt, H. Strehlow (Ed.): Zoo animal keeping birds. Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1636-2 , p. 750.
  34. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 233.
  35. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 386.
  36. ↑ a b Frith: The Bowerbirds - Ptilonorhynchidae. P. 360.
  37. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 409.
  38. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 366.
  39. ↑ Frith: The Bowerbirds - Ptilonorhynchidae. P. 405.