Palm cockatoo
| Palm cockatoo | ||||||||||
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Young female Palm Cockatoo ( Probosciger aterrimus ) on the Cape York Peninsula |
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| Scientific name | ||||||||||
| Probosciger aterrimus | ||||||||||
| ( Gmelin , 1788) |
The Palm Cockatoo or Arakakatu ( Probosciger aterrimus ) is a species of parrot . Among the more recent species of cockatoo, this species is the first to separate from the ancestors of the cockatoo in Australia. The Palm Cockatoo is the only representative of its genus.
The black plumage, the unusually large beak and the bare facial skin are characteristic of the Palm Cockatoo. The gender dimorphism is only weak. Its distribution is limited to New Guinea, a few neighboring islands and the Cape York Peninsula in the extreme northeast of Australia. The Palm Cockatoo is the largest species of parrot in Australia's fauna . He shows an unusual display behavior. Among other things, he drums with sticks, stones or large seeds against dead tree trunks and thus creates a sound that reverberates from far away. They are typical forest birds. Unlike most of the cockatoos, it has only a little distinctive swarming behavior. Swarms that contain more than eight individuals are rare.
description
Palm cockatoos reach a body length of 56 centimeters. The males weigh between 882 and 1040 grams. The females are generally slightly smaller and weigh between 710 and 765 grams.
Male Palm Cockatoos have black plumage. But they cover their feathers with the powder of powder down, so that the body dress often appears blue-gray. The thighs are not feathered. The bare skin of the face changes color depending on the state of excitement and is crimson red in the excited male. The beak is blackish gray. When the beak is compressed, the two halves of the beak only touch at one point. This makes the two-tone tongue visible. This is red, but has a black tip of the tongue. The iris is dark brown.
The females largely resemble the males. Apart from their smaller body size, they differ from them by a noticeably smaller beak. Young birds not yet sexually mature are colored in a similar way to the adults. However, they have yellow feather fringes on the belly feathers and the under wing coverts. The tip of the beak is still horn-colored. The black coloration only occurs at an age of eighteen to twenty-four months.
The flight of the palm cockatoo seems slow and cumbersome to humans. This is due to the wide-reaching wing beats. During the flight they lower their beak on their chest. They are also good sailors and turn their wings downward when soaring.
Possible confusion
In the distribution area of the Palm Cockatoo there is only one other species of Cockatoo, the Banks Black Cockatoo, which has blackish plumage. The palm cockatoo is easy to distinguish from the Banks black cockatoo on the basis of the usually bristling feather bonnet. The Palm Cockatoo also has a more conspicuous facial skin, a significantly stronger bill and completely dark tail plumage. Banks cockatoos, on the other hand, have red transverse bands in their tail plumage.
distribution and habitat
The distribution area of the Palm Cockatoo is limited to a small part of north-east Australia, the so-called Cape York Peninsula , and to parts of the island of New Guinea . In the heartland of the distribution area, which includes New Guinea, West Irish and Papua New Guinea, Palm Cockatoos can be found in all habitats except in the higher mountain regions. They use densely forested savannas up to altitudes of meters above sea level and are particularly common in the mangrove swamp areas of the coasts.
It lives in pairs and in small groups in tropical primary and secondary rainforests as well as in savannas with a lot of trees and is a resident bird . In contrast to the red-headed parrot and the noble parrot , the palm cockatoo is less tied to the rainforest. It can also be found in the savannah, but never more than a few hundred meters from the edge of a rainforest or a watercourse lined with gallery forest. The palm cockatoo can therefore also be found in the eucalyptus savannah, if it still has small rainforest islands.
behavior
Palm cockatoos live singly or in pairs. Occasionally they can also be found in small schools, which however never contain more than 30 individuals. Basically, they are loud, loud birds that are happy to call, observe their surroundings attentively and are very curious. Outside of the breeding season, they allow humans to approach within around 20 meters. They sit more often on exposed branches or can be seen flying above the tree canopy. Their behavior changes during the breeding season: They are noticeably shy and their calls are less audible. Palm cockatoos resting together keep a distance of about two meters from each other. They leave their resting places shortly after sunrise.
Palm cockatoos living in flocks show a very noticeable imposing behavior, which is accompanied by a two-syllable contact sound. At the first syllable of the call, the Palm Cockatoo assumes a very upright posture. The hood is only slightly raised. When the second, elongated syllable is called, the bird bows jerkily forward, spreading its wings and spreading its hood. Palm cockatoos usually rest on bare branches of large trees in protected areas of the savannah forests or on the edge of the rainforest. Often the same trees are used regularly.
Palm cockatoos also show a very unusual marking behavior: with the help of branches, stones or a large seed, they hit a dead tree and thus produce reverberant knocking noises. The hood is ruffled, the wings are spread out and the cheeks are colored intensely red. According to previous observations, this marking occurs all year round, but particularly more frequently in the months of June and July. Occasionally the birds hit the tree trunk up to 100 times. In addition, they use the same trees over and over again, so that over time they have noticeable markings.
food
Palm cockatoos feed mainly on nuts, buds, fruits and seeds of all kinds. Insects and larvae are also occasionally on their menu. Among other things, they eat the seeds of the katappen tree , screw trees and silver areas . The ripe fruits of the screw trees resemble a large pineapple, each segment of which has a small core surrounded by hard, fibrous pulp. Palm cockatoos eat both the kernels and the pulp and also ingest the fruit on the ground. They usually find their food in the treetops, but occasionally they come to the ground to take up fallen fruit.
Reproduction
Palm cockatoos are monogamous. Once a couple has been bonded, the couples exist until one of the partners dies. Nests can be found in all months of the year. But there is a tendency towards seasonal breeding. The peak of oviposition is in August.
Palm cockatoos breed in tree hollows. Couples visit their nesting trees year round, inspecting the nest cavity and adding additional nesting material. Territorial or aggressive behavior is rarely observed in both captivity and the wild. However, males defend their territory and drive other males out of the vicinity of the nest building.
Evidence of nesting is mainly from Australia and there especially from the tree savannah, as these nests are easier to find and the Australian population has been better studied than that in New Guinea. Breeding trees in the areas examined were between 6 and 37 meters high. The nest holes were usually between 10 and 13 meters above the ground. A breeding cave is on average 1.3 meters deep with a diameter of 25 to 60 centimeters. The Palm Cockatoo is one of the few parrot species that bring in nesting material from outside. A similar behavior is only known in parrots from the taranta parrot , the orange and gray-headed and the pink cockatoo . There are several layers of split twigs at the bottom of the nest box. In extreme cases - if the nest hole is very deep - the layer can be up to two or three meters deep. It is not entirely clear why palm cockatoos build a nest base from split branches. It is possible that the branches allow rainwater to drain, as many nesting holes are unprotected against the ingress of water. The registered green parts of the plant also increase the humidity in the nest cavity and thus make it easier for the young birds to hatch later.
The clutch of the Palm Cockatoo consists of an egg. The eggs vary considerably in shape and size. There are very different descriptions of the male's brood participation. According to studies by some authors, only females breed in the wild; in the case of Palm Cockatoos breeding in captivity, pairs have been observed in which only the female brooded as well as those in which the male took part in the incubation of the individual egg. The breeding season is about 33 days. The palm cockatoo has one of the longest breeding seasons among parrots. A comparable breeding period can only be found in the Moluccan and White-hooded cockatoos as well as in the hyacinth macaw . Newly hatched nestlings are naked. The eyelids and ear opening are initially closed. The eyes open from the 17th day of life. The young bird leaves the nest at around 80 days of life. It is then fed by both parent birds for a period of three to four months. In the case of Palm Cockatoos that were reared in captivity, however, the time during which the parent birds fed their young birds varied greatly: periods of between 6 weeks and 8 months were observed.
Palm cockatoos in human care can reach an age of more than 40 years.
Systematics
The number of subspecies belonging to this cockatoo species is debatable. In addition to the nominate form living on the Aru Islands, up to three other subspecies are distinguished. Body size is often used as a distinguishing feature. However, studies using bellows in museums as early as the 1970s showed that the differences in body size did not follow any recognizable geographical rule. It has therefore been proposed to completely dispense with a distinction between subspecies. In his 2003 work on Australia's parrots, ornithologist Joseph Michael Forshaw mentions the Cape York Palm Cockatoo ( P. a. Macgillivrayi ) as a subspecies in addition to the nominate form Probosciger aterrimus aterrimus . This occurs in southern New Guinea and in the far north of Australia. However, he does not rule out the existence of possible further subspecies in New Guinea and in the western Papua region.
Palm cockatoos and people
Palm cockatoos are very rarely kept in human care. They are listed in Appendix I of the Washington Convention on Endangered Species . This means that trading in this rare species of cockatoo is generally prohibited.
Singapore only signed the Washington Convention on Wildlife Conservation in 1989. Between the mid-1970s and the time it was signed, hundreds of wild-caught Palm Cockatoos were exported through Singapore. Such catches often cause great damage to the wild population, as nesting trees are often felled or adult birds are shot. There was no sustainable breeding of these birds. Basically, the Palm Cockatoo is one of the most difficult parrots to breed.
Palm cockatoos are only shown in a few zoos today. In Germany, these include the Walsrode Bird Park and the Berlin Zoo . Often these animals are confiscated by customs or - especially in Australia - palm cockatoos that are unable to survive due to injuries in the wild. You need very large aviaries with a warm, humid climate and only very little temperature fluctuations. Palm cockatoos do not show the unusual drumming in captivity. Presumably the aviaries are too small to trigger this territorial behavior.
literature
- Bruce M. Beehler & Thane K. Pratt: Birds of New Guinea: Distribution, Taxonomy, and Systematics Princeton University Press, Princeton, New Jersey, 2016, ISBN 978-0691164243 .
- Sharmila Choudhury, Adam White: Parrots. The new compact identification book ("Parrots. The new compact study guide and identifer", 1997). Könemann, Cologne 1999, ISBN 3-8290-1291-8 .
- Joseph M. Forshaw : Australian Parrots, Vol. 1 ("Australian Parrots," 1981). Arndt-Verlag, Bretten 2002/03 (2 vol.)
- 2002, ISBN 3-9808245-1-9 .
- 2003, ISBN 3-9808245-2-7 .
- Peter J. Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Bird, Vol. 4: Parrots to Dollarbird . Oxford University Press, Oxford 1999, ISBN 0-19-553071-3 .
- Dieter Hoppe : Cockatoos. Way of life, keeping and breeding . Eugen Ulmer Verlag, Stuttgart 1986, ISBN 3-8001-7155-4 .
- Werner Lantermann: parrot science. Biology, behavior, husbandry, species selection of parakeets and parrots . Parey, Berlin 1999, ISBN 3-8263-3174-5 .
- Ken Simpson, Nicolas Day (Ed.): Field Guide to the Birds of Australia . Christopher Helm Publ., London 1989, ISBN 0-7470-3023-5 .
Web links
- Videos, photos and sound recordings for Probosciger aterrimus in the Internet Bird Collection
- Probosciger aterrimus inthe IUCN Red List of Threatened Species 2013.2. Listed by: BirdLife International, 2012. Retrieved December 26, 2013.
Individual evidence
- ↑ a b c Joseph M. Forshaw, p. 52.
- ↑ a b Dieter Hoppe , p. 75.
- ^ Joseph M. Forshaw, p. 52 and p. 53.
- ↑ a b Joseph M. Forshaw, p. 53.
- ↑ Dieter Hoppe, p. 72.
- ↑ a b Higgins (HSG.): Handbook of Australian, New Zealand & Antarctic Birds: Volume 4 Parrots to Dollarbird . P. 32.
- ^ Joseph M. Forshaw, p. 54.
- ↑ a b c Joseph M. Forshaw, pp. 56 and 62.
- ↑ a b Joseph M. Forshaw, p. 55.
- ↑ Higgins (HSG.): Handbook of Australian, New Zealand & Antarctic Birds: Volume 4 Parrots to Dollarbird . P. 33.
- ↑ a b c Joseph M. Forshaw, p. 59
- ^ Joseph M. Forshaw, p. 60.
- ↑ Higgins (HSG.): Handbook of Australian, New Zealand & Antarctic Birds: Volume 4 Parrots to Dollarbird . P. 34.
- ↑ Higgins (HSG.): Handbook of Australian, New Zealand & Antarctic Birds: Volume 4 Parrots to Dollarbird . P. 35.
- ↑ a b Werner Lantermann, p. 168.
- ^ Joseph M. Forshaw, p. 61.
- ↑ Higgins (HSG.): Handbook of Australian, New Zealand & Antarctic Birds: Volume 4 Parrots to Dollarbird . P. 37.
- ↑ Werner Lantermann, p. 176.
- ↑ Higgins (HSG.): Handbook of Australian, New Zealand & Antarctic Birds: Volume 4 Parrots to Dollarbird . P. 36.
- ↑ a b c Joseph M. Forshaw, p. 63.
- ^ Joseph M. Forshaw, p. 64.