Yellow-headed
| Yellow-headed | ||||||||||||
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Yellow-headed or mohua |
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| Mohoua ochrocephala | ||||||||||||
| ( Gmelin , 1789) |
The yellow-headed yellowhead (in New Zealand yellowhead or in Maori Mohua , Mohoua ochrocephala ) is a small insectivorous passerine bird that is endemic to the South Island of New Zealand . It belongs to the monotypical family Mohouidae , which only three species of birds belong to. Within this family, the yellow-headed species is the heaviest, although the white-headed species is similar in body length. The third species, the brown-headed , is around two centimeters smaller than the yellow-headed.
The yellow-headed population has been declining since the 1880s. The main cause is the disappearance of forests and the introduction of species such as deer and possums , which changed the composition of the forest flora. The IUCN estimates the stock of yellow head as vulnerable ( endangered ) a.
Appearance
anatomy
The yellow head reaches a body length of 15 centimeters, of which 6 to 7.3 centimeters are on the tail. the wing length is 7.7 to 8.5 centimeters, the beak is 1.4 to 1.7 centimeters long. They weigh a weak 23 and 32.5 grams. There is no pronounced gender dimorphism .
Adult birds
The head and neck are bright yellow with an olive tone or olive-colored patches on the center back of the neck. In many individuals, the parting is also slightly olive-colored. Males tend to have more yellow head and neck plumage. The rest of the upper part of the body is olive-colored, with the upper tail-coverts a little lighter and the tail plumage on the upper side a little more yellow. The underside of the body is predominantly bright yellow, the lower abdomen, rump and tail-coverts are whitish with a yellowish tinge. In many individuals, the flanks and sides of the chest also have an olive shade.
The beak, the inside of the beak, the legs and feet are black. The iris is black-brown.
Fledglings
Young birds are very similar to adult birds, but they still have an olive-colored crown.
Possible confusion
The yellow head is only introduced in the 19th century in New Zealand Goldammer confused, which is widely used there now and the males also have a bright yellow head, neck and lower body. However, the goldenhammer colonizes more open habitats than the golden head.
Distribution area and habitat
The yellow-headed species occurs disjointly on New Zealand's South Island. The habitat are large contiguous areas of pseudo-beech forests . It is particularly common in forests that are dominated by red or silver beeches . It needs stocks with old, tall trees, because only these with their branch holes offer the yellow-headed sufficient nesting opportunities.
Way of life
The yellow-headed species lives in pairs or in small family groups during the breeding season. Outside the breeding season, larger groups form, which can contain up to 40 individuals. It is then sometimes with brown heads and other small songbirds such as the Gray Warbler socialized, especially common but it is near Spring parakeets to see that the flat tail parakeets belong. These mixed swarms fall due to their curious and restless behavior and are often widely audible. They mainly look for food in the upper to middle canopy area. During their foraging for food, golden heads occasionally come to the ground or settle on tree trunks lying on the ground.
Yellow-headed birds are mainly insect-eater, but occasionally also eat fruit or drink nectar. While foraging for food, they see insects from the foliage, twigs, branches and tree trunks. They also tear off bits of bark and moss or examine crevices and hollows in tree trunks for insects. During their foraging, they often hang upside down from the branches or they sit on the tree trunks and support themselves with their stiffened tails.
Reproduction
Breeding season, nest and clutch
Yellow-headed breed from October to February. The peak of the breeding season is in early November, a second, but less pronounced, peak falls between late December and early January, when most yellow-headed pairs begin to raise a second brood. Young birds can be seen from the beginning of November to around the beginning of March.
The nest is built in hollows in tree trunks and branches of large beeches. It is often located high up in the crown area. A bowl-shaped nest is built in the caves, made of small roots, small twigs, grass and plant fibers. The clutch consists of one to four eggs. There is no significant difference between the clutch size of the first brood and the second brood. The female lays the eggs one to two days apart. It begins with the brood as soon as the clutch is complete. The breeding season lasts about 21 days and the female breeds alone. During the breeding season, the male provides food for the female. The nestlings are naked when they hatch and do not begin to wear a down dress until they are 7 days old. They are fed by both parent birds.
Cooperative breeding behavior
Yellow-headed birds are one of the bird species in which "helpers" are occasionally found when rearing the young birds: In a population in Arthur's Pass National Park that was observed more closely for over two years , 30 percent of the parent birds had such support in feeding the young birds. In another population residing in the Eglinton River valley , of 63 breeding pairs, 62 had a helper who was always a yellow-headed male. It has not yet been answered whether, as with some other bird species with breeding cooperation, the helper is a descendant of the parent birds from a previous breeding season or a non-related bird that takes on the role of the dominant male when the male dies .
Systematics and risk
The yellow-headed together with the white-headed ( M. albicilla ) and brown-headed M. novaeseelandiae form the endemic songbird genus Mohoua in New Zealand . Since 2013 the genus has been placed in the new monotypical family Mohouidae.
Yellow-headed and white-headed have a sympatric development. The yellow head developed on the South Island, the white head on the North Island and several small surrounding islands. The species was still widespread in the 1800s, especially in beech forests from Nelson and the Marlborough Sounds to the Southland and Stewart Island / Rakiura region . At the beginning of the 20th century, the species of imported rats and martens was severely decimated. Today they have disappeared from 75% of their original range. In New Zealand, the mohua has the status of a protected endangered species, and the IUCN classifies the species as endangered. To preserve the species, it was settled on several islands free from imported predators such as Breaksea Island , in Fiordland and on Ulva Island .
literature
- Barrie D. Heather, Hugh A. Robertson, Derek Onley: The field guide to the birds of New Zealand. Viking Press, Albany 2000, ISBN 0-670-89370-6 .
- PJ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds. Volume 2: Raptors to Lapwings. Oxford University Press, Oxford 1993, ISBN 0-19-553069-1 .
Web links
- Datasheet of the species at BirdLife (English)
- Yellowhead / mohua. on the website of the Department of Conservation
- Mohoua ochrocephala in the endangered Red List species the IUCN 2011. Posted by: BirdLife International, 2008. Accessed November 13, 2011th
Individual evidence
- ↑ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1033.
- ↑ Yellowhead (Mohoua ochrocephala). In: Handbook of the Birds of the World. accessed on June 7, 2017.
- ↑ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1039.
- ↑ a b c Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1032.
- ↑ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1034.
- ↑ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1036.
- ↑ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1037.
- ↑ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds . Volume 2, p. 1035.
- ↑ Frank Gill, David Donsker: IOC World Bird List v 3.5 (online)
- ↑ Zachary Aidala et al. : Phylogenetic relationships of the genus Mohoua, endemic hosts of New Zealand's obligate brood parasitic Long-tailed Cuckoo (Eudynamys taitensis). In: Journal of Ornithology. 154.4, 2013, pp. 1127-1133. (on-line)