Nepal crested eagle
| Nepal crested eagle | ||||||||||||
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Nepal crested eagle |
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| Scientific name | ||||||||||||
| Nisaetus nipalensis | ||||||||||||
| ( Hodgson , 1836) |
The Nepal Hawk-Eagle or Mountain Eagle ( Nisaetus nipalensis , Syn. : Spizaetus nipalensis ) is a bird of prey art from the family of Accipitridae (Accipitridae). This medium-sized, powerful and very agile eagle inhabits mountain forests on the Indian subcontinent , in Southeast Asia and in Japan , where it feeds on small to medium-sized vertebrates . The worldwide population is considered safe.
description
The external appearance of the Nepal-crested eagle with the broad, relatively short wings and the relatively long and broadly banded tail corresponds more to that of a large member of the genus Accipiter than that of a member of the Aquilinae . The feather hood on the back of the head , which is clearly or weakly developed, depending on the subspecies, is striking .
The body length is 66–84 cm, of which 26–39 cm are on the tail. The wingspan is 134–175 cm. Females are on average 3–8%, occasionally up to 21% larger and probably significantly heavier than males, otherwise the sexes do not differ. Females of the nominate form have a wing length of 445–508 mm, males reach 419–465 mm. So far there are hardly any data on weight; a male of the nominate form weighed 1.83 kg, a female of the largest subspecies N. n. orientalis weighed 3.5 kg, and a male of this subspecies 2.5 kg. The legs are relatively long and, like all members of the subfamily Aquilinae, feathered down to the toes, the toes and claws are very large and strong.
In flight the species looks very broad-winged, with only weakly fingered hand wings and slightly S-shaped rear edge of the wings. The joint is long and clearly rounded at the end.
In adult birds of the nominate form, the upper sides of the trunk and wings as well as the sides of the head are dark brown in one color. The top of the head is black, the feathers on the back of the head, which are lengthened to the hood, have a light brown border. The throat shows a strong black throat stripe on a white background, the beard stripe is also black. The tail and wings are broadly dark banded on top on a brown background. The tail shows a broad dark subterminal band and a narrow white end band.
The sides of the neck, the underside of the trunk, the under-tail-coverts, the legs and the under-wing coverts are broadly, lightly reddish-brown banded or scaled on a white background. The sides of the neck, throat and chest are also variably more or less densely dashed in black. Wings and tail are clearly dark banded underneath on a light gray background. The bases of the hand wings are clearly lightened whitish.
The iris is golden yellow to orange, wax skin and beak are black-gray. The toes are pale yellow, the nails black.
The youth dress differs significantly from that of the adult birds in terms of color and drawing. The upper sides of the wings and fuselage are also dark brown, but all the cover feathers have a whitish edge, so that the upper side appears significantly lighter. The head and back of the neck are dashed in strong brown on a light beige background. The underside of the trunk, the under tail-coverts, the legs and the under wing coverts are monochrome yellowish-ocher. All wings and control feathers show a narrow, dark banding on a light gray background, which is finer and less contrasting than that of the adult birds, and the black subterminal band of the tail is only weakly pronounced.
The irises of the young birds are pale blue-gray or pale yellow, the wax skin is pale gray and the toes are yellow as in adult birds. After the first moult, juveniles show a mixture of juvenile and adult plumage; they are presumably colored after 3 or 4 years and can no longer be distinguished from adult birds.
Vocalizations
The most frequent utterance in the breeding area is a high-pitched , three-syllable call, which is described as " kii-kikik " and which can be heard both in flight and while seated. Apparently only during courtship flights do the animals call quickly in a row and chopped off something like " bibibibibibi ", not unlike a little grebe .
distribution and habitat
The distribution area includes mountainous regions on the Indian subcontinent , in Southeast Asia and in Japan . A relatively densely populated area extends over a narrow zone from the western Himalayas in eastern Pakistan along this mountain range to the north of Assam and Bhutan and from there across south and east China including Taiwan . The occurrence in Japan then follows to the northeast. Occurrences in Southeast India and Sri Lanka as well as in the highlands of Burma and Thailand are geographically isolated . The species may also be found in northern Laos and Vietnam .
The Nepal-crested eagle inhabits forest habitats in the hill country and in mountains up to the tree line, especially original evergreen forests and mixed forests, but also secondary forests . The altitude range in the Chinese province of Yunnan extends up to 4000 m, in southern India and Sri Lanka, however, forests are predominantly settled at altitudes between 600 m and 1500 m, in Japan mostly only forests at altitudes between 250 and 600 m.
Systematics
Until a few years ago, the Nepal crested eagle was united with the other Asian crested eagles, one African and two South American species in the genus Spizaetus (see article Aquilinae ). However, according to recent molecular genetic studies, this genus cannot be preserved in this composition. The Asian species of the genus, on the other hand, form a well-founded monophyletic group and were therefore placed in their own genus Nisaetus .
For the Nepal-crested eagle, Ferguson-Lees and Christie recognize three subspecies:
- Nisaetus nipalensis nipalensis ; the nominate form populates all of Southeast Asia excluding South India and Sri Lanka
- N. n. Kelaarti ; South India and Sri Lanka; overall paler and less contrasting in color than the nominate form. Wing length, thrust and tarsometatarsus are slightly shorter than in the nominate form (wing length of females 403–473 mm, of males 398–453 mm), but the beak is larger and toes and claws are longer than this.
- N. n. Orientalis ; Japan; also clearly paler than nominate shape and shorter hood than this; significantly larger (wing length of females 500–540 mm, of males 470–518 mm).
Based on morphological and molecular genetic studies, it was proposed in 2008 to delimit the subspecies N. n. Kelaarti as a separate species. This proposal was adopted by the International Ornithological Committee in 2009.
Hunting style and diet
The prey is apparently mostly hunted in the manner of a hawk from covered perch and mainly preyed near the ground. The diet consists mainly of medium-sized bottom-dwelling mammals, for example rabbits , and birds such as crested chickens , pheasants , ducks and domestic chickens. Reptiles and, as an exception, fish are captured less often .
In a dauerbeobachteten via video breeding in the prefecture of Niigata in Japan brought to the nest main prey were Japanese Hare ( Lepus brachyurus ), Japanese squirrel ( Sciurus lis ), Japanese Mole ( Mogera wogura ), copper pheasant ( Syrmaticus soemmerringi ), the raptors Kiefernteesa ( Butastur indicus ) and trilling sparrow ( Accipiter gularis ), jay ( Garrulus glandarius ) and indefinite snakes. These 8 species or groups of species made up about 80% of the diet.
Reproduction
The couples seem to be present in the districts all year round. The beginning of the courtship is unknown; the courtship flight consists of high circles and wave flights over the nest area, with intensive calls. The nests are built on large trees in the forest, the nest diameter is up to 1.8 m, the nest height 0.9–1.2 m. The nest hollow is laid out with green branches. In most of the distribution area, eggs are laid from the end of January or February, only in Sri Lanka from December. The clutch usually consists of one or two, very rarely three eggs . The incubation period and nestling time are unknown. The young birds apparently only become independent very late; in breeding pairs examined in Japan, the young birds only left their parents' territory after 2 to 3 years.
hikes
Regular hikes are not known. Young birds evidently migrate from their place of birth undirected. Adult crested eagles are resident birds ; At least some adult birds that breed in the high altitudes of the mountains, however, apparently seek lower altitudes in winter.
Existence and endangerment
The species is mostly under-recorded because of its habitat, its relatively secret way of life and because it is confused with other species. Large-scale population estimates are only available for Japan, where the nationwide population in 1984 was estimated at 900–1000 birds. Due to recent studies, the population in 2004 was given as at least 1,800 birds.
There is no reliable information on the size of the world population. Ferguson-Lees & Christie assumed a population density of less than one pair per 400 km² in 2001 and estimated the total population to be less than 10,000 birds. The IUCN thinks this estimate is far too pessimistic. Overall, the IUCN classifies the species as not endangered ( "least concern" ) for 2004 , even if it does not rule out population declines.
swell
Individual evidence
- ↑ a b c d e J. Ferguson-Lees, DA Christie: Raptors of the World. Christopher Helm, London 2001, ISBN 0-7136-8026-1 , p. 776.
- ^ J. Ferguson-Lees, DA Christie: Raptors of the World. Christopher Helm, London 2001, ISBN 0-7136-8026-1 , p. 775.
- ↑ a b M. A. Brazil, S. Hanawa: The status and distribution of diurnal raptors in Japan. In: RD Chancellor, B.-U. Meyburg (Ed.): Bird of Prey Bulletin. No. 4, 1991, ISSN 0254-6388 , pp. 175-238.
- ↑ HRL Lerner, DP Mindell: Phylogeny of eagles, Old World vultures and other Accipitridae based on nuclear and mitochondrial DNA . In: Molecular Phylogenetics and Evolution. 37, 2005, pp. 327-346.
- ↑ a b A. J. Helbig, A. Kocum, I. Seibold, MJ Braun: A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level. In: Molecular Phylogeny and Evolution. Volume 35, 2005, pp. 147-164.
- ↑ a b E. Haring, K. Kvaløy, J.-O. Gjershaug, N. Røv, A. Gamauf: Convergent evolution and paraphyly of the hawk-eagles of the genus Spizaetus (Aves, Accipitridae) - phylogenetic analyzes based on mitochondrial markers. In: Journal of Zoological Systematics and Evolutionary Research. Volume 45, 2007, pp. 353-365.
- ↑ a b J. O. Gjershaug, OH Diserud, PC Rasmussen, D. Warakagoda: An overlooked threatened species of eagle: Legge's Hawk Eagle Nisaetus kelaarti (Aves: Accipitriformes). In: Zootaxa. No. 1792, June 2008, pp. 54-66.
- ^ IOC World Bird List Version 2.11. ( Memento from January 11, 2012 in the Internet Archive )
- ↑ T. Funo (Niigata Univ. (Japan)), S. Fujitsuka, K. Motomura, M. Ohishi, K. Takahashi, Y. Sekiya, M. Horitou, Y. Wakui, H. Kaminushi, Y. Horinaka, T Sekijima, M. Abe: Food habits analysis of Hodgson's hawk eagle, Spizaetus nipalensis by CCD camera observation system in the breeding season. In: Bulletin of the Faculty of Agriculture. Niigata University (Japan). Volume 53, Issue 1, 2000, pp. 71-79. (Japanese) (Abstract) ( Memento from July 29, 2012 in the web archive archive.today )
- ^ A b S. Asai, Y. Yamamoto, S. Yamagishi: Genetic diversity and extent of gene flow in the endangered Japanese population of Hodgson's hawk-eagle, Spizaetus nipalensis. In: Bird Conservation International. 16, 2006, pp. 113-129.
literature
- J. Ferguson-Lees, DA Christie: Raptors of the World. Christopher Helm, London 2001, ISBN 0-7136-8026-1 , pp. 228-229 and 774-776.
Web links
- Nisaetus nipalensis in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed October 13 of 2008.
- Photo of a Nepal crested eagle in flight ( memento from March 27, 2009 in the web archive archive.today )
