The Mountain Hawk-eagle or Hodgson's Hawk-eagle (Nisaetus nipalensis earlier treated under Spizaetus) is a bird of prey. Like all eagles, it is in the family Accipitridae. It breeds in southern Asia from Pakistan, India and Sri Lanka to China, Taiwan and Japan.

Japanese subspecies, N. n. orientalis

The Mountain Hawk-eagle is a medium-large raptor at about 70"?72 cm in length. The typical adult has brown upperparts and pale underparts, with barring on the undersides of the flight feathers and tail. The breast and belly and underwing coverts are heavily streaked. The wings are broad with a curved trailing edge, and are held in a shallow V in flight. Sexes are similar, but young birds are often whiter-headed.

The Sri Lankan and south Indian subspecies (S. n. kelaarti) is smaller and has unstreaked buff underwing coverts. A 2008 study based on the geographic isolation and differences in call suggest that this be treated as a full species Nisaetus kelaarti. The Japanese subspecies N. n. orientalis is larger, lighter, and has only a very small crest, which is large in the other two subspecies.

The heavier underpart streaking and wing shape help to distinguish this species from the similar Changeable Hawk-eagle, (Nisaetus cirrhatus).

It is a bird of mountain woodland, which builds a stick nest in a tree and lays usually a single egg. Mountain Hawk-eagles eat small mammals, birds and reptiles.

Not considered a globally threatened species, the Japanese population is declining however. As the species is a K-strategist like all eagles, it was feared that the ongoing population reduction of N. n. orientalis might lead to loss of genetic diversity, and consequently inbreeding depression. However, genetic diversity was shown to be still considerable at present.

Notes

1. ^ BirdLife International (2004). Spizaetus nipalensis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern
2. ^ Helbig AJ, Kocum A, Seibold I & Braun MJ (2005) A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level. Molecular phylogenetics and evolution 35(1):147-164 PDF
3. ^ Grimmett, Richard; Inskipp, Carol, Inskipp, Tim & Byers, Clive (1999): Birds of India, Pakistan, Nepal, Bangladesh, Bhutan, Sri Lanka, and the Maldives. Princeton University Press, Princeton, N.J. ISBN 0-691-04910-6
4. ^ Gjershaug, J. O.; Diserud, O. H.; Rasmussen, P. C. & Warakagoda, D. (2008) "An overlooked threatened species of eagle: Legge's Hawk Eagle Nisaetus kelaarti (Aves: Accipitriformes)" (PDF) Zootaxa 1792: 54"?66
5. ^ Asai, Shigeki; Yamamoto, Yoshihiro & Yamagishi, Satoshi (2006): Genetic diversity and extent of gene flow in the endangered Japanese population of Hodgson's hawk-eagle, Spizaetus nipalensis. Bird Conservation International 16(2): 113"?129. doi:10.1017/S0959270906000050