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 the Indian subcontinent, from India, Nepal (hence the epithet nipalensis) through Bangladesh to Thailand, Taiwan, Indonesia and Japan.
The mountain hawk-eagle is a medium-large raptor at 69–84 cm (27–33 in) in length and a wingspan of 134–175 cm (53–69 in). 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 population 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, Legge's hawk-eagle.
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 Japanese subspecies usually weighs 2.2–3.6 kg (4.9–7.9 lb).
The heavier underpart streaking and wing shape help to distinguish this species from the similar crested hawk-eagle (Nisaetus cirrhatus).
Though it is not considered a globally threatened species, the Japanese population is declining. 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.
- BirdLife International (2012). "Nisaetus nipalensis". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Hodgson, B.H. (1836). "Summary description of some new species of Falconidae". Journal of the Asiatic Society of Bengal: 227–231.
- 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[permanent dead link]
- 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
- 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
- . JSTOR 1592923. Missing or empty
- 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