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Wallace's Hawk-eagle
Nisaetus nanus

Status: Vulnerable

Population Trend: Declining.

Other Names: Small Hawk-eagle, Spizaetus nanus, Wallace's Hawk Eagle.

Nisaetus nanus
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Distribution: Indomalayan. Southern MYANMAR and THAILAND south through the Malay Peninsula to SUMATRA and BORNEO. more....

Subspecies: 2 races. S. n. nanus: Southern MYANMAR and southern THAILAND through Malay Peninsula to SUMATRA and BORNEO; S. n. stresemanni: Western SUMATRA (Nias I.).

Taxonomy: Traditionally placed in the genus Spizaetus, but recent molecular studies by Helbig et al. (2005) showed that the Asian hawk-eagle species represent a different lineage from the New World hawk-eagle species and should therefore be assigned to a new genus for which the name Nisaetus Hodgson 1836 is available. The same conclusion was reached independently by Lerner and Mindell (2005), based on the molecular sequences of one nuclear and two mitochondrial genes. Haring et al. (2007) also confirmed that Asian Spizaetus (Nisaetus) species are monophyletic and are distributed in two sub-clades, one of which consists of N. alboniger, N. bartelsi, N. nanus, and N. nipalensis. This species was formerly considered to be conspecific with N. alboniger, due to confusion with immature plumages of the latter species (Clark 1994).

Movements: Non-migratory, but juveniles disperse from breeding areas (Bildstein 2006).

Habitat and Habits: In the Malay Peninsula, it occurs exclusively in dry-land evergreen and semi-evergreen lowland forest, both undisturbed and logged, and occasionally at heavily degraded sites, but never without access to patches of continuous high canopy (Wells 1999). In Sabah, it was found in primary, logged, and riverine forest (Sheldon et al. 2001), and it reportedly occurs in heavily logged forest in Kalimantan and Sumatra (BirdLife International 2007). The few nest records are all from tall forest in the level lowlands, although further investigations may also show nesting in foothill forests (Wells op cit.). Thiollay (1983) regarded it as primarily a species of the level lowlands forest, but he also saw it in low hills and secondary forest, where it was sometimes sympatric with N. alboniger. The two species have a nearly identical range, except that N. nanus is more confined to lowland forests, while N. alboniger tends to occur at higher elevations.

Food and Feeding Behavior: Known to prey on lizards, birds, bats, frogs, and skinks (Smythies 1981, Clark 1994, Sheldon et al. 2001). In Malaysia, lizard parts were found in the stomach of a probable Wallace's Hawk-eagle collected in Trang (Riley 1938), and another one was seen eating a lizard (Wells 1999). Prey is captured by still hunting from a perch.

Breeding: The nest is a moderate-sized stick platform, lined with fresh, leafy branchlets added to the cup-lining until the chick is grown. It is typically placed in a branch fork or near the base of a high crown at main canopy level in an emergent tree (Wells 1999). The egg is not described, but clutch size is probably one, since only single chicks have been recorded (Wells op cit.). Pairs remain on the nesting territory through the year. more....

Conservation: Assessing the status of this species is complicated by the difficulty of separating it from the similar Blyth's Hawk-eagle (N. alboniger) in the field. However, it seems certain that populations are now generally uncommon or rare and have been seriously reduced by habitat loss in many areas (Wells 1999). It may be near extinction in Thailand, as the result of clearing of virtually all lowland forest (Wells op cit.). Categorized as Vulnerable by BirdLife International. more....

Population Estimates: Ferguson-Lees and Christie (2001) estimated the global population, including all adults and immatures at the start of the breeding season, in the range of 101 to 1,000 individuals. BirdLife International (2009) placed the population of mature birds between 2,500 to 9,999 individuals.

Important References: 
Amadon, D. 1953. Remarks on the Asiatic hawk-eagles of the genus
  Spizaetus. Ibis 95:492-500.
BirdLife International. 2000. Threatened birds of the world. Lynx
  Edicions, Barcelona, Spain, and BirdLife International, Cambridge, UK.
Clark, W.S. 1994. Wallace's Hawk-eagle. P. 204 in del Hoyo, J., A.
  Elliott, and J. Sargatal (eds). Handbook of birds of the world. Vol. 2. New
  World vultures to guineafowl. Lynx Edicions, Barcelona, Spain.
Ferguson-Lees, J., and D.A. Christie. 2001. Raptors of the world. Houghton
  Mifflin, Boston, MA.
Gamauf, A., J.O. Gjershaug, K. KvalÝy,K., N. RÝv, and E. Haring. 2005.
  Molecular phylogeny of the hawk-eagles (genus Spizaetus). Zoologische
  Mededelingen Leiden 79-3(21):179-180.
Gjershaug, J.O.. 2006. Taxonomy and conservation status of hawk-eagles
  (Genus Nisaetus) in South-east Asia. Ph.D. dissertation, Norwegian
  University of Science and Technology, Trondheim, Norway.
Haring, E., K. KvalÝy, J.O. Gjershaug, and A. Gamauf. 2007. Convergent
  evolution and paraphyly of the hawk-eagles of the genus Spizaetus (Aves,
  Accipitridae) -- phylogenetic analyses based on mitochondrial markers.
  Journal of Zoological Systematics and Evolutionary Research 45:353-365.
Helbig, A.J., A. Kocum, I. Seibold, and M.J. Braun. 2005. A multi-gene
  phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive
  paraphyly at the genus level. Molecular Phylogenetics and Evolution
Lerner, H.R., and D.P. Mindell. 2005. Phylogeny of eagles, Old World
  vultures, and other Accipitridae based on nuclear and mitochondrial DNA.
  Molecular Phylogenetics and Evolution 37:327-346.
Stresemann, E. 1938. Spizaetus alboniger (Blyth) und Spizaetus nanus
  Wallace, zwei fšlschlich vereinigte Arten. Journal fŁr Ornithologie
van Balen, B.S. 1998. Tropical forest raptors in Indonesia: recent
  information on distribution, status, and conservation. Journal of Raptor
  Research 32:56-63.
Wells, D.R. 1999. The birds of the Thai-Malay Peninsula. Volume 1.
  Non-passerines. Academic Press, London.

Sites of Interest:
Red Data Book Threatened Birds of Asia
Detailed information on status, threats, and conservation measures.
ARRCN Spizaetus distribution maps
Aims to create distribution maps and habitat analysis for the genus Spizaetus (Nisaetus) in Asia.

Gamauf, Anita
Gjershaug, Jan Ove
Kim Chye, Lim
Lim, Aun -Tiah

Last modified: 2/15/2010

Recommended Citation: Global Raptor Information Network. 2020. Species account: Wallace's Hawk-eagle Nisaetus nanus. Downloaded from http://www.globalraptors.org on 4 Jul. 2020

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