• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Justification of Red List category
This species is suspected to be undergoing a rapid population decline owing to the widespread and on-going loss of lowland forest, which qualifies it as Vulnerable.

Population justification
The population size is preliminarily estimated to fall into the band 2,500-9,999 mature individuals. This equates to 3,750-14,999 individuals in total, rounded here to 3,500-15,000 individuals.

Trend justification
The species has suffered as a result of extensive forest loss owing to logging, conversion to plantations and agriculture, and major forest fires. Tree cover within the range is being lost at a rate of approximately 35% over the three generations (22.8 years; Global Forest Watch 2020). While some populations have shown resilience to habitat modification, others have been found absent from disturbed forests. Thus, it may be precautionarily assumed that population changes are proportional to forest cover change.

Nisaetus nanus occurs in southern Tenasserim, Myanmar, peninsular Thailand, Peninsular and East (Sabah and Sarawak) Malaysia, Brunei, and Kalimantan and Sumatra, Indonesia (BirdLife International 2001). Although still widespread, it is uncommon or rare throughout its range. It may be nearing extinction in Thailand and is declining everywhere. However, its status is somewhat unclear because of the difficulties of separating it from N. alboniger.

It is resident in evergreen forests, chiefly in the lowlands and on lower hill-slopes, but has occasionally been reported up to 1,000 m. It may tolerate some habitat degradation, having been recorded in heavily logged forest in Kalimantan and Sumatra (although a survey of high conservation value forest found the species to be seen more readily in remnant lowland forest patches within oil palm plantations in Kalimantan than Sumatra [M. Iqbal in litt. 2016]), as well as in logged forest in Malaysia. However, a study in Malaysia recorded it in primary forest prior to selective logging, but not subsequently.

The species is increasingly threatened by the loss, degradation and fragmentation of lowland rainforest as a result of large-scale commercial logging. Even within protected areas, forests are cleared for conversion into palm oil and rubber plantations, as well as into agricultural land. Between 1985-1997, nine million and nearly seven million hectares of forest were lost on Kalimantan and Sumatra, respectively. Forest fires are becoming increasingly frequent and severe (Clark and Kirwan 2020). In Thailand, virtually all lowland forest has now been cleared, and encroachment continues on the lower slopes of almost all mountains. Despite these negative statistics, the species has shown resilience to at least a degree of habitat modification, even recorded within small lowland forest patches across oil palm plantations in Sabah (Yeap Chin Aik in litt. 2007) and logging camps in Perak, Malaysia (Yeap Chin Aik in litt. 2008).

Conservation Actions Underway
CITES Appendix II. It occurs in numerous protected areas, including at least six (four national parks and two wildlife reserves) on Sumatra, at least three (two national parks and one wildlife reserve) in Kalimantan, at least five (one national park and four wildlife sanctuaries) in Thailand, at least three (two national parks and one wildlife reserve) in Malaysia, and one wildlife sanctuary in Myanmar.

Conservation Actions Proposed
Conduct extensive surveys to more clearly establish its distribution and status compared with N. alboniger. Conduct research into its ecological requirements, particularly its tolerance of habitat degradation and its ranging behaviour. Promote the concept of Forest Management Units in Sabah. Assist forest managers in habitat identification and zoning of concession areas. Afford it full legal protection under Myanmar, Thai, Indonesian and Malaysian law. An assessment of the occurrence of this species in high conservation value forest within oil palm plantations under Roundtable on Sustainable Palm Oil scheme may be necessary to help integrate conservation and sustainable agricultural landscape approaches (M. Iqbal in litt. 2016).

46 cm. Small, boldly-patterned hawk-eagle. Rufescent sides of head with blackish streaks, dark crest broadly tipped white, three dark bands on tail. Buffish-white base-colour to underside flight feathers and warm buffish coverts with narrow dark barring. Similar spp. Blyth's Hawk-eagle S. alboniger is larger, has narowly white-tipped crest, blackish tail with pale grey broad, central band and narrow tip. Whitish underwing with heavy black barring on coverts and dark sides of head. Voice Shrill, high-pitched yik-yee or kliit-kleeik, with rising second note. Fledged juveniles give high-pitched, breathless yii-yii-yii-yii and ee-ee-ee-ee-eeee.

Text account compilers
Hermes, C.

Contributors
Aik, Y.C., Benstead, P., Bird, J., Davidson, P., Davison, G., Iqbal, M., Peet, N., Taylor, J., Tobias, J. & Westrip, J.R.S.

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Recommended citation
BirdLife International (2024) Species factsheet: Wallace's Hawk-eagle Nisaetus nanus. Downloaded from https://datazone.birdlife.org/species/factsheet/wallaces-hawk-eagle-nisaetus-nanus on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 23/11/2024.