Justification of Red List Category
This newly-split forest eagle qualifies as Endangered because its very small population, of which the majority is in two main subpopulations, is undergoing a continuing and very rapid decline owing to lowland forest loss, exacerbated by hunting and trade.
The species stronghold appears to be Luzon where 200-220 pairs were estimated in the late 1990s (Preleuthner and Gamauf 1998). Given that rapid declines have presumably continued since then, a preliminary population estimate is of a total of 400-600 mature individuals, roughly equating to 600-900 individuals.
Deforestation in the Philippines is reported to have been very rapid in recent decades, and it is said that the country lost c.40% of its forest cover in the 20 years between 1970 and 1990 (Uitamo 1999). Data from ESSC (Environmental Science for Social Change) suggest that the area of closed-canopy forest in the Philippines decreased by c.44% between 1987 and 2002 (Walpole 2010). Assuming rapid losses of primary forest over the past 56 years, and impacts from hunting and trapping pressure, it is likely that this species has experienced population declines of more than 50% over the past three generations.
Spizaetus philippensis is endemic to the northern Philippines, where there have been records from 15 localities on Luzon (primarily in the Sierra Madre mountains) since 1980, and on Mindoro (Collar et al. 1999). It is uncommon in the Sierra Madre lowlands, very scarce on Mindoro, and is very probably already extinct on some smaller islands within its former range. In the late 1990s 200-220 pairs were estimated to remain on Luzon (Preleuthner and Gamauf 1998).
It inhabits primary, selectively logged and disturbed forest, occasionally frequenting open areas, from the lowlands to lower mountain slopes, almost exclusively below 1,000 m. It appears not to tolerate much forest degradation. No migration is known, although unconfirmed reports from the migration funnel of Dalton Pass (Luzon) hint at intra-island movements.
Deforestation for plantation agriculture, livestock and logging throughout its extensive, predominantly lowland range is the chief threat. In 1988, forest cover was as low as 24% on Luzon, which is likely to be an overestimate, with most lowland forest leased to logging concessions. Habitat loss is exacerbated by considerable hunting and trapping pressure.
Conservation Actions Underway
CITES Appendix II. It has been recorded recently from numerous protected areas, including Mts Isarog and Makiling National Parks, the Northern Sierra Madre Natural Park and Bataan Natural Park/Subic Bay and recently on Mount Irid-Angilo-Binuang of the Southern Sierra Madre in Luzon (J. Ibanez in litt. 2007), as well as Tadao Ilocos Norte, Mt Palay Palay and Mt Banahao (D. Allen in litt. 2012). These sites are legally protected through local government decrees, but the efficacy of this legislation is often unclear and is ineffective at Mt Malindang and in the Southern Sierra Madre (D. Allen in litt. 2012). The species is regularly recorded during surveys for Philippine Eagle Pithecophaga jeffreyi in Luzon (J. Ibanez in litt. 2007).
65-70 cm. Medium-sized eagle with longish, black crest. Rufescent-brown crown and face, with fine dark streaks. Dark brown upperparts. Brown tail with 4-5 darker bars. White throat, bordered by dark malars. Black mesial stripe. Rufous underparts with black streaking. Finely barred black-and-white trousers. Pale iris. In flight, shows broad, rounded wings and well-barred flight feathers. Juvenile has white head and underparts, upperparts fringed paler. Acquires adult plumage over four years. Similar spp. Difficult to separate from Barred Honey-buzzard Pernis celebensis and Changeable Hawk-eagle Spizaetus cirrhatus unless seen well. Combination of long crest and feathered legs separates N. philippensis and N. pinskeri from the above. N. pinskeri (occurring on the southern Philippine islands and only recently recognised) is very similar, but has ochraceous-tawny throat and breast, and plain brownish belly and underwing coverts. Voice Loud, disyllabic whistle. Hints Look around forest edge.
Text account compilers
Benstead, P., Bird, J., Lowen, J., Taylor, J., Martin, R & Symes, A.
Allen, D. & Ibanez, J.
BirdLife International (2020) Species factsheet: Nisaetus philippensis. Downloaded from http://www.birdlife.org on 28/11/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 28/11/2020.