Archived 2014 discussion: Philippine Hawk-eagle (Nisaetus philippensis) is being split: list both N. philippensis and N. pinskeri as Endangered?

This is part of a consultation on the Red List implications of extensive changes to BirdLife’s taxonomy for non-passerines

Lynx Edicions and BirdLife International will soon publish the HBW-BirdLife Illustrated Checklist of the Birds of the World, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist.

The new Checklist will be based on the application of criteria for recognising species limits described by Tobias et al. (2010). Full details of the specific scores and the basis of these for each new taxonomic revision will be provided in the Checklist.

Following publication, an open and transparent mechanism will be established to allow people to comment on the taxonomic revisions or suggest new ones, and provide new information of relevance in order to inform regular updates. We are also actively seeking input via a discussion topic here regarding some potential taxonomic revisions that currently lack sufficient information.

The new Checklist will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List. The taxonomic changes that will appear in volume 1 of the checklist (for non-passerines) will begin to be incorporated into the 2014 Red List update, with the remainder, and those for passerines (which will appear in volume 2 of the checklist), to be incorporated into subsequent Red List updates.

Preliminary Red List assessments have been carried out for the newly split or lumped taxa. We are now requesting comments and feedback on these preliminary assessments.

Philippine Hawk-eagle Nisaetus philippensis is being split into N. philippensis and N. pinskeri, following the application of criteria set out by Tobias et al. (2010).

Prior to this taxonomic change, N. philippensis (BirdLife species factsheet) was listed as Vulnerable under criteria A2cd+3cd+4cd; C2a(i), because its very small population, of which the majority was in two main subpopulations, was inferred to be undergoing a continuing and rapid decline (30-49% over 56 years [estimate of three generations]) owing to lowland forest loss, exacerbated by hunting and trapping pressure.

N. philippensis (as defined following the taxonomic change) is found in the northern Philippines, from Luzon to Mindoro, whilst N. pinskeri is found in the southern Philippines, on the islands of Mindanao, Samar and Negros at least (with records from Basilan, Biliran, Bohol, Leyte and Siquijor probably relating to this taxon) (Preleuthner and Gamauf 1998, Kennedy et al. 2000, Ferguson-Lees and Christie 2001). Both species occupy lowland and montane forest, including mature secondary forest and semi-open areas, but show a marked preference for large tracts of continuous primary forest (Gamauf et al. 1998, Preleuthner and Gamauf 1998, Ferguson-Lees and Christie 2001).

Each of these newly-defined species is estimated to have a very small and declining population, numbering fewer than 2,500 mature individuals, but probably fewer than 1,000 mature individuals in both species, as in the late 1990s only 320-340 pairs were estimated on Mindanao and only 200-220 pairs were estimated on Luzon (Preleuthner and Gamauf 1998). Within each species’ population, all subpopulations are thought to number fewer than 1,000 mature individuals (but probably not fewer than 250 mature individuals in every case) (these numbers relate to the thresholds set under criterion C2a(i), under which both species would probably qualify as Vulnerable).

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 very possible that these Nisaetus species have experienced population declines of more than 50% over the past three generations.

It is suggested that both N. philippensis and N. pinskeri be listed as Endangered under criterion A2cd, on the basis that they are suspected to have undergone very rapid population declines (50-79% over the past 56 years), as a result of extensive and on-going habitat loss and persecution (Ferguson-Lees and Christie 2001).

Comments on these suggested categories and further information would be welcomed.


del Hoyo, J., Elliott, A. and Sargatal, J. (1994) Handbook of the birds of the world, Vol 2: New World Vultures to Guineafowl. Barcelona, Spain: Lynx Edicions.

Ferguson-Lees, J. and Christie, D. A. (2001) Raptors of the world. London, UK: Christopher Helm.

Gamauf, A., Preleuthner, M. and Pinsker, W. (1998) Distribution and field identification of Philippine birds of prey: 1. Philippine Hawk Eagle Spizaetus philippensis and Changeable Hawk Eagle Spizaetus cirrhatus. Forktail 14: 1-11.

Kennedy, R. S., Gonzales, P. C., Dickinson, E. C., Miranda, H. C., Jr. and Fisher, T. H. (2000) A guide to the birds of the Philippines. Oxford, UK: Oxford University Press.

Preleuthner, M. and Gamauf, A. (1998) A possible new subspecies of the Philippine hawk-eagle (Spizaëtus philippensis) and its future prospects. J. Raptor Research 32(2): 126-135.

Tobias, J. A., Seddon, N., Spottiswoode, C. N., Pilgrim, J. D., Fishpool, L. D. C. and Collar, N. J. (2010) Quantitative criteria for species delimitation. Ibis 152: 724–746.

Uitamo, E. (1999) Modelling deforestation caused by the expansion of subsistence farming in the Philippines. J. Forest Economics 5(1): 99-122.

Walpole, P. (2010) Figuring the Forest Figures: Understanding Forest Cover Data in the Philippines and where we might be proceeding. Quezon City, Philippines: Environmental Science for Social Change. Downloaded from:

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3 Responses to Archived 2014 discussion: Philippine Hawk-eagle (Nisaetus philippensis) is being split: list both N. philippensis and N. pinskeri as Endangered?

  1. Desmond Allen says:

    The distinctiveness of the West Visayan population needs further investigation. It is quite likely they are distinct, and the only photo of one that I have seen looks different. Check Godo’s opinion.

  2. Joe Taylor says:

    Preliminary proposals

    Based on available information, our preliminary proposals for the 2014 Red List would be to treat:

    N. philippensis as Endangered under criterion A2cd

    N. pinskeri as Endangered under criterion A2cd

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Andy Symes says:

    Recommended categorisations to be put forward to IUCN

    Following further review, there have been no changes to our preliminary proposals for the 2014 Red List status of these species.

    The final categorisations will be published later in 2014, following further checking of information relevant to the assessments by BirdLife and IUCN.

Comments are closed.