The Philippine Eagle: one hundred years of solitude
by N.J. Collar, from OBC Bulletin 24, December 1996.
A century ago the agony and ecstasy of ornithological exploration were rather more extreme than they are today, when the greatest rewards (new species to science) are so much less predictable and the consolations (comfort and safety) so much more so. Few people can remind us of the gulf between past and present as powerfully as the British naturalist explorer John Whitehead, who died on Hainan of fever on 2 June 1899 at the age of 38 (Ibis 1899: 642). He began his short career with the mildly sensational discovery, when only 23, of the Corsican Nuthatch, Sitta whiteheadi (Proc. Zool. Soc. Lond. 1884: 233), and soon went on to South-East Asia, focusing his attention first on northern Borneo and then the Philippines, both places with which his name will permanently be associated.
Disease and "slow starvation" afflicted him throughout the years he worked in the Philippines, and he often fell victim to gross misfortune; yet his most celebrated moment resulted from one of the cruelest pieces of luck he endured. In 1895 an entire consignment of skins, the result of several months' concentrated collecting on Samar and containing many anticipated new species, was lost when its carrier, the German ship Weiland, caught fire and had to be scuttled off Singapore (Ibis 1896: 485). Whitehead was therefore forced to go back to the island in May 1896 and try again. His luck immediately changed: within days of arriving at Bonga in the uplands of the interior he saw a new, gigantic eagle, missed during the entire time of his previous visit. After weeks without the chance of obtaining a specimen, on 13 June his servant Juan brought in the male of a pair that had been seen daily in the forest opposite his camp. Even in death the bird had put up a fight, hanging by its talons at the top of a tree until Juan climbed the full height to fetch it down. This discovery was declared by W. R. Ogilvie Grant, who described the species for science, as "the most remarkable of Mr Whitehead's achievements in the Philippine Islands", but at the time the achiever himself was yet again in the throes of illness, reporting that when Juan handed over the body "it was so heavy that I could hardly hold it out at arm's length in my then enfeebled state of health".
Six months later the specimen had safely negotiated the semi-circumnavigation of the earth, and found itself in abler-bodied and assuredly better-fed company. At the Restaurant Frascati, 32 Oxford Street, London, on the evening of 16 December 1896, Ogilvie Grant, doubtless rather overshadowing a report of swallows hibernating in a cowhouse in Yorkshire, exhibited Juan's prize to the members of the British Ornithologists' Club; the name he gave it, Pithecophaga jefferyi, was formally published two weeks later, on 30 December. Whitehead, whose surname had by then already been inscribed in ornithological nomenclature nine times or so, had requested that this glorious animal be named for his father Jeffery, who had financed his explorations.
The remarkability of the bird lay as much in its great taxonomic distinctiveness as in its size and success in avoiding discovery for so many years, and Ogilvie Grant's new genus, Pithecophaga, "monkey-eater", reflected the rather unusual food-habits Whitehead reported. He may well have assumed that this habit was directly related to the evolution of the bird's most notable character, namely "the extraordinary shape and size of the bill", the depth of which "is greater than that of any known bird of prey, except Pallas's [= Steller's] Sea-Eagle (Haliaëtus pelagicus), in which it is sometimes a trifle greater, while such extreme narrowness, compared with the depth, is quite unique in birds of this order". Although he thought the species most closely allied to the Harpy Eagle Harpia harpyja or to the genus Harpyhaliaetus, noting the similarity of structure and size of the legs, feet and talons of these birds, he found that in Pithecophaga "the skull is enormous, very much larger than that of the Harpy".
So began the Philippine Eagle's first century of life as an entity of zoological classification. For precisely two-thirds of that period it remained a neglected mystery, and even in the past 33 years, during which there has been almost continuous conservation-oriented effort on its behalf, the species has yielded up very few of its secrets. We still do not know the densities at which it lives, or whether these densities vary with island. We therefore cannot extrapolate local or island or total population sizes. We do not know the extent to which individual birds cross between islands or even between forested fragments. We therefore do not know how to identify viable or unviable populations (if any are either), or what size or type of ecological barrier would prevent dispersal or recolonisation. We know nothing, effectively, of the influence of "selective" logging on the species or its prey, of juvenile survival rates and recruitment, or of the influence of habitat or prey availability on these things.
Perhaps most surprisingly, we do not even know all the places where the eagle survives. There are sites in Luzon's Cordillera Central and even the Zambales Mountains which still bear investigation, irrespective of their lack of records; and there is the question of how far south into Quezon the species penetrates. There are forested mountains on Mindanao, ranging along the western side of the Agusan valley in particular, which have never been explored by ornithologists, and there are many sites where the species has been reported in the past where it may yet survive. Samar and Leyte remain the least familiar of all the large islands of the Philippines, and the few sites on them where the species has been recorded in the 1990s merit further intensive investigation.
This is where responsible birdwatchers and itinerant biologists, both within the Philippines and outside, may be able to help. Although the eagle lives in tough terrain, sometimes in what were until recently political no-go areas, there is now more than ever a crying need for comprehensive surveys of the most neglected parts of the bird's range by small teams of capable, self-supporting volunteers (university expeditions would in some cases be ideal), coordinating their plans through the Haribon Foundation in Manila.
By the year 2000 we ought to have the species and its rapidly dwindling habitat fully mapped in all the four islands where it occurs. Even while this is happening, the conservation of known areas, and research on the basic elements of the species's ecology, must proceed. There is no time to lose, and there is one of the greatest prizes in the Oriental avifauna to gain. Indeed, as was pointed out 10 years ago in Forktail (2: 89), if we save the Philippine Eagle then we will inevitably save an inordinate number of other species of fauna and flora into the bargain. Moreover, the ghost of John Whitehead should find new peace, and the OBC members in the year 2096 will surely be eager to raise their glasses, in more senses than one.
Reference The sources on which this account draws, if not abbreviated in the text, are given in full in BirdLife's Threatened birds of the Philippines, to appear in early 1997.