The collector John Whitehead first saw the new eagle within days of arriving at Bonga, in the uplands of Samar's interior. Ogilvie Grant, who named the eagle, showed the new eagle to the British Ornithologists' Club on 16 December 1896, and the name Pithecophaga jefferyi was formally published on 30 December. The genus name Pithecophaga means monkey-eater, and the species was named for the collector's father, Jeffery, who had financed his explorations. Ogilvie Grant said its skull was enormous, very much larger than that of the Harpy eagle. The bird used to be called the monkey-eating eagle, though it also eats birds, snakes and lizards.
A history of the species' first century said it remained a neglected mystery for two-thirds of that time, and that very few of its secrets have been learned. The same history said scientists did not know the densities at which the eagle lives, so total population sizes could not be worked out from local counts. In 1965 the Filipino scientist Dr. Dioscoro Rabor alerted the world that the eagle was endangered. A program to save the Philippine eagle began in 1969. In 1987 the eagle project began operating as a private institution.
As of November 2026, the Philippine Eagle Foundation says it has produced 29 eagles at the Philippine Eagle Center since 1992, the year its project produced the first two Philippine eagles bred and hatched in captivity. A study of the mitochondrial DNA of 32 captive Philippine eagles found 17 haplotypes, and the captive-bred birds carried all 17, although mitochondrial DNA is only a fragment of the genetic puzzle, so the authors call for studies using nuclear DNA and larger samples from other islands.
A 2026 study in BMC Genomics sequenced the DNA of 35 Philippine eagles and found extremely low genetic diversity, among the lowest measured in raptors. It suggested the population has been declining for around 3,000 years, long before modern forest loss. As of November 2026, about 400 pairs are estimated to be left in the wild. A 2023 study by the Philippine Eagle Foundation estimated that the forests could support an average of 392 pairs, in a range of 318 to 447 pairs. That estimate came from a habitat model and the home range size of tracked eagles, not from counting every eagle.
One study followed six breeding adult Philippine eagles on Mindanao with GPS trackers from April 2013 to September 2021, collecting 80,481 location fixes. A home range is the area an eagle uses, and in that study the typical home range was between 39 and 68 square kilometers, depending on the method used to calculate it. The tracked eagles spent 75 to 80 percent of their time outside their core territory, probably while searching for food.
The eagle population on Leyte was wiped out by Typhoon Yolanda in 2013, and a reintroduction program had released five eagles there as of May 2026, with room for about 16 eagles on the island.
A Philippine eagle builds a huge nest of sticks high in a tree, and a Philippine eagle nest sits 27 to 50 meters above the ground, while both parents protect and feed the chick for 7 to 8 weeks.
Words to know
- genus: group of species
- mitochondrial: from the mother
- haplotypes: gene lineage types
- reintroduction: bringing back
- endangered: at risk
