Philippine eagle
The Philippine eagle, also known as the monkey-eating eagle or great Philippine eagle, is a critically endangered species of eagle of the family Accipitridae which is endemic to forests in the Philippines. It has brown and white-colored plumage, a shaggy crest, and generally measures in length and weighs.
The Philippine eagle is considered the largest of the extant eagles in the world in terms of length and wing surface area, with only Steller's sea eagle and the Harpy eagle being larger in terms of weight and bulk. It has been declared the national bird of the Philippines. It is also depicted in the Philippine one thousand-peso note. The species had been classified by the IUCN Red List as critically endangered with a declining population and is one of the most endangered raptors in the world. The most significant threat to the species is loss of habitat, a result of high levels of deforestation throughout most of its range. Since 2019, more than 20 eagles have been rescued mostly due to injuries from gunshot wounds.
Killing a Philippine eagle is a criminal offence, punishable by law with up to 12 years' imprisonment and heavy fines.
Names
The Philippine eagle has numerous native names in the Philippine languages. These include bánoy and ágila in Tagalog; manaul or manaol in the Visayan languages; manaol or garuda in Maranao and Maguindanao; tipule in Subanen; and mam-boogook or malamboogook in the Manobo languages, Klata, Tagabawa, Mandaya, and Kalagan. Some of these names are also used for other large eagles in general, such as the white-breasted sea eagle. In modern Filipino, it is usually referred to as háribon.Taxonomy
The first European to study the species was the English explorer and naturalist John Whitehead in 1896, who observed the bird and whose servant, Juan, collected the first specimen a few weeks later. The skin of the bird was sent to William Robert Ogilvie-Grant in London in 1896, who initially showed it off in a local restaurant and described the species a few weeks later.Upon its scientific discovery, the Philippine eagle was first called the monkey-eating eagle because of reports from natives of Bonga, Samar, where the species was first discovered, that it preyed exclusively on monkeys. These reports gave its generic name, from the Greek and . The species name commemorates Jeffery Whitehead, the father of John Whitehead. Later studies revealed, however, that the alleged monkey-eating eagle also ate other animals, such as colugos, large snakes, monitor lizards, and even large birds such as hornbills. This, coupled with the fact that the same name applied to the African crowned eagle and the Central and South American harpy eagle, it was renamed "Philippine eagle" in a 1978 proclamation by then-President Ferdinand Marcos. In 1995, it was declared a national emblem under President Fidel V. Ramos. This species has no recognized subspecies.
Evolutionary history
A 1919 study of the bird's skeletal features led to the suggestion that the nearest relative was the harpy eagle. The species was included in the subfamily Harpiinae until a 2005 study of DNA sequences which identified them as not members of the group, finding instead that the nearest relatives are snake eagles, such as the bateleur. The species has subsequently been placed in the subfamily Circaetinae.Description
The Philippine eagle's nape is adorned with long, brown feathers that form a shaggy, mane-like crest. The eagle has a dark face and a creamy-brown nape and crown. The back of the Philippine eagle is dark brown, while the underside and underwings are white. The heavy legs are yellow, with large, powerful, dark claws, and the prominent, large, high-arched, deep beak is a bluish-gray. The eagle's eyes are blue-gray. Juveniles are similar to adults except their upperpart feathers have pale fringes.The Philippine eagle is typically reported as measuring in total length, but a survey of several specimens from some of the largest natural history collections in the world found the average was for males and for females. Based on the latter measurements, this makes it the longest extant species of eagle, as the average for the female equals the maximum reported for the harpy eagle and Steller's sea eagle. The longest Philippine eagle reported anywhere and the longest eagle outside of the extinct Haast's eagle is a specimen from Field Museum of Natural History with a length of, but it had been kept in captivity so may not represent the wild individuals due to differences in the food availability.
The level of sexual dimorphism in size is not certain, but the male is believed to be typically about 10% smaller than the female, and this is supported by the average length provided for males and females in one source. In many of the other large eagle species, the size difference between adult females and males can exceed 20%. For adult Philippine eagles, the complete weight range has been reported as, while others have found the average was somewhat lower than the above range would indicate, at for males and for females. One male was found to weigh. The Philippine eagle has a wingspan of and a wing chord length of.
The maximum reported weight is surpassed by two other eagles and the wings are shorter than large eagles of open country, but are quite broad. The tarsus of the Philippine eagle ties as the longest of any eagle from long, which is about the same length as that of the much smaller but relatively long-legged New Guinea eagle. The very large but laterally compressed bill rivals the size of Steller's sea eagle's as the largest bill for an extant eagle. Its bill averages in length from the gape. The tail is fairly long at, while another source lists a tail length of.
The most frequently heard noises made by the Philippine eagle are loud, high-pitched whistles ending with inflections in pitch. Additionally, juveniles have been known to beg for food by a series of high-pitched calls.
Distribution and habitat
The Philippine eagle is endemic to the Philippines and can be found on four major islands: eastern Luzon, Samar, Leyte, and Mindanao. The largest numbers of eagles reside on Mindanao, with between 82 and 233 breeding pairs. Only six pairs are found on Samar, two on Leyte, and a few on Luzon. It can be found in Northern Sierra Madre National Park on Luzon and Mount Apo, Mount Malindang, and Mount Kitanglad National Parks on Mindanao.This eagle is found in dipterocarp and mid montane forests, particularly in steep areas. Its elevation ranges from the lowlands to mountains of over. Only an estimated of old-growth forest remain in the bird's range. However, its total estimated range is about.
Ecology and behavior
Evolution in the Philippines, without other predators, made the eagles the dominant hunter in the Philippine forests. The Philippine eagle has a wide range of prey which includes birds, reptiles and mammals.Each breeding pair requires a large home range to successfully raise a chick, thus the species is extremely vulnerable to deforestation. Earlier, the territory has been estimated at, but a study on Mindanao Island found the nearest distance between breeding pairs to be about on average, resulting in a circular plot of.
The species' flight is fast and agile, resembling the smaller hawks more than similar large birds of prey.
Juveniles in play behavior have been observed gripping knotholes in trees with their talons, and using their tails and wings for balance, inserting their heads into tree cavities. Additionally, they have been known to attack inanimate objects for practice, as well as attempt to hang upside down to work on their balance. As the parents are not nearby when this occurs, they apparently do not play a role in teaching the juvenile to hunt.
Life expectancy for a wild eagle is estimated to be from 30 to 60 years. A captive Philippine eagle lived for 41 years in Rome Zoo, and it was already an adult when it arrived at the zoo. Another captive Philippine eagle lived for 46 years at the Philippine Eagle Center in Davao City. However, wild birds on average are believed to live shorter lives than captive birds.
Diet
The Philippine eagle was known initially as the Philippine monkey-eating eagle because it was believed to feed on monkeys almost exclusively. The only two monkeys native to the Philippines are Philippine long-tailed macaque and common long-tailed macaques, both are subspecies of crab-eating macaque and weighing in males and in females. Though Philippine eagles do prey on these monkeys, they are an opportunist apex predator, taking prey based on their local level of abundance and ease. This misconception may have come from the first examined specimen which was found to have undigested pieces of a monkey in its stomach.Prey specimens found at the eagle's nest have ranged in size from a small bat weighing to a Philippine deer weighing. The primary prey is usually the tree squirrel-sized Philippine flying lemurs, which can make up an estimated 90% of the raptor's diet in some locations. However, primary prey species vary from island to island depending on species availability, particularly in Luzon and Mindanao, because the islands are in different faunal regions. For example, flying lemurs are preferred prey in Mindanao, but are absent in Luzon. The primary prey for the eagles seen in Luzon are macaques, reptiles, and Northern Luzon giant cloud rat which can weigh twice as much as flying lemurs at. In many regions, civets are taken as supplemental prey, mainly cat-sized Asian palm civets but occasionally larger Malay civets. Other mammalian prey can include flying squirrels, tree squirrels, flying foxes, rats and mouse-deer. Birds are also taken, including large species such as owls, hawks and hornbills. Reptiles occasionally form a large part of their diet, snakes such as Ptyas luzonensis and Gonyosoma oxycephalum are mainly taken. Venomous pit vipers are also taken as prey, and in one instance, a breeding pair delivered a Philippine cobra to the nest. Monitor lizards, including marbled water monitors and even larger Northern Sierra Madre forest monitors have been taken. While most of the prey consists of wild prey, they have been reported to capture domestic fowls, cats, young pigs and small dogs.
Philippine eagles primarily use two hunting techniques. One is still-hunting, in which it watches for prey activity while sitting almost motionlessly on a branch near the canopy. The other is perch-hunting, which entails periodically gliding from one perch to another. While perch-hunting, they often work their way gradually down from the canopy down the branches, and if not successful in finding prey in their initial foray, they fly or circle back up to the top of the trees to work them again. Eagles in Mindanao often find success using the latter method while hunting flying lemurs, since they are nocturnal animals that try to use camouflage to protect themselves by day. Eagle pairs sometimes hunt troops of monkeys cooperatively, with one bird perching nearby to distract the primates, allowing the other to swoop in from behind, hopefully unnoticed, for the kill. Since the native macaque is aggressive and often around the same size as the eagle itself or even larger, up to in adult males, it is a potentially hazardous prey, and an eagle has been reported to suffer a broken leg after it struggled and fell along with a large male monkey.