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Philippine Eagle
Conservation status
Critically Endangered  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Falconiformes (or Accipitriformes, q.v.)
Family:	Accipitridae
Genus:	Pithecophaga Ogilvie-Grant, 1897
Species:	P. jefferyi
Binomial name
Pithecophaga jefferyi Ogilvie-Grant, 1897
Range map in blue green

The Philippine Eagle, Pithecophaga jefferyi, also known as the Great Philippine Eagle, Haribon, or Monkey-eating Eagle, is a bird of prey belonging to the family Accipitridae. It is considered the world’s largest eagle, but not the heaviest. It is the only member of the genus Pithecophaga and is believed to be most closely related to the snake eagles genetically . The Philippine Eagle has a dark-brown back and white underbelly. Long, brown feathers adorn its nape like a crest. The bill and talons are large. This eagle is endemic to the Philippines and can be found on four major islands: eastern Luzon, Samar, Leyte, and Mindanao, with most of the population living in Mindanao. It lives in dipterocarp and mid-montane forests, particularly in steep areas.

The Philippine Eagle eats flying lemurs, Asian palm civets, reptiles, birds, and, occasionally, monkeys. Pairs are known to hunt cooperatively, with one eagle distracting a group of monkeys while the other swoops in unnoticed for the kill. A pair requires a large territory of up to 130 square kilometers (50 sq mi). These eagles are believed to live to 60 years. Philippine Eagles mate for life and breeding occurs between September and February, depending on rainfall, prey accessibility, and on which island the birds are found. Nests resemble huge platforms made of sticks. One egg is laid and incubation lasts from 58 to 68 days. The parents will care for their young for nearly 20 months.

This eagle is critically endangered with only 180 to 500 birds surviving in the wild. Deforestation, pollution, and poaching are major threats. Charles Lindbergh led the first conservation efforts in the 1960s. The Philippines has recognized the eagle as a national symbol and major conservation efforts are underway.

The species was discovered in 1896 by the English explorer and naturalist John Whitehead, who observed the bird and whose servant, Juan, collected the first specimen a few weeks later.^[2] The bird's skin was sent to William Robert Ogilvie-Grant in London in 1897. Ogilvie-Grant initially showed it off at a local restaurant before describing the species a few weeks later.^[3]

Initially, the Philippine Eagle was called the Monkey-eating Eagle because of reports by the locals that it preyed exclusively on monkeys; from these reports it gained its generic name Pithecophaga, from the Greek pithecus, meaning "ape or monkey," and phagus, meaning "eater of."^[4] The specific name commemorates Jeffery Whitehead, the father of John Whitehead.^[3] Later studies revealed, however, that its diet consisted of other animals, including colugos, civets, large snakes, monitor lizards, and even large birds such as hornbills. This discovery, and because the same name applied to the African Crowned Hawk-eagle and the South American Harpy Eagle, resulted in a 1978 presidential decree to have its name changed to "Philippine Eagle." This species has no recognized subspecies.^[5]

The eagle is locally known today as "Haribon" or "Haring Ibon," which means "Bird King." It is also known as the "Banog."^[6]

A 2007 study of the Philippine Eagle's DNA suggests that the bird has a unique evolutionary history. Its genetic sequence differs from those of other large eagles. Researchers from the University of Michigan analyzed the DNA isolated from blood samples of the Philippine Eagle and compared these sequences to those of the Harpy Eagle, Crested Eagle, and the New Guinea Harpy Eagle. These latter three are related genetically, but they are not closely related to the Philippine Eagle as previously thought. This belief arose because of their similar sizes, habitat, and habits; however, these similarities are now believed to be the result of convergent evolution.^[7] It is currently believed that the closest relatives of the Philippine Eagle is the much smaller snake eagles.^[7]

The Philippine Eagle's nape is adorned with long brown feathers that form a shaggy crest. The color of the feathers and the shape of the crest give this eagle the appearance of possessing a lion's mane, which in turn is a feature reminiscent of the mythical griffin. 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 or sometimes a sallow cream. The heavy legs are yellow with large, powerful dark claws, and the prominent large, high-arched, deep bill is bluish-gray. The eagle's eyes are blue-gray. Juveniles are similar to adults but their upperpart feathers have pale fringes.^[8]

The average female is about 102 centimeters (3.36 ft) long and weighs about 7 kilograms (15.5 lb).^[9] The adult male is about 10 to 20% smaller and averages at about 91 centimeters (3 ft) and 5 kilograms (11 lb).^[10] The Philippine Eagle is the world's largest living eagle in terms of length. The species has a wingspan of approximately 2 meters (6.6 ft).^[11] The wings of this eagle are shorter than the wings of large eagles that live in open country (such as the Martial Eagle, Wedge-tailed Eagle and Steller's Sea Eagle), but are quite broad and have a greater surface area than those of any other eagle.^[12]

The most frequently heard sounds made by the Philippine Eagle are loud high-pitched whistles. Juveniles can make a series of high-pitched calls when begging for food.^[8]

The Philippine Eagle is endemic to the Philippines and can be found on four major islands: eastern Luzon, Samar, Leyte, and Mindanao. Most of the eagles are found on Mindanao, with between 82 and 233 breeding pairs present. 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 and Mount Kitanglad National Parks on Mindanao.^[3]

This eagle is found in dipterocarp and mid-montane forests, particularly in steep areas. The elevation of its habitat extends from the lowlands to mountains of over 1,800 meters (5,905 ft). It is estimated that only 9,220 square kilometers (2,280,000 acres) of old-growth forest remains in the bird's range.^[3] However, the species' total estimated range is about 146,000 square kilometers (56,000 sq mi).^[8]

Evolution in the Philippine islands, in the absence of other predators, made the eagles the dominant hunter in the Philippine forests. Each breeding pair requires a large home range of 65 to 130 square kilometers (25-50 sq mi) to successfully raise a chick, and thus the species is extremely vulnerable to the unchecked deforestation of its range.

The species' flight is fast and agile, resembling that of the smaller hawks more than that of larger birds of prey.^[13]

Juveniles in play behavior have been observed gripping knotholes in trees with their talons and, using their tail and wings for balance, inserting their head into a tree cavity.^[14] They are also known to attack inanimate objects for hunting practice as well as attempt to hang upside down to work on their balance.^[14] Because the parents are away when this behavior occurs, it has been suggested that parent eagles do not play a role in teaching the juvenile to hunt.^[14]

Life expectancy for a wild eagle is estimated to be anywhere from 30 to 60 years. A captive Philippine Eagle lived for over 41 years in a zoo in Rome.^[14] However, it is thought that wild birds on average have a shorter lifespan than captive birds.^[14]

This eagle was initially known as the Monkey-eating Eagle because it was believed to only feed on monkeys; this has since proved to be inaccurate. The Philippine Eagle's prey varies from island to island depending on the availability of prey species, especially between Luzon and Mindanao. This is due to the islands being in different faunal regions. For example, Philippine flying lemurs, which are the preferred prey in Mindanao, are absent in Luzon.^[3] It is unknown what the primary prey for the species on Luzon is.^[3] The small mammals, reptiles and birds, such as snakes, monitor lizards, hornbills, owls, and even other birds of prey.^[3][13] There have been reports of this eagle capturing young pigs and small- to medium-sized dogs.^[13] It is estimated that the flying lemur could make up 90% of the bird's diet in some locations.^[13]

The Philippine Eagle also eats monkeys ^[13], but infrequently. Pairs sometimes hunt troops of monkey cooperatively, with one bird perching nearby to distract the primates so that the other can swoop in unnoticed for the kill.^[13]

The complete breeding cycle of the Philippine Eagle lasts two years. The female sexually matures at five years and the male, at seven. Like most eagles, the Philippine Eagle is monogamous. Once paired, a couple remains together for the rest of their lives.^[2] However, if one bird of the pair dies, the survivor often finds a new mate to replace the one lost.^[14]

The beginning of courtship is signaled by nest-building and the eagle remaining near its nest. Aerial displays also play a major role in the courtship. These displays include paired soaring over a nesting territory, the male chasing the female in a diagonal dive, and mutual talon presentation, where the male presents his talons to the female's back and she flips over in mid-air to present her own talons. Advertisement displays coupled with loud calling have also been reported. The willingness of an eagle to breed is displayed by the eagle bringing nesting materials to the bird's nest. Copulation follows and occurs repeatedly both on the nest and on nearby perches. The earliest courtship has been reported in July.^[14]

Breeding begins between September and February; birds on different islands, most notably Mindanao and Luzon, begin breeding at different ends of this range.^[2] The amount of rainfall and population of prey may also affect the breeding season.^[2] The nest is normally built on an emergent dipterocarp, or any tall tree with an open crown, in primary or disturbed forest and may be nearly 1.5 - 2.7 meters (5-8 feet) across and about 30 meters (99 ft) above the ground.^[3][13] The eagle's nest resembles a huge platform made of sticks.^[13] The eagle frequently reuses the same nesting site for several different chicks.^[3] Eight to ten days before the egg is ready to be laid, the female is afflicted with a condition known as egg lethargy. In this condition, the female does not eat but drinks frequently, and droops its wings.^[14] The female typically lays one egg in the late afternoon or at dusk, although occasionally two have been reported.^[13][14] If an egg fails to hatch or the chick dies early, the parents will likely lay another egg the following year. Copulation may last a few days after the egg is laid to enable another egg to be laid should the first one fail. The egg is incubated for 58 to 68 days after being laid. Both sexes participate in the incubation, but the female does most of the incubating during the day and all of it at night.^[14]

Both sexes help feed the newly hatched eaglet. The parents have been observed taking turns shielding the eaglet from the sun and rain until it is seven weeks old.^[14] The young eaglet fledges after four or five months.^[13] The earliest that a juvenile has been observed making a kill is 304 days after hatching.^[14] However, the parents will care of the eaglet for a total of 20 months.^[2]

The 2008 IUCN Red List listed this species as critically endangered.^[8] The International Union for the Conservation of Nature believes that between 180 and 500 Philippine Eagles survive in the Philippines.^[2] They are threatened primarily by deforestation through logging and expanding agriculture. Old-growth forest is being lost at a high rate. with most of the eagle's forest in the lowlands owned by logging companies.^[3] Mining, pollution, exposure to pesticides that affect breeding, and poaching are also major threats.^[2][11] Occasionally, they are caught in traps laid by the local people for deer. In the past, the eagles were also captured for zoo collections, though today this is no longer a major problem. ^[2]

Charles Lindbergh, best known for crossing the Atlantic alone and nonstop in 1927, was fascinated by this eagle. As a representative of the World Wildlife Fund, Lindbergh traveled to the Philippines several times between 1969 and 1972, where he helped persuade the government to protect the eagle. In 1969, the Monkey-eating Eagle Conservation Program was started to help preserve this species. In 1992, the first Philippine Eagles were born in captivity through artificial insemination; however, it wasn't until 1999 that the first naturally bred eaglet hatched. The first captive-bred bird to be released into the wild, Kabayan, was released in 2004 on Mindanao; however, he was accidentally electrocuted in January 2005. Another eagle, Kagsabua, was released March 6, 2008, but was shot and eaten by a farmer.^[2] Killing this critically endangered species is punishable under Philippine law by 12 years imprisonment and heavy fines.^[11]

The species has slowly dwindled over the decades to the current population of 180 to 500 eagles. A series of floods and mudslides, caused by deforestation, has further decimated the remaining population. The Philippine Eagle may soon disappear from the wild unless direct intervention is taken. The Philippine Eagle Foundation of Davao City, Mindanao is one organization that is dedicated to the protection and conservation of the Philippine Eagle and its forest habitat. The Philippine Eagle Foundation has successfully bred Philippine Eagles in captivity for over a decade now and has conducted the first experimental release of a captive-bred eagle into the wild. The foundation has 32 eagles at its center, of which 18 were bred in captivity.^[2] Ongoing research on behavior, ecology, and population dynamics is also underway. In recent years, protected lands have been established specifically for this species; these include the 700-square kilometer (170,000 acres) Cabuaya Forest and the 37.2-square kilometer (9,200 acres) Taft Forest Wildlife Sanctuary on Samar.^[15] Unfortunately, a large proportion of the population is still found on unprotected land.^[2]

The Philippine Eagle was named the national bird of the Philippines in 1995 by President Fidel V. Ramos under Proclamation No. 615.^[15] This eagle, because of its size and rarity, is also a highly desired bird among birdwatchers.^[13]

The Philippine Eagle has also been featured over the years (1967 to 2007) on at least 12 Philippine stamps.^[16]

Wikimedia Commons has media related to Pithecophaga jefferyi.

Wikispecies has information related to Pithecophaga jefferyi.

• Extensive Documented Studies of Philippine Eagles[1]
• Philippine Eagle Foundation A foundation devoted to saving the Philippine Eagle.
• Haribon.org (The Largest Eagle in the World.)
• Animal Diversity Web - Pithecophaga jefferyi
• Philippine Eagle on ThinkQuest
• National Geographic Magazine - "The Lord of the Forest"
• Bringing Back Ol' Blue Eyes - article on Philippine Eagle Foundation work on Mindanao