Philippine eagle

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Philippine eagle
Philippine eagle at the Philippine Eagle Center, Davao City

Critically Endangered  (IUCN 3.1)[1]
CITES Appendix I (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Accipitriformes
Family: Accipitridae
Subfamily: Circaetinae
Genus: Pithecophaga
Ogilvie-Grant, 1896
Species:
P. jefferyi
Binomial name
Pithecophaga jefferyi
Range in blue

The Philippine eagle (Pithecophaga jefferyi), 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 86 to 102 cm (2.82 to 3.35 ft) in length and weighs 4.04 to 8.0 kg (8.9 to 17.6 lb).

The Philippine eagle is considered the largest of the extant eagles in the world in terms of length and wing surface area, with only

national bird of the Philippines.[5][6] The most significant threat to the species is loss of habitat, a result of high levels of deforestation throughout most of its range. Because of this, the IUCN Red List
has classified the species as “critically endangered”.

Killing a Philippine eagle is a criminal offence, punishable by law with up to 12 years imprisonment and heavy fines.[7]

Names

The Philippine eagle has numerous native names in the

portmanteau of "haring ibón”, literally "bird king").[5][8]

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.[9] 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.[10]

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.[11] These reports gave its generic name, from the Greek pithecus (πίθηκος, "ape” or “monkey") and phagus (-φάγος, "eater of").[12] The species name commemorates Jeffery Whitehead, the father of John Whitehead.[10] 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.[13] In 1995, it was declared a national emblem under President Fidel V. Ramos. This species has no recognized subspecies.[14]

Evolutionary history

A 1919 study of the bird’s skeletal features led to the suggestion that the nearest relative was the

Snake eagles (Circaetinae), such as the bateleur. The species has subsequently been placed in the subfamily Circaetinae.[16]

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.[17] The Philippine eagle is typically reported as measuring 86–102 cm (2 ft 10 in – 3 ft 4 in) in total length,

extant species of eagle, as the average for the female equals the maximum reported for the harpy eagle[19] and Steller's sea eagle.[4] 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 112 cm (3 ft 8 in), but it had been kept in captivity[3] so may not represent the wild individuals due to differences in the food availability.[21][22]

The level of sexual dimorphism in size is not certain, but the male is believed to be typically about 10% smaller than the female,[4] and this is supported by the average length provided for males and females in one source.[20] In many of the other large eagle species, the size difference between adult females and males can exceed 20%.[4] For adult Philippine eagles, the complete weight range has been reported as 4.7 to 8.0 kg (10.4 to 17.6 lb),[4][23][24] while others have found the average was somewhat lower than the above range would indicate, at 4.5 kg (9.9 lb) for males and 6.0 kg (13.2 lb) for females.[20] One male (age not specified) was found to weigh 4.04 kg (8.9 lb).[25] The Philippine eagle has a wingspan of 184 to 220 cm (6 ft 0 in to 7 ft 3 in) and a wing chord length of 57.4–61.4 cm (22.6–24.2 in).[4][26]

The maximum reported weight is surpassed by two other eagles (the harpy and Steller's sea eagles) and the wings are shorter than large eagles of open country (such as the

gape.[3] The tail is fairly long at 42–45.3 cm (16.5–17.8 in),[4] while another source lists a tail length of 50 cm (20 in).[27]

The most frequently heard noises made by the Philippine eagle are loud, high-pitched whistles ending with inflections in pitch.[28] Additionally, juveniles have been known to beg for food by a series of high-pitched calls.[17]

Distribution and habitat

Philippine Eagle’s habitat representation in Philippine National Museum
.

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.[10][29]

This eagle is found in

dipterocarp and mid montane forests, particularly in steep areas. Its elevation ranges from the lowlands to mountains of over 1,800 m (5,900 ft). Only an estimated 9,220 km2 (2,280,000 acres) of old-growth forest remain in the bird's range.[10] However, its total estimated range is about 146,000 km2 (56,000 sq mi).[17]

Ecology and behavior

Illustration of a Philippine eagle kept in captivity in London in 1909–1910

Evolution in the

Philippine islands, 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 (mainly civets and colugos).[30]
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 100 km2 (39 sq mi), but a study on Mindanao Island found the nearest distance between breeding pairs to be about 13 km (8.1 mi) on average, resulting in a circular plot of 133 km2 (51 sq mi).[31]

The species' flight is fast and agile, resembling the smaller

hawks more than similar large birds of prey.[32]

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.[33] Additionally, they have been known to attack inanimate objects for practice, as well as attempt to hang upside down to work on their balance.[33] As the parents are not nearby when this occurs, they apparently do not play a role in teaching the juvenile to hunt.[33]

Life expectancy for a wild eagle is estimated to be from 30 to 60 years. A captive Philippine eagle lived for 41 years in

birds.[33]

Diet

The Philippine eagle was known initially as the Philippine monkey-eating eagle because it was believed to feed on monkeys almost exclusively.[4] 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 4.7 to 8.3 kg (10 to 18 lb) in males and 2.5 to 5.7 kg (5.5 to 12.6 lb) in females.[35] 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.[36] This misconception may be come from the first examined specimen which was found to have undigested pieces of a monkey in its stomach.[36]

Prey specimens found at the eagle's nest have ranged in size from a small bat weighing 10 g (0.35 oz) to a

domestic fowls (Gallus gallus domesticus), cats (Felis catus), young pigs (Sus domesticus) and small dogs (Canis familiaris).[36][32][38][37]

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.[4] 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.[4][32] Since the native macaque is aggressive and often around the same size as the eagle itself or even larger, up to 9 kg (20 lb) 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.[36]

Reproduction

A Philippine eagle nestling

The complete breeding cycle of the Philippine eagle lasts two years. The female matures sexually at five years of age 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.[9] If one dies, the remaining eagle often searches for a new mate to replace the one lost.[33]

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 midair 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.[33]

Breeding season is in July; birds on different islands, most notably Mindanao and Luzon, begin breeding at different ends of this range.

dipterocarp, or any tall tree with an open crown, in primary or disturbed forest. The nests are lined with green leaves, and can be around 1.5 m (4.9 ft) across. The nesting location is around 30 m (98 ft) or even more above the ground.[10][32] As in many other large raptors, the eagle's nest resembles a huge platform made of sticks.[4][32] The eagle frequently reuses the same nesting site for several different chicks.[10] Eight to 10 days before the egg is ready to be laid, the female is afflicted with a condition known as egg lethargy. In this experience, the female does not eat, drinks much water, and holds her wings droopingly.[33] The female typically lays one egg in the late afternoon or at dusk, although occasionally two have been reported.[32][33] If an egg fails to hatch or the chick dies early, the parents likely lay another egg the following year. Copulation may take place 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 (typically 62 days) after being laid.[4] Both sexes participate in the incubation, but the female does the majority of incubating during the day and all of it at night.[33]

Both sexes help feed the newly hatched eaglet. Additionally, the parents have been observed taking turns shielding the eaglet from the sun and rain until it is seven weeks old.[33] The young eaglet fledges after four or five months.[32] The earliest an eagle has been observed making a kill is 304 days after hatching.[33] Both parents take care of the eaglet for a total of 20 months and, unless the previous nesting attempt had failed, the eagles can breed only in alternate years.[4][9] The Philippine eagle rivals two other large tropical eagles, namely the crowned eagle and harpy eagle, for having the longest breeding cycle of any bird of prey.[4][41] Even nests have no predators other than humans, as even known nest predators such as palm civets and macaques (being prey species) are likely to actively avoid any area with regular eagle activity.[42]

Conservation

A Philippine eagle named Sir Arny, at the Philippine Eagle Center, Davao City

In 1994, the IUCN and

critically endangered.[1][17] The IUCN believed that between 180 and 500 Philippine eagles survive in the Philippines.[9] In 2015, about 600 were estimated to be left in the wild.[43] The Zoological Society of London listed the Philippine eagle as the top 15 EDGE species, out of all the world's recorded species, making it the Philippines' most "evolutionary distinct and globally endangered" species.[44]

They are threatened primarily by deforestation through logging and expanding agriculture. Old-growth forest is being lost at a high rate, and most of the forest in the lowlands is owned by logging companies.

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 hatched in captivity through artificial insemination; however, the first naturally bred eaglet was not hatched until 1999. The first captive-bred bird to be released in the wild, Kabayan, was released in 2004 on Mindanao; however, he was accidentally electrocuted in January 2005. Another eagle, Kagsabua, was released in March 2008, but was shot and eaten by a farmer.[9] In June 2015, an eagle was released after being treated for a gunshot wound; two months later it was shot and killed.[43] Killing this critically endangered species is punishable under Philippine law by 12 years in jail and heavy fines.[7]
Its numbers have slowly dwindled over the decades to the current population of 180 to 600 eagles. A series of floods and mud slides, caused by deforestation, further devastated the remaining population. The Philippine eagle may soon no longer be found in the wild, unless direct intervention is taken. The Philippine Eagle Foundation in Davao City, is one organization 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 and conducted the first experimental release of a captive-bred eagle to the wild. The foundation has 36 eagles at its center, of which 19 were bred in captivity, including one born in 2015, the first for two years.[48][43]

Ongoing research on behavior, ecology, and population dynamics is also underway. In recent years, protected lands have been established specifically for this species, such as the 700 km2 (170,000 acres) of Cabuaya Forest and the 37.2 km2 (9,200 acres) of Taft Forest Wildlife Sanctuary on Samar.[49] However, a large proportion of the population is found on unprotected land.[9]

Philippine Eagle Diplomacy

In a June 2019 wildlife loan agreement, a pair of Philippine eagles; (as of 2019) Geothermica, a 15 year old male and Sambisig (meaning one unity) a 17 year old female, were loaned to the Jurong Bird Park Singapore.[50] This was part of conservation efforts for the species and also commemorated 50 years friendship between the Philippines and Singapore. Before the pair were shipped, they were given 2 specially printed passports dedicated to them. The pair were scheduled to stay at Singapore for 10 years as part of the agreement.[51] The move marked the initiation of the government's Philippine Eagle Diplomacy program.[52][53]

Representation

Symbolic passports issued to Geothermica and Sambisig, individual eagles which were loaned to Singapore.

The Philippine eagle was officially declared the national bird of the Philippines on July 4, 1995, by President

birdwatchers.[32]

The Philippine eagle has been featured on at least 12 stamps from the Philippines, with dates ranging from 1967 to 2007. It was also depicted on the

World War II martyrs: Chief Justice José Abad Santos, suffragist Josefa Llanes Escoda, and General Vicente Lim
.

Historically, about 50 Philippine eagles have been kept in

Planckendael Zoo in Belgium).[58] The first captive breeding was only achieved in 1992 at the facility of the Philippine Eagle Foundation in Davao City, Philippines, which has bred it several times since then.[9][60]

The Philippine eagle is also used in sporting events as a mascot, most notably one in the

2005 Southeast Asian Games held in Manila known as "Gilas". The Philippine eagle is also the animal used in the Philippines men's national basketball team
or Gilas Pilipinas' logo/team crest.

See also

References

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External links

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