Harpy Eagles
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Harpy Eagle

The Harpy Eagle (Harpia harpyja) is a Neotropical species of eagle. It is sometimes known as the American Harpy Eagle to distinguish it from the Papuan Eagle which is sometimes known as the New Guinea Harpy Eagle or Papuan Harpy Eagle. It is the largest and most powerful[quantify] raptor found in the Americas, and among the largest extant species of eagles in the world. It usually inhabits tropical lowland rainforests in the upper (emergent)canopy layer. Destruction of its natural habitat has seen it vanish from many parts of its former range, and it is nearly extirpated in Central America.

Taxonomy

The Harpy Eagle was first described by Linnaeus in his Systema Naturae in 1758 as Vultur harpyja,[2] after the mythological beast harpy. The only member of the genus Harpia, the Harpy Eagle is most closely related to the Crested Eagle (Morphnus guianensis) and the New Guinea Harpy Eagle (Harpyopsis novaeguineae), the three composing the subfamilyHarpiinae within the large family Accipitridae. Previously thought to be related, the Philippine Eagle has been shown by analysis of DNA to belong elsewhere in the raptor family as it is related to the Circaetinae.[3]

Its name refers to the Harpies of Ancient Greek mythology. These were wind spirits that took the dead to Hades, and were said to have a body like an eagle and the face of a human.

Description

The upper side of the Harpy Eagle is covered with slate black feathers, and the underside is mostly white, except for the feathered tarsi, which are striped black. There is a broad black band across the upper breast, separating the gray head from the white belly. The head is pale grey, and is crowned with a double crest. The upperside of the tail is black with three gray bands, while the underside of it is black with three white bands. The iris is gray or brown or red, the cere and bill are black or blackish and the tarsi and toes are yellow. The plumageof male and female is identical. The tarsus is up to 13 cm (5.1 in) long.[4][5]

Upper body of an adult in captivity

Female Harpy Eagles typically weigh 6 to 9 kg (13 to 20 lb).[4][6] One source states that adult females can scale up to 10 kg (22 lb).[7] An exceptionally large captive female, "Jezebel", weighed 12.3 kg (27 lb).[8] Being captive, this large female may not be representative of the weight possible in wild Harpy Eagles due to differences in the food availability.[9][10] The male, in comparison, is much smaller and weighs only about 4 to 4.8 kg (8.8 to 11 lb).[4][6] Harpy Eagles are 86.5–107 cm (2 ft 10 in–3 ft 6 in) long[5][6] and have a wingspan of 176 to 224 cm (5 ft 9 in to 7 ft 4 in).[4][5] Among the standard measurements, the wing chord measures 54–63 cm (1 ft 9 in–2 ft 1 in), the tail measures 37–42 cm (1 ft 3 in–1 ft 5 in), the tarsus is 11.4–13 cm (4.5–5.1 in) long and the exposed culmen from the cere is 4.2 to 6.5 cm (1.7 to 2.6 in).[4][11][12] It is sometimes cited as the largest eagle, however thePhilippine Eagle is somewhat longer on average and the Steller's Sea Eagle is slightly heavier on average. The wingspan of the Harpy Eagle is relatively small, an adaptation that increases maneuverability in forested habitats and is shared by other raptors in similar habitats. The wingspan of the Harpy Eagle is surpassed by several large eagles who live in more open habitats, such as those in the Haliaeetus and Aquila genera.[4] The extinctHaast's Eagle was significantly larger than all extant eagles, including the Harpy.[13]

This species is largely silent away from the nest. There, the adults give a penetrating, weak, melancholy scream, with the incubating male's call described as Wheeeeeeeeee-wheeeeeee-wheeeeeeeee. The females calls while incubating are similar but are lower pitched. While approaching the nest with food, the male calls out "rapid chirps, goose-like calls, and occasional sharp screams". Vocalization in both parents decreases as the nestlings age, while the nestlings become more vocal. The nestlings call Chi-chi-chi...chi-chi-chi-chi, seemingly in alarm in respond to rain or direct sunlight. When humans approach the nest, the nestlings have been described as uttering croaks, quacks and whistles.[14]

Distribution and habitat

Rare throughout its range, the Harpy Eagle is found from Mexico, through Central America and into South America to as far south asArgentina. With the exception of some areas of Panama, the species is almost extinct in Central America, subsequent to the logging of much of the rainforest there.[15] The Harpy Eagle inhabits tropical lowland rainforests and may occur within such areas from the canopy to the emergent vegetation. They typically occur below an elevation of 900 m (3,000 ft) but have been recorded at elevations of up to 2,000 m (6,600 ft).[1] Within the rainforest, they hunt in the canopy or sometimes on the ground, and perch on emergent trees looking for prey. They do not generally occur in disturbed areas but will regularly visit semi-open forest/pasture mosaic, mainly in hunting forays.[16] However, they have been found in areas where high-grade forestry is practiced.

Behavior

Feeding

Feeding at Zoo Miami, USA

The Harpy Eagle is an actively hunting carnivore and is an apex predator, meaning that adults are at the top of a food chain and have no natural predators. Its main prey are tree-dwelling mammals and a majority of the diet has been shown to focus on sloths andmonkeys. Research conducted by Aguiar-Silva between 2003 and 2005 in a nesting site inParintins, Amazonas, Brazil, collected remains from prey offered to the nestling and after sorting them, concluded that, in terms of individuals preyed upon, the harpy's prey basis was composed in 79% by sloths from two species: Bradypus variegatus amounting to 39% of the individual prey base, and Choloepus didactylus to 40%; various monkeys amounted to 11.6% of the same prey base. In a similar research venture in Panama, where a couple of captive-bred subadults was released, 52% of the male's captures and 54% of the female's were of two sloth species (Bradypus variegatus and Choloepus hoffmanni).[17] At oneVenezuelan nest, all remains found around the nest site were comprised by sloths. Monkeys regularly taken can include capuchin monkeys, saki monkeys, howler monkeys, titi monkeys, squirrel monkeys and spider monkeys. Smaller monkeys, such as tamarinsand marmosets, are seemingly ignored as prey by this species.[4] At several nest in Guyana, monkeys made up approximately 37% of the prey remains found at the nests.[18] Similarly, cebid monkeys made up 35% of the remains found at 10 nest in Amazonian Ecuador.[19] Other partially arboreal mammals are also predated given the opportunity, including porcupines, squirrels, opossums,anteaters, and even relatively large carnivores such as kinkajous, coatis and tayras.[4] In the Pantanal, a pair of nesting eagles preyed largely on the porcupine Coendou prehensilis and on the agouti Dasyprocta azarae.[20] The eagle may also attack bird species such asmacaws: At the Parintins research site, the Red-and-green Macaw made up for 0.4% of the prey base, with other birds amounting to 4.6%.[21] Other parrots, including the large Hyacinth Macaw, have also been predated, as well as cracids such as curassows andseriemas.[4] Additional prey items reported include reptiles such as iguanas, tejus and snakes.[4][22] Snakes of up to 5 cm (2.0 in) in diameter have been observed to be cut in half, then the pieces are swallowed whole.[4] On occasion, larger prey such as capybaras,peccaries and deer are taken and they are usually taken to a stump or low branch and partially eaten, since they are too heavy to be carried whole to the nest.[4][23][24] Red brocket deer, a species commonly weighing over 30 kg (66 lb), have been reportedly predated and, in such cases, the eagle may have to tear it into pieces or feed on at the killing site rather than fly with as it would be too heavy.[25][26] The Harpy have been recorded as taking domestic livestock, including chickens, lambs, goats and young pigs, but this is extremely rare under normal circumstances.[4] They control population of mesopredators such as capuchin monkeys which prey extensively on bird's eggs and which (if not naturally controlled) may cause local extinctions of sensitive species.[27]

The Harpy Eagle routinely favors prey weighing over 7 kg (15 lb).[4] The harpy eagle possess the largest talons of any living eagle, each exceeding the length of grizzly bear's claw at around 13 cm (5.1 in).[23] The Harpy's feet are extremely powerful and assist with suppressing prey. A typical Harpy Eagle can exert a pressure of 42 kgf/cm² (4.1 MPa or 530 lbf/in2 or 400 N/cm2) with its talons.[28]The Harpy Eagle has been recorded as lifting prey up to equal their own body weight.[4] That allows the bird to snatch a live sloth from tree branches, as well as other huge prey items. Males have been shown to focus on relatively smaller prey, with a typical range of 0.5 to 2.5 kg (1.1 to 5.5 lb) or about half their own weight.[4] The larger females almost invariably take larger prey, with a minimum recorded prey weight of around 2.7 kg (6.0 lb). Adult female Harpys regularly grab large male howler or spider monkeys or mature sloths weighing 6 to 9 kg (13 to 20 lb) in flight and fly off without landing, an enormous feat of strength.[4][23][29] Prey items taken to the nest by the parents are normally medium-sized, having been recorded from 1 to 4 kg (2.2 to 8.8 lb).[4] The prey brought to the nest by males averaged 1.5 kg (3.3 lb), while the prey brought to the nest by females averaged 3.2 kg (7.1 lb).[14]

Sometimes, Harpy Eagles will still-hunt, a common hunting strategy in other forest-dwelling raptors.[4] In Harpys, this consists of looking and listening for long periods of time from a high perch near an opening, a river or salt-lick (where many mammals go to feed for nutrients).[4] The more common hunting technique of the species is perch-hunting, which consists of scanning around for prey activity while briefly perched between short flights from tree to tree.[4] When prey is spotted, a fast swoop or snatch occurs, after which the talons often kill the prey in seconds.[4] On occasion, Harpy Eagles may also hunt by flying adjacent to or right over the canopy.[4] They have also been observed tail-chasing, a predation style common to the bird-hunting Accipiter hawks.[4] While tail-chasing, they pursue a bird closely in flight while twisting between trees, vines and branches, a skill that requires both considerable speed and great agility.[4]

Breeding

In ideal habitats, nests can be found fairly close to one another. In some parts of Panama and Guyana, active nests were located 3 km (1.9 mi) away from one another, while they are within 5 km (3.1 mi) of each other in Venezuela. In Peru, the average distance between nests was 7.4 km (4.6 mi) and the average area occupied by each breeding pairs was estimated at 4,300 ha (11,000 acres). In less ideal areas, with fragemented forest, breeding territories were estimated at 25 km (16 mi).[22] The female Harpy Eagle lays two white eggs in a large stick nest, which commonly measures 1.2 m (3.9 ft) deep and 1.5 m (4.9 ft) across and may be used over several years. Nests are located high up in a tree, usually in the main fork, at 16 to 43 m (52 to 141 ft), depending on the stature of the local trees. The harpy often builds its nest in the crown of the kapok tree, one of the tallest trees in South America. In many South American cultures it is considered bad luck to cut down the kapok tree, which may help safeguard the habitat of this stately eagle.[30] The bird also uses other huge trees to build its nest on, such as the Brazil nut tree.[31] A nesting site found in the Brazilian Pantanal was built on a Cambará tree (Vochysia divergens).[32]

There is no known display between pairs of eagles and they are believed to mate for life. A pair of Harpy Eagles usually only raise one chick every 2–3 years. After the first chick hatches, the second egg is ignored and normally fails to hatch unless the first egg perishes. The egg is incubated for around 56 days. When the chick is 36 days old, it can stand and walk awkwardly. The chick fledges at the age of 6 months, but the parents continue to feed it for another 6 to 10 months. The male captures much of the food for the incubating female and later the eaglet, but will also take an incubating shift while the female forages and also brings prey back to the nest. Breeding maturity is not reached until birds are 4 to 6 years of age.[4][14][16] Adults can be aggressive toward humans who disturb the nesting site or appear to be a threat to its young.[33]

Status and conservation

Sub-adult, "Panama," in Belize Zoo, Belize

Although the Harpy Eagle still occurs over a considerable range, its distribution and populations have dwindled considerably. It is threatened primarily by habitat loss provoked by the expansion of logging, cattle ranching, agriculture and prospecting. Secondarily, it is threatened by being hunted as an actual threat to livestock and/or a supposed one to human life, due to its great size.[34] Although not actually known to predate humans and only rarely a predator of domestic stock, the species' large size and nearly fearless behavior around humans reportedly make it a "irresistible target" for hunters.[22] Such threats apply throughout its range, in large parts of which the bird has become a transient sight only: inBrazil, it was all but totally wiped out from the Atlantic rainforest and is only found in numbers in the most remote parts of the Amazon Basin; a Brazilian journalistic account of the mid-1990s already complained that at the time it was only found in numbers, in Brazilian territory, on the northern side of the Equator.[35] Scientific 1990s records, however, suggest that the Harpy Atlantic Forest population may be migratory.[36] Subsequent research in Brazil has established that, as of 2009, the Harpy Eagle, outside the Brazilian Amazon, is critically endangered in Espírito Santo,[37] São Paulo and Paraná, endangered in Rio de Janeiro, and probably extirpated in Rio Grande do Sul and Minas Gerais[38] – the actual size of their total population in Brazil is unknown.[39]

Globally, The Harpy Eagle is considered Near Threatened by IUCN[1] and threatened with extinction by CITES (appendix I). The Peregrine Fund until recently considered it a "conservation-dependent species", meaning it depends on a dedicated effort for captive breeding and release to the wild as well as habitat protection in order to prevent it from reaching endangered status but now has accepted the Near Threatened status. The Harpy Eagle is considered critically endangered in Mexico and Central America, where it has been extirpated in most of its former range: in Mexico, it used to be found as far North as Veracruz, but today probably occurs only inChiapas in the Selva Zoque. It is considered as Near Threatened or Vulnerable in most of the South American portion of its range: at the Southern extreme of its range, in Argentina, it's found only in the Parana Valley forests at the province of Misiones.[40][41] It has disappeared from El Salvador, and almost so from Costa Rica.[15]

National initiatives

Adult at São Paulo Zoo, Brazil
Adult in Belize

Various initiatives for restoration of the species are currently afoot in various countries: Since 2002, Peregrine Fund initiated a conservation and research program for the Harpy Eagle in the Darién Province, Panama.[42] A similar—and grander, given the dimensions of the countries involved—research project is currently occurring in Brazil, at the National Institute of Amazonian Research, through which 45 known nesting locations (presently updated to 62, only three outside the Amazonian Basin and all three presently inactive) are being monitored by researchers and volunteers from local communities. A Harpy Eagle chick has been fitted with a radio transmitter that allows it to be tracked for more than three years via a satellite signal sent to INPE (Brazilian National Institute for Space Research).[43] Also, a photographic recording of a nest site in the Carajás National Forest is presently being made by the photographer for the Brazilian edition of National Geographic MagazineJoão Marcos Rosa.[44]

In Belize, there exists The Belize Harpy Eagle Restoration Project. It began in 2003 with the collaboration of Sharon Matola, Founder & Director of The Belize Zoo and The Peregrine Fund. The goal of this project was the reestablishment of the Harpy Eagle within Belize. The population of the eagle declined as a result of forest fragmentation, shooting, and nest destruction, resulting in nearextirpation of the species. Captive bred Harpy Eagles were released in the Rio Bravo Conservation and Management Area in Belize, chosen for its quality forest habitat and linkages with Guatemalaand Mexico. Habitat linkage with Guatemala and Mexico were important for conservation of quality habitat and the Harpy Eagle on a regional level. As of November 2009, fourteen Harpy Eagles have been released and are monitored by the Peregrine Fund, through satellite telemetry.[45]

In January 2009, a chick from the all but extirpated population in the Brazilian state of Paraná was hatched in captivity at the preserve kept at the vicinity of the Itaipu dam by the Brazilian/Paraguayan state-owned company Itaipu Binacional.[46] In September 2009, an adult female, after being kept captive for twelve years in a private reservation, was fitted with a radiotransmitter before being restored to the wild in the vicinity of the Pau Brasil National Park (formerly Monte Pascoal NP), in the State of Bahia.[47]

In December 2009, a 15th Harpy Eagle was released into the Rio Bravo Conservation and Management Area in Belize. The release was set to tie in with the United Nations Climate Change Conference 2009, in Copenhagen. The 15th eagle, nicknamed "Hope," by the Peregrine officials inPanama, was the "poster child" for forest conservation in Belize, a developing country, and the importance of these activities in relation to global warming and climate change. The event received coverage from Belize's major media entities, and was supported and attended by the U.S. Ambassador to Belize, Vinai Thummalapally, and British High Commissioner to Belize, Pat Ashworth.[48]

In Colombia, as of 2007, a couple of Harpies composed of an adult male and a subadult female confiscated from wildlife trafficking were restored to the wild and monitored in Paramillo National Park in Córdoba, another couple being kept in captivity at a research center for breeding and eventual release.[49] A monitoring effort with the help of volunteers from local Native American communities is also afoot inEcuador, including the joint sponsorship of various Spanish universities[50]—this effort being similar to another one going on since 1996 in Peru, centered around a Native Community in the Tambopata Province, Madre de Dios Region.[51] Another monitoring project, begun in 1992, was operating as of 2005 in the state of Bolívar, Venezuela.[52]

 
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