These were wind spirits who flew the dead to Hades or Tartarus, purported to have the lower body and talons of a raptor and the head of a woman, standing anywhere from the height of a tall child to as high as a grown man; some depictions have the creatures possessing an eagle-like body with the exposed breasts of an elderly female human, a giant wingspan and the head of a grotesque, sharp-toothed, mutant eagle—something more akin to a goblin with wings.

The irises are gray or brown or red, the cere and bill are black or blackish and the tarsi and toes are yellow.

[18] Being captive, however, this large female may not be representative of the weight possible in wild harpy eagles due to differences in the food availability.

[30] With the exception of some areas of the aforementioned Panama and Costa Rica, the species is nearly extinct in Central America, likely due to the logging industry’s decimation of much of the Meso-American rainforests.

[31] The harpy eagle prefers tropical, lowland rainforests and may also choose to nest within such areas from the canopy to the emergent vegetation.

They do not generally occur in disturbed areas, avoiding humans whenever possible, but regularly visit semi-open forest and pasture mosaic, in hunting forays.

[32] Harpies, however, can be found flying over forest borders in a variety of habitats, such as cerrados, caatingas, buriti palm stands, cultivated fields, and cities.

[34] They possess the largest talons of any living eagle and have been recorded as carrying prey weighing up to roughly half of their own body weight.

Sometimes, harpy eagles are "sit-and-wait" predators (common in forest-dwelling raptors), perching for long periods on a high point near an opening, a river, or a salt lick, where many mammals go to attain nutrients.

[37] Research conducted by Aguiar-Silva between 2003 and 2005 in a nesting site in Parintins, Amazonas, Brazil, collected remains from prey offered to the nestling by its parents.

In the Pantanal, a pair of nesting eagles preyed largely on the porcupine (Coendou prehensilis) and the agouti (Dasyprocta azarae).

[53] Both species of tamanduas (Tamandua mexicana & T. tetradactyla) are taken and armadillos, especially nine-banded armadillo (Dasypus novemcinctus) are also taken,[35][36] as well as carnivores such as kinkajous (Potos flavus), coatis (Nasua nasua & N. narcia), tayras (Eira barbara), and occasionally margays (Leopardus wiedii) and crab-eating foxes (Cerdocyon thous).

[12][35] In one instant, an adult greater grison (Galictis vittata) was killed and partly consumed by subadult female harpy eagle.

[35] The eagle has been recorded as taking domestic livestock, including chickens, lambs, goats, and young pigs, but this is extremely rare under normal circumstances.

[57] Males usually take 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.

Adult female harpies 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.

In many South American cultures, cutting down the kapok tree is considered bad luck, which may help safeguard the habitat of this stately eagle.

It is threatened primarily by habitat loss due to 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.

[16] Such threats apply throughout its range, in large parts of which the bird has become a transient sight only; in Brazil, it was all but wiped out from the Atlantic rainforest and is only found in appreciable 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 significant numbers in Brazilian territory on the northern side of the Equator.

[67] Subsequent research in Brazil has established that, as of 2009, the harpy eagle, outside the Brazilian Amazon, is critically endangered in Espírito Santo,[68] São Paulo and Paraná, endangered in Rio de Janeiro, and probably extirpated in Rio Grande do Sul (where a recent (March 2015) record was set for the Parque Estadual do Turvo) and Minas Gerais[69] – the actual size of their total population in Brazil is unknown.

Since 2002, the Peregrine Fund initiated a conservation and research program for the harpy eagle in the Darién Province.

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 the Brazilian National Institute for Space Research.

[77] The Peregrine Fund has also carried out a research and conservation project on this species since the year 2000, making it the longest-running study on harpy eagles.

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 Guatemala and Mexico.

[80] In September 2009, an adult female, after being kept captive for 12 years in a private reservation, was fitted with a radio transmitter before being restored to the wild in the vicinity of the Pau Brasil National Park (formerly Monte Pascoal NP), in the state of Bahia.

[81] In December 2009, a 15th harpy eagle was released into the Rio Bravo Conservation and Management Area in Belize.

The 15th eagle, nicknamed "Hope" by the Peregrine officials in Panama, was the "poster child" for forest conservation in Belize, a developing country, and the importance of these activities in relation to climate change.

[82] In Colombia, as of 2007, an adult male and a subadult female confiscated from wildlife trafficking were restored to the wild and monitored in Paramillo National Park in Córdoba, and another couple was being kept in captivity at a research center for breeding and eventual release.

[83] A monitoring effort with the help of volunteers from local Native American communities is also being made in Ecuador, including the joint sponsorship of various Spanish universities[84]—this effort being similar to another one going on since 1996 in Peru, centred around a native community in the Tambopata Province, Madre de Dios Region.