The harpy eagle is one of the largest and most powerful eagles in the world, and a harpy eagle's body is about 89 to 102 centimeters (35 to 40 inches) long. A harpy eagle's wings can spread up to about 2 meters (6.5 feet) from tip to tip, and a female weighs up to about 9 kilograms (20 pounds). A male weighs about 9 to 11 pounds, much less than a female, and a female harpy eagle is bigger than her mate. A harpy eagle's back claws are about as big as a grizzly bear's claws. Zoos and a university museum report that a back talon is up to about 5 inches (12.5 to 13 centimeters) long. Reported lengths of the rear talon differ: The Peregrine Fund says about 3 to 4 inches, while a wildlife magazine gives the hind claw as up to 7 cm.

A harpy eagle has a ring of feathers around its face, like an owl, and harpy eagles share a facial disk with owls, but are one of only a few daytime birds of prey to have one, and the disk can be lifted or lowered at will. The disk may focus sound waves to improve hearing, similar to owls. In the dark interior of the rainforest, hearing is more important to the harpy eagle than vision, and a harpy eagle has sharp eyesight and uses it to find animals in the trees. The San Diego Zoo reports that a harpy eagle can see something less than 1 inch (2 centimeters) in size, and harpy eagles have a crest of a few long feathers that can be raised and lowered at will.

A harpy eagle has relatively short wings, which help it steer between trees in thick forest, and a harpy eagle can fly between trees and branches with great skill for such a big bird. Harpy eagles can fly low, below the tops of the trees, to look for prey, and a harpy eagle is not built for true soaring; it flies between the trees of the forest. Harpy eagles hunt alone and in the daytime. One report says a harpy eagle can reach about 50 miles per hour (80 kilometers per hour) in a serious chase, but the report does not say how this was measured, and harpy eagles travel relatively slowly from tree to tree through the forest when they hunt.

Harpy eagles live in forests in Central America and South America, and harpy eagles prefer large areas of mature, unbroken forest. The Animal Diversity Web says a harpy eagle needs a territory of about 30 square kilometers for hunting, and a nature-center account says a harpy eagle territory can exceed 10,000 acres.

Harpy eagles eat monkeys and sloths that live in the trees, and harpy eagles also eat opossums and iguanas. Harpy eagles do not need to eat every day: they can go a week or more without food, and researchers followed 16 harpy eagle nests in Brazil's Mato Grosso region with camera traps and identified bone fragments at the nests to learn what the eagles ate. Of 306 prey remains found at those nests, nearly half were two-toed sloths, brown capuchin monkeys and grey woolly monkeys.

Harpy eagles build their nests in some of the tallest trees in the forest, about 27 to 43 meters (90 to 140 feet) above the ground, and a nest is built of woven sticks lined with soft plants and animal fur, and more than 300 branches go into one. Harpy eagles reuse the same nest, which can be six feet across and more than a foot deep, and harpy eagles pair up with one mate, and scientists believe a pair may stay together for life. A female harpy eagle lays one or two eggs, but usually only one chick grows up, and a harpy eagle egg takes about 55 days to hatch.

A newly hatched nestling is so small that it fits in the palm of a person's hand, and a newly hatched chick is all white and does not get its full adult coloring until its third year. Both harpy eagle parents care for their chick for about 10 months, and a young harpy eagle first leaves the nest at about five to seven months old. Young harpy eagles stay within about 100 meters of the nest for at least 15 months. Harpy eagles reach adulthood when they are about five years old. A pair of harpy eagles raises a chick only about every two to three years. A harpy eagle lives about 25 to 35 years.

The Peregrine Fund says it was the first organization to set up a program to breed harpy eagles in captivity and release them to the wild. In the first Belize releases, in 2003, all four captive-bred harpy eagles stayed within 1 to 5 km of their release site.

Telemetry researchers fitted the released harpy eagles with backpack transmitters weighing 60 to 105 grams. Satellite units on the released eagles recorded 11 consecutive hours of GPS fixes, one per hour, every four days. Researchers recorded 6,873 location fixes from 36 released harpy eagles in Belize and Panama, with an average tracking period of 670 days per bird. Researchers estimated the area each bird used only for eagles with at least 180 days of continuous tracking data that showed home-ranging behavior.

Tracking each bird for one to four years, researchers estimated 55 yearly areas where released eagles lived and roamed. The busiest part of each area, its core, averaged 247.5 km2, and the whole area averaged 1039.5 km2. In this tracking study, females used larger areas than males.

Harpy eagles can only be seen predictably at the nest during the first 12 months of a 30 to 36 month nest cycle. Camera-trap researchers estimated that a minimum of 13, 17 and 26 harpy eagle nests are needed to have at least one nestling visible on 90, 95 and 99 percent of days. The Peregrine Fund has found and monitored 56 harpy eagle nest sites in Panama since 2000, as of November 2026. In 2017, local people reported five previously unknown harpy eagle nests to The Peregrine Fund in Panama.

Harpy eagles once lived in forests from southern Mexico through Central and South America. Harpy eagles have disappeared from much of their former range, mostly because forests were cut down and people hunted them. Deforestation and hunting are the two main threats to harpy eagles. About 93 percent of the harpy eagle's distribution range lies within Amazonian forests, a 2021 study reported.

In most countries of Central America, harpy eagles are listed as Critically Endangered, as of November 2026. For the species as a whole, the IUCN Red List lists the harpy eagle as Vulnerable, a species facing a high risk of extinction in the wild, as of November 2026. In 2021 the IUCN Red List moved the harpy eagle from Near Threatened (as classed in 2017) up to Vulnerable.

In Belize, harpy eagles are found only in the Maya Mountains. The largest known breeding population of harpy eagles is in Panama, close to the border with Colombia. The harpy eagle is Panama's national bird and a flagship species for its rain forests.

Words to know

• telemetry: remote tracking
• transmitters: radio devices
• flagship: symbol species
• nestling: baby bird