What Do Harpy Eagles Eat? Sloths, Monkeys and More

The main foods of the harpy eagle

The harpy eagle is the top predator of the rainforest canopy in Central and South America. Researchers study its diet mainly by collecting bones and fur below nests and by watching what parents bring to their chick. A review of these studies and camera-trap work lists 116 prey species, but a few groups dominate.

Sloths: the harpy’s favorite meal

Sloths are slow, live high in the trees and spend much time in exposed positions, which makes them ideal prey for a forest eagle. At a nest near Parintins in the Brazilian Amazon, studied between 2003 and 2005, sloths made up 79 percent of the prey brought to the chick: 39 percent brown-throated sloths and 40 percent Linnaeus’s two-toed sloths. In Panama, released young harpies caught mostly brown-throated and Hoffmann’s two-toed sloths.

Female harpies can kill fully grown two-toed sloths of up to about 9 kg (20 lb). Learn more about the prey in our profiles of the brown-throated sloth and Hoffmann’s two-toed sloth, and in what do sloths eat?, which explains why these leaf-eaters move so slowly.

Monkeys and other mammals

Monkeys are the second big group. At several nests in Guyana, monkeys made up about 37 percent of prey remains, and at nests in Amazonian Ecuador cebid monkeys formed about 35 percent. Capuchins and sakis of 1–4 kg (2.2–8.8 lb) are taken most often, but females also catch howler monkeys and spider monkeys of 6 kg (13 lb) or more. Tiny monkeys such as tamarins and marmosets seem to be largely ignored, probably because they are too small to be worth the effort.

Many other mammals are taken where they are common. In the Pantanal of Brazil, one nesting pair fed largely on prehensile-tailed porcupines and agoutis. Opossums, coatis, kinkajous, olingos, tayras, tamanduas, armadillos, squirrels, and young deer and peccaries also appear in the diet.

Birds and reptiles

Birds form only a small part of the diet, usually a few percent. They include macaws, other parrots and large ground birds such as curassows. A young harpy in one study learned to catch black vultures. Reptiles are minor overall, but in Suriname green iguanas can be important prey, and snakes, tegus and even tortoises have been recorded.

How harpy eagles hunt

Harpy eagles rely on patience and surprise rather than long chases. Their main methods are:

• Perch hunting: flying short distances from tree to tree, then perching for a while to watch and listen before moving on.
• Sit and wait: perching for long periods near an opening, a river or a mineral lick, where mammals come to feed.
• Fast pursuit: occasionally chasing birds or monkeys through the branches at high speed.

When it strikes, the eagle swoops in and grabs the prey with its enormous feet, often pulling it straight off a branch. Its broad, relatively short wings let it maneuver between trees. Its huge talons are described in how big are harpy eagle talons?

How big is harpy eagle prey?

Typical prey weighs about 0.3–6.5 kg (0.7–14 lb), with an average of around 2.6 kg (5.7 lb). Because females are much larger than males, they take bigger prey: in one study, prey brought to the nest averaged about 1.5 kg (3.3 lb) for males and 3.2 kg (7.1 lb) for females. Adult females have been seen carrying sloths and monkeys of 6–9 kg (13–20 lb), close to their own weight.

Feeding the chick

A pair raises a single chick, and feeding it takes well over a year. While the female incubates the egg for about 56 days, the male hunts for both of them. After hatching, the male continues to bring most of the food at first, and the female tears it into small pieces for the chick. Later both parents hunt.

The chick leaves the nest at about 6 months old but stays nearby for another 6–10 months, still fed by its parents every few days while it learns to hunt. This long dependence is why harpies breed only every two to three years.

Why the harpy’s diet matters

As a top predator, the harpy eagle helps keep populations of sloths, monkeys and other medium-sized mammals in balance. By hunting capuchin monkeys, which raid birds’ nests, it may also indirectly protect some forest birds. Because it depends on large numbers of tree-dwelling mammals, the harpy needs big areas of intact forest. Where forests are cut or hunting removes its prey, harpy eagles soon disappear. Read about other species of these forests in our list of rainforest animals.