Class: Aves (Birds)
Body length: 35 to 41 inches (89 to 105 centimeters), with female larger than male
Weight: female—14 to 20 pounds (6.3 to 9 kilograms); male—8.5 to 12 pounds (3.8 to 5.4 kilograms)
Wingspan: up to 7 feet (2.1 meters)
Life span: 25 to 35 years
Incubation: 53 to 56 days
Number of eggs laid: 1 to 2 eggs in a clutch
Age of maturity: 4 to 5 years
Conservation status: Lower risk
Early South American explorers named these great birds after
Harpyja, the predatory half-woman, half-bird monster of Greek mythology.
Harpy eagles mate for life.
The harpy eagle is the national bird of Panama.
The strong, silent type: harpy eagles do not vocalize much; when heard they wail (wheeeeeee, wheeeeooooo), croak, whistle, click, and mew.
In 1994, the San Diego Zoo became the first facility in North America to hatch and successfully rear a harpy eagle. We are the only zoo in the U.S. to breed this species.
Animal Bytes: Harpy Eagle
Bold and beautiful
The harpy eagle is legendary, although few people have seen one in the wild. This large bird of prey has a very distinctive look, with feathers atop its head that fan into a bold crest when the bird feels threatened. Some smaller feathers create a facial disk that may focus sound waves to improve the hearing, similar to owls. Like most eagle species, the female harpy is almost twice as large as the male. The harpy eagle's legs can be as thick as a small child's wrist and their curved talons are larger than grizzly bear claws: 5 inches (13 centimeters) long! Harpies may not be the largest bird of prey (that title belongs to the Andean condor), but they are definitely the heaviest and most powerful of birds.
Living the high life
For nesting, harpies favor silk-cotton trees (kapok trees) and usually build nests 90 to 140 feet (27 to 43 meters) above the ground. These eagles like trees with widely spaced branches for a clear flight path to and from the nest. They use large sticks to create the huge frame and line the nest with softer greens, seedpods, and animal fur to make it warm and comfortable. A harpy nest will measure about four feet (1.2 meters) thick and five feet (1.5 meters) across-large enough for a person to lie across! Once built, an eagle pair will reuse and remodel the same nest for many years.
Harpy eagle parents fiercely defend their eggs and young. The mother lays one or two eggs but only the first chick to hatch survives. That first eaglet gets all of the attention, while the other egg dies from lack of incubation. So why does the female lay two eggs? The second egg acts as an insurance policy just in case there is something wrong with the first egg. If the first egg fails to hatch, the second egg has a decent chance of hatching, saving the parents the need to start over with a new egg!
Both parents feed the single eaglet for about 10 months. Harpy eagle chicks are ready to fledge at about six to seven months of age, but they usually hang around the nest for over a year, begging a meal from mother and father. Maybe returning once in 10 days, the parents provide less and less food, forcing Junior to fend for him/herself. Once mature, it is not unusual for chicks to return to nest in their "home tree."
Rain forest take-out
The powerful harpy eagle is fast and agile, flying low over the forest and using its great talons to snatch up monkeys and sloths that can weigh up to 17 pounds (7.7 kilograms)! Harpies also feed on opossums, porcupines, young deer, snakes, and iguanas. Heavier prey is taken to a stump or low branch and partially eaten, since it is too heavy to be carried whole to the nest. Most of their food is found in the rain forest canopy and understory instead of on the forest floor. The larger females tend to take the sloths and monkeys; the smaller, more agile, faster males tend to take more quantities of the smaller food items. This increases the pair's odds of eating on a regular basis. Here at the San Diego Zoo, the harpy eagles are fed thawed rodents and rabbits.
Harpy hunting habits
Harpies are great at saving precious energy. You will never see a harpy eagle soaring over the top of a rain forest. Harpies hunt in and below the rain forest canopy; they perch silently for hours—up to 23 hours!—in a tree, waiting to drop on unsuspecting prey. These eagles have excellent vision and can see something less than 1 inch (2 centimeters) in size from almost 220 yards (200 meters) away. Flying below the canopy, the birds are capable, in a serious chase, of reaching speeds of 50 miles per hour (80 kilometers per hour). The eagle dives down onto its prey and snatches it with outstretched feet. Its short, broad wings help the harpy fly almost straight up, too, so it can attack prey from below as well as above. And the harpy eagle can turn its head upside down to get a better look at its potential meal.
You would think that the massive harpy eagle is invincible. But think again. Years of hunting, in addition to logging, destruction of nesting sites, and poaching have eliminated this bird species from much of its former range, especially the northern part, and it is now rare in many areas. Harpy parents raise, at most, a single eaglet every two years, so once the number of harpy eagles in a particular area has been reduced, it is hard for the population to recover. The San Diego Zoo is the only zoo in the United States to breed this rare species. Fifteen harpy eagles have hatched here since 1992, and two offspring have been released into their native habitat in Panama. We continue to work with The Peregrine Fund to help harpy eagles in the wild.