Harpia harpyja
harpy eagle

Harpy eagles (Harpia harpyja) are distributed throughout Central to South America. They are found from southern Mexico to the eastern part of Bolivia, southern Brazil, and northern Argentina. (Beacham, 2000; Frost, 2007; Grzimek, 2003; Merrick, 2006; Rettig and Hayes, 1995; Tingay, 2010)

Harpy eagles live in the canopies of tropical lowland rainforests. They prefer undisturbed forests but will also hunt along open patches of land. They generally are found in mid to upper levels of rain forest canopies where they are able to find preferred prey. (Beacham, 2000; Fowler and Cope, 1964; Frost, 2007; Grzimek, 2003; Merrick, 2006; Rettig and Hayes, 1995; Tingay, 2010; Trinca, et al., 2008; de Carvalho, jr. and Galetti, 2000)

Harpy eagles are the largest species of eagle with a body length that can range from 89 to 102 cm and a wing span of 2 m. Their talons can be up to 12.5 cm long. Females are normally larger with an average weight of 7 to 9 kg, while the males weigh an average of 5 to 8 kg. The mantle, scapulars, the top of the secondaries and primaries, secondary coverts, greater primary coverts, and the rump are slate black in color, but can vary to gray. The tail is made up of long gray feathers with horizontal black bars. The breast, belly, and flanks, are light grey with horizontal black stripes. The head, thighs and vent are light gray and the nape has a dark band across it. The crown of harpy eagles consists of long black feathers which raise when threatened, though some theorize they also raise them to direct sound to their ears. Their bills are black and their feet are yellow with black talons. (Beacham, 2000; Fowler and Cope, 1964; Frost, 2007; Grzimek, 2003; Merrick, 2006)

Harpy eagles form breeding pairs that last for life. The pair builds the nest together and chirp to each other while doing so. They will occasionally rub their bills together for a few seconds before going back to work. This activity seems to help them to preserve their bond. They build their nests in large, tall trees, high above the forest floor. During the nest building phase, the pair will rarely radiate more than 180 m from the nest. The mating pair of harpy eagles does not have a courtship display before mating, and will mate multiple times over a period of a few days. (Rettig and Hayes, 1995; Rettig, 1978)

The breeding season for harpy eagles coincides with the start of the rainy season which usually begins in April or May. Harpy eagles construct large nests that measure 1.2 m thick and 1.5 m across. The nests are built 27 to 43 m above ground, and consist of woven sticks lined with soft vegetation and animal fur. These impressive nests are reused by breeding pairs every year. The female lays two eggs, but will raise only one chick. Eggs are incubated for an average of 56 days. Both parents tend the chick for 10 months, well after the chick fledges between 6 and 7 months of age. Juveniles often stay near their parents for some time and will occasionally beg for food. Juveniles do not reach maturity until 5 or 6 years old, at which time they often return to their original nesting area to breed. Pairs of harpy eagles only breed once every 2 to 3 years. (Rettig and Hayes, 1995; Rettig, 1978; de Carvalho, jr. and Galetti, 2000)

Harpy eagles invest a lot of time and energy into their offspring. Both parents incubate the egg for the 56 day incubation period. The female will perform most of the incubation while the male is in search of food. Chicks are hatched altricial, and thus are helpless with downy feathers and eyes open. They will only tend a single chick, so if two eggs are laid, the first born will be fed and the second will perish from starvation. The parents actively tend the young for 10 months, which is several months after the chick fledges at 6 or 7 months old. The parents feed the juvenile once every few days and during this time the juvenile is mostly inactive while occasionally making small flights within the nesting tree. Juvenile harpy eagles often remain in the parents' territory for at least 1 year. (Rettig and Hayes, 1995; Rettig, 1978)

Harpy eagles are estimated to live 25 to 35 years if they remain healthy. Disease and injury dramatically affects their chances of survival by inhibiting their ability to find and capture prey. (Beacham, 2000; Rettig and Hayes, 1995; Tingay, 2010)

Harpy eagles are most often found in pairs as they form monogamous pairs that mate for life. Pairs are also observed with a third, juvenile eagle which is their offspring from the most recent breeding season. They are solitary hunters which use their keen sense of sight to locate arboreal prey in thick rainforests. Harpy eagles can potentially perch for up to 23 hours in search of prey. They are incredibly skilled in flight and are adept at maneuvering through their dense, forest habitat. They are diurnal and hunt during the day. (Rettig, 1978; de Carvalho, jr. and Galetti, 2000)

Harpy eagles require territories of about 30 square km for adequate hunting. They are very territorial and will drive out any competing individuals. (Rettig and Hayes, 1995; Rettig, 1978)

Harpy eagles use vocalizations to communicate with one another and visual displays and vocalizations in mating rituals. They will often produce vocalizations while sitting on perches, which sound like "uahaaaau...uahaaaau...uahaaaau". This is believed to be territorial behavior. Pairs of harpy eagles will often rub their bills together, which is believed to be part of mate bonding. Like all birds, harpy eagles perceive their environment through visual, tactile, auditory and chemical stimuli. (Rettig and Hayes, 1995; Rettig, 1978)

Harpy eagles depend on their 5 inch long talons and powerful legs to subdue prey items. They are well-adapted to snatching prey from the canopy and are powerful enough fliers to carry their prey away to a perch to feed. Harpy eagles' main food sources are sloths and primates, but have also been known to prey upon lizards, birds, small rodents, and sometimes small deer. (Fowler and Cope, 1964; Grzimek, 2003; Rettig and Hayes, 1995; Rettig, 1978; Trinca, et al., 2008; de Carvalho, jr. and Galetti, 2000)

Harpy eagles are apex predators of their rainforest ecosystems. Hatchling harpy eagles may be at risk from predation by other harpy eagles. This type of predation is a rare occasion as the parents defend the nest and their territory. (Rettig, 1978)

Harpy eagles are apex predators of their rainforest ecosystems. Like most predators, they aid in keeping prey populations in check. They have an important role in controlling mesopredators such as capuchin monkeys (Cebus). Capuchin monkeys often prey on bird eggs, and if left unchecked these mesopredators could lead to the local extintions of sensitive species. (Rettig and Hayes, 1995; Trinca, et al., 2008)

Harpy eagles will occasionally be used in ceremonial rituals by indigenous hunters. Harpy eagles are also the national birds of both Panama and Parana, Brazil. (Trinca, et al., 2008)

There have been reports of harpy eagles preying on small livestock, such as chickens, of local farmers. However, this is a rare occurrence and the eagles overall have no adverse effects on humans. (Trinca, et al., 2008)

Harpy eagles are listed as least concern by the IUCN Red List but notes the population is declining. They are listed as endangered by the United States Federal List in isolated regions of Mexico. The international trade of this species is regulated under CITES which considers harpy eagles to be under the greatest threat of becoming endangered. There have been many cases of local extinctions in areas with a lot of human activity. This is caused mainly to the destruction of its habitat due to logging and farming. There have also been reports of harpy eagles being shot by farmers who perceive the eagles as livestock predators. Programs are being set up to educate farmers and hunters to increase awareness and understanding of harpy eagles. (Rettig and Hayes, 1995; Tingay, 2010; Trinca, et al., 2008)