Among the estimated 632 bird species found within the Tambopata National Reserve in southeastern Peru, one of the most magnificent is the crested eagle (Morphnus guianensis). This large bird-of-prey, similar in appearance to the even more massive harpy eagle, is found in the lowland tropical and subtropical forests of both Central and South America.
In addition to the difference in size, which can be hard to establish in a forest environment when the birds are spotted separately, a crested eagle can be distinguished from a harpy eagle by its large head, which appears even larger thanks to the single, pointed crest that has given the bird its name, and which is often extended. The crested eagle can also be distinguished from the harpy eagle by the absence of the black chest feathers seen in the adult harpy, and by the barring on its underparts. It also has a proportionately longer tail than the larger eagle.
In common with other forest-dwelling birds-of-prey, the crested eagle has a relatively short wingspan relative its body size. In fact, the crested eagle is perfectly adapted to hunting in its preferred tropical or subtropical forest habitat. Its short, broad, rounded wings enable the crested eagle to maneuver as its flies through the dense foliage of the forest canopy in pursuit of its prey. At the same time, the eagle’s extremely keen eyesight allows it to detect the tiniest of movements amid the dense tree cover, while its powerful legs and sharp talons are well-designed for catching and disabling its prey.
Adult crested eagles can grow to an average of around 84 centimeters (33 inches) in length and weigh up to 3 kilograms (6.6 pounds). Their wingspan averages around 157 centimeters (62 inches). In common with all species of raptors, female crested eagles are somewhat larger than males. Unlike the harpy eagle, the color of the adult crested eagle’s plumage is variable, ranging from a light to a dark morph and encompassing shades that range from light brown to a dark gray or even black.
While crested eagles are often found in ranges that overlap with those of harpy eagles, they appear to avoid direct competition for food sources by targeting smaller prey. Typically, crested eagles will hunt small monkey species, including tamarin monkeys, woolly monkeys and capuchins. They are also known to hunt opossums and kinkajous, as well as rodents and snakes. Crested eagles have also been spotted hunting small bird species, including jays and guans, and some observers believe that birds may constitute a greater proportion of their diet than that of harpy eagles.
Solitary except when breeding, in common with other raptors crested eagles are always observed singly or in pairs. They breed every two or three years, just as the annual dry season begins in their tropical and subtropical habitats (from March to April), using twigs to build a spacious nest in one of the main forks of large trees, often emergent from the canopy with good views of the surrounding forest. Crested eagles are believed to incubate two eggs, while rearing only one of the chicks. During its first month of life, the female will remain in the nest with the chick, often shading it from heat and protecting it from rain, after which she will support the male in hunting forays. Crested eagle chicks are thought to remain semi-dependent upon their parents for up to sixteen months, before achieving full independence and establishing their own territory.
Crested eagles are rare throughout their range, and the IUCN (International Union for Conservation of Nature) Red List classifies them as near threatened. A breeding pair will typically range over a territory in excess of one hundred square kilometers, and this reliance on broad swathes of forest makes them particularly vulnerable to habitat destruction.