Appearance

Crested Eagle is a very large raptor. It is similar in many ways to the even larger Harpy Eagle (Harpia harpyja), but, unlike the Harpy Eagle, the Crested Eagle exhibits plumage polymorphism. The adult of the more frequent light morph has a light gray head and upper breast. The back and wings are blackish brown or blackish gray, the feathers narrowly tipped with white. The lower breast and belly are white, with a variable amount of narrow brown or rufous barring. The underwing coverts are white, but the under surfaces of the remiges and rectrices are boldly barred black and white. The dark or barred morph is primarily blackish to dark gray, with a blackish breast, underparts that are barred blackish, and the underwing coverts are barred or mottled with black. Adults of both morphs have gray or blackish, elongated feathers on the crown and nape that form an erectile crest. Juvenile Crested Eagles are white below, lacking the gray chest and barred belly of the adult, and generally are pale gray above, including the crest. They are very similar in appearance to immature Harpy Eagle (Harpia harpyja); see Similar Species.

Harpy Eagle (Harpia harpyja) is very similar in appearance to Crested Eagle and shares much of the same geographic range.

In all plumages, Harpy Eagle is larger in overall body size, bill size, and in the thickness of the tarsi, but has a proportionately shorter tail. Another key difference is that the Crested Eagle has a single point to the crest, whereas the crest of the Harpy Eagle is divided in the middle, forming two distinct “horns”. Adult Harpy Eagle also is readily distinguished by its broad black band across the upper breast, and, in flight, by its blackish underwing coverts. Juvenile and immature plumages of the two species are much more similar. Birds in these plumages are best distinguished, with care, by size and proportions; note, however, that with age Harpy Eagle gradually acquires some black on breast band and on underwing coverts, facilitating identification.

The coloration of males and females is very similar. The following description is based on Wetmore (1965), Brown and Amadon (1968), Blake (1977), Bierregaard (1994), and Howell and Webb (1995).

Adult: Sexes similar.

Light morph: The head (including the nape) and the upper breast are pale ashy brown or gray. The crown feathers are streaked and spotted with darker gray. Elongated feathers of crown and nape, forming an erectile crest, have white bases and black tips. Back and scapulars black; uppertail coverts narrowly tipped with white. Lesser wing coverts black, with narrow white tips. Median and greater secondary coverts marbled brown and gray, and barred with dusky. Remiges dusky, with blackish tips, and obscurely mottled with gray. Rectrices black, with narrow white tips and crossed by three gray bands, mottled with mouse brown. Throat white. Lower breast and belly white, narrowly barred with cinnamon. Underwing coverts white. Under surface of remiges white basally and gray distally, and throughout barred with black.

Dark (or barred) morph: Plumage primarily blackish, or, more commonly, the lower breast and belly are blackish, barred with white. Underwing coverts white, but with dark barring.

Juvenile: Plumage overall whitish. The tips of the crest feathers are dusky. Upperparts otherwise vermiculated with pale gray. Remiges blackish, with paler mottling and barring. Underwing coverts white. Under surfaces of remiges barred, similar to the adult but with narrower barring. Rectrices gray-brown with 7-10 narrow blackish bars; under surface of tail whiths with 6-8 narrow dark bars. There is no dark morph juvenile.

First Basic: Similar to Juvenile, but the upperparts have darker mottling, contrasting with paler wing coverts. The tips of the crest feathers are black. Head and chest washed with light gray. Dark morph may become apparent by this stage, with duskier head and breast, and the wing coverts are less contrasting.

Second Basic: Similar to adult, but head and breast paler. Underparts have little or no cinnamon or rufous barring. Upper wing coverts more extensively mottled with pale gray. The rectrices have 3-4 pale gray to gray-brown bands on the upper surface, and the under surfaces have 3-4 whitish to pale gray bands. Dark morph: Similar to adult, but head and breast paler. Upper wing coverts more extensively mottled with pale. Underwing coverts mostly white, with only a few black marks. Tail as in light morph.

Molt of Crested Eagle is only partially understood. Presumably this species follows the Complex Basic Molt strategy. It also may well have a stepwise molt of the remiges, but this has not been documented. Does not attain definitive plumage until at least the third prebasic molt (Howell and Webb 1995).

The iris is brown. Bill is dull black; cere and loral area are dark gray. Tarsus and toes are dull yellow and devoid of feathers.

Bare parts color data are from Wetmore (9165) and Brown and Amadon (1968).

As is true of most species of raptors, females are larger than males (Wetmore 1965, Sick 1993). Refer to Table 1 for recorded measurements.

Total length: 79-89 cm (Hilty and Brown 1986), 81 cm (Stiles and Skutch 1989)

Mass: 1750 g (Terborgh et al. 1990, Dunning 2008)