A large, distinctive forest raptor, the adult Ornate Hawk-Eagle does not present much of an identification challenge. Adults have rich rufous neck sides, heavily barred underparts, a banded tail, and a long crest. The crest can be erected or laid back on the head, and sometimes the species is misidentified by those who expect Ornate Hawk-Eagle to be prominently crested at all times. Immatures of the smaller Gray-bellied Hawk (Accipiter poliogaster) are remarkably similar in plumage and probably the most significant confusion species for adults. Immature Ornate Hawk-Eagles are distinctive as well, but do present more of an identification challenge and are discussed in full below. As with most raptors, distant soaring birds can be difficult to identify.
Adult Ornate Hawk-Eagles are distinctive, but in South America immature Gray-bellied Hawk (Accipiter poliogaster) looks surprisingly similar, sharing the rufous neck sides, dark cap, dark back, and barred flanks. Although overall plumage pattern is very similar, the Gray-bellied Hawk is much slimmer and smaller (length 38-46 cm versus 56-65 cm in Ornate Hawk-Eagle), has unfeathered tarsi, no crest, and is unlikely to be seen soaring.
Immature Ornate Hawk-Eagle is pale overall, with a short crest, whitish head, breast, and belly, narrow black barring on flanks and fully feathered legs, whitish underwing coverts with faint barring and faintly banded flight feathers. Its crest is shorter and less prominent than adults. Fortunately, relatively few Neotropical raptors (including all Buteo) have pale heads.
Black-and-white Hawk-Eagle (Spizaetus melanoleucus) is perhaps most similar, sharing the large size and extensively white underparts. Black-and-white Hawk-Eagle can be distinguished by its lack of flank and thigh barring, the presence of black around the eye, the darker and more crisply demarcated upperparts, the red cere, and the lack of a crest. Ornate Hawk-Eagle also has a dark shoulder, whereas Black-and-white Hawk-Eagle has a whitish shoulder. In flight, especially at a distance, these characters can be more difficult to see. Ornate Hawk-Eagle is a larger, broader-winged, and shorter-tailed bird compared to Black-and-white Hawk-Eagle, which is proportioned a bit more like an Accipiter with a longer tail and narrower wings. Immature Black-and-chestnut Eagle (Spizaetus isidori) is somewhat similar in size and shape, and is also crested, but has a head washed with brownish, unbarred underparts, and whitish color on the back and upperparts.
Crested Eagle (Morphnus guianensis) and Harpy Eagle (Harpia harpyja) are both much larger and thicker-legged at rest and their heads are grayish or dark, not whitish; adult Harpy Eagle has a black breastband. In flight, note the larger size and even broader wings of the two larger eagles, as well as the prominently barred tail of immature Ornate Hawk-Eagle (the tails of Crested and Harpy are faintly barred from below).
The smaller Gray-headed Kite (Leptodon cayanensis) is superficially similar, sharing a pale head and dark upperparts. However, the larger size, flank and thigh barring, feathered tarsi, presence of a crest, pale iris, and longer legs give the Ornate Hawk-Eagle a quite different appearance. Black Hawk-Eagle (Spizaetus tyrannus) is similar in size and shape but much darker below; even immature Black Hawk-Eagle is extensively washed with dusky on the breast, belly, and underwings.
Flying Ornate Hawk-Eagles should be carefully distinguished from other large tropical raptors. In shape it is very similar to Black Hawk-Eagle, but perhaps broader winged with a relatively longer and more rounded tail (Howell and Webb 1995). Adult Ornates in flight have a distinctively dark-bodied appearance contrasting with the largely pale underwings. Immatures are pale when seen from below, but the faint barring on the flanks and thighs is unlike most other pale-bellied raptors.
Sexes similar in plumage, but differ in size; females are larger than males. The following description is based on Howell and Webb (1995), Ridgely and Greenfield (2001b), and Hilty (2003).
Adult. Face, sides of neck, and chest rufous with crown and crest black. Long crest comes to a point and can be raised or lowered. Bold black malar stripe. Throat and central chest white. Underparts whitish with bold black barring on flanks, belly, and leg feathering, thickest and boldest on the flanks. Undertail coverts whitish with narrow, black bars. Upperparts dark-brown, but mantle darker blackish. Narrow white tips to lesser upperwing coverts giving scalloped appearance to shoulder. White tips on uppertail coverts. Tail boldly banded with broad black and gray-brown bands with pale grayish tip. Underwings whitish, contrasting strongly with dark body. Underwing coverts with scattered dark bars and markings. Remiges pale gray distally with blackish barring boldest on outer primaries, indistinct on secondaries. Outer primaries may appear as translucent panel when backlit.
Juvenile. Head and upperparts unmarked white. Longest crest feathers tipped blackish. Crown streaked with blackish. Malar stripe indistinct or lacking. Sides, flanks, and leg feathering barred like adult, but with much narrower and sparser bars. Upperparts dark brown. Lesser upperwing coverts tipped with white. Upperside of remiges darker than the rest of the wing. Upperside of tail gray with 4-5 broad black bars; tip of tail is white. Tail appears paler from below, looking whitish with 3-5 narrow black bands. Underwings like adult, but barring on remiges less distinct than on adult.
Immature: Molts into first-basic plumage within a few months. First-basic plumage resembles adult but face and chest paler rufous and black malar less distinct. Upper mantle mottled with black. Underparts overall whiter than adult, with black barring on flanks, belly, and leggings intermediate between juvenile and adult. Tail like adult 3-4 broad pale bands on upperside and 3-4 broad black bands on underside. Reaches adult plumage in second pre-basic molt when about two years old. Uppersurface of the wings, the back and the rump are dark gray or blackish. There is a broad black band across the upper breast, separating the gray head from the white belly. The lower breast and the belly are white. The tibial feathers are white, barred with black. The uppersurface of the tail is black, with three broad, ashy gray bands; there also is a narrow, grayish white tip to the tail. The undersurface of the tail is black, with three broad white bands; the basal of these white bands often is largely covered by the undertail coverts. The lesser and median underwing coverts are mostly black, barred or mottled with white. The primary underwing coverts are mostly white, tipped with black. The undersides of the remiges are white, barred with black and with broad black tips; the dark tips are particularly broad at the ends of the outer primaries.
Wings broad and rounded and narrower at base. Tail rather long and squared to slightly rounded. In flight appears quite broad-winged with wings thrust forward. Seen head-on, wings are held flat or slightly bowed.
First pre-basic molt occurs several months after fledging; flight feathers are replaced towards the end of body molt (Howell and Webb 1995). First-basic plumage is similar to adult plumage but paler and less distinctly marked. Second pre-basic molt occurs at about two years of age and in it adult plumage is attained (Howell and Webb 1995).
The below based on Howell and Webb (1995) and Hilty (2003):
Adult: Iris tawny-orange, amber, or yellow. Cere, lores, and orbital ring greenish-yellow or gray-olive. Legs fully feathered but feet are yellow.
Immature: Eyes paler, more yellowish. Lores and orbital ring blue-gray.
Mass: 1.2 kg (Stiles and Skutch 1989)
Length: 56-68.5 cm (Howell and Webb 1995)
Wingspan: 117-142 cm (Howell and Webb 1995)