The Black Hawk-Eagle is a large raptor that exhibits a conspicuous crest on the crown, of black feathers with white bases. Otherwise the plumage is mostly glossy black. Wings are very broad, and tail is long rounded. The under surfaces of the wings are barred with white, and tail has broad gray bars. Females are like males, but larger. In juveniles the plumage is much paler. The head is a mixture of white and yellowish beige, the breast is streaked black and brown, and belly is mottled black and white. Two subspecies are distinguished, differing in size and the pattern of barring.
The distribution of the Ornate Hawk-Eagle (Spizaetus ornatus) overlaps very broadly with that of the Black Hawk-Eagle, except for the Pacific coast of Colombia and Ecuador, where the Black Hawk-Eagle does not occur. The flight profile of Spizaetus ornatus resembles that of S. tyrannus, but tyrannus has a much darker plumage.
Also, no other blackish raptor shows such a conspicuous boldly banding on the underside of the wings, as well as the checkered flight feathers, and the obvious rounded wings swept forward narrowed at rear base (Hilty and Brown 1986, Ridgely and Greenfield 2001). Dark morph Hook-billed Kites (Chondrohierax uncinatus) have somewhat similar flight patterns and profile (Ridgely and Greenfield 2001), but are much smaller, and the under surfaces of the wings are much blacker.
Adult: Sexes similar, although the female is larger. Plumage overall silky black. Feathers of occipital crest black, with white bases. Wings are very broad; undersides of primaries and secondaries with wide white bars, and the underwing coverts also extensively marked with white. Tail is rounded and long, with brownish gray tips and three wide bands across the tail. Feathered tarsi and thighs narrowly barred white.
Juvenile: Forehead, throat, tips of crest feathers and supercilium white. Head is also white and yellowish-beige. Breast is streaked black and brown,; belly mottled black and white.
Immature: Upperparts brownish black with whitish mottling, with white throat and eyestripe, and blackish cheeks. Underparts buffy white and heavily streaked blackish, while its flanks and sides are solid blackish. Abdomen and thighs barred with black.
Iris: bright orange or golden yellow
Bill: blue-black; cere slaty
Tarsi and toes: tarsi feathered; toes yellow
Data primarily from Wetmore (1965).
Female are similar to males, but they are larger.
Total length: 57-68 cm (Wetmore 1965), 58-71 cm (Bierregaard 1994), 64-71 cm (Hilty and Brown 1986)
Wingspan: 140 cm (Bierregaard 1994)
Linear measurements (mm) of Spizaetus tyrannus serus (Wetmore 1965)
| || || wing|| tail|| culmen from cere|| tarsus|
| male|| mean|| 378.2|| 302.8|| 28.4|| 82.0|
| || range (n=5)|| 371-383|| 291-312|| 27.3-30.2|| 78.1-86.0|
| female|| mean|| 391.2|| 303|| 30.0|| 87.9|
| || range (n=3, except for wing)|| 390-393 (n=2)|| 296-311|| 29.5-30.2|| 84.6-92.0|
Comparison of the two subspecies of Spizaetus tyrannus (Blake 1977)
| || || || wing|| tail|
| male|| serus || mean|| 380.2|| 309.2|
| || || range (n=11)|| 354-401|| 291-325|
| || tyrannus|| mean|| 398.3|| 366|
| || || range (n=?)|| 362-422|| 365-367|
| female|| serus|| mean|| 400.4|| 320.1|
| || || range (n=8)|| 353-445|| 289-386|
| || tyrannus|| mean|| 443.7|| 388.8|
| || || range (n=?)|| 428-460|| 370-405|
Mass: male, 950 g; female, 1120 g (Bierregaard 1994)