Mountain Hawk-Eagle vs Changeable Hawk-Eagle

In short

Juvenile Mountain Hawk-Eagles and Changeable Hawk-Eagles can look confusingly similar in flight, but the best field mark is the underwing and underpart pattern: juvenile Mountain Hawk-Eagles show a plain buffy to tawny underside with minimal streaking, while juvenile Changeable Hawk-Eagles are usually much whiter below with fine streaks or spots on the chest and a more variable head pattern. Adults are easier: Mountain Hawk-Eagles have a boldly barred rufous underside and a rusty, streaked head, while Changeable Hawk-Eagles are streaked below with a white or buff base and have a more variable crest. Both have short, broad wings and long tails, but Mountain Hawk-Eagle's wings are more rounded and bulging, giving a pinched-in look at the rear base. Structure and flight style differ subtly, but plumage—especially in immatures—is the most reliable separator.

Identification tips

1. Juvenile underpart color: Juvenile Mountain Hawk-Eagles are plain buffy to tawny below with little or no streaking, while juvenile Changeable Hawk-Eagles are much whiter below, often with fine streaks or spots on the chest and more variable head pattern. This is the most reliable mark for immatures.
2. Juvenile upperwing coverts: Mountain Hawk-Eagle juveniles have a scaled effect on the upperwing coverts with tawny mid-wing patches; Changeable Hawk-Eagle juveniles have more extensive white scaling, sometimes with median coverts almost all white.
3. Juvenile head pattern: Mountain Hawk-Eagle juveniles have dark streaks on the crown, cheek, nape, and hind-neck, but the rest of the head is buffy; Changeable Hawk-Eagle juveniles can have a buff or whitish head with dark spots or streaks on the rear crown and nape, and a white-tipped black crest (especially in peninsular India and Sri Lanka).
4. Juvenile tail pattern: Both have a pale-tipped, banded tail, but Mountain Hawk-Eagle's bands are less distinct and fewer, while Changeable Hawk-Eagle's tail is light brown with about seven thin dark bars.
5. Adult underpart pattern: Adult Mountain Hawk-Eagles are barred rufous over white below, with bold blackish stripes on the throat; Changeable Hawk-Eagles are white to buff below with bold black or dark brown streaks, not bars.
6. Adult head and crest: Mountain Hawk-Eagle adults have a rusty, strongly streaked head and a mostly black crest with a buffy tip; Changeable Hawk-Eagle adults have a variably streaked, sometimes rufous-tinged head and a blackish, often floppy crest (sometimes absent).
7. Adult tail pattern: Mountain Hawk-Eagle adults have a grey-brown tail with obscure blackish bands; Changeable Hawk-Eagle adults have a paler brown tail with a broad blackish subterminal band and 3–4 narrower bars.
8. Underwing pattern in flight: Mountain Hawk-Eagle adults show rusty underwing linings with dusky mottling and broad blackish bars on secondaries; Changeable Hawk-Eagle adults have paler underwing linings and less contrasty barring.
9. Wing shape in flight: Mountain Hawk-Eagle shows bulging secondaries and a pinched-in rear wing base, giving a rounded, broad-handed look; Changeable Hawk-Eagle has straighter trailing edges and a slightly more slender wing.
10. Perched wing length: On perched birds, Changeable Hawk-Eagle's wings reach only about one-third to halfway down the tail, a subtle but sometimes useful mark.
11. Flight style: Mountain Hawk-Eagle glides with shallow beats and a shallow V, wings pressed forward; Changeable Hawk-Eagle's flight is powerful but with less pronounced V and more level wings.
12. Eye color: Adult Mountain Hawk-Eagles have golden to yellowish-orange eyes; Changeable Hawk-Eagle adults have yellow to orange-yellow eyes. Juveniles differ: Mountain Hawk-Eagle juveniles have pale bluish-grey to pale yellow eyes; Changeable Hawk-Eagle juveniles have grey-brown to pale greenish eyes.
13. Crest shape and presence: Mountain Hawk-Eagle's crest is mostly black with a small buffy tip and always present; Changeable Hawk-Eagle's crest is blackish, often floppy or sometimes absent, and can vary in length.
14. Leg feather color: Juvenile Mountain Hawk-Eagles have whitish leg feathers; Changeable Hawk-Eagle juveniles show tawny barring or are less distinctly colored.
15. Habitat context: In high-elevation or dense mountain forest, Mountain Hawk-Eagle is more likely; in lowland, open woodland, or plantation, Changeable Hawk-Eagle is favored. Always use habitat as supporting evidence, not a primary mark.

Size

Both species are large, powerful raptors with similar overall size and proportions. There is no reliable size difference in the field: both have short, broad wings and long tails. Any perceived size difference is likely due to posture or angle rather than actual measurements. [wikipedia][avonet]

Plumage

• Juvenile/immature (first 2–3 years):
• Mountain Hawk-Eagle juveniles are dark brown above with clear cream to whitish feather edges, creating a scaled effect on the wing coverts and tawnier mid-wing patches. The underparts are plain buffy to tawny, extending to the head and neck flanks, with dark streaks only on the crown, cheek, nape, and hind-neck. The underwing linings are also buff to tawny, and the wing-tips are black, sometimes forming a vague carpal arc. The tail is thinly banded brown with a whitish tip.
• Changeable Hawk-Eagle juveniles are also dark brown above but have much more conspicuous white edges on mantle and wings, sometimes with median coverts largely white. The underparts are more variable: in much of India and Sri Lanka, they show thin brown streaks on the chest or small spots on the breast, with obscure tawny barring on the thighs and legs; elsewhere, they can be almost pure white below. The head can be buff with a white-tipped black crest or nearly all whitish, but always with some dark spotting or streaking on the rear crown and nape. The tail is light brown with about seven thin dark bars and a whitish tip.
• Adults:
• Mountain Hawk-Eagle adults are dark brown above with paler edges on the coverts, a rusty head with strong black streaks, a mostly black crest with a buffy tip, and a tail with obscure blackish banding. The throat has bold blackish stripes, and the underparts are barred rufous over a whitish ground. The underwing linings are rusty, paler on the forepart, and the secondaries are broadly barred blackish over grey. The primaries are whiter-based and darker-tipped.
• Changeable Hawk-Eagle adults are dark brown above with faint pale edges on the coverts, a variably streaked and rufous-tinged head, and a blackish crest (sometimes floppy or absent). The tail is paler brown with a broad blackish subterminal band and 3–4 narrower bars. The underparts are white to buff with bold black or dark brown streaking, more subtle on the abdomen and more obvious on the legs. There are also intermediate and dark morphs, but the pale morph is most similar to Mountain Hawk-Eagle.
• Aging: Both species take up to 4 years to reach full adult plumage, but Mountain Hawk-Eagle juveniles remain much plainer below for longer, while Changeable Hawk-Eagle juveniles develop streaks and lose white more quickly.

Behaviour

Both species perch upright and can be seen in open or semi-open areas, but Mountain Hawk-Eagle is more likely to be found in dense forest or at higher elevations, often gliding with shallow beats and glides, wings in a shallow V and pressed slightly forward. Changeable Hawk-Eagle perches bolt upright and may use more open perches. In flight, Mountain Hawk-Eagle shows a prominent head and bulging secondaries, creating a pinched-in look at the rear wing base, while Changeable Hawk-Eagle has somewhat straighter trailing edges and a more slender wing shape. Both are agile and powerful, but Mountain Hawk-Eagle is noted for especially fast, maneuverable flight.

Habitat

Mountain Hawk-Eagle is typically associated with hilly or mountainous forests, especially in the Himalayas and other upland areas. Changeable Hawk-Eagle is more adaptable, found in a wider range of wooded habitats from dense forest to open woodland and even plantations, often at lower elevations. If seen in dense mountain forest, Mountain Hawk-Eagle is more likely; in open or lowland areas, Changeable Hawk-Eagle is favored.