So named because of its highly variable plumage, the changeable hawk-eagle is a very large bird of prey that can easily be recognized by its distinctive screeching call, and less so by the way it looks. More often seen in flight than perched, the changeable hawk-eagle has two basic forms, the pale morph and the dark morph, with the pale morph being coloured an overall dull brown on its upperparts and with its breast and belly covered in dark streaks and its thighs and undertail coverts covered in pale rufous bars. As for the dark morph, the entire bird is coloured a very dark brown. In flight, the pale morph changeable hawk-eagle has numerous black bars running across the length of its primaries and secondaries (flight feathers) and dark streaks running down its breast and belly while the dark morph is dark brown overall with slightly grey flight feathers.