The Changeable Hawk Eagle (Spizaetus cirrhatus) found in this part of the world is the subspecies limnaeetus. It is crestless and is found from the Himalayan foothills down through Southeast Asia into Greater Sundas to Philippines. This subspecies is polymorphic, with a dark and a pale morph (above).
The sexes are similar but the female is slightly larger. The juvenile (pale morph) is distinct, with its head and underparts largely white (left). Juveniles begin to breed in the third year and become fully adult in fourth year or later.
The adult pale morph is brown above, with pale edges, especially on wing coverts. The pale brown tail has a thin whitish tip, broad blackish subterminal band and three to four other narrower, browner and often much more obscure bars. The white to buff area of the throat to breast and upper belly and flanks are more or less boldly streaked with black to dark brown.
The adult dark morph is entirely blackish-brown, including the uppertail, the inner half being greyer.
The wings are shortish, with the wing tips about one-third to half down tail; tail long and thinly-banded.
Legs are long, feathered; appearing spindly because of the short tibial feathering.
The bird perches upright, especially in the early morning and afternoon. It stays for long periods waiting patiently for prey. These may include squirrels, birds, snakes and lizards.
During mornings, the eagle soars alone or in pairs, taking advantage of the thermals.
(Images by Mark Chua except the dark morph eagle by Chan Yoke Meng.)