Adult Crested Serpent Eagle:
The head, neck, upper back, rump, and tail are black. The outermost tail feathers have a very narrow white edge. The feathers on the back have white bases, occasionally visible. The black shoulders have reddish-brown streaks, with the base of the scapular feathers sometimes showing as small streaks. The wing coverts and primary feathers are black, with brown streaks at the feather bases. The secondary feathers are black. The tertiary feathers have reddish-brown and white markings similar to those on the shoulders, and the underside of the neck has a broad white band, followed by a black band, sometimes mixed with brown. The center of the belly and the underside of the tail are black. The remaining underside of the belly is rufous with brown streaks. The underwing and undertail are gray. The remaining portions of the wing are black. The third primary feather is the longest, and the nape has a long crest. The eyes are reddish-brown. The beak is bluish-gray, with a black tip on the upper mandible; the tip of the lower mandible is pale white. The skin at the base of the beak is bluish-gray. The legs are slate gray.
Measurements:
- Wing: 225 – 244 mm
- Tail: 130 – 145 mm
- Tarsus: 26 – 27 mm
- Bill: 20 – 22 mm
Distribution:
The Crested Serpent Eagle is distributed in India, Myanmar, Thailand, Indochina, and Northern Malaysia.
Vietnam:
This species is found in Hòa Bình, Thừa Thiên, Kontum, Tây Ninh, and Biên Hòa (Phú Riềng).