Adult Description:
The adult bird exhibits the following characteristics:
- Plumage: The head and neck are black, transitioning to dark slate-gray on the chest, flanks, and back. The remaining dorsal plumage is dark brown. The shoulders and adjacent feathers are gray tinged with yellowish-green, and the undertail coverts are pale black. The primary coverts, primary and secondary flight feathers are pale black, with the first primary feathers and wing edges edged in white. The chest exhibits a grayish-slate hue, gradually lightening to pale gray on the abdomen. The undertail is white, except for the central feathers, which are black. The underwings are gray with white tips.
- Eyes: Red.
- Bill: The bill, the outer nape, and the base near the forehead are bright red; the remaining parts are pale yellowish-green.
- Legs: The lower leg and front of the tarsus are pale yellowish-black. The rear of the tarsus and toes are greenish-gray. On the upper part of the tarsus, near the feathers, there is an orange-yellow ring.
Measurements:
- Wing: 150 – 172 mm
- Tail: 52 – 68 mm
- Tarsus: 47 – 50 mm
- Bill (Male): 38 – 41 mm
- Bill (Female): 32 – 35 mm
Distribution:
The species is distributed in India, Myanmar, Sri Lanka, Thailand, Laos, Cambodia, Vietnam, eastern and southern China, and Korea.
Vietnam:
This species is found in almost all large lakes and ponds with abundant aquatic plants.