Adult:
Head and nape are dark black with a bluish sheen. Back is gray, slightly tinged with brown. Flanks and upper tail coverts are gray. Wings are black with the inner webs of the primaries having a pale white base. Tail feathers are black with gray tips; the gray area at the tip increases in size towards the outer feathers. Chin and undertail coverts are pure white. The remaining underparts are white, slightly tinged with gray. This species is similar to the subspecies H. m. tonkinnensis but slightly larger in size.
Eyes are brown or reddish-brown. Bill is black. Legs are dark brown or pale black.
Measurements:
Wing: 89 – 106 mm; Tail: 110 mm; Tarsus: 32 mm; Bill: 17 mm.
Distribution:
The Black-headed Sibia has only been found in Lào Cai and Hoàng Liên Sơn at altitudes above 1,500 meters.