The hooded merganser has a length between 16 and 19 inches. This duck's small, thin bill and crested head give it a distinctive profile. Breeding males may have a glossy black head with a neat, rounded crest, and a prominent white head patch starting behind the eye. Rusty flanks are separated from a white breast by two vertical black bars and a black back. Females are dark with a grayish-brown head and a prominent rust-orange crest. The back is dull black, the flanks brownish-gray, and the chin and throat paler.