Adult male has black head, neck, and back; the black-margined white crest and chestnut flanks of the male are very distinct. Female is brown with a rust-colored crest. The bill is slim, serrated, with a hooked tip; bill is dark in male and bicolored in female. Male gives a low, froglike sound; female a hoarse “gak.” Mergansers are divers, and the legs are far back on the body; on land, the posture is upright. The head crest may be raised to a nearly circular shape or lowered so that it trails behind the head. Hooded mergansers can leap straight out of the water and is our only merganser that can do so.
Similar species: Common and Red-breasted mergansers don’t breed in Missouri and are only seen as migrants and as winter residents. The males of both have green heads and red bills; red-breasted males have a dark chest and ragged crest; common merganser males have a white chest and lack a crest. The females of both have rusty heads and gray bodies.