The American Black duck has a blackish-brown body with a greenish-yellow bill and iridescent purple patches on its upper wings. The female has slightly paler and duller colors than the males.
Black scoters have black plumage with a bright yellowish-orange knob on the bill. Female black scoters are slightly different with a brown body, pale cheeks, and a dark cap.
East Indie ducks can be recognized by their striking iridescent blackish-green plumage, a black bill and black legs, and a female with dull or pale gray plumage.