American black ducks are similar to mallards in size, and resemble the female mallard in coloration, though the black duck’s plumage is darker. The male and female black duck are similar in appearance, but the male’s bill is yellow while the female’s is a dull green. The head is slightly lighter brown than the dark brown body, and the speculum is iridescent violet-blue with predominantly black margins. In flight, the white underwings can be seen in contrast to the dark brown body.
