The trailing legs and rounded wings of these slow flying ducks makes them look bigger than they are.
Both species are primarily Mexican. In the U. S., the black-bellied is found only in south Texas and Louisiana. The fulvous also occurs there and in Florida with occasional stragglers further north along both coasts and the Mississippi Valley. The fulvous is the more common of the two species in the United States. Sexes are alike. Both species have shrill whistling calls.