[4] Under a traditional classification proposed by ornithologist Jean Théodore Delacour based on morphological and behavioral traits,[5][6] whistling ducks belong to the tribe Dendrocygnini under the family Anatidae and subfamily Anserinae.

[7][8] In 1997, Bradley C. Livezey proposed that Dendrocygna were a separate lineage from Anserinae, placing it and its tribe in its own subfamily, Dendrocygninae.

Alternatively Charles Sibley and Jon Edward Ahlquist recommended placing Dendrocygna in its own family, Dendrocygnidae, which includes the genus Thalassornis.

However, Johnsgard considers the white-backed duck (Thalassornis leuconotus) from Africa and Madagascar to be distinct ninth species,[13] a view first proposed in 1960 and initially supported by behavioral similarities.

[citation needed] The whistling ducks have long legs and necks, and are very gregarious, flying to and from night-time roosts in large flocks.