Eight species of whistling duck are currently recognized in the genus Dendrocygna.
 However, Johnsgard considers the white-backed duck (Thalassornis leuconotus) from Africa and Madagascar to be distinct ninth species, a view first proposed in 1960 and initially supported by behavioral similarities.
 Later, similarities in anatomy, duckling vocalizations, and feather proteins gave additional support.
 Molecular analysis in 2009 also suggested that the white-backed duck was nested within the whistling duck clade.
 In addition to the extant species, subfossil remains of an extinct, undescribed species have been found on Aitutaki of the Cook Islands.
Eight species of whistling duck are currently recognized in the genus Dendrocygna.  However, Johnsgard considers the white-backed duck (Thalassornis leuconotus) from Africa and Madagascar to be distinct ninth species, a view first proposed in 1960 and initially supported by behavioral similarities.  Later, similarities in anatomy, duckling vocalizations, and feather proteins gave additional support.  Molecular analysis in 2009 also suggested that the white-backed duck was nested within the whistling duck clade.  In addition to the extant species, subfossil remains of an extinct, undescribed species have been found on Aitutaki of the Cook Islands.
Whistling duck