T. ferruginea T. cana T. tadornoides T. variegata T. cristata T. tadorna see text The shelducks, most species of which are found in the genus Tadorna (except for the Radjah shelduck, which is now found in its own monotypic genus Radjah), are a group of large birds in the Tadorninae subfamily of the Anatidae, the biological family that includes the ducks and most duck-like waterfowl such as the geese and swans.

Shelducks are a group of large, often semi-terrestrial waterfowl, which can be seen as intermediate between geese (Anserinae) and ducks[citation needed].

[6] It may originally derive from Celtic roots meaning "pied waterfowl", essentially the same as the English "shelduck".

[8] The namesake genus of the Tadorninae, Tadorna is very close to the Egyptian goose and its extinct relatives from the Madagascar region, Alopochen.

While the classical shelducks form a group that is obviously monophyletic, the interrelationships of these, the aberrant common and especially Radjah sheducks, and the Egyptian goose were found to be poorly resolved by mtDNA cytochrome b sequence data;[9] this genus may thus be paraphyletic.