Systematics
The genus name Tadorna comes from Celtic roots and means "pied waterfowl", essentially the same as the English "shelduck".
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 Raja Shelducks, and the Egyptian Goose were found to be poorly resolved by mtDNA cytochrome b sequence data; this genus may thus be paraphyletic.
- Ruddy Shelduck Tadorna ferruginea
- South African Shelduck Tadorna cana
- Australian Shelduck Tadorna tadornoides
- Paradise Shelduck Tadorna variegata
- Crested Shelduck Tadorna cristata - possibly extinct (late 20th century?)
- Common Shelduck Tadorna tadorna
- Raja Shelduck Tadorna radjah
Fossil bones from Dorkovo (Bulgaria) described as Balcanas pliocaenica may actually belong to this genus. They have even been proposed to be referable to the Common Shelduck, but their Early Pliocene age makes this rather unlikely.
Read more about this topic: Shelduck