The Blue Duck is endemic to New Zealand. It lives along clear rivers with forested banks and occurs on both the North and South Islands.
Adults are slate blue-grey with chestnut spots on the breast, a pale grey bill ending in a black flap, and yellow eyes. Males are larger and have more breast spots and stronger green iridescence.
It is now patchily distributed along forested headwater rivers. Occupied streams tend to have stable channels, clear water, and forest remaining along their banks.
An extinction-risk assessment has not been added yet.