A duck whose breeding male is slate blue with white markings and chestnut sides; it breeds in fast streams and winters on rough rocky coasts.
Breeding males are slate blue with white markings and chestnut sides. Females are grayish-brown with white facial patches.
It breeds on mountain streams and whitewater rivers. In winter it dives for aquatic invertebrates along rough rocky coasts.
An extinction-risk assessment has not been added yet.