It is sometimes included in Anas, but it belongs to a South American clade that diverged early in dabbling duck evolution.

The feathers of the mantle, back and scapulars are dark brown with pale centers, giving a mottled appearance.

The two subspecies co-occur in a zone of intermediate elevational habitats in Mendoza, Argentina and Talca, Chile.

[5] They reside in sheltered bays and on beaches along the coast, where they forage for clams and other marine amphipods among rocks and kelp beds [6] Crested ducks are non-gregarious, flocking only in areas of unusually high food supplies.

For these reasons they are considered highly territorial [7][4] Nesting birds are found almost throughout the year, depending on location within the range of crested duck.