The adult male is all black except for white flanks and a blue-grey bill. It has an obvious head tuft that gives the species its name. The adult female is brown with paler flanks, and is more easily confused with other diving ducks. In particular, some have white around the bill base which resembles the scaup species, although the white is never as extensive as in those ducks.
Habitat and Distribution
They breed widely throughout temperate and northern Eurasia. It occasionally visits coasts of the United States and Canada in winter. These ducks are migratory in most of their range, and winter in the milder south and west of Europe, southern Asia and all year in most of the United Kingdom. Their breeding habitat is close to marshes and lakes with plenty of vegetation to conceal the nest. They are also found on coastal lagoons, the seashore, and sheltered ponds.
These birds feed mainly by diving, but they will dabble. They eat molluscs, aquatic insects and some plants and sometimes feed at night.
Calls and Songs
The females' call is a harsh, growling `karr`, mostly given in flight. The males are mostly silent but they make whistles during courtship based on a simple `wit-oo`.