Best time to see: mid Oct to mid Apr

Key facts

Mostly dark duck with white in the wing, sometimes seen out at sea with common scoter

Winter visitor to the UK from its breeding grounds in Scandinavia

Recognition

Male: large black duck with black and yellow bill, white on wings; female is brown with white patches; 55 cm

Forms flocks with common scoter, often revealing presence by flapping wings

Feeds by diving for shrimps, crabs and mussels; flies low and strongly over surface