Description:
Smaller than common Guillemot, body plump and pear-shaped. Summer breeding plumage: Body all black with large oval white upperwing patches; underwing white with dark trailing edge, red legs and feet. Winter plumage: Underparts become white and the upperparts barred white but white wing patch still obvious. Juvenile/1cy: similar to adult winter but white wing patch heavily barred; head and breast duskier than adult.
