These birds breed in large colonies on coastal cliffs, laying single elongated conical eggs directly on cliff ledges. They move south in winter to keep in ice-free waters. They dive for food from the surface, swimming underwater and being among the deepest divers of all birds, using their stubby wings to routinely dive to more than 100 meters, and feeding on fish and crustaceans, also some molluscs, insects and plant material. Adult birds are black or brown on the head, neck, back and wings with white underparts. The bill is long and pointed. They have a small rounded black tail. The lower face becomes white in winter. The flight is strong and direct, and these species have fast wing beats due to the short wings. Uria guillemots produces a variety of harsh cackling calls at the breeding colonies, but are silent at sea.