Adults are large and bright white with black wingtips. They are distinctively shaped with a long neck and long pointed beak, long pointed tail, and long pointed wings. At sea they flap and then glide low over the water, often traveling in small groups. They feed by flying high and circling before plunging into the sea. They breed in significant numbers at only a few localities and so is an Amber List species. The nest (built mostly by male) is pile of grass, seaweed, dirt, feathers, compacted and held together by droppings, used by same pair for years and gradually building up to tall mound. It requires regular maintenance during the nesting season. Claimed nesting territory is aggressively defended.