(Rissa tridactyla) also black-legged, or Atlantic, kittiwake, a bird of the family Laridae. The body length measures about 40 cm, and the weight about 400 g. The back and wings are bluish gray on top, and the flight feathers are black with white spots at the tips. The remaining plumage is white. The kittiwake is distributed in the northern parts of the Atlantic and Pacific oceans and in the Artie Ocean. It nests on coastal cliffs and on islands in colonies of up to several tens of thousands of couples. Together with murres, the kittiwakes form large breeding colonies.
The kittiwakes build their nests out of grass and mud on rock ledges. There are two or three eggs per clutch, and both the male and female incubate them for about 25 days. The plumage of the young grows in at about one month, at which time the young begin to fly. During the nonreproductive period kittiwakes travel widely over the open water, feeding on small fish and on invertebrates, which they snatch from the surface of the water. The red-legged kittiwake (R. brevirostris) nests on the Komandorskie and Aleutian islands.