Other Names: none
Distribution: St. Matthew and Hall islands in the Bering Sea in summer; western coast of Alaska in winter.
Size: 16-18 cm in length with a 30-33 cm wingspan. Adults weigh an average of 54.5 g.
Plumage: Breeding adult males are almost pure white, except for the ends of the flight and mantle feathers and the tips of the central tail feathers. Females show some black on the back but are otherwise similar to the males. In winter plumage both sexes are lightly streaked with brown.