Skua, the common name of the web-footed birds of the gull family, subfamily lestridinoe, and genus stercorarius (Briss.). The bill is strong, the basal half with a membranous or corneous cere distinct from the tip, the nostrils opening under it in advance of the middle of the bill; the tip is abruptly and strongly curved; the wings very long, the first quill the longest; the tail wedge-shaped, the two central feathers projecting; tarsi strong, with prominent scales; claws sharp and curved, and feet fully webbed, with the hind toe short and but little elevated; body full and stout. They inhabit the high latitudes of both the northern and southern hemispheres; they chase gulls and other marine birds, even the albatross, forcing them to disgorge a part of their food, and are hence called jagers or yagers; they feed also on the carcasses of cetaceans, the eggs and young of sea birds, and the smaller petrels. Their flight is elevated, rapid, long sustained, and generally in circles, as in birds of prey, which they represent among the natatores; the nests are made in company, of coarse grass, and are placed on rocks or sand, or in desolate heaths; the eggs are one or two. - The common skua (S. catarractes, Temm.), the largest species, is about 2 ft. long, with an alar extent of about 4½ ft.; the bill is 2½ in.; the color above is dark brown, the feathers tipped with gray; wings chocolate brown with the shafts and basal parts white; tail dark brown, white at the base; lower parts dark grayish brown; legs, feet, and bill black, the latter with a tinge of bluish; the central tail feathers project only an inch beyond the others.

The favorite haunts of this species are the seas of northern Europe, especially about the Orkney and Shetland islands, where great numbers are killed for their feathers; it has been obtained on the California coast, and either this or a nearly allied species occurs about Cape Horn, the cape of Good Hope, and in the antarctic seas. The arctic skua (S. [lestris] parasiticus, Temm.) is 21 in. long and 44 in. in extent of wings; the central tail feathers extend about 3 in. beyond the others, and are pointed at the end. This species breeds in arctic America, coming down as far as New York in summer and to the gulf of Mexico in winter; it breeds also in the Orkney and Shetland islands.

Common Skua (Stercorarius catarractes).