Species (Catharacta skua, family Stercorariidae) of predatory seabird, called great skua in Britain (where the jaegers are also called skua). It is about 24 in. (60 cm) long. It resembles a heavily built gull, with brownish body and large white wing patches. It is the only bird that breeds in both the Arctic and the Antarctic. The agile, swift skuas force other birds to disgorge food; they nest near penguins, petrels, murres, and terns, stealing their eggs and young. They also eat lemmings and carrion.