Large, dark brown skua with a very robust beak. Several subspecies vary in plumage from largely dark to mottled pale brown. In flight, exhibits a broad white patch on both upperwings and underwings. Usually seen well offshore, less often towards the coast; often follows boats. Lacks the capped appearance of Great and Chilean Skuas, and has darker underwing coverts than those species. The dark morph of South Polar Skua has colder tones and a smaller bill, but field separation is difficult.