South Polar Skua

South Polar Skua (Stercorarius maccormicki) is a large brown Antarctic skua with broad wings, a heavy hooked bill and conspicuous white wing flashes. Body shape, bill structure, plumage pattern and voice provide the strongest field characters. Age, sex and season may alter its appearance, so identification should combine several features and careful direct comparisons with similar species in the same habitat (Wikipedia, general species account).

It breeds on ice-free Antarctic ground, scavenges and hunts around seabird colonies, and spends the non-breeding season roaming at sea. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. Japanese records place it within the country's documented avifauna as a resident, migrant or visitor (Wikipedia, general species account; Wildlife of Japan occurrence records).