White-winged Tern

White-winged Tern (Chlidonias leucopterus) is a small marsh tern whose breeding adults are black-bodied with contrasting white wings and tail. 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 field comparisons with similar species in the same habitat (Wikipedia, general species account).

It hawks insects and picks aquatic prey over marshes and flooded fields, nesting on floating vegetation before migrating widely. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. The Korean vertebrate catalogue used for this guide records the species in South Korea (Wikipedia, general species account; Wildlife of Korea occurrence records).