Common Tern

Common Tern (Sterna hirundo) is a slim tern with pale grey upperparts, forked tail, black cap and usually a red bill tipped black. 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 plunge-dives for fish in marine and fresh water and nests on open beaches, islands and artificial rafts. 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).