サンドイッチアジサシ Thalasseus sandvicensis

Pale medium-sized tern with a geographically variable bill pattern: black with a distinct yellow tip in most of its range; entirely yellow in the Caribbean and parts of South America. Shows a shaggy black cap in breeding plumage; nonbreeding birds develop white forehead. Strictly coastal; most commonly found on beaches and estuaries, often mixed with flocks of other terns. Harsh grating calls similar to other terns.