Utterly unmistakable large shorebird: adult gleaming white, with black back, black flight feathers, and very heavy dark bill used to dispatch crustaceans and other invertebrates. Narrow dark smudge around the eye imparts a sleepy appearance. Juvenile similar to adult but back pale brown. Inhabits sandy beaches and shorelines as well as also coral outcrops, rocky coasts, and mangroves. Forages in flocks, often giving raucous, tern-like calls in flight.