With a black back, black flying feathers, and a powerful, dark beak for taking down crabs and other invertebrates, the gleaming white adult has a striking appearance. A thin, dark smudge around the eye gives the image of sleepiness. Juvenile and adult alike, with a pale brown back. inhabits mangroves, rocky shores, coral outcrops, and sandy beaches and shorelines. feeds in groups and is known to make loud, tern-like sounds while in the air.