The Royal Tern is a seabird. It has a long yellow bill, pale grey upperparts and white underparts. Its legs are black. In winter, the black cap becomes patchy. Juvenile Royal Terns have a scaly-backed appearance.
This species breeds in colonies on coasts and islands. It nests in a ground scrape and lays one or two eggs. Like all white terns, it is fiercely defensive of its nest and young.
Royal Tern feeds by plunge-diving for fish, usually from saline environments. The offering of fish by the male to the female is part of the courtship display.