The Caspian tern travels between breeding areas in Australia and parts of Asia and is the world's largest tern.
Caspian terns have an almost worldwide distribution, with breeding colonies on inland lakes, coastlines, and islands across Europe, Asia, Africa, North America, and Oceania. Many populations migrate after breeding, while others are resident or move only short distances. Australian birds can travel north into Southeast Asia.
The species is large and powerful, with a black cap, pale gray body, deeply forked tail, and a long red bill marked with black. It hunts fish by plunging into water, but it may also take insects, crustaceans, and small birds.
The Caspian tern is sometimes confused with royal or great crested terns. Its massive red bill and large size are especially useful identification features. Despite its broad range, it is one species rather than a collection of regional species, and its migration differs among populations.