UKBirds

Caspian Tern

Hydroprogne caspia

The Caspian Tern (Hydroprogne caspia, formerly Sterna caspia; syn. Hydroprogne tschegrava, Helopus caspius) is a species of tern, with a subcosmopolitan but scattered distribution. Despite its extensive range, it is monotypic of its genus, and has no subspecies accepted either. In New Zealand it is also known by the Maori name Taranui.

It is the world's largest tern with a length of 48-56 cm, a wingspan of 127-140 cm and a weight of 574-782g. Adult birds have black legs, and a long thick red-orange bill with a small black tip. They have a white head with a black cap and white neck, belly and tail. The upper wings and back are pale grey; the underwings are pale with dark primary feathers. In flight, the tail is less forked than other terns and wing tips black on the underside. In winter, the black cap is still present (unlike many other terns), but with some white streaking on the forehead. The call is a loud heron-like croak.