Scientific name: Sterna caspia Pallas, 1770
Bird group: Gulls and Terns
Field characters. 50 cm. Largest tern, about the size of a Herring Gull. Easy to recognise by huge red bill and black crested cap. Bill has black tip. Upperwings and back grey, remainder of plumage white. Underside of primaries black. Tail with a shallow fork; legs black. Juvenile has a dusky orange bill, a dark brow cap and heavily brown barred upperparts. Legs dark red-brown. Flight heavy with slow wing beats, like a large gull. Characteristically found standing on sand or mud banks, often together with Black-headed Gull or other small gulls.
Voice. Very loud and hoarse, crow-like 'craaah'. Begging call of juvenile a high whistling 'wiiii'.
Distribution. Summer visitor. Rare and local. Declining in many parts of its range.
Habitat. During breeding season mainly coastal, outside breeding season on migration also found in large shallow inland lakes.
Food. Mainly fish, obtained by diving; occasionally invertebrates.