
Photo: Amber M. King · CC BY 4.0
Gelochelidon nilotica
Rare visitor: recorded only occasionally in this country
Diet
Mainly insects taken in flight; also other small animals
Habitat
Lakes, marshes and coasts
Range
Scattered breeding in Europe, Asia, north-west Africa and the Americas
Clutch size
2–5 eggs
Size
33–42cm
Wingspan
76–91cm
Weight
150–292g
The gull-billed tern is a fairly large, powerful tern, 33–42cm long with a wingspan of 76–91cm, similar in size to a Sandwich tern but with a short, thick, gull-like bill, broad wings, long legs and a robust body. The summer adult is grey above and white below with a black cap and strong black bill and legs. In winter the cap is lost, leaving a dark patch through the eye, and juveniles look much like winter adults. Its call is a characteristic ker-wik (Wikipedia, general species account).
Unlike most white terns it does not normally plunge-dive for fish. It feeds more like a marsh tern, largely on insects caught in flight, and has a broader diet than most terns. It breeds in colonies on lakes, marshes and coasts, laying two to five eggs in a ground scrape, and northern breeders migrate south for the winter. SoIB 2023 lists it as resident and a winter migrant in India, estimates a long-term decline of about 81% and a current fall of about 7.5% a year, and rates it a High conservation priority (Wikipedia, general species account; SoIB 2023).