Australian tern

John Gould described Sterna macrotarsa from a specimen held at Kings College, London in 1837.[2]

This is a fairly large and powerful tern, similar in size and general appearance to a Sandwich tern, but the short thick gull-like bill, broad wings, long legs and robust body are distinctive. The summer adult has grey upperparts, white underparts, a black cap, strong black bill and black legs. The call is a characteristic ker-wik. It is 33–42 cm (13–17 in) in length and 76–91 cm (30–36 in) in wingspan.[3][4] Body mass ranges from 150–292 g (5.3–10.3 oz).[5]

In winter, the cap is lost, and there is a dark patch through the eye like a Forster's tern or a Mediterranean gull. Juvenile Australian terns have a fainter mask, but otherwise look much like winter adults.

It breeds in Australia and New Guinea.

This species breeds in colonies on lakes, marshes and coasts. It nests in a ground scrape and lays two to five eggs.

This is a somewhat atypical tern, in appearance like a Sterna tern, but with feeding habits more like the Chlidonias marsh terns, black tern and white-winged tern.

The Australian gull-billed tern does not normally plunge dive for fish like the other white terns, and has a broader diet than most other terns. It largely feeds on insects taken in flight, and also often hunts over wet fields and even in brushy areas, to take amphibians and small mammals.[3] It is also an opportunistic feeder, and has been observed to pick up and feed on dead dragonflies from the road.[6]

• BirdLife species factsheet for Gelochelidon macrotarsa
• Interactive range map of Gelochelidon macrotarsa at IUCN Red List maps