Gull-billed Tern

The Gull-billed Tern is an unusual member of the tern family, behaving more like a gull in its foraging habits. It is a medium-sized, pale gray-and-white tern found on coasts and wetlands across much of the world, distinguished by its short, thick bill.

Appearance

Adults have pale gray upperparts, white underparts, a black cap in breeding plumage, and black legs. The bill is notably short, stout, and entirely black, unlike the slender, often red or orange bills of many other terns. In non-breeding plumage the black cap is reduced to a smudgy patch through and behind the eye.

Key field marks

• Thick, all-black, gull-like bill, shorter and heavier than in most terns
• Black legs, longer than typical for a tern
• Pale gray upperparts with a slightly forked tail
• Broad-winged, buoyant flight, often seen hawking insects over fields far from water

Similar species

Compared with Common Tern or Forster's Tern, the Gull-billed Tern looks stockier with a shorter, thicker bill lacking any red or orange tone, and it frequently forages over dry land, which those species rarely do. Sandwich Tern has a slimmer black bill with a yellow tip and a shaggy crest, quite different from the Gull-billed Tern's stubby bill.

Habitat and range

Gull-billed Terns breed in scattered colonies on sandy or shelly ground near coastal lagoons, salt marshes, and estuaries, and also use inland wetlands, rice fields, and grasslands far from the sea. The species has a broad, patchy global distribution across the Americas, Europe, Africa, Asia, and Australia.

Migration

Northern populations are migratory, moving to tropical and subtropical coasts for the winter, while populations in warmer regions may be resident or make only short-distance movements. Its willingness to forage on land and take a wide variety of prey allows it to use habitats other terns avoid.

Behavior

Unlike most terns, the Gull-billed Tern rarely plunge-dives for fish. Instead, it hawks insects on the wing, hovers and drops onto prey in fields and marshes, and snatches crabs, lizards, frogs, and even small mammals or the eggs and chicks of other birds from the ground.

Voice

Its call is a distinctive, nasal, laughing "kay-wek" or "za-za-za," quite different from the sharper calls of many other terns.

Nesting and breeding

Pairs nest colonially, often with other terns or gulls, laying two to three eggs in a shallow scrape on open, sparsely vegetated ground. Both parents incubate and feed the young, which are fledged within about four weeks.