Gull-billed Tern

The Gull-billed Tern is an unusual member of the tern family, more heavily built than most relatives and behaving almost as much like a gull as a typical tern. It is widespread but generally scarce, found across scattered wetland regions on several continents.

Appearance

Adults show pale grey upperparts, white underparts, and a black cap in breeding plumage that fades to a streaky grey-and-white head pattern outside the breeding season. The stout, all-black bill is a key feature, along with long black legs and a relatively short, only shallowly forked tail.

Key field marks

• Thick, stubby black bill without any red or orange, unlike most terns
• Pale grey upperparts and clean white underparts
• Long black legs, longer-legged than most terns
• Shallowly forked tail, less deeply forked than Common or Roseate Terns
• Often seen flying over fields and marshes rather than open water

Similar species

Compared to Common and Sandwich Terns, the Gull-billed Tern has a shorter, thicker bill lacking any orange or yellow tip, and a stockier gull-like build. Its habit of foraging over dry land for insects is unusual among terns and is a useful behavioral clue.

Habitat and range

Gull-billed Terns breed locally across warm-temperate and tropical regions of the Americas, Europe, Africa, Asia, and Australia, favoring coastal lagoons, salt marshes, salt pans, and adjacent open fields. Populations are often patchily distributed and can shift breeding sites between years.

Many populations are migratory, moving to wintering grounds along tropical and subtropical coasts, estuaries, and wetlands, though some populations in warmer climates are largely resident.

Behavior

Unlike most terns, which dive for fish, the Gull-billed Tern frequently hunts on the wing over dry land, snapping up large insects such as dragonflies and grasshoppers, and will also take small lizards, crabs, and even the chicks of other birds. It forages with a buoyant, gull-like flight, often quartering over fields.

Voice

Its call is a harsh, laughing "ke-wek" or rasping "kay-wek," quite different from the sharper calls of many other terns.

Nesting and breeding

Gull-billed Terns nest in loose colonies on bare ground near marshes or salt pans, laying two to three eggs in a shallow scrape. Both parents share incubation and defend the nest vigorously against intruders.