Gull-billed Tern

The Gull-billed Tern is a medium-sized, pale tern that stands apart from its relatives by bill shape rather than plumage extravagance. Its stout, all-black bill gives it a slightly gull-like profile, and it forages more often over land and marsh than the plunge-diving terns it resembles at rest.

Found in scattered, often localized colonies on coasts and wetlands across much of the temperate and tropical world, it is a bird of open, flat ground near water.

• Upperwing and mantle feathers are a soft, even pearl-gray, lacking the bold dark wedge on the outer primaries seen in Common or Forster's Terns
• Tail feathers are only shallowly forked compared with the deeply forked "swallow-tail" of most Sterna terns
• Body (contour) feathers are unmarked white below and plain gray above, without streaking or barring
• Flight feathers are broad and rounded at the tip relative to the narrower, more pointed remiges of slimmer terns
• Feather shafts are pale, matching the generally unmarked, clean-toned plumage

• Breeding adults show a full glossy black cap extending from the bill to the nape
• Non-breeding adults and juveniles show a whitish forehead and crown, with the black reduced to a smudged patch through and behind the eye
• Juveniles have a scaly, buff-fringed appearance to the upperpart feathers that wears to plainer gray by the first winter
• A single complete molt of body feathers occurs after breeding, with flight feathers replaced on a slower, staggered schedule
• Sexes are alike in plumage

Gull-billed Terns breed in discontinuous, widely scattered colonies on barren shell ridges, sand flats, salt-marsh islands, and dikes near coastal lagoons, estuaries, and inland saline lakes across parts of the Americas, Europe, Africa, Asia, and Australia. Northern populations are migratory, withdrawing from higher latitudes to spend the non-breeding season along tropical and subtropical coastlines and wetlands, while some populations in warmer regions are largely resident.

Unlike most terns, this species feeds heavily over dry land as well as water, hawking large flying insects on the wing and dropping onto marshes, fields, and mudflats to snatch crabs, insects, and small vertebrates rather than relying mainly on plunge-diving for fish. It nests in loose, often mixed colonies alongside other terns and shorebirds, laying eggs in a simple scrape on open ground. Its voice is a nasal, rasping two- or three-note call quite unlike the sharper cries of typical sea terns.