Gull-billed tern

Voice

The English name misses what the Dutch one captures: a nasal, slightly creaking ka-wek with stress on the second syllable, and a repeated keh-weh keh-weh when agitated. It sounds more like a laugh than the sharp screaming of other terns. Listen for it over saltmarsh, rice fields and wet grassland, especially as birds quarter low over the land.

Identification

Bulkier and broader-winged than a Sandwich Tern, with a short, shallowly forked tail and long black legs that stand out in flight. The bill is thick, blunt and wholly black, more gull than tern. In summer a solid black cap reaching the nape, with very pale grey upperparts and white underparts; in winter and juvenile plumage the cap disappears and a dark smudge remains through and behind the eye, giving a masked face. In flight the primaries look silvery grey with a darker trailing edge, and the wingbeat is slow and buoyant, without the busy hovering of other terns.

Confusion species

Sandwich Tern is slimmer, has a black bill with a yellow tip, a shaggy crest, shorter legs and plunges into the water with a splash. Common and Arctic Terns are smaller, red-billed and far lighter in build. In winter a Gull-billed Tern with its white head and eye mask suggests a small gull; the short black bill and the long black legs then settle it. Caspian Tern is much larger with a deep red bill.

Habitat

Saltpans, lagoons, river mouths, rice fields and steppe lakes, with colonies on bare islets and shell banks. It feeds strikingly often over land, taking grasshoppers, dragonflies, frogs, lizards and small chicks from the vegetation in passing, and in Spain regularly follows tractors over freshly ploughed ground. For nesting it chooses dry, bare ground close to shallow water, often in the company of Common Terns and Avocets.

Range and movements

The main European breeding grounds lie in Spain, in the marismas of the Guadalquivir, the Ebro delta and the Andalusian saltpans, with smaller populations in Denmark, Germany, Italy, Greece and Ukraine. The Netherlands lost the species as a breeder in the 1950s, with a last nesting in 1958 and a breeding attempt at Balgzand in 2005; today a few dozen migrants appear each year, mainly in July and August in the north of Noord-Holland. The whole population winters in West Africa.

• Breeding (summer)
• Winter
• Passage
• Migration direction
• dark = core range, pale = thinly spread

Where and when to look

In the Netherlands the second half of July to late August is best: scan tern flocks at high-tide roosts along the Wadden coast and watch flooded bulb fields, where the birds hunt. In Spain, visit Doñana or the Ebro delta in May and June, early in the morning over rice fields and saltpans, when birds quarter low and searching. If in doubt, go by the bill: a thick, wholly black bill on a tern the size of a Sandwich Tern leaves little room for anything else.

Conservation status

Not globally threatened, but the European population is small and declining. Drainage of wetlands, abandonment or intensification of traditional saltpans, disturbance of island colonies and insecticide use in the surrounding farmland are the main causes. Protection of the Spanish core colonies effectively determines how many Gull-billed Terns north-west Europe still sees in late summer.