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May 08 2011

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Gull billed Tern (Gelochelidon nilotica)

Gull-billed Tern

[order] Charadriiformes | [family] Sternidae | [latin] Gelochelidon nilotica | [UK] Gull-billed Tern | [FR] Sterne hansel | [DE] Lachseeschwalbe | [ES] Gaviotin de Pico Negro | [IT] Sterna zampenere | [NL] Lachstern

Subspecies

Genus Species subspecies Breeding Range Breeding Range 2 Non Breeding Range
Hydroprogne nilotica
Gelochelidon nilotica Worldwide widespread
Gelochelidon nilotica affinis Japan, s and e China through se Asia to Philippines, Sumatra, Sulawesi and Borneo to Australia
Gelochelidon nilotica aranea e and s USA through Greater Antilles Central America to Peru and Brazil
Gelochelidon nilotica gronvoldi French Guiana to ne Argentina
Gelochelidon nilotica macrotarsa Australia n Australia, New Guinea
Gelochelidon nilotica nilotica Europe, n Africa through the Middle East and sc Asia to w China and Thailand Africa, s Asia
Gelochelidon nilotica vanrossemi s California (USA) to nw Mexico to Ecuador

Physical charateristics

Unique heavy-billed, long-legged tern whit slightly formed tail, broad wings and very pale body. 35-40 cm, 130-300 g, wingspan 85-100 cm.
All black bill has sharp gonydeal angle, but no terminal hook, resembling that of small gull. Eye dark brown, crown and nape black, upperparts including rump pale grey, primaries slightly darker but wingtips whitish to pale grey. Tail and underparts white.
Races differ mainly in size, especially of bill and also in color tone of upperparts. macrotarsa is largest race, especially in bill and feet.

Listen to the sound of Gull-billed Tern

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Copyright remark: Most sounds derived from xeno-canto

wingspan min.: 76 cm wingspan max.: 86 cm
size min.: 35 cm size max.: 42 cm
incubation min.: 22 days incubation max.: 23 days
fledging min.: 28 days fledging max.: 35 days
broods: 1   eggs min.: 1  
      eggs max.: 4  

Range

In the New World, the subspecies G.n. groenvoldi breeds locally in eastern South America from Brazil to northern Argentina. Two subspecies occur in North erica. G.n. Aranea breeds along the Atlantic and Gulf of Mexico coasts of the United States and northeastern Mexico, with most of the population withdrawing
southward to winter locally from the Gulf Coast south to northern South America. G.n. Vanrossemi breeds very locally on the Pacific Coast and in the lower Colorado River delta region of southern California and northwestern Mexico, and very locally farther south in Mexico from Sinaloa to at least
Colima; it winters in western Mexico and to an unknown extent south to the Pacific Coast of Central America and possibly northwestern South America. Nunerous migrant in Suirname alomst everywhere along the coast and along more inland freshwater bodies.

Habitat

Breeds on barrier beaches and dunes, salt marshes, and rivers and freshwater lagoons. Far more along coastal plains then in continental interiors, but also breeds on hypersaline lakes.
Often feeds in large numbers on emerging insects over lakes, fields and grassland and even over semi desert. Winters on estuaries, lakes and salt-pans.

Reproduction

Breeds May-June in North America and Europe, April-May in India and October-December in Australia. Loosely to densely colonial. Nests are built on barren beaches, on sand, shell bars, dry mud, dykes, sea wrack, floating vegetation and nesting on roofs. 2-3 eggs are laid incubated for 23 days.
Chicks are white, usually unspotted. Parents attend young for 3 months. Returns to colony at 4 years old, but first breeding at 5 years.

Feeding habits

More insectivorous than most other terns, prey including mainly grasshoppers, dragonflies, moths and grubs, also takes spiders, earthworms small reptiles and frogs, small fish and aquatic invertebrates.
Flies slowly and then darts swiftly down to seize prey item from surface of ground, water or vegetation. Occasionally pirates food from other terns.

Conservation

This species has a large range, with an estimated global Extent of Occurrence of 1,000,000-10,000,000 km

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