Medium large. Strong thick bill, heavy body, shallow tail fork. Sexes alike. Subspecies differ in size.
Adults: Breeding: Black cap covering eye. Sides of face, neck, rump, tail, underparts, white. Eye, dark brown. Back, wings, very light peal grey, primaries greyer and darker inner webs. Bill, black. Legs, long, black. Non-breeding: Similar to breeding but black spot before eye continues to ear coverts and around nape. Nape band not as distinct. Bill, black. Legs, long, black.
Immatures: 1st Winter: Similar to non-breeding but rear of crown, hind neck, washed or finely streaked brown. Some back feathers and wing coverts edged buff or brown, primaries blacker. Bill, black. Legs, long, black.
Other Scientific Names
Gelochelidon nilotica [Cramp and Simmons (1977-1994)], Gelochelidon nilotica [Christidis and Boles (2008)], Gelochelidon nilotica [AOU checklist (1998 + supplements)], Gelochelidon nilotica Turbott (1990)], Gelochelidon nilotica [Stotz et al. (1996)]
Other Names (World)
Common Gull-billed Tern, Gull-billed Tern, Long-legged Gull
Derivation
Stern'-a - N.L., a gull: nilotica - L., from the River Nile
Habitat
Fresh, brackish wetlands, beaches, mudflats, inland swamps, lakes, grasslands, cultivated land. Mostly small groups but occasionally large groups at a source of food.
Afghanistan (B) (P), Albania (B), Algeria, Anguilla, Antigua and Barbuda, Argentina, Armenia (B), Aruba, Australia (B), Austria (P), Azerbaijan (B), Bahamas, Bahrain, Bangladesh, Barbados, Belize, Benin (NB), Brazil, Brunei Darussalam, Bulgaria (B) (NB) (P), Burkina Faso, Burundi, Cambodia, Cameroon, Canada, Cayman Islands, Chad, China (mainland), Colombia, Congo [The Democratic Republic of the], Costa Rica, Côte dIvoire, Cuba, Cyprus (P), Czech Republic, Denmark (B), Djibouti, Dominica, Dominican Republic, Ecuador (B), Egypt, El Salvador, Eritrea, Ethiopia, France (B) (P), French Guiana, Gambia, Germany (B), Ghana, Gibraltar, Greece (B) (P), Guadeloupe, Guatemala, Guinea, Guinea-bissau, Guyana, Haiti, Honduras, India, Indonesia, Iran [Islamic Republic of] (B) (NB), Iraq (B) (NB) (P), Israel, Italy (B) (P), Japan, Jordan (B) (P), Kazakhstan (B), Kenya, Kuwait, Kyrgyzstan (B), Liberia, Libyan Arab Jamahiriya, Macedonia [The Former Yugoslav Republic of] (B), Malawi, Malaysia (NB), Maldives (B), Mali, Malta, Martinique, Mauritania (B), Mexico, Moldova [Republic of] (B), Mongolia (B), Montserrat, Morocco, Myanmar, Nepal, Netherlands Antilles, New Zealand, Nicaragua, Niger, Nigeria, Oman, Pakistan, Panama, Paraguay, Peru, Philippines, Portugal (B), Puerto Rico, Qatar, Romania (B) (P), Russia (Asian) (B), Russia (Central Asian) (B), Russia (European) (B) (P), Rwanda, Saudi Arabia (NB), Senegal (B), Sierra Leone, Singapore, Somalia, Spain (B) (NB) (P), Sri Lanka, St Kitts and Nevis, St Lucia, St Vincent and The Grenadines, Sudan, Suriname, Switzerland, Taiwan (China), Tajikistan (B), Tanzania [United Republic of], Thailand, Timor-Leste (NB), Togo, Trinidad and Tobago, Tunisia (B) (NB), Turkey (B) (NB), Turkmenistan (B), Turks and Caicos Islands (B), Uganda, Ukraine (B) (P), United Arab Emirates, Uruguay (B), USA (B), Uzbekistan (B), Venezuela, Vietnam, Virgin Islands (British) (NB), Virgin Islands (U.S.) (NB), Western Sahara, Yemen (NB) (P), Zambia.
Vagrant to Angola, Belgium, Bermuda, Bosnia and Herzegovina, Botswana, Comoros, Croatia (Local Name: Hrvatska), Finland, Gabon, Guam, Hungary, Ireland, Jamaica, Lebanon, Luxembourg, Montenegro, Norway, Poland, Serbia, Seychelles, Slovakia (Slovak Republic), Slovenia, South Africa, South Korea, Sweden, Syrian Arab Republic, United Kingdom, Zimbabwe.
Unknown to Northern Mariana Islands.
Population
Estimated population is 150,000 - 420,000 (2010).
Status LC
Loss and degradation of habitat through drainage, conversion to agriculture, pollution are the main threats.
For more information see BirdLife International Species Factsheet.
Habits
Forages by flying low over water to pluck prey from the surface, but also plunges head first into the water.
Food
A range of mammals, young birds, amphibians, fish, small reptiles and insects.
Voice
Harsh bleat 'ka-huk, ka-huk', in alarm or threat. A loud, deep three syllable call. Otherwise silent.
Gull-billed Tern (Gelochelidon) [XC563063]
by Francesco Sottile from Campi\u00f1a Sur (near Llera), Badajoz, Extremadura, Spain (flight call)
Gull-billed Tern (Gelochelidon nilotica) [XC257581]
by John V. Moore from Guayas: Pacoa Beach, Ecuador (call, calls)
Nest
A depression in the ground, lined with vegetation, close to a grassy tuft or other object, surrounded by debris, which is added to as incubation proceeds. In colonies.
Eggs (Guide)
1 - 4; glossy, smooth, yellow-grey to olive, blotched dark grey and dusky brown; ellipsoidal; about 50 x 37 mm. Incubation: 22 - 23 days; by both sexes.
Young
Precocial, nidifugous. Fledge in about 3 months.
Subspecies
Listed as Gelochelidon anglica in many older works.
Proposed subspecies affinis for birds of eastern Asia and south-eastern China is not separable.
The following 8 subspecies are recognised:
nilotica (Gmelin, 1789) - Europe south to Mauritania and Tunisia, and eastern through Middle East, Kazakhstan and Indian Subcontinent to north-western China. Winters from tropical Africa through Persian Gulf to India.
addenda Mathews, 1912 - Transbaikalia, Manchuria and eastern China (Fuzhou to Hainan). Winters mainly south-eastern Asia.
macrotarsa (Gould, 1837) - Australia. Considered by some authors to be a distinct species, Australian Gull-billed Tern (Gelochelidon macrotarsa).
aranea (Wilson, A, 1814) - New Jersey (rarely New York) south to Texas, Cuba, Bahamas and Puerto Rico, and sparsely along Mexican coast to Yucatán. Winters along Central American coasts and south to Brazil and Peru.
vanrossemi Bancroft, 1929 - California (coastal plain and Salton Sea) to northern Baja California and Sinaloa (and probably south to Gulf of Tehuantepec), with isolated breeding recorded in Alaska (Copper R Delta). Winters south to Ecuador.
groenvoldi Mathews, 1912 - Coast and river valleys from French Guiana (Cayenne) to north-eastern Argentina (Buenos Aires). Ecuador and northern Peru breeders may be this subspecies or vanrossemi, or an undescribed subspecies.
affinis (Horsfield, 1821) - Transbaikalia to Manchuria and eastern China. Winters south-eastern Asia.
gronvoldi Mathews, 1912 - Coasts and rivers of French Guiana to north-eastern Argentina.
Similar Species
Caspian Tern (Hydroprogne caspia)
At a distance. Much larger. Longer broader wings, and a shorter, less deeply forked tail. Bill, much longer and heavier, red. Underwing has a large dark tip.
Compare Images
The Field Guide to the Birds of Australia Pizzey, G., and Knight, E., 1997, Angus & Robertson, Sydney ISBN 0 207 19691 5
Field Guide to Australian Birds Morecombe, M., 2000, Steve Parish Publishing Pty Ltd. ISBN 1 876282 10 X
Field Guide to the Birds of Australia Simpson, K., and Day, N., 1999, 6th Edition, Viking ISBN 0 670 87918 5
Reader's Digest Complete Book of Australian Birds 1988, 2nd Edition, Reader's Digest ISBN 0 949819 99 9
What Bird is That? 1984, Revised Edition, Angus & Robertson, Sydney ISBN 0 207 14846 5
Handbook of Australian, New Zealand & Antarctic Birds 1990 - , Oxford University Press, Melbourne ISBN 0 19 553244 9