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Bridled Tern Sterna anaethetus

IUCN Red List history

Year Category
2012 Least Concern
2009 Least Concern
2008 Least Concern
2004 Least Concern
2000 Lower Risk/Least Concern
1994 Lower Risk/Least Concern
1988 Lower Risk/Least Concern

Species attributes

Migratory status full migrant Forest dependency Does not normally occur in forest
Land mass type   Average mass -


  Estimate Data quality
Extent of Occurrence breeding/resident (km2) 516,000 medium
Extent of Occurrence non-breeding (km2) 30,200,000 medium
Number of locations -
Fragmentation -

Population & trend

  Estimate Data quality Derivation Year of estimate
No. of mature individuals poor Estimated 2009
Population trend Unknown -
Number of subpopulations - - -
Largest subpopulation - - -
Generation length (yrs) 11.3 - - -
Population justification: The global population is estimated to number c.610,000-1,500,000 individuals (Wetlands International 2006), while national population estimates include: c.100-10,000 breeding pairs and c.50-1,000 individuals on migration in China; c.10,000-1 million breeding pairs and > c.1,000 individuals on migration in Taiwan and < c.100 breeding pairs and < c.50 individuals on migration in Japan (Brazil 2009).
Trend justification: The overall population trend is uncertain, as some populations are decreasing, while others are increasing or have unknown trends (Wetlands International 2006).

Country/Territory distribution

Country/Territory Occurrence status Presence Breeding Non-breeding Passage
Anguilla (to UK) Native Extant Yes    
Antigua and Barbuda Native Extant      
Aruba (to Netherlands) Native Extant      
Australia Native Extant Yes    
Bahamas Native Extant      
Bahrain Native Extant Yes    
Barbados Native Extant      
Belize Native Extant      
Benin Unknown Extant      
Bermuda (to UK) Native Extant     Yes
Bonaire, Sint Eustatius and Saba (to Netherlands) Native Extant      
Brunei Native Extant      
Cambodia Native Extant      
Canada Native Extant      
Cayman Islands (to UK) Native Extant      
Chile Vagrant Extant      
China (mainland) Native Extant Yes    
Christmas Island (to Australia) Unknown Extant      
Cocos (Keeling) Islands (to Australia) Vagrant Extant      
Colombia Native Extant      
Comoros Native Extant      
Costa Rica Native Extant      
Cuba Native Extant      
Curaçao (to Netherlands) Native Extant      
Denmark Vagrant Extant      
Djibouti Native Extant      
Dominica Native Extant      
Dominican Republic Native Extant      
Ecuador Native Extant Yes    
Egypt Native Extant      
El Salvador Native Extant      
Equatorial Guinea Native Extant      
Eritrea Native Extant      
Fiji Native Extant      
French Southern Territories Unknown Extant      
Gambia Unknown Extant      
Ghana Vagrant Extant      
Greece Vagrant Extant      
Grenada Native Extant      
Guadeloupe (to France) Native Extant Yes    
Guatemala Unknown Extant      
Guinea Unknown Extant      
Guinea-Bissau Native Extant      
Guyana Native Extant      
Haiti Native Extant      
Honduras Native Extant      
India Native Extant      
Indonesia Native Extant      
Iran, Islamic Republic of Native Extant Yes    
Iraq Native Extant Yes    
Israel Native Extant      
Jamaica Native Extant Yes    
Japan Native Extant      
Jordan Native Extant     Yes
Kenya Native Extant      
Kuwait Native Extant Yes    
Liberia Vagrant Extant      
Madagascar Native Extant      
Malaysia Native Extant      
Maldives Native Extant Yes    
Martinique (to France) Native Extant      
Mauritania Native Extant      
Mauritius Native Extant Yes    
Mayotte (to France) Unknown Extant      
Mexico Native Extant      
Montserrat (to UK) Native Extant      
Mozambique Native Extant      
Myanmar Unknown Extant      
New Caledonia (to France) Native Extant      
New Zealand Vagrant Extant      
Nicaragua Native Extant      
Nigeria Native Extant      
Oman Native Extant Yes    
Pakistan Native Extant      
Palau Native Extant Yes    
Panama Native Extant      
Papua New Guinea Native Extant      
Philippines Native Extant      
Puerto Rico (to USA) Native Extant      
Qatar Native Extant Yes    
Réunion (to France) Unknown Extant      
São Tomé e Príncipe Native Extant      
Saudi Arabia Native Extant Yes    
Senegal Native Extant      
Seychelles Native Extant      
Sierra Leone Unknown Extant      
Singapore Native Extant      
Sint Maarten (to Netherlands) Native Extant      
Solomon Islands Native Extant      
Somalia Native Extant Yes    
South Africa Native Extant      
Sri Lanka Native Extant      
St Kitts and Nevis Native Extant      
St Lucia Native Extant      
St Martin (to France) Native Extant Yes    
St Vincent and the Grenadines Native Extant      
Sudan Native Extant Yes    
Taiwan (China) Native Extant Yes    
Tanzania Native Extant      
Thailand Native Extant      
Timor-Leste Native Extant   Yes  
Togo Native Extant      
Trinidad and Tobago Native Extant      
Turks and Caicos Islands (to UK) Native Extant Yes    
United Arab Emirates Native Extant Yes   Yes
United Kingdom Vagrant Extant      
USA Native Extant Yes    
Vanuatu Vagrant Extant      
Venezuela Native Extant      
Vietnam Native Extant      
Virgin Islands (to UK) Native Extant Yes    
Virgin Islands (to USA) Native Extant Yes    
Wallis and Futuna Islands (to France) Native Extant Yes    
Western Sahara Native Extant Yes    
Yemen Native Extant Yes   Yes

Important Bird Areas where this species has triggered the IBA criteria

Country/Territory IBA Name IBA link
Anguilla (to UK) Dog Island site factsheet
Anguilla (to UK) Sombrero site factsheet
Aruba (to Netherlands) San Nicolas Bay Reef Islands site factsheet
Australia Cape York to Cape Grenville Islands site factsheet
Australia Higginson Island site factsheet
Australia Lowendal Islands site factsheet
Australia South Barnard Islands site factsheet
Australia Stapleton Island site factsheet
Australia Three Hummocks Island site factsheet
Bahamas Booby Island site factsheet
Bahamas Cay Lobos site factsheet
Bahamas Cay Sal site factsheet
Bahamas Conception Island site factsheet
Bahamas Goulding Cay Wild Bird Reserve site factsheet
Bahamas Graham's Harbour site factsheet
Bahamas Great Isaac Cay site factsheet
Bahamas Guana Cays site factsheet
Bahamas Low Cay, High Cay and Sandy Hook site factsheet
Bahamas North Atlantic Abaco Cays site factsheet
Bahamas Peterson Cay National Park site factsheet
Bahamas Samana Cay site factsheet
Bahamas Tee Cay, Goat Cay and Long Rocks site factsheet
China (mainland) Beiji Islands site factsheet
China (mainland) Dongtou Islands site factsheet
China (mainland) Nanji Islands Nature Reserve site factsheet
China (mainland) Taizhou Islands site factsheet
China (mainland) Wuyu Dao Island site factsheet
China (mainland) Yushan Islands site factsheet
China (mainland) Zhongjieshan Islands site factsheet
Cuba Gran Humedal del Norte de Ciego de Ávila site factsheet
Dominica L'llet site factsheet
Dominica Point Des Foux site factsheet
Dominican Republic Siete Hermanos Keys site factsheet
Guadeloupe (to France) Falaises Nord et Îlet de Vieux-Fort de Marie-Galante site factsheet
Guadeloupe (to France) Pointe des Châteaux site factsheet
Indonesia Pulau Gunung Api site factsheet
Indonesia Pulau Manuk site factsheet
Iran, Islamic Republic of Nakhilu, Morghu and Ummal Karam islands site factsheet
Iran, Islamic Republic of Sheedvar island site factsheet
Jamaica Morant Cays and Bank site factsheet
Jamaica Pedro Cays and Bank site factsheet
Japan Yaeyama islands site factsheet
Martinique (to France) Îlets et falaises de Sainte Anne site factsheet
Martinique (to France) Rocher du Diamant site factsheet
Nicaragua Farallones de Cosiguina site factsheet
Nicaragua Farallones de Cosiguina - Marine site factsheet
Oman Barr al Hikman site factsheet
Oman Daymaniyat Islands site factsheet
Oman Halaaniyaat Islands site factsheet
Oman Masirah island site factsheet
Oman Musandam islands site factsheet
Panama Frailes del Sur Islands site factsheet
Saudi Arabia Farasan Islands site factsheet
Saudi Arabia Gulf coral islands site factsheet
Saudi Arabia Gulf of Salwah site factsheet
Saudi Arabia Tarut Bay site factsheet
Somalia Jasiira Ceebaad and Jasiira Sacaada Diin site factsheet
St Kitts and Nevis Booby Island site factsheet
St Lucia Point Sables site factsheet
Taiwan (China) Cat Islet Seabird Refuge, Penghu County Refuge site factsheet
Taiwan (China) Matsu (Mazu) Islands Tern Refuge site factsheet
Taiwan (China) Northern Sea Islets site factsheet
Trinidad and Tobago Little Tobago Island site factsheet
Turks and Caicos Islands (to UK) Caicos Bank Southern Cays site factsheet
Turks and Caicos Islands (to UK) Turks Bank Seabird Cays site factsheet
United Arab Emirates Islands off Sir Bani Yas island site factsheet
United Arab Emirates Umm Amin site factsheet
Virgin Islands (to USA) Saba Island and Cays site factsheet

Habitats & altitude

Habitat (level 1) Habitat (level 2) Importance Occurrence
Marine Coastal/Supratidal Sea Cliffs and Rocky Offshore Islands suitable breeding
Marine Intertidal Rocky Shoreline suitable breeding
Marine Intertidal Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc major breeding
Marine Intertidal Shingle and/or Pebble Shoreline and/or Beaches major breeding
Marine Intertidal Tidepools suitable breeding
Marine Neritic Macroalgal/Kelp major breeding
Marine Neritic Macroalgal/Kelp major non-breeding
Marine Neritic Pelagic major breeding
Marine Neritic Pelagic major non-breeding
Marine Neritic Seagrass (Submerged) major breeding
Marine Neritic Seagrass (Submerged) major non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel major breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel major non-breeding
Marine Neritic Subtidal Rock and Rocky Reefs major breeding
Marine Neritic Subtidal Rock and Rocky Reefs major non-breeding
Marine Neritic Subtidal Sandy major breeding
Marine Neritic Subtidal Sandy major non-breeding
Marine Neritic Subtidal Sandy-Mud major breeding
Marine Neritic Subtidal Sandy-Mud major non-breeding
Marine Oceanic Epipelagic (0-200m) suitable breeding
Marine Oceanic Epipelagic (0-200m) suitable non-breeding
Marine Oceanic Mesopelagic (200-1000m) suitable breeding
Marine Oceanic Mesopelagic (200-1000m) suitable non-breeding
Altitude 0 - 50 m Occasional altitudinal limits  


Purpose Primary form used Life stage used Source Scale Level Timing
Pets Whole Adults and juveniles Wild International Non-trivial Recent

Recommended citation
BirdLife International (2014) Species factsheet: Sterna anaethetus. Downloaded from on 11/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 11/07/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Least Concern
Family Laridae (Gulls and terns)
Species name author Scopoli, 1786
Population size mature individuals
Population trend Unknown
Distribution size (breeding/resident) 516,000 km2
Country endemic? No
Links to further information
- Summary information on this species
- Climate change species distributions