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Bridled Tern Onychoprion anaethetus
BirdLife is updating this factsheet for the 2016 Red List
Please email us with any relevant information

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 Resident
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       Yes
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       Yes
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 Island 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 Houtman Abrolhos 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 (superseded 26/03/2015) 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
USA Dry Tortugas National Park 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 (2016) Species factsheet: Onychoprion anaethetus. Downloaded from on 22/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 22/10/2016.

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, Terns, Skimmers)
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
- Projected distributions under climate change