LC
Royal Tern Thalasseus maximus



Taxonomy

Taxonomic note
Thalasseus maximus (del Hoyo and Collar 2014) was previously placed in the genus Sterna as S. maxima.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
SACC. 2005 and updates. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.htm#.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2018 Least Concern
2016 Least Concern
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 -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 73,800,000 medium
Extent of Occurrence non-breeding (km2) 82,400,000 medium
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals poor estimated 2009
Population trend Stable suspected -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations - - -
Largest subpopulations - - -
Generation length (yrs) 11.2 - - -

Trend justification: The overall population trend is stable, although some populations have unknown trends (Wetlands International 2006). This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) Note, however, that these surveys cover less than 50% of the species's range in North America.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Angola N Extant
Anguilla (to UK) N Extant
Antigua and Barbuda N Extant
Argentina N Extant
Aruba (to Netherlands) N Extant
Bahamas N Extant
Barbados N Extant
Belize V Extant
Benin N Extant
Bermuda (to UK) N Extant
Bonaire, Sint Eustatius and Saba (to Netherlands) N Extant Yes
Brazil N Extant
Cameroon N Extant
Canada N Extant
Cayman Islands (to UK) N Extant
Chile U Extant
Colombia N Extant
Congo N Extant
Congo, The Democratic Republic of the N Extant
Costa Rica N Extant Yes
Côte d'Ivoire N Extant
Cuba N Extant
Curaçao (to Netherlands) N Extant Yes
Dominica N Extant
Dominican Republic N Extant
Ecuador N Extant Yes
El Salvador N Extant
Equatorial Guinea N Extant
French Guiana N Extant
Gabon N Extant
Gambia N Extant Yes
Ghana N Extant
Gibraltar (to UK) V Extant
Grenada N Extant
Guadeloupe (to France) N Extant
Guatemala N Extant
Guinea N Extant Yes
Guinea-Bissau N Extant Yes
Guyana N Extant
Haiti N Extant
Honduras N Extant
Ireland V Extant
Jamaica N Extant Yes
Liberia N Extant
Martinique (to France) N Extant
Mauritania N Extant Yes
Mexico N Extant
Montserrat (to UK) N Extant
Morocco N Extant
Mozambique U Extant
Namibia N Extant
Nicaragua N Extant
Nigeria N Extant
Norway V Extant
Panama N Extant
Paraguay V Extant Yes
Peru N Extant
Portugal V Extant
Puerto Rico (to USA) N Extant
Senegal N Extant Yes
Sierra Leone N Extant
Sint Maarten (to Netherlands) N Extant Yes
Spain V Extant
St Barthelemy (to France) N Extant
St Kitts and Nevis N Extant
St Lucia N Extant Yes
St Martin (to France) N Extant Yes
St Vincent and the Grenadines N Extant
Sudan V Extant Yes
Suriname N Extant
Togo N Extant
Trinidad and Tobago N Extant
Turks and Caicos Islands (to UK) N Extant Yes
United Kingdom V Extant
Uruguay N Extant Yes
USA N Extant Yes
Venezuela N Extant
Virgin Islands (to UK) N Extant Yes
Virgin Islands (to USA) N Extant Yes
Western Sahara N Extant

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Benin Lake Ahémé and Aho complex
Gabon Gamba Protected Areas Complex
Gabon Akanda
Gabon Ogooué delta and Mandji island
Ghana Amansuri wetland
Ghana Densu Delta Ramsar Site and vicinity
Ghana Keta Lagoon Ramsar Site
Ghana Muni-Pomadze Ramsar Site
Ghana Songor Ramsar Site
Gambia Niumi National Park
Gambia Tanbi wetland complex
Gambia Tanji River (Karinti) Bird Reserve
Guinea Ile Alcatraz et Ile du Naufrage
Guinea Rio Kapatchez
Guinea Ile Blanche
Guinea-Bissau Arquipélago dos Bijagós
Liberia Lake Piso (Cape Mount)
Mauritania Banc d'Arguin National Park
Sierra Leone Yawri Bay
Senegal Parc National de la Langue de Barbarie
Senegal Joal-Fadiouth
Senegal Delta du Saloum
Ecuador Archipiélago de Jambelí
Venezuela Parque Nacional Archipiélago Los Roques
Jamaica Yallahs
Jamaica Morant Cays and Bank
Jamaica Pedro Cays and Bank
Jamaica Kingston Harbour (Palisadoes) and Port Royal Cays
Turks and Caicos Islands (to UK) Fish Ponds and Crossing Place Trail, Middle Caicos
Turks and Caicos Islands (to UK) North, Middle and East Caicos Ramsar Site
Turks and Caicos Islands (to UK) East Caicos and adjacent areas
Turks and Caicos Islands (to UK) Caicos Bank Southern Cays
Turks and Caicos Islands (to UK) Grand Turk Salinas and Shores
Cuba Gran Humedal del Norte de Ciego de Ávila
Sint Maarten (to Netherlands) Pelikan Rock, Sint Maarten
St Vincent and the Grenadines Ashton Wetland
Bahamas Gilliam Bay
Bahamas Gambier Lake
Bahamas Harrold and Wilson Ponds National Park
Bahamas Graham's Harbour
Bahamas Samana Cay
Bahamas Booby Rocks and Pirates Bay
Bahamas Cay Sal
Bahamas Great Inagua
Aruba (to Netherlands) San Nicolas Bay Reef Islands
Bonaire, Sint Eustatius and Saba (to Netherlands) Lac Bay, Bonaire
Bonaire, Sint Eustatius and Saba (to Netherlands) Pelkermeer Saltworks, Bonaire
Antigua and Barbuda McKinnons Salt Pond
Antigua and Barbuda Valley Church Bay
Costa Rica Nicoya Gulf mangroves and coastal areas
Costa Rica Sierpe Wetlands and Osa Peninsula
Antigua and Barbuda Offshore Islands
Puerto Rico (to USA) Culebra
Cuba Delta del Cauto
Cuba Cayería Centro - Oriental de Villa Clara
Bahamas Mangrove Cay
Bahamas Cat Island Wetlands
Bahamas South Beach Tidal Flats
St Lucia Pitons (Qualibou and Canaries)
St Lucia Point Sables
St Lucia Iyanola and Grande Anses, Esperance and Fond D'ors
St Lucia Mandelé Protected Landscape
Anguilla (to UK) Scrub Island
Virgin Islands (to USA) Southgate and Green Cay
Anguilla (to UK) Cove Pond
Anguilla (to UK) Long Salt Pond
St Barthelemy (to France) Turtle Island
Virgin Islands (to UK) Anegada: Western salt ponds and coastal areas
Virgin Islands (to USA) John Brewer's Bay
Virgin Islands (to USA) Saba Island and Cays
Bahamas North Atlantic Abaco Cays
Bahamas Allan's Cays
Bahamas Red Bays
Jamaica Black River Great Morass
Argentina Reserva de Biosfera Albufera de Mar Chiquita
St Vincent and the Grenadines All Awash Island
St Vincent and the Grenadines Petit Canouan
St Vincent and the Grenadines Battowia Island
St Vincent and the Grenadines Mustique Island
Mexico Humedales Costeros del Norte de la Península de Yucatán
Mexico Yum-balam
Mexico Ría Lagartos
French Guiana Connétable
French Guiana Plaine Kaw et Pointe Béhague
Trinidad and Tobago West Coast Mudflats
USA Altamaha River Delta
USA Barrier Island/Lagoon System
USA Chandeleur Islands (Breton National Wildlife Refuge)
USA Crab Bank
Jamaica Font Hill
Bahamas Kemp Cay to Pigeon Cay
Bahamas Joulter Cays
French Guiana Connétable - Marine
Costa Rica Sierpe Wetlands and Osa Peninsula - Marine
Costa Rica Nicoya Gulf mangroves and coastal areas - Marine
Senegal Delta du Saloum - Marine
Guinea-Bissau Île Alcatraz et Île du Naufrage - Marine
Mauritania Banc d'Arguin National Park - Marine
Senegal Parc National de la Langue de Barbarie - marine
USA Big Marco Pass Shoal
USA Bird Key Stono
USA Cape Canaveral-Merritt Island
USA Cape Romain National Wildlife Refuge
USA Cumberland Island National Seashore
USA Deveaux Bank
USA Huguenot Park-Nassau Sound
USA Lower Tampa Bay
USA Sundown Island
USA Tomkins Island
USA Turtle Island
Dominican Republic Jaragua National Park
Anguilla (to UK) West End Pond
Anguilla (to UK) Meads Bay Pond
Mexico Estero Santa Cruz
Mexico Estero Cardonal
Mexico Laguna Cuyutlán y Estero Palo Verde
USA Big Foot Island
USA Ferry Slip Island
USA Sand Bag Island
USA Laguna Vista Spoils
USA Jigsaw Islands
Mexico Laguna de Tamiahua
Mexico Sistema Arrecifal Veracruzano
Mexico Complejo de Presas de Río Fuerte
Mexico Sistema San Luis Gonzaga
Argentina Punta León - Marina
Senegal Northern Senegal shelf break
Senegal Delta du Saloum - marine
Gambia Delta du Saloum – Niumi – Tanbi
Guinea-Bissau Arquipélago dos Bijagós - marine
Mauritania Canary current shelf-break South
Morocco Canary current shelf-break North
Argentina Banco Nordeste

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Marine Coastal/Supratidal Coastal Brackish/Saline Lagoons/Marine Lakes suitable non-breeding
Marine Intertidal Salt Marshes (Emergent Grasses) suitable breeding
Marine Intertidal Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc major breeding
Marine Neritic Estuaries suitable non-breeding
Marine Neritic Macroalgal/Kelp major non-breeding
Marine Neritic Macroalgal/Kelp major breeding
Marine Neritic Pelagic suitable passage
Marine Neritic Pelagic suitable breeding
Marine Neritic Seagrass (Submerged) major non-breeding
Marine Neritic Seagrass (Submerged) major breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel major non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel major breeding
Marine Neritic Subtidal Rock and Rocky Reefs major non-breeding
Marine Neritic Subtidal Rock and Rocky Reefs major breeding
Marine Neritic Subtidal Sandy major non-breeding
Marine Neritic Subtidal Sandy major breeding
Marine Neritic Subtidal Sandy-Mud major non-breeding
Marine Neritic Subtidal Sandy-Mud major breeding
Altitude 0 - 100 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species disturbance, Reduced reproductive success, Species mortality
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species disturbance, Reduced reproductive success

Utilisation
Purpose Primary form used Life stage used Source Scale Level Timing
Pets/display animals, horticulture - - International Non-trivial Recent

Recommended citation
BirdLife International (2020) Species factsheet: Thalasseus maximus. Downloaded from http://www.birdlife.org on 15/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 15/08/2020.