Ring-billed Gull Larus delawarensis


Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: # _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: #

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 -

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 8,890,000 medium
Extent of Occurrence non-breeding (km2) 18,400,000 medium
Number of locations -
Severely Fragmented -
Population and trend
Value Data quality Derivation Year of estimate
No. of mature individuals poor estimated 2006
Population trend Increasing estimated -
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 - - -
Percentage in largest subpopulation - - -
Generation length (yrs) 10.9 - - -

Population justification: Wetlands International (2018) estimate the population size at 2,550,000 individuals.

Trend justification: 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).

Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Anguilla (to UK) N Extant
Antigua and Barbuda N Extant
Aruba (to Netherlands) N Extant
Austria V Extant
Bahamas N Extant
Barbados N Extant
Belgium V Extant
Belize N Extant Yes
Bermuda (to UK) N Extant
Brazil N Extant
Bulgaria V Extant
Canada N Extant Yes Yes
Cayman Islands (to UK) N Extant
Colombia N Extant
Costa Rica N Extant Yes
Cuba N Extant
Denmark V Extant
Dominica N Extant
Dominican Republic N Extant
Ecuador N Extant
El Salvador N Extant
Faroe Islands (to Denmark) V Extant
France V Extant
Germany V Extant
Gibraltar (to UK) V Extant
Greenland (to Denmark) V Extant
Guadeloupe (to France) N Extant
Guatemala N Extant
Haiti N Extant
Honduras N Extant
Hungary V Extant
Iceland V Extant
Ireland V Extant
Jamaica V Extant
Kiribati V Extant
Martinique (to France) N Extant
Mexico N Extant
Montserrat (to UK) N Extant
Morocco V Extant
Netherlands V Extant
Norway V Extant
Panama N Extant
Poland V Extant
Portugal V Extant
Puerto Rico (to USA) N Extant
Senegal V Extant
Sint Maarten (to Netherlands) U Extant
South Africa V Extant Yes
Spain V Extant
St Barthelemy (to France) N Extant
St Kitts and Nevis N Extant
St Lucia N Extant
St Martin (to France) U Extant
St Pierre and Miquelon (to France) N Extant Yes Yes
St Vincent and the Grenadines N Extant
Svalbard and Jan Mayen Islands (to Norway) V Extant
Sweden V Extant
Switzerland V Extant
Trinidad and Tobago N Extant
Turks and Caicos Islands (to UK) N Extant
United Kingdom V Extant
USA N Extant Yes
Venezuela N Extant
Virgin Islands (to UK) N Extant Yes
Virgin Islands (to USA) N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Bahamas Harrold and Wilson Ponds National Park
Canada St. Mary Reservoir
Canada Lake Newell and Kitsim Reservoir
Canada McGregor Lake and Travers Reservoir
Canada Dowling Lake
Canada Sullivan Lake
Canada Muriel Lake
Canada Utikuma and Utikumasis Lakes
Canada Cardinal Lake
Canada Hay and Zama Lakes
Canada Peace-Athabasca Delta
Canada Pakowki Lake
Canada Miquelon Lake
Canada Hays Reservoir
Canada Eagle, Namaka and Stobart Lakes
Canada Frank Lake (south)
Canada Lac La Biche
Canada Pelican Lake (Alberta)
Canada Kaweenakumik Lake
Canada Pipestone Rocks
Canada Dog Lake
Canada Duck Island
Canada North, West, and East Shoal Lakes
Canada Little George Island
Canada North Channel Island
Canada Dory's Reef
Canada South Long Island
Canada Kasakeemeemisekak Islands
Canada Louis Island and Associated Reefs
Canada Riverton Sandy Bar
Canada Sand Reef Islands
Canada Spruce Island Reef
Canada Quoddy Region
Canada Niagara River Corridor
Canada Presqu'ile Provincial Park
Canada The Watchers
Canada The Cousins
Canada Port Colborne (breakwater and mainland)
Canada Hamilton Harbour Waterbird Colonies
Canada Pittock Reservoir
Canada Leslie Street Spit
Canada Pigeon Island
Canada Wildwood Gull Roost
Canada Lower Detroit River
Canada Limestone Islands
Canada Hannah Bay
Canada Nottawasaga Island
Canada Baie de Gaspé
Canada Île Blanche
Canada Saint-Augustin Migratory Bird Sanctuary
Canada Îles aux Perroquets
Canada Baie des Loups
Canada Cayes à Meck
Canada Île Nue de Mingan
Canada Baie Comeau
Canada Île Rouge
Canada Le Pilier de Pierre
Canada Réserve nationale de faune des Îles-de-Contrecoeur
Canada Île Deslauriers
Canada Île de la Couvée
Canada Barrage de Beauharnois
Canada Île a Calculot
Canada Old Wives-Frederick Lakes
Canada Bigstick Lake Plain
Canada Tobin Lake
Canada Suggi Lake
St Vincent and the Grenadines Ashton Wetland
Antigua and Barbuda McKinnons Salt Pond
Bahamas Gilliam Bay
Bahamas North Atlantic Abaco Cays
Jamaica Black River Great Morass
Bahamas Conception Island National Park
Mexico Delta del Río Colorado
USA Salton Sea
USA Saginaw Bay
Mexico Estero Cardonal

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Aquatic & Marine Artificial/Aquatic - Water Storage Areas (over 8ha) suitable non-breeding
Grassland Temperate suitable breeding
Marine Coastal/Supratidal Coastal Freshwater Lakes suitable non-breeding
Marine Neritic Estuaries suitable non-breeding
Marine Neritic Macroalgal/Kelp suitable non-breeding
Marine Neritic Pelagic suitable non-breeding
Marine Neritic Seagrass (Submerged) suitable non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable non-breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable non-breeding
Marine Neritic Subtidal Sandy suitable non-breeding
Marine Neritic Subtidal Sandy-Mud suitable non-breeding
Wetlands (inland) Bogs, Marshes, Swamps, Fens, Peatlands suitable breeding
Wetlands (inland) Permanent Freshwater Lakes (over 8ha) suitable breeding
Altitude 0 - 100 m Occasional altitudinal limits  

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

Recommended citation
BirdLife International (2021) Species factsheet: Larus delawarensis. Downloaded from on 21/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from on 21/10/2021.