Data Zone
Taxonomic source(s)
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.
| Critically Endangered | Endangered | Vulnerable |
|---|---|---|
| - | - | - |
| 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 |
| 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) | 656,000 km2 | medium |
| Extent of Occurrence (non-breeding) | 1,400,000 km2 | medium |
| Severely fragmented? | no | - |
| Estimate | Data quality | Derivation | Year of estimate | |
|---|---|---|---|---|
| Population size | unknown | poor | estimated | 2009 |
| Population trend | increasing | - | suspected | - |
| Generation length | 12.8 years | - | - | - |
Population justification: The global population has been estimated at between 115,500 and 118,500 individuals (Delany and Scott 2009).
Trend justification: The overall population trend is increasing, although some populations have unknown trends (Delany and Scott 2009). 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 | Presence | Origin | Resident | Breeding visitor | Non-breeding visitor | Passage migrant |
|---|---|---|---|---|---|---|
| Canada | extant | native | yes | |||
| Mexico | extant | native | yes | yes | ||
| USA | extant | native | yes | yes |
| Country/Territory | IBA Name |
|---|---|
| Mexico | Área de San Quintín |
| Mexico | Isla Asunción |
| Mexico | Isla Natividad |
| Mexico | Isla San Jerónimo |
| Mexico | Isla San Roque |
| Mexico | Islas Coronado |
| Mexico | Islas San Benito |
| USA | Farallon Islands |
| USA | Farallon Islands Pelagic |
| USA | Heceta Bank |
| USA | Marbled Murrelet IBA |
| USA | Santa Barbara Basin, CA |
| USA | Santa Barbara Island, CA |
| USA | Santa Cruz Basin 120W33N |
| USA | Yaquina Head Outstanding Natural Area |
| Habitat (level 1) | Habitat (level 2) | Importance | Occurrence |
|---|---|---|---|
| Marine Coastal/Supratidal | Sea Cliffs and Rocky Offshore Islands | major | breeding |
| Marine Intertidal | Rocky Shoreline | suitable | non-breeding |
| Marine Intertidal | Rocky Shoreline | suitable | breeding |
| Marine Intertidal | Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc | suitable | non-breeding |
| Marine Intertidal | Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc | suitable | breeding |
| Marine Intertidal | Shingle and/or Pebble Shoreline and/or Beaches | major | breeding |
| Marine Intertidal | Tidepools | suitable | non-breeding |
| Marine Intertidal | Tidepools | suitable | breeding |
| Marine Neritic | Macroalgal/Kelp | major | non-breeding |
| Marine Neritic | Macroalgal/Kelp | major | breeding |
| Marine Neritic | Pelagic | suitable | non-breeding |
| 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 | Occasional altitudinal limits |
| Purpose | Scale |
|---|---|
| Pets/display animals, horticulture | international |
Recommended citation
BirdLife International (2024) Species factsheet: Western Gull Larus occidentalis. Downloaded from
https://datazone.birdlife.org/species/factsheet/western-gull-larus-occidentalis on 24/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 24/11/2024.