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LC
Glaucous-winged Gull Larus glaucescens

Justification
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

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#.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

Distribution and population
This species ranges from northern Mexico in the Gulf of California and on the western coast of Baja California, up the Pacific coast of North America to Alaska, across the Aleutian Islands (USA) to the northern coast of Japan. Its breeding range begins on the coast of Washington (USA), through Canada and Alaska to the Commander Islands (Russia) (del Hoyo et al. 1996)

Population justification
The global population is estimated to number > c.570,000 individuals (Wetlands International 2006), while the population in Russia has been estimated at c.100-10,000 breeding pairs and c.50-1,000 individuals on migration (Brazil 2009).

Trend justification
The overall population trend is increasing (Wetlands International 2006), although some populations are stable. This species has had stable population trends over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).

Ecology
This species can be found in coastal areas and over shelf waters. Its diet is comprised of fish, various marrine invertebrates, carrion, offal, bird eggs and small mammals, with the exact composition varying depending on locality. It uses a variety of feeding methods, including plunge-diving, diving from the surface and dropping shellfish on rocks. It arrives at breeding colonies between February and March, and will nest on a wide variety of substrates including rocky islands, cliffs, inland lakes, city parks and buildings. It is usually colonial but can be solitary. Some birds remain on their territories over winter, but others will migrate to the southern edges of its range (del Hoyo et al. 1996).

References
Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

del Hoyo, J.; Elliott, A.; Sargatal, J. 1996. Handbook of the Birds of the World, vol. 3: Hoatzin to Auks. Lynx Edicions, Barcelona, Spain.

Delany, S.; Scott, D. 2006. Waterbird population estimates. Wetlands International, Wageningen, The Netherlands.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Butchart, S., Calvert, R.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Larus glaucescens. Downloaded from http://www.birdlife.org on 17/09/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/09/2014.

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.

Additional resources for this species

ARKive species - Glaucous-winged gull (Larus glaucescens) 0

Key facts
Current IUCN Red List category Least Concern
Family Laridae (Gulls, Terns, Skimmers)
Species name author Naumann, 1840
Population size mature individuals
Population trend Increasing
Distribution size (breeding/resident) 707,000 km2
Country endemic? No
Links to further information
- Additional Information on this species