Justification This species has an extremely 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 is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely 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.

Family/Sub-family Laridae

Species name author Linnaeus, 1758

Taxonomic source(s) AERC TAC (2003), AOU checklist (1998 + supplements), Christidis and Boles (2008), Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), Sibley and Monroe (1990, 1993), Stotz et al. (1996)

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

2,500,000 - 3,700,000

unset

-

No

Range & population The Mew Gull breeds in northern Europe, northern Asia and north-west North America. Most populations, except those in Iceland, around the North and Baltic Sea, and some off the coast of Canada migrate south. This expands its range to include the Pacific coast of North America down to Baja California (Mexico), the Pacific coast of Asia down to northern Vietnam, the Atlantic coasts of France and Portgual, the southern and eastern coasts of the Mediterranean, the entire coasts of the Black Sea and Persian Gulf, and the south coast of the Caspian Sea¹.

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

Ecology: Behaviour This species is fully migratory¹. It breeds from May onwards in solitary pairs or in single- and mixed-species colonies of up to 300 pairs^{1, 3} or more (e.g. 1,000 pairs in Baltic region)⁴. Outside of the breeding season the species remains gregarious, foraging in flocks of up to one hundred or more individuals during the winter, flock sizes depending upon the habitat and conditions⁴. Habitat Breeding The species breeds along the coast^{1, 2, 4} and inland^{1, 2, 3, 4} in a variety of sites not necessarily close to wetlands¹. On the coast it nests on grassy and rocky cliff-ledges^{1, 4}, grassy slopes^{2, 4}, inshore rocky islets, islands and stacks^{1, 2, 4}, and on sand and shingle beaches, banks and dunes^{1, 4} amongst tide-wrack or flood debris⁴. Inland the species nests on small islands in freshwater and saline lakes³, shingle bars or small islets in streams or rivers², islets, artificial structures and shores of artificial waterbodies with short, sparse vegetation⁶, and on bogs^{1, 4}, marshes¹, meadows¹ and grass or heather moorland near small pools^{2, 4} or lakes⁴. After the young fledge the species often disperses to coasts, tidal estuaries, agricultural land and reservoirs^{1, 4}. Non-breeding Outside of the breeding season it occupies similar habitats to when it is breeding, although it may occur more frequently along the coast during this period⁴ on estuaries with low salinities, sandy beaches and estuarine mudflats⁷. Diet Its diet consists of earthworms, insects, aquatic and terrestrial invertebrates¹ (e.g. planktonic crustaceans¹, crayfish and molluscs³) and small fish¹. During the spring the species will also take agricultural grain¹ and often scavanges⁷. Breeding site The nest is a shallow cup of vegetation placed on grass, rock, sand, shingle, earth or floating and marshy vegetation¹ in a variety of coastal and inland locations^{1, 2, 3, 4}. The species may also nest off the ground on artificial structures, in nest-boxes and in trees^{1, 2}. Management information The species may benefit from the removal of introduced predators such as American mink Neovison vison from small breeding islands⁵, and has been known to nest on artificial rafts intended to encourage other species (e.g. Common Tern Sterna hirundo) to breed⁷.

Threats Breeding In north and west Europe the species is threatened at breeding colonies by predation from introduced ground predators such as American mink Neovison vison⁷, and by disturbance from tourism, angling and research activities during the laying period⁷. Inland populations breeding in colonies near rivers are also vulnerable to mass outbreaks of black flies (Simuliidae)⁷. The species is also threatened by the transformation and loss of its breeding habitats through land reclamation, drainage, afforestation (e.g. with conifers) and dam construction⁷. Non-breeding In its wintering range the species is potentially threatened by the activities of fisheries (e.g. reductions in fishing effort, increases in net mesh sizes and exploitation of formerly non-commercial fish species) and their effects on competition for prey resources⁷. Other threats to wintering sites include land reclamation and drainage⁷. Utilisation Egg collecting from in colonies occurs in Germany, Scotland, the Russian Federation and Poland, and the species is shot in the Russian Federation⁷.

References 1. del Hoyo et al. (1996). 2. Richards (1990). 3. Flint et al. (1984). 4. Snow and Perrins (1998). 5. Nordstrom et al. (2003). 6. Skorka et al. (2006). 7. Bukacinski and Bukacinska (2003).

Further web sources of information

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Text account compilers Stuart Butchart (BirdLife International), Rob Calvert (BirdLife International), Lucy Malpas (BirdLife International), Peter Newton (BirdLife International)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International)

Recommended citation BirdLife International (2010) Species factsheet: Larus canus. Downloaded from http://www.birdlife.org on 6/9/2010

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.

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