LC
Mew Gull Larus canus



Justification

Justification of Red List Category
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.

Population justification
The global population is estimated to number c.2,500,000-3,700,000 individuals (Wetlands International 2015). The European population is estimated at 640,000-1,080,000 pairs, which equates to 1,280,000-2,160,000 mature individuals (BirdLife International 2015). National population sizes have been estimated at c.100-10,000 breeding pairs and c.50-1,000 wintering individuals in China and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009).

Trend justification
The population trend is difficult to determine because of uncertainty over the extent of threats to the species across its wide range (del Hoyo et al. 1996). In Europe the population size is estimated to be decreasing by less than 25% in 29.4 years (three generations) (BirdLife International 2015).

Distribution and population

This species 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 Portugal, 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 Sea (del Hoyo et al. 1996).

Ecology

Behaviour This species is fully migratory (del Hoyo et al. 1996). It breeds from May onwards in solitary pairs or in single- and mixed-species colonies of up to 300 pairs (Flint et al. 1984, del Hoyo et al. 1996) or more (e.g. 1,000 pairs in Baltic region (Snow and Perrins 1998)). 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 conditions (Snow and Perrins 1998).

Habitat
Breeding The species breeds along the coast (Richards 1990, del Hoyo et al. 1996, Snow and Perrins 1998) and inland (Flint et al. 1984, Richards 1990, del Hoyo et al. 1996, Snow and Perrins 1998) in a variety of sites not necessarily close to wetlands (del Hoyo et al. 1996). On the coast it nests on grassy and rocky cliff-ledges (del Hoyo et al. 1996, Snow and Perrins 1998), grassy slopes (Richards 1990, Snow and Perrins 1998), inshore rocky islets, islands and stacks (Richards 1990, del Hoyo et al. 1996, Snow and Perrins 1998), and on sand and shingle beaches, banks and dunes (del Hoyo et al. 1996, Snow and Perrins 1998) amongst tide-wrack or flood debris (Snow and Perrins 1998). Inland the species nests on small islands in freshwater and saline lakes (Flint et al. 1984), shingle bars or small islets in streams or rivers (Richards 1990), islets, artificial structures and shores of artificial waterbodies with short, sparse vegetation (Skorka et al. 2006), and on bogs (del Hoyo et al. 1996, Snow and Perrins 1998), marshes (del Hoyo et al. 1996), meadows (del Hoyo et al. 1996) and grass or heather moorland near small pools (Richards 1990, Snow and Perrins 1998) or lakes (Snow and Perrins 1998). After the young fledge the species often disperses to coasts, tidal estuaries, agricultural land and reservoirs (del Hoyo et al. 1996, Snow and Perrins 1998). 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 period (Snow and Perrins 1998) on estuaries with low salinities, sandy beaches and estuarine mudflats (Bukacinski and Bukacinska 2003).

Diet
Its diet consists of earthworms, insects, aquatic and terrestrial invertebrates (del Hoyo et al. 1996) (e.g. planktonic crustaceans (del Hoyo et al. 1996), crayfish and molluscs (Flint et al. 1984)) and small fish (del Hoyo et al. 1996). During the spring the species will also take agricultural grain (del Hoyo et al. 1996) and often scavenges (Bukacinski and Bukacinska 2003).

Breeding site
The nest is a shallow cup of vegetation placed on grass, rock, sand, shingle, earth or floating and marshy vegetation (del Hoyo et al. 1996) in a variety of coastal and inland locations (Flint et al. 1984, Richards 1990, del Hoyo et al. 1996, Snow and Perrins 1998). The species may also nest off the ground on artificial structures, in nest-boxes and in trees (Richards 1990, del Hoyo et al. 1996).

Management information
The species may benefit from the removal of introduced predators such as American mink Neovison vison from small breeding islands (Nordström et al. 2003), and has been known to nest on artificial rafts intended to encourage other species (e.g. Common Tern Sterna hirundo) to breed (Bukacinski and Bukacinska 2003).

Threats

In the past this species has been thought to be threatened by habitat loss and disturbance through human activities (including tourism, research, fishing and development) and predation by invasive American Mink Neovison vison (Bukacinski and Bukacinska 2003). Currently, it seems as though none of these represent a significant threat to the population.

Conservation actions

Conservation Actions Underway
The following information refers to the species's European range only: The species is listed under the African Eurasian Waterbird Agreement. In the EU it is listed on Annex II of the Birds Directive. 83 Important Bird Areas have been identified for the species across the European region. In the EU it is listed in 381 Special Protection Areas.

Conservation Actions Proposed
The following information refers to the species's European range only: Continued invasive predator eradication programmes at breeding sites; monitoring of egg collection activities to ensure sustainability. Management of existing protected sites and Important Bird Areas to reduce habitat degradation and conversion. On board fisheries observer programmes to monitor levels of fisheries bycatch.

Acknowledgements

Text account compilers
Newton, P., Bennett, S., Calvert, R., Malpas, L., Butchart, S.


Recommended citation
BirdLife International (2020) Species factsheet: Larus canus. Downloaded from http://www.birdlife.org on 22/10/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/10/2020.