LC
Lesser Black-backed Gull Larus fuscus



Justification

Justification of Red List Category
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.

Population justification
The global population is estimated at 940,000-2,070,000 individuals (Wetlands International 2015). The European population is estimated at 394,000-460,000 pairs, which equates to 788,000-920,000 mature individuals or 1,200,000-1,400,000 individuals (BirdLife International 2015).

Trend justification
The overall population trend is increasing, although some populations are decreasing or have unknown trends (Wetlands International 2015). The population trend is increasing in North America (based on BBS/CBC data: Butcher and Niven 2007). The European population is estimated to be increasing (BirdLife International 2015).

Distribution and population

This species breeds from the central-north of Russia, around Scandinavia, Germany, Belgium, the Netherlands and northern United Kingdom to Iceland. It also breeds year-round on the coast of Portugal, southern Ireland, the United Kingdom and northern France, and one seasonally breeding population is found in north-east Spain. Seasonal breeders disperse widely, expanding its range to include the entire North Sea coast, much of the Mediterranean, Black Sea and Caspian Sea coasts, the northern and eastern coasts of Africa (including rivers inland), and around the Arabian Peninsula to north-west India (del Hoyo et al. 1996).

Ecology

Behaviour Most populations of this species are fully migratory (del Hoyo et al. 1996) and travel in leapfrog-like stages (del Hoyo et al. 1996), using many stopovers en-route (Olsen and Larsson 2003). The Autumn migration is started by the non-breeding birds in late-June, the breeding birds following from late-July to September (Olsen and Larsson 2003). The return migration takes place between February and late-June (del Hoyo et al. 1996), with the species arriving at breeding colonies from March onwards, and breeding from May or late-April to mid-June (del Hoyo et al. 1996). It breeds colonially (Richards 1990, Mitchell et al. 2004), often with other gull species (especially Herring Gull Larus argentatus) (Mitchell et al. 2004), in colonies ranging in size from a few pairs (Snow and Perrins 1998) to several tens of thousands (Richards 1990). Outside of the breeding season the species remains gregarious, normally migrating singly or in small groups of less than 10 (Urban et al. 1986), and often feeding in flocks of hundreds of individuals on rubbish dumps or over shoals of fish at sea (Urban et al. 1986, Snow and Perrins 1998). It may also feed singly or in small groups (Urban et al. 1986). In its African wintering grounds the species may roost communally during the day on salt or fresh waterbodies (Urban et al. 1986, Bustnes et al. 2006). Habitat Breeding The species breeds on coastal grassy slopes (flat and unbroken) (Richards 1990), sand-dunes (Richards 1990, Mitchell et al. 2004), cliffs (Richards 1990, del Hoyo et al. 1996, Mitchell et al. 2004), rocky offshore islands (del Hoyo et al. 1996, Mitchell et al. 2004), saltmarshes (Mitchell et al. 2004), and on inland habitats such as the margins of lakes (Richards 1990, Olsen and Larsson 2003), high moorland (Richards 1990, Mitchell et al. 2004), and islands in lakes and rivers (Olsen and Larsson 2003) . It shows a preference for well vegetated sites, with fairly close, short vegetation (Richards 1990, Snow and Perrins 1998), and may forage on arable land, pasture land (Richards 1990), and on refuse dumps (Richards 1990, del Hoyo et al. 1996). Non-breeding Outside of the breeding season the species chiefly inhabits inshore and offshore seas (Snow and Perrins 1998), as well as lagoons, estuaries, harbours and seashores in the tropics (Snow and Perrins 1998). It may also frequent inland habitats during this season, such as large lakes and rivers (Urban et al. 1986), in England preferring flooded gravel pits and reservoirs, canals, river weirs, flood-lands and sewage treatment areas (Snow and Perrins 1998). As in the breeding season it is often seen foraging on arable land, pasture land (Richards 1990), and on refuse dumps (Richards 1990, del Hoyo et al. 1996). Diet The species is an omnivorous, opportunistic feeder (BirdLife International 2000) that forages extensively at sea. Its diet consists of small fish (especially Baltic herring Clupea harengus) (del Hoyo et al. 1996), aquatic and terrestrial invertebrates (e.g. beetles, flies and larvae, ants, moths (Urban et al. 1986), grasshoppers (Olsen and Larsson 2003), crustaceans, molluscs, segmented worms and starfish (Urban et al. 1986)), bird eggs and nestlings, carrion, offal (del Hoyo et al. 1996), rodents, berries (del Hoyo et al. 1996) and grain (Urban et al. 1986). It often follows fishing fleets, feeding on discarded bycatch (BirdLife International 2000). Breeding site The nest can be anything between a heap of grass, seaweed (Richards 1990), lichen, feathers (or other local materials) (del Hoyo et al. 1996), and a simple sparsely-lined scrape (Richards 1990), that is usually positioned on open ground on a flat rock or a bare peat hag (Mitchell et al. 2004). The species breeds in colonies, showing a preference for level-ground (Hume and Pearson 1993, del Hoyo et al. 1996) that is well covered with fairly close, short vegetation (Snow and Perrins 1998, Mitchell et al. 2004), often nesting under heather, bracken or other vegetation (Richards 1990) (sometimes under pine trees) (del Hoyo et al. 1996). Suitable sites include flat, unbroken grassy slopes (Richards 1990), sand-dunes,the tops and ledges of coastal cliffs (Richards 1990, Mitchell et al. 2004), rocky offshore islands (del Hoyo et al. 1996, Mitchell et al. 2004), saltmarshes (Mitchell et al. 2004), the margins of inland lakes (Richards 1990, Olsen and Larsson 2003), islands in lakes and rivers (Olsen and Larsson 2003), and high moorland (Richards 1990, Mitchell et al. 2004), although the species will also nest on buildings and rooftops (del Hoyo et al. 1996).

Threats

Some populations of this species have significantly declined due to decreasing food availability caused by competition and predation from Larus argentatus and Larus marinus (Barcena et al. 1984, del Hoyo et al. 1996, Olsen and Larsson 2003) and by changes in fishing and refuse disposal practices (Olsen and Larsson 2003, Mitchell et al. 2004) (e.g. closure of landfill sites and the covering of waste) (Barcena et al. 1984, del Hoyo et al. 1996, Olsen and Larsson 2003, Mitchell et al. 2004). Population declines may also have been aided by poisoning from organochloride pollution (Bustnes et al. 2006). Contamination from pesticides is no longer considered a likely threat (I. C. T. Nisbet in litt. 2010). Colonies have been culled in Britain and Ireland in order to protect other breeding seabirds (e.g. terns) from predation and competition (Mitchell et al. 2004). The species is exploited on its African wintering grounds (del Hoyo et al. 1996), is hunted unsustainably in Denmark (Bregnballe et al. 2006), and is threatened by egg-collecting and general human disturbance on the Iberian Peninsula (Barcena et al. 1984). Human disturbance occurs at wintering sites, caused by local people checking snare traps set to catch other species (Hario 2006). The species is susceptible to avian botulism, so may be threatened by future outbreaks of this disease (Mitchell et al. 2004).

Conservation actions

Conservation Actions Underway
The following information refers to the species's European range only: The species is covered within the African Eurasian Waterbird Agreement. In the EU it is listed on Annex II of the Birds Directive. There are 77 Important Bird Areas identified for this species within Europe. In the EU there are 391 Special Protection Areas which list this species. 

Conservation Actions Proposed
The following information refers to the species's European range only: Management of existing protected areas, and monitoring of human activities (egg collection; disturbance etc.). Fisheries management to ensure long term sustainability of fish stocks. Reduction of marine litter on coasts and within the water column.

Acknowledgements

Text account compilers
Ashpole, J, Butchart, S., Calvert, R., Ekstrom, J., Malpas, L., Taylor, J.

Contributors
Nisbet, I.


Recommended citation
BirdLife International (2017) Species factsheet: Larus fuscus. Downloaded from http://www.birdlife.org on 25/11/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/11/2017.