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 and travel in leapfrog-like stages, using many stopovers en-route (del Hoyo et al. 1996, 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, 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, often with other gull species (especially Herring Gull Larus argentatus), in colonies ranging in size from a few pairs to several tens of thousands (Richards 1990, Snow and Perrins 1998, Mitchell et al. 2004). Outside of the breeding season the species remains gregarious, normally migrating singly or in small groups of less than 10, 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 in colonies, showing a preference for level-ground that is well covered with fairly close, short vegetation, often nesting under heather, bracken or other vegetation (sometimes under pine trees) (Richards 1990, Hume and Pearson 1993, del Hoyo et al. 1996, Snow and Perrins 1998, Mitchell et al. 2004). Suitable sites include flat, unbroken grassy slopes, sand-dunes,the tops and ledges of coastal cliffs, rocky offshore islands, saltmarshes, the margins of inland lakes, islands in lakes and rivers, and high moorland, although the species will also nest on buildings and rooftops (Richards 1990, Olsen and Larsson 2003, Mitchell et al. 2004).. Non-breeding Outside of the breeding season the species chiefly inhabits inshore and offshore seas, 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, in England preferring flooded gravel pits and reservoirs, canals, river weirs, flood-lands and sewage treatment areas ((Urban et al. 1986, Snow and Perrins 1998). As in the breeding season it is often seen foraging on arable land, pasture land, and on refuse dumps (Richards 1990, del Hoyo et al. 1996). Diet The species is an omnivorous, opportunistic feeder that forages extensively at sea. Its diet consists of small fish (especially Baltic herring Clupea harengus), aquatic and terrestrial invertebrates (e.g. beetles, flies and larvae, ants, moths, grasshoppers, crustaceans, molluscs, segmented worms and starfish), bird eggs and nestlings, carrion, offal, rodents, berries and grain (Urban et al. 1986, del Hoyo et al. 1996, BirdLife International 2000, Olsen and Larsson 2003). 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, lichen, feathers (or other local materials), and a simple sparsely-lined scrape, that is usually positioned on open ground on a flat rock or a bare peat hag (Richards 1990, del Hoyo et al. 1996, Mitchell et al. 2004).

Threats

Declines in the most northerly breeding subspecies L. f. fuscus have been attributed in part to the high level of DDE residues accumulated during the non-breeding season, when this subspecies is found further south than the rest of the species (Bustnes 2006, Burger et al. 2018). High levels of PCBs have also been recorded with the potential to lead to mortality in chicks (Hario et al. 2000). Lesser Black-backed Gulls are also persecuted in some areas of its range, which may lead to displacement or even local declines.

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
Ekstrom, J., Malpas, L., Stuart, A., Ashpole, J, Taylor, J., Butchart, S., Bennett, S., Calvert, R.

Contributors
Nisbet, I.


Recommended citation
BirdLife International (2020) Species factsheet: Larus fuscus. Downloaded from http://www.birdlife.org on 30/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 30/09/2020.