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 Pontoppidan, 1763

Taxonomic source(s) AOU checklist (1998 + supplements), Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), SACC (2005 + updates), Sibley and Monroe (1990, 1993), Stotz et al. (1996)

Taxonomic note Larus cachinnans (Sibley and Monroe 1990, 1993) has been split into L. cachinnans and L. michahellis; L. armenicus (Sibley and Monroe 1990, 1993; AERC TAC) has been lumped into L. michahellis. These changes to the BirdLife checklist follow examination by the BirdLife Taxonomic Working Group (BTWG) of a recent review of large white-headed gulls in the Holarctic by Collinson et al. (2008) and associated literature referred to therein. The following species level treatment, shown with subspecific placements, has been adopted by the BTWG: L. fuscus (with intermedius, graellsii, heuglini, taimyrensis and barabensis); L. argentatus (with argenteus, smithsonianus, vegae and mongolicus); L. michahellis (with atlantis and armenicus) and L. cachinnans. This treatment is based on evidence of sympatry, and morphological and behavioural differences, but rejects further splits derived from phylogentic analyses based on mtDNA because Collinson et al. (2008) admit that (1) mtDNA lineages can disappear by random events, resulting in misplacements and displacements in phylogenies, and (2) hybridisation, which seems very widespread in these white-headed gulls, can result in "adoption" of mtDNA sequences by another taxon, completely obscuring the real situation. Collinson et al. (2008) explicitly state "these complications do not just make gull phylogenies difficult: they may cause entirely false conclusions to be drawn about species boundaries… it must be recognised that splits or lumps based solely on mtDNA cannot be regarded as robust". While proposed splits not adopted here are not based solely on mtDNA, the morphological evidence presented is not conclusive, taxa are only diagnosable in some cases and there is hybridisation between them.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

2,700,000 - 5,700,000

unset

19,800,000 km²

No

Range & population The Herring Gull breeds in most of Canada and Alaska, as well as the north-east USA, on the northern coastline of Europe including inland Iceland, Ireland, Scandinavia and the United Kingdom, and in the north of Russia from the centre to its eastern tip. Some populations winter further south, being found in much of the USA, Mexico and Central America, on the northern coasts of Spain and France, in much of Japan and on the south-eastern coast of China¹.

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

Ecology: Behaviour Northern breeding populations of this species are migratory¹ although populations in the south are nomadic or completely non-migratory³. The species breeds between mid-April and late-June^{1, 3} in colonies of up to several thousand pairs, occasionally nesting solitarily or as single pairs on the edge of other seabird colonies¹. Outside of the breeding season the species is highly gregarious and gathers in large flocks in favoured sites^{2, 4}. Individuals show foraging site fidelity⁸. Habitat The species inhabits coastal and near-coastal areas¹ but may also forage inland on large lakes and reservoirs, fields and refuse dumps^1. It has no specific breeding habitat¹ but may show a preference for rocky shores with cliffs, outlying stacks or islets^{1, 4}, otherwise nesting on rocky and grassy islands, sandy beaches¹, dunes², gravel bars, saltmarshes, rocky outcrops, buildings, claypits¹, tundra with reeds or hummocks³, swampy lowlands near lakes and on river islands³. When inland on migration the species also shows a preference for large river valleys³. Diet The species has a highly opportunistic diet and will exploit almost any superabundant source of food¹. It takes fish, earthworms, crabs and other marine invertebrates (e.g. molluscs, starfish or marine worms), adult birds, bird eggs and young, rodents, insects (e.g. ants), berries and tubers (e.g. turnips)¹. It also scavenges at refuse dumps, fishing wharves and sewage outfall zones and frequently follows fishing boats^1,9. Breeding site The nest is a depression in a mound of vegetation^{2, 3} placed on the ground, e.g. on a cliff ledge or roof, usually in the shelter of vegetation¹. Although Herring Gulls exploit refuse tips and farmland extensively all year round, their breeding distribution is extremely coastal compared to other Larus gulls (other than L. marinus)¹⁰. Foraging range The species shows increasing foraging distances later in the breeding period¹¹. The feeding range has been variously reported as 35 km (for breeding herring gulls in a Dutch colony)¹², 41 km (in Westphalia, Germany, outside the breeding season)¹³, 50 km (for breeding birds in Morocco)¹⁹ and 70 to 100 km (for herring gulls breeding in Denmark)¹⁴. Several other studies have reported shorter foraging distances^{15,16,17,18,19,20,21,22}. Refuse tips are frequently exploited by foraging individuals^16,17,20 and so the feeding distribution of some colonies will be determined by location of refuse dumps²². On the basis of a simple density model of birds at sea, it has been estimated that 95% of herring gulls breeding on Terschelling in the Dutch Wadden Sea foraged within 54 km of the colony²². Radio-tracking of four gulls at an inland lake in Ontario indicated extreme specialisation in foraging patterns, with two of the gulls feeding within 1 km whereas two others took extended flights to destinations more than 30 km away^22,23.

Threats The species is threatened by coastal oil pollution⁷ and is susceptible to avian influenza so may be threatened by future outbreaks of the virus⁵. Utilisation The species is hunted in Denmark^6.

Conservation measures underway Preventative and control measures are frequently used against this species as it is regarded as a pest and a threat to many other colonial bird species (it usurps habitats and preys upon bird eggs and young), and also to airports (frequently causes collisions)¹.

References 1. del Hoyo et al. (1996). 2. Richards (1990). 3. Flint et al. (1984). 4. Snow and Perrins (1998). 5. Melville and Shortridge (2006). 6. Bregnballe et al. (2006). 7. Gorski et al. (1977). 8. Shamoun-Baranes and van Loon (2006). 9. Hiippop and Wurm (2000). 10. Gibbons et al. (1991). 11. Belant et al. (1993). 12. Spaans (1971). 13. Sell and Vogt (1986). 14. Klein (1994). 15. Andersson (1970). 16. Nogales et al. (1995). 17. Pons and Migot (1995). 18. Verbeek (1977). 19. Witt et al. (1981). 20. Sibly and McCleery (1983). 21. Cramp and Simmons (1983). 22. BirdLife International (2000). 23. Morris and Black (1980).

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), Jonathan Ekstrom (BirdLife International), Jess Hatchett (BirdLife International), Lucy Malpas (BirdLife International)

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

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

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.

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