Species

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 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.

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.

Distribution and population
Larus michahellis can be found in Europe, the Middle East and north Africa. It is resident in much of southern Europe, on the coasts of the Mediterranean, Black Sea and Caspian Sea, on the Azores and Madeira, Portugal, and on the Canary Islands. Spain. Wintering grounds include the coast of south-west Asia (breeders from the steppes), most of the European coast up to Denmark and the coast of Africa from Western Sahara through tho the eastern Mediterranean (del Hoyo et al. 1996).

Population justification
The global population size is unknown owing to recent taxonomic splits.

Trend justification
The overall population trend is increasing, although some populations have unknown trends (Wetlands International 2006).

Ecology
Behaviour Populations may be dispersive or sedentary (del Hoyo et al. 1996). Post-breeding movements to wintering areas occur from July to November, with the return migration occurring from mid-February to mid-June (Olsen and Larsson 2003). The species breeds from mid-March to April (del Hoyo et al. 1996, Snow and Perrins 1998), although the exact timing varies geographically (Olsen and Larsson 2003). It breeds colonially in groups of up to 8,000 pairs, and may nest in monospecific clusters within mixed-species colonies (del Hoyo et al. 1996). Outside of the breeding season the species remains gregarious, congregating around ports, harbours and refuse dumps (le Grand et al. 1984). Habitat Breeding During the breeding season the species nests near lakes surrounded by reedbeds (Olsen and Larsson 2003), pastures (Madeira) (le Grand et al. 1984), reservoirs, rivers (de Juana 1984), and on grassy or shrubby river islands (del Hoyo et al. 1996), also forming colonies on sea cliffs (de Juana 1984), rocky and sandy offshore islands, rocky coasts (del Hoyo et al. 1996, Snow and Perrins 1998), sandy beaches, spits (del Hoyo et al. 1996), sand-dunes, and salt-pans (Snow and Perrins 1998), and foraging in intertidal zones (del Hoyo et al. 1996) and in brackish coastal marshes (Snow and Perrins 1998). Non-breeding Outside of the breeding season the species is more common along the coast (e.g. at harbours and ports) and in other marine habitats (though seldom far from land). During this season it also forages in cultivated fields (del Hoyo et al. 1996, Snow and Perrins 1998, Olsen and Larsson 2003) and along rivers, and is especially common at refuse dumps (del Hoyo et al. 1996, Snow and Perrins 1998). Diet Its diet consists of fish, invertebrates (including insects, molluscs (Olsen and Larsson 2003) and crabs (Munilla 1997)), reptiles, small mammals (e.g. voles (del Hoyo et al. 1996) and ground squirrels (Snow and Perrins 1998)), refuse, offal, and bird eggs and chicks (del Hoyo et al. 1996) (e.g. of petrels and shearwaters) (le Grand et al. 1984). Breeding site The nest is constructed of nearby vegetation, feathers, debris and old carcasses, and is preferably positioned close to or under bushes (del Hoyo et al. 1996), or on rocky and sandy islands, beaches, spits, sea cliffs, grassy or shrubby river islands (del Hoyo et al. 1996), and occasionally on high ground hundreds of metres from water (del Hoyo et al. 1996). The species breeds colonially in monospecific or mixed-species groups, with pairs usually nesting a few metres apart (del Hoyo et al. 1996).

Threats
This species is vulnerable to oil pollution (James 1984, del Hoyo et al. 1996), and is killed by longlines (fishing lines) in the Mediterranean Sea and Macaronesia (Cooper 2003). It suffers from habitat destruction and disturbance from tourism at breeding sites in the Spanish Mediterranean (le Grand et al. 1984, de Juana 1984), and many colonies are regularly robbed of eggs by local communities (James 1984, de Juana 1984, del Hoyo et al. 1996). The species was also persecuted in the past (adults were shot and nests destroyed) due to its predation on Mediterranean Gull Larus melanocephalus (del Hoyo et al. 1996), culled in the Spanish Mediterranean (to protect Audouin's Gull Larus audouinii) (James 1984, del Hoyo et al. 1996), and controlled by poisoning due to its predation on White-faced Storm-petrel Pelagodroma marina (le Grand et al. 1984). Culling of the species still occurs in the Mediterranean region, resulting in decreases in breeding colony size (mainly due to emigration rather than actual population decrease) (Bosch et al. 2000). Utilisation The species is hunted for sport in Ukraine (Rudenko 2006).

References
Le Grand, G.; Emmerson, K.; Martin, A. 1984. The status and conservation of seabirds in the Macaronesian Islands. In: Croxall, J.P.; Evans, P.G.H.; Schreiber, R.W. (ed.), Status and conservation of the world's seabirds, pp. 377-391. International Council for Bird Preservation, Cambridge, U.K.

James, P. C. 1984. The status and conservation of seabirds in the Mediterranean Sea. In: Croxall, J.P.; Evans, P.G.H.; Schreiber, R.W. (ed.), Status and conservation of the world's seabirds, pp. 371-375. International Council for Bird Preservation, Cambridge, U.K.

de Juana, E. 1984. The status and conservation of seabirds in the Spanish Mediterranean. In: Croxall, J. P.; Evans, P. G. H.; Schreiber, R. W. (ed.), Status and conservation of the world's seabirds, pp. 347-361. International Council for Bird Preservation, Cambridge, U.K.

del Hoyo, J.; Elliott, A.; Sargatal, J. 1996. Handbook of the Birds of the World, vol. 3: Hoatzin to Auks. Lynx Edicions, Barcelona, Spain.

Snow, D. W.; Perrins, C. M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Cooper, D. S. 2003. New distributional and ecological information on birds in south-western Guatemala. Cotinga 19: 61-63.

Olsen, K. M.; Larsson, H. 2004. Gulls of Europe, Asia and North America. Christopher Helm, London.

Bosch, M.; Oro, D.; Cantos, F. J.; Zabala, M. 2000. Short-term effects of culling on the ecology and population dynamics of the Yellow-legged Gull. Journal of Applied Ecology 37: 369-385.

Rudenko, A. G. 2006. Migration of Pontic Gulls Larus cachinnans form 'ponticus' ringed in the south of Ukraine: a review of recoveries from 1929 to 2003. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 553-559. The Stationary Office, Edinburgh, UK.

Munilla, I. 1997. Henslow’s swimming crab (Polybius henslowii) as an important food for yellow-legged gulls (Larus cachinnans) in NW Spain. ICES Journal of Marine Science 54: 631-634.

Further web sources of information
Hear sounds for this species from xeno-canto, the community database of shared bird sounds from around the world.

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

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Larus michahellis. Downloaded from http://www.birdlife.org on 22/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/05/2013.

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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