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LC
Dolphin Gull Larus scoresbii

Justification
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 stable, 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 may be moderately small to large, but it is not believed to 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 source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
SACC. 2006. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.

Taxonomic note
Larus scoresbii (del Hoyo and Collar 2014) was previously placed in the genus Leucophaeus.

Synonym(s)
Gabianus scoresbii Stotz et al. (1996), Larus scoresbii BirdLife International (2004), Larus scoresbii Sibley and Monroe (1990, 1993), Leucophaeus scoresbii Traill, 1823

Distribution and population
This species is known from colonies around the coasts of southern Chile and Argentina, Tierra de Fuego, and the Falklands Islands (Islas Malvinas). Colonies are numerous along the South American coast, but tend to be very small, rarely exceeding 200 pairs (del Hoyo et al. 1996). In Argentina, the total population has been estimated at c.700 pairs. On the Falklands, there are 3,000-6,000 pairs which are widely distributed in small colonies (Woods and Woods 1997).

Population justification
The population is estimated to number 10,000-28,000 individuals, roughly equating to 6,700-19,000 mature individuals.

Trend justification
Although Wetlands International consider the current population trend to be unknown, it is suspected to be stable in the absence of evidence for any declines or substantial threats (del Hoyo et al. 1996).

Ecology
This species can be found on rocky coasts, feeding mainly on carrion, offal, bird eggs and chicks, but will also take marine invertebrates and other natural food. It scavenges around marine mammals for dead fish, placentae and particularly faeces. It exploits human intrusion into colonies by preying on unguarded eggs and chicks. It probes seaweed, captures swarming beach flies and will pick mussels which are then dropped onto rocks. It does not frequent rubbish dumps but will sometimes feed at sewage outlets. Colony attendance begins in September laying highly asynchronous broods. Colonies are small, with a maximum of 210 pairs recorded, and can be found on low sea cliffs, sand or gravel beaches, marshy depressions or headlands, usually in the vicinity of seabird colonies, marine mammals, slaughterhouses, sewers or farmyards (del Hoyo et al. 1996).

Threats
Cats, rats, mink Mustela vison and Patagonian fox Dusicyan culpaeus have been introduced to the Falklands, but their effect on L. scoresbii is not known (Croxall et al. 1984). Habitat destruction and modification due to introduced rabbits and stock may have had some effect on the distribution on the species. Chiloe Island, an important breeding site for the species in Chile, is heavily populated and many aquaculture farms have been established inshore and along shorelines (Duffy et al. 1984).

References
Croxall, J. P.; Prince, P. A.; Hunter, I.; McInnes, S. J.; Copestake, P. G. 1984. Seabirds of the Antarctic Peninsula, islands of the Scotia Sea, and Antarctic continent between 80ºW and 20ºW: their status and conservation. In: Croxall, J.P.; Evans, P.G.H.; Schreiber, R.W. (ed.), Status and conservation of the world's seabirds, pp. 637-666. 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.

Delany, S.; Scott, D. 2006. Waterbird population estimates. Wetlands International, Wageningen, The Netherlands.

Duffy, D. C.; Hays, C.; Plenge, M. A. 1984. The conservation status of Peruvian seabirds. In: Croxall, J.P.; Evans, P.G.H.; Schreiber, R.W. (ed.), Status and conservation of the world's seabirds, pp. 245-259. International Council for Bird Preservation, Cambridge, UK.

Wetland International - China Office. 2006. Relict Gull surveys in Hongjianao, Shaanxi Province. Newsletter of China Ornithological Society 15(2): 29.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Butchart, S., Harding, M., Calvert, R.

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

Recommended citation
BirdLife International (2014) Species factsheet: Larus scoresbii. Downloaded from http://www.birdlife.org on 02/09/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 02/09/2014.

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.

Key facts
Current IUCN Red List category Least Concern
Family Laridae (Gulls, Terns, Skimmers)
Species name author Traill, 1823
Population size 6700-19000 mature individuals
Population trend Stable
Distribution size (breeding/resident) 472,000 km2
Country endemic? No
Links to further information
- Additional Information on this species