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Ross's Gull Rhodostethia rosea

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 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 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)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls.
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Distribution and population
Ross's Gull breeds in the high Arctic of North America and Siberia. It is found in north-east Siberia, Russia, from the Taymyr Peninsula to the Kolyma River, locally in Greenland (to Denmark) and irregularly in Canada. Its wintering range in Siberia expands further west and east down to the tip of the Kamchatkan Peninsula, with other wintering sites including the north coast of Alaska (USA) and the south-eastern coast of Greenland (del Hoyo et al. 1996).

Population justification
The global population is estimated to number c.25,000-100,000 individuals (Wetlands International 2006), while the population in Russia has been estimated at c.100-10,000 breeding pairs and c.50-1,000 individuals on migration (Brazil 2009).

Trend justification
The population trend is difficult to determine because of uncertainty over the extent of threats to the species (del Hoyo et al. 1996).

Ecology
Behaviour This species is migratory (del Hoyo et al. 1996, Snow and Perrins 1998) and travels north after breeding to overwinter in the Arctic Ocean (Snow and Perrins 1998). It arrives on its breeding grounds in late-May where it breeds from early-June in loose colonies of 2-10 pairs (rarely up to 18 pairs) (del Hoyo et al. 1996) often with other species (e.g. Arctic Tern Sterna paradisaea) (del Hoyo et al. 1996, Snow and Perrins 1998). The departure from the breeding grounds occurs from late-July onwards with the species migrating in small flocks of 2-16 individuals (del Hoyo et al. 1996). It forages solitarily or in small loose flocks (del Hoyo et al. 1996). Habitat Breeding The species breeds in the upper boreal forest (taiga) and tundra (del Hoyo et al. 1996) zones of the high Arctic (Olsen and Larsson 2003), showing a preference for nesting on small, low islets in shallow pools (created by snow-melt on tundra underlain with permafrost) (Snow and Perrins 1998) surrounded by stands of stunted alder Alnus spp. and willow Salix spp. (del Hoyo et al. 1996, Snow and Perrins 1998) and by muddy, boggy or marshy (Richards 1990, del Hoyo et al. 1996, Snow and Perrins 1998, Olsen and Larsson 2003) ground with sedges and moss (Snow and Perrins 1998). The species also breeds on marshy tundra in high Arctic river deltas (del Hoyo et al. 1996) and on marshy ground in well-wooded river valleys (Richards 1990). Non-breeding Outside of the breeding season the species forages pelagically on the open sea or along the edges of pack-ice (del Hoyo et al. 1996). Diet Breeding On its breeding grounds the species is chiefly insectivorous (del Hoyo et al. 1996), its diet including Coleoptera and dipteran flies (Richards 1990). Non-breeding On migration and in the winter its diet consists of small fish and surface-dwelling marine invertebrates (del Hoyo et al. 1996, Snow and Perrins 1998) (including plankton, crustaceans, molluscs and priapulid marine worms) (del Hoyo et al. 1996). Breeding site The nest is constructed of dry grass, sedge and moss (del Hoyo et al. 1996), usually on a tussock on an island in a pool in tundra or forest (del Hoyo et al. 1996). The species nests in near invisible colonies, often with other species, with an average distance between neighbouring nests of 43 m (del Hoyo et al. 1996).

Threats
The species is potentially threatened by the development of oil extraction in the Beaufort Sea, and also suffers from nest failures as a result of human disturbance in Canada (del Hoyo et al. 1996). Utilisation The species is shot whilst on passage by native Alaskan peoples for food (del Hoyo et al. 1996).

References
Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

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.

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

Richards, A. 1990. Seabirds of the northern hemisphere. Dragon's World Ltd, Limpsfield, U.K.

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

Further web sources of information
Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

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

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

Recommended citation
BirdLife International (2014) Species factsheet: Rhodostethia rosea. Downloaded from http://www.birdlife.org on 23/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/07/2014.

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.

Additional resources for this species

ARKive species - Ross’s gull (Rhodostethia rosea) 0

Key facts
Current IUCN Red List category Least Concern
Family Laridae (Gulls and terns)
Species name author (MacGillivray, 1824)
Population size mature individuals
Population trend Unknown
Distribution size (breeding/resident) 30,400 km2
Country endemic? No
Links to further information
- Additional Information on this species