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Sandwich Tern Thalasseus sandvicensis

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 fluctuating, 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 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#.
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.
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
Thalasseus sandvicensis (del Hoyo and Collar 2014) was previously placed in the genus Sterna.

Synonym(s)
Sterna sandvicensis Latham, 1787, Thalasseus sandvicensis Stotz et al. (1996), Thalasseus sandvicensis AOU checklist (1998 + supplements)

Distribution and population
The Sandwich Tern can be found in Europe, Africa, western Asia, and the southern Americas. It breeds seasonally on the coast of much of Europe east to the Caspian Sea, wintering from the Caspian, Black and Mediterranean Seas to the coasts of western and southern Africa, and from the south Red Sea to north-west India and Sri Lanka. In the Americas, it breeds from Virginia to Texas (USA), on the coasts of the Yucatan Peninsula, Lesser Antilles, Venezuala, French Guiana, eastern Brazil and Argentina. It winters from Texas, USA down to southern Argentina, in the Greater Antilles and from southern Mexico down to northern Chile1.

Trend justification
The overall population trend is fluctuating, although some populations are stable, others have unknown trends (Wetlands International 2006). This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) Note, however, that these surveys cover less than 50% of the species's range in North America.

Ecology
Behaviour This species is migratory, undergoing post-breeding dispersive movements north and south to favoured feeding grounds before migrating southward (del Hoyo et al. 1996). It breeds in dense colonies with other terns or Black-headed Gulls Larus ridibundus (del Hoyo et al. 1996) and is gregarious throughout the year, often forming feeding flocks where prey is abundant or concentrated (although it may also feed solitarily) (Snow and Perrins 1998). Habitat Breeding During the breeding season the species forms colonies on sandy islands, rocky calcareous islets, sand-spits, sand-dunes, shingle beaches and extensive deltas (Snow and Perrins 1998) with immediate access to clear waters with shallow sandy substrates rich in surface-level fish (Snow and Perrins 1998). It shows a preference for raised, open, unvegetated sand, gravel, mud or bare coral substrates for nesting (del Hoyo et al. 1996). Non-breeding Outside of the breeding season the species frequents sandy or rocky beaches, mudflats fringed by mangroves, estuaries, harbours and bays, often feeding over inlets and at sea (del Hoyo et al. 1996). Diet Its diet consists predominantly of surface-dwelling marine fish (Snow and Perrins 1998) 9-15 cm long (del Hoyo et al. 1996) as well as small shrimps, marine worms and shorebird nestlings (del Hoyo et al. 1996). Breeding site The nest is a shallow scrape on raised, open, unvegetated sand, gravel, mud or bare coral substrates preferably far from upright vegetation (del Hoyo et al. 1996) on sandy islands, rocky calcareous islets, sand-spits, sand-dunes and shingle beaches (Snow and Perrins 1998). The species forms very dense colonies during the breeding season in which the eggs of neighbouring pairs may only be 20 cm apart (del Hoyo et al. 1996). Management information The species responds favourably to habitat management such as vegetation clearance, and can be readily attracted to suitable nesting habitats by the use of decoys (del Hoyo et al. 1996). Breeding pairs are also known to be attracted to coastal locations where artificial nesting sites have been constructed (e.g. beaches of bare shingle and islands or rafts covered with sparse vegetation) (Burgess and Hirons 1992). A conservation scheme for the protection of gull and tern breeding colonies in coastal lagoons and deltas (e.g. Po Delta, Italy) involves protection from human disturbance, prevention of erosion of islet complexes, habitat maintenance and the creation of new islets for nest sites (Fasola and Canova 1996). The scheme particularly specifies that bare islets with 30-100 % cover of low vegetation (sward heights less than 20 cm) should be maintained or created as nesting sites (Fasola and Canova 1996).

Threats
The species is particularly vulnerable to human disturbance (del Hoyo et al. 1996) (e.g. from tourists) especially near breeding colonies on beaches early in the breeding season (Bourne and Smith 1974). It is also sensitive to disturbance from coastal wind farms (wind turbines) (Garthe and Huppop 2004). It is threatened by the loss or degradation of its favoured breeding habitats through inundation, wind-blown sand and erosion (del Hoyo et al. 1996), and has suffered previous local declines from to exposure to bioaccumulated organochlorine pollutants in marine fish (Koeman et al. 1967, del Hoyo et al. 1996). Egg collecting at breeding colonies also poses a threat to the species throughout the tropics (del Hoyo et al. 1996). Utilisation This species is hunted in West Africa during the winter (del Hoyo et al. 1996).

References
Bourne, W. R. P.; Smith, A. J. M. 1974. Threats to Scottish Sandwich Terns. Biological Conservation 6(3): 222-224.

Burgess, N. D.; Hirons, J. M. 1992. Creation and management of articficial nesting sites for wetland birds. Journal of Environmental Management 34(4): 285-295.

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.

Fasola, M.; Canova, L. 1996. Conservation of gull and tern colony sites in north-eastern Italy, an internationally important bird area. Colonial Waterbirds 19: 59-67.

Garthe, S.; Hüppop, O. 2004. Scaling possible adverse effects of marine wind farms on seabirds: developing and applying a vulnerability index. Journal of Applied Ecology 41(4): 724-734.

Koeman, J. H.; Oskamp, A. A. G.; Brouwer, E.; Rooth, J.; Zwart, P.; van den Broek, E.; van Genderen, H. 1967. Insecticides as a factor in the mortality of the sandwich tern (Sterna sandvicensis). A preliminary communication. Meded. Rijksfac. LandbWet. Gent. 32((3-4)): 841-854.

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

Sparks, T. H.; Huber, K.; Bland, R. L.; Crick, H. Q. P.; Croxton, P. J.; Flood, J.; Loxton, R. G.; Mason, C. F.; Newnham, J.A.; Tryjanowski, P. 2007. How consistent are trends in arrival (and departure) dates of migrant birds in the UK? Journal of Ornithology 148: 503-511.

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

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

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., Malpas, L., Calvert, R.

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

Recommended citation
BirdLife International (2014) Species factsheet: Thalasseus sandvicensis. Downloaded from http://www.birdlife.org on 01/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 01/11/2014.

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 - Sandwich tern (Sterna sandvicensis) 0

Key facts
Current IUCN Red List category Least Concern
Family Laridae (Gulls, Terns, Skimmers)
Species name author Latham, 1787
Population size mature individuals
Population trend Stable
Distribution size (breeding/resident) 1,200,000 km2
Country endemic? No
Links to further information
- Additional Information on this species