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River Tern Sterna aurantia

Justification
This species has been uplisted to Near Threatened on the basis that increasing human disturbance and dam construction projects are expected to drive a moderately rapid population decline over the next three generations.

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.

Distribution and population
Sterna aurantia occurs across a wide range in southern Asia, being found in Pakistan, India, Nepal, Bhutan, Bangladesh, Myanmar, Thailand, Laos, Cambodia, Vietnam and southern China (Yunnan) (del Hoyo et al. 1996), with vagrant records from Iran and Afghanistan, although it is generally resident over most of its range. The global population is estimated at between 50,000 and 100,000 individuals (Delaney and Scott 2006). It has reportedly declined in abundance in Thailand, where it is now considered very rare (del Hoyo et al.1996). The species has also declined in Laos since the early 20th century (Thewlis et al. 1998), and is very close to being extirpated from the country (W. Duckworth in litt. 2011). It is said to be declining throughout its range in Cambodia (F. Goes in litt. 2011), with sharp declines noted in the number of pairs in the largest breeding colony on the Mekong, and the number of breeding locations, during the period 2007-2011 (A. Claassen in litt. 2011). In view of its historical and recent precipitous decline in Cambodia, the species is said to be heading towards extinction there in 5-10 years if no specific conservation action is carried out (A. Claassen in litt. 2011). The species is now a rare and very local visitor in Nepal, with a maximum population of 20 individuals estimated in 2011, having rapidly declined since the 1990s (C. Inskipp and H. S. Baral in litt. 2011). The species is described as uncommon along the Dayingjiang river in south-western Yunnan (Yang Liu in litt. 2011). In contrast to declines noted in South-East Asia, the species is now more regular in southern India than was once thought, having probably benefitted from the development of reservoirs (Praveen J. in litt. 2012). Likewise, the species is described as having increased in Andhra Pradesh over the past 10 years (S. Riyazuddin in litt. 2012).

Population justification
The population in India has been estimated to number more than 50,000 individuals, thus the global population is put at 50,000-100,000 individuals (Delany and Scott 2006).

Trend justification
Precipitous declines have occurred in parts of South-East Asia, whilst local increases have been noted in India, making the deciphering of past population trends difficult. The species is expected to undergo a moderately rapid reduction over the next three generations, as threats, such as dam construction and disturbance, increase in prevalence.

Ecology
It inhabits rivers and freshwater lakes, also occurring rarely on estuaries, and breeds on sandy islands (del Hoyo et al. 1996). It has been recorded up to 600 m in Nepal. It feeds predominantly on fish, small crustaceans and insects. Breeding occurs mainly in February-May (del Hoyo et al. 1996).

Threats
Nesting areas are vulnerable to flooding, predation and disturbance (del Hoyo et al. 1996). The negative population trend in Laos is probably due mainly to excessive human disturbance on sandbars (Thewlis et al. 1998). The multitude of dam construction projects completed, underway or planned in South-East Asia (e.g. along the Mekong river [F. Goes in litt. 2011]) may also threaten the species through changes to flow regime and flooding of nest-sites. Its habitat may be threatened by the construction of dams in the Dayingjiang region of south-western Yunnan (Yang Liu in litt. 2011).

Conservation Actions Underway
The species occurs in a number of protected areas.

Conservation Actions Proposed
Carry out regular surveys to monitor the population throughout its range. Conduct education activities to help alleviate human pressures on river and lake habitats. Lobby against high-risk dam projects, especially in South-East Asia.

References
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.

Thewlis, R. M.; Timmins, R. J.; Evans, T. D.; Duckworth, J. W. 1998. The conservation status of birds in Laos.

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
Butchart, S., Ekstrom, J., Taylor, J.

Contributors
Baral, H., Claassen, A., Duckworth, W., Goes, F., Inskipp, C., Praveen, J., Riyazuddin, S., Thewlis, R., Yang, L.

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

Recommended citation
BirdLife International (2014) Species factsheet: Sterna aurantia. Downloaded from http://www.birdlife.org on 29/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 29/11/2014.

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 - River tern (Sterna aurantia) 0

Key facts
Current IUCN Red List category Near Threatened
Family Laridae (Gulls, Terns, Skimmers)
Species name author Gray, 1831
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 5,100,000 km2
Country endemic? No
Links to further information
- Additional Information on this species