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Sterna aurantia 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Laridae

Scientific Name: Sterna aurantia
Species Authority: Gray, 1831
Common Name(s):
English River Tern, Indian River Tern
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Baral, H., Claassen, A., Duckworth, W., Goes, F., Inskipp, C., Praveen, J., Riyazuddin, S., Thewlis, R. & Yang, L.
Facilitator/Compiler(s): Butchart, S., Ekstrom, J., Taylor, J., Ashpole, J
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.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species occurs across a wide range in southern and south-east 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 has been undergoing a strong decline in Cambodia since 2003, with extirpation or sharp declines noted in the number of pairs throughout its breeding range since 2007 (Goes 2014, F. Goes in litt. 2016). It no longer breeds on the Tonle Sap or the Mekong below Kratie (Goes 2014). In Cambodia the species has declined by >75% in the past 15 years and the population is now likely to be fewer than 50 individuals (Claassen in prep.). The species is expected to be virtually extinct from the lower Mekong basin in just five years if no specific conservation action is immediately carried out (F. Goes in litt. 2016). The species is now a rare and very local visitor in Nepal, with a maximum population of 20 individuals estimated in 2016, having rapidly declined since the 1990s (Inskipp et al. 2016). 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).
Countries occurrence:
Native:
Bangladesh; Bhutan; Cambodia; China; India; Lao People's Democratic Republic; Myanmar; Nepal; Pakistan; Thailand; Viet Nam
Vagrant:
Afghanistan; Iran, Islamic Republic of
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:9730000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: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.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and 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).
Systems:Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):10.1
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): 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). In Cambodia, a study of breeding colonies in 2010-2015 found that egg collection, predation by rodents, crows and domestic dogs and trampling by domestic water buffalo were responsible for low breeding success (Claassen in prep). The study found very little evidence of direct hunting of the species, although a snare was once found at a nest (A. Claassen in litt. 2016). hat many adult birds failed to return to the breeding colonies but the reasons for their absence were not known. 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). In Nepal it is severely threatened by food shortages owing to illegal fishing inside protected areas and overfishing outside protected areas, it is also threatened by destruction of breeding habitat, disturbance and hunting (Inskipp et al. 2016).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The species is considered At Risk in Laos, Critical in Thailand, Critical in Cambodia (Goes 2014) and Critically Endangered in Nepal (Inskipp et al. 2016). The species occurs in a number of protected areas. In Cambodia, nest protection programmes have been implemented by the World Wildlife Fund on the Mekong River and by the Royal University of Phnom Penh on the Sekong and Sesan rivers (A. Claassen in litt. 2016). These programmes involve education, employing local people as nest guards and the use of predator exclosures (A. Claassen in litt. 2016). In Cambodia, a Species Action Plan is in preparation (F. Goes in litt. 2016).

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. Introduce nest protection measures where nesting sites are vulnerable to disturbance.

Citation: BirdLife International. 2016. Sterna aurantia. The IUCN Red List of Threatened Species 2016: e.T22694537A93456605. . Downloaded on 30 March 2017.
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