Sterna aurantia 


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
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.
Taxonomic Notes: The BirdLife Taxonomic Working Group is aware that phylogenetic analyses have been published which have proposed generic rearrangements which may affect this species, but prefers to wait until work by other taxonomists reveals how these changes affect the entire groups involved.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
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.
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:
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: 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).
Countries occurrence:
Bangladesh; Bhutan; Cambodia; China; India; Lao People's Democratic Republic; Myanmar; Nepal; Pakistan; Thailand; Viet Nam
Afghanistan; Iran, Islamic Republic of
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 5100000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme 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: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All 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). 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 [top]

Conservation Actions: 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.

Citation: BirdLife International. 2012. Sterna aurantia. The IUCN Red List of Threatened Species 2012: e.T22694537A38846248. . Downloaded on 25 November 2015.
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