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Overview

Distribution

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).
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Range

Pakistan to s India, Sri Lanka, Nepal and sw China.

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Ecology

Habitat

inland
  • UNESCO-IOC Register of Marine Organisms
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Habitat and Ecology

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
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2012

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.

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.
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Population

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).

Population Trend
Decreasing
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Threats

Major 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).
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Management

Conservation Actions

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.
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Wikipedia

River tern

For the river in Shropshire, England, see River Tern.
Immature
Adult and immature

The Indian river tern or just river tern (Sterna aurantia) is a bird in the tern family . It is a resident breeder along inland rivers from Iran east into the Indian Subcontinent and further to Myanmar to Thailand, where it is uncommon. Unlike most Sterna terns, it is almost exclusively found on freshwater, rarely venturing even to tidal creeks.

This species breeds from March to May in colonies in less accessible areas such as sandbanks in rivers. It nests in a ground scrape, often on bare rock or sand, and lays three greenish-grey to buff eggs, which are blotched and streaked with brown.

This is a medium-sized tern, 38–43 cm long with dark grey upperparts, white underparts, a forked tail with long flexible streamers, and long pointed wings. The bill is yellow and the legs red. It has a black cap in breeding plumage. In the winter the cap is greyish white, flecked and streaked with black, there is a dark mask through the eye, and the tip of the bill becomes dusky.

The sexes are similar but juveniles have a brown head, brown-marked grey upperparts, grey breast sides and white underparts. The bill is yellowish with a dark tip

As with other Sterna terns, the river tern feeds by plunge-diving for fish, crustaceans, tadpoles and aquatic insects in rivers, lakes, and tanks. Its numbers are decreasing due to the pollution of their habitat.

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