EN
Black-bellied Tern Sterna acuticauda



Justification

Justification of Red List Category
This species is almost extinct in a large part of its range and is thought to be in very rapid decline overall, owing to a multitude of threatening processes that affect riverine species in southern Asia. It is therefore listed as Endangered.

Population justification
Despite its large range, the species could now number fewer, perhaps significantly fewer, than 10,000 mature individuals (Perennou et al. 1994, S. Mahood in litt. 2012, 2016). The population estimate is currently placed at 10,000-25,000 individuals, roughly equating to 6,700-17,000 mature individuals, until more data are available.

Trend justification
A very rapid and on-going decline is suspected based on the comparison of its current rarity and former abundance in many parts of its range, as well as the prevalence of a multitude of threats.

Distribution and population

Sterna acuticauda is known from southern China (previously regular in Yunnan, now very rare and possibly extinct [S. Mahood in litt. 2016]), Pakistan, India (widespread, but some evidence for localised declines), Nepal (once locally fairly common, declining since the early 1990s at least, and judged to be a rare and very local visitor in the lowlands, with a maximum population of 20 estimated in 2016 [Inskipp et al. 2016]), Bangladesh (locally common up until the early to mid 1990s [BirdLife International 2001], in 2016 one pair was found attending a presumed nest after a lack of confirmed records for several years despite a targeted search for the species, while the provenance of some recent records has been questioned [Choudhury 2012, P. Thompson in litt. 2011, 2016]), Myanmar (previously abundant, now declining rapidly and a scarce to uncommon resident, with some surveys since 2002 failing to record the species at all [J. C. Eames in litt. 2012]), Thailand (formerly resident in the north-west, now very rare and probably extinct as breeding species), Laos (previously bred in large numbers along the Mekong channel, now very rarely recorded, and possibly extinct [S. Mahood in litt. 2016]), Cambodia (in early 1960s the species was apparently fairly common along the Mekong; the last breeding record was of just two pairs in 2003 [C. Poole in litt. 2003], and it is now considered probably extinct there [Goes et al. 2010]) and Vietnam (formerly occurred regularly in Cochinchina, and occasionally in Annam, but now probably extinct). There has been a precipitous decline in South-East Asia and it is now almost extinct in the region. Despite its large range, the species may now number fewer, perhaps significantly fewer, than 10,000 mature individuals (Perennou et al. 1994, S. Mahood in litt. 2012).

Ecology

It is found on large rivers (usually breeding on sandspits and islands) and marshes, occasionally on smaller pools and ditches, in lowlands (but not on the coast), up to 730 m.

Threats

Threats include the destruction of breeding habitat (islands and sandspits in larger rivers are increasingly cultivated), the collection of eggs for food, illegal fishing in protected areas (e.g. in Nepal [Inskipp et al. 2016]), overfishing and the flooding of nests, often caused by dams. Increased disturbance and over-harvesting of wetland products are blamed for the recent complete disappearance of the breeding population within Chitwan National Park (Nepal) (F. Cuthbert in litt. 2002). Inadequate fish ladders at Koshi Barrage may also be impacting on this species (Inskipp et al. 2016). River damming, disturbance, predation by dogs and egg collecting are highlighted as causes of the species’s disappearance from Cambodia (Goes et al. 2010). In India, the species faces many threats, which include, in addition to those already listed, water extraction, sand and gravel extraction for development, disturbance and predation by cats, dogs and corvids, such as House Crows Corvus splendens, which are attracted to human settlements, pollution from industry and agriculture, and mortality through fisheries bycatch (A. Rahmani in litt. 2010, S. Mahood in litt. 2012).

Conservation actions

Conservation Actions Underway
It is known from a number of protected areas throughout its range, including Bhitarkanika National Park, Satkosia Tiger Reserve, Harike Wildlife Sanctuary, Keoladeo National Park, Rajiv Gandhi National Park, Dibru-Saikhowa National Park, Kaziranga National Park, Koshi Tappu Wildlife Reserve and Chitwan National Park.

Conservation Actions Proposed
Organise a population census in Pakistan, India, Bangladesh and Nepal during the breeding season, and conduct further surveys in Myanmar to clarify its current distribution and status. Monitor population trends through regular surveys across its range. Carry out awareness-raising activities to alleviate human pressures on riverine ecosystems. Campaign for increased representation of large waterways in protected-area systems.

Identification

33 cm. Small tern. Breeding adults have orange bill, black cap and nape, dark grey breast and blackish belly and vent. Non-breeding birds show a whitish belly and lack tail streamers and the orange bill has a dark tip. Similar spp Told from other terns by smaller size and orange bill. Voice A clear piping peuo.

Acknowledgements

Text account compilers
Taylor, J., Westrip, J., Benstead, P., Martin, R, Butchart, S., Mahood, S.

Contributors
Davidson, P., Htin Hla, T., Inskipp, C., Duckworth, W., Praveen, J., Sundar, G., Li, Z., Rahmani, A., Rafeek, K., Mahood, S., Palei, H., Singh, A., Khan, A., Baral, H., Timmins, R.J., Thompson, P., Parveen, A., Eames, J.C., Cuthbert, F., Poole, C., Yasmeen, R.


Recommended citation
BirdLife International (2017) Species factsheet: Sterna acuticauda. Downloaded from http://www.birdlife.org on 17/12/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/12/2017.