Current view: Data table and detailed info
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. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
IUCN Red List criteria met and history
Red List criteria met
Red List history
| Migratory status |
not a migrant |
Forest dependency |
does not normally occur in forest |
| Land-mass type |
continent
|
Average mass |
- |
Population justification: The global population of this species has declined drastically in recent decades such that previous estimates are thought to have considerably overestimated the population. The vast majority (>90%) of the population is now confined to India where, collating more than 1,400 records (eBird 2021) of the species between 2016 and 2020, and attributing maximum likely counts to critical sites, the population in India is estimated to number no more than 1,000 mature individuals with critical strongholds (containing more than 30 birds) being: the National Chambal Sanctuary, Madhya Pradesh, Uttar Pradesh and Rajasthan Morena (150 individuals); Yamuna Khadar, Delhi (44 individuals); River Godavari, Andhra Pradesh (approximately 25 individuals), Walayar Lake, Coimbatore, Tamil Nadu (35 individuals); Talab Shahi, Dhaulpur (30 individuals); Haiderpur and Narora on River Ganga (likely to be more than 30) and River Mahanadi, Odisha (likely more than 40) [P. Shaikh in litt. 2021]. The true population estimate may be substantially fewer than 1,000 mature individuals and determining an accurate estimate is a priority for future research. Populations in Nepal and Pakistan are very small and unlikely to host more than 20 and 50 birds each respectively (Inskipp et al. 2016, P. Shaikh in litt. 2021, eBird 2021). In Bangladesh, the population is also now estimated to be tiny. Despite being formerly common, extensive surveys in December 2011 and April 2012 of suitable habitat along the Jamuna and Padma rivers (199 km and 103 km were surveyed of the Jamuna and Padma respectively) failed to detect the species at all (Chowdhury et al. 2014). Six birds in breeding plumage were later sighted on a previously un-surveyed section of the Padma River in 2016, and two nests were found later that year (Kabir et al. 2016). Even accounting for the now-limited areas that have not been surveyed, the population is estimated to number no more than 30 individuals (S. Chowdhury in litt. 2021).
The population and range of this species has undergone a drastic decline in South-East Asia. The species is now regarded as extinct in Cambodia (Thomas and Poole 2003, Goes et al. 2010, Goes 2014), China (P. Holt in litt. 2021), Laos (Duckworth et al. 1999), Thailand (Treesucon and Limparungpatthanakij 2018) and Vietnam (Le et al. 2011, Craik and Le 2018). If any population does in fact persist in any of these countries, it must be extremely small. In Myanmar, extensive annual surveys along a 500-km stretch of the middle reaches of the Ayeyarwady river in 2017-2019 recorded just 3-5 birds (Zockler et al. 2020), representing a likely steep decline since 2001-2003, when 13 birds were found along a single stretch of river (Davies et al. 2004). This most-recent survey encompassed the vast majority of the species's former range in the country, such that it is estimated to contemporarily number no more than 30 birds. Overall, and acknowledging some uncertainty, the global population is estimated to number 800-1,600 mature individuals, with a best estimate in the range of 900-1,100. This species is capable of long-distance dispersal (see, e.g., Jansen 2005) such that the populations in Pakistan, India, Nepal and Bangladesh are likely to comprise a single subpopulation with some gene flow between them. This may be true also of the Myanmar population (comprising 1.3-2.5% of the global estimate), however it is rather disjunct and separated from north-east India by unsuitable habitat, so may constitute a separate subpopulation.
Trend justification: The species is inferred to be declining, although an exact rate has not been determined. This species had a range that formerly spanned from Pakistan through South Asia to Indochina, however is now principally confined to India, where >90% of the population resides. Despite being locally abundant in South-East Asia historically, it is now considered extinct there except for a few pairs in Myanmar (Zockler et al. 2020). With such a catastrophic range contraction, the species is inferred to have declined rapidly. Such declines continue: the species is no longer present at numerous sites in India it bred even a decade ago (eBird 2021, P. Shaikh in litt. 2021). Limited data from Myanmar suggest it also continues to decline: extensive surveys along a 500-km stretch of the middle reaches of the Ayeyarwady river (including all formerly surveyed areas for this species) in 2017-2019 recorded just 3-5 birds (Zockler et al. 2020), representing a likely steep decline since 2001-2003, when 13 birds were found along a single stretch of river (Davies et al. 2004). In Bangladesh, a count of 98 birds was made at Sirajganj in 1995; the species is now apparently extinct in this area (Chowdhury et al. 2014). The threats affecting this species are not abating and may be getting worse, with worryingly low breeding productivity now recorded at the species' stronghold, Chambal, in India (P. Shaikh in litt. 2021).
Country/territory distribution
Important Bird and Biodiversity Areas (IBA)
Recommended citation
BirdLife International (2024) Species factsheet: Black-bellied Tern Sterna acuticauda. Downloaded from
https://datazone.birdlife.org/species/factsheet/black-bellied-tern-sterna-acuticauda on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.
