This discussion was first published on Dec 1 2010 as part of the 2010-2011 Red List update.
Initial deadline for comments: 31 January 2012.
Black-bellied Tern Sterna acuticauda is listed as Near Threatened under criteria A2c; A3c; A4c, on the basis that it is inferred to be undergoing a continued decline of 20-29% over 27 years (estimate of three generations).
This decline is due to a number of threats including habitat destruction through conversion to agriculture, river flooding and flow impediment through damming, egg collecting, disturbance and depletion of food supplies through overfishing. The species is now considered probably extinct in Cambodia, with none recorded since the last breeding record in 2003 (Goes et al. 2010). River damming, disturbance, predation by dogs and egg collecting are highlighted as causes of the species’s disappearance from Cambodia (Goes et al. 2010). The species is also regarded as probably extinct in Vietnam, and likely extinct as a breeding species in Thailand. It has undergone severe declines in China, Myanmar and Laos, and while it seems more secure in India, Nepal and Bangladesh, declines have been noted in those countries as well (Sykes 2010). In India, the species faces many threats, which include, in addition to those already listed, water extraction, disturbance and predation by cats, dogs and corvids attracted to human settlements, pollution from industry and agriculture, and mortality through fisheries bycatch (A. Rahmani in litt. 2010).
The widespread declines and ongoing threats raise the question of whether the currently inferred rate of global population decline is correct. If the available evidence were to suggest an overall decline of at least 30% over 27 years, the species could be eligible for uplisting under the A criterion. Up-to-date information is requested on the likely trends in this species’s population at national, regional and global scales. It has been suggested that its total population now numbers fewer than 10,000 mature individuals, which seems unlikely given the species’s range size; however, if evidence were to suggest this, the species could qualify for uplisting under the C criterion, thus current estimates for the species’s population size would also help in the assessment of its Red List status.
Goes, F., Claassen, A. and Nielsen, H. (2010) Obituary to the black-bellied tern. Cambodian Journal of Natural History 1: 5-6.
Sykes, B. (2010) River terns: is the Black-bellied Tern Sterna acuticauda heading to oblivion? BirdingASIA 13: 73.