The black-bellied tern (Sterna acuticauda) is a tern found near large rivers in the Indian subcontinent, its range extending from Pakistan, Nepal and India to Myanmar. It has become very scarce in the eastern part of its range and the International Union for Conservation of Nature has assessed its conservation status as being endangered.
The black-bellied tern grows to a length of 32 to 35 cm (13 to 14 in). In the breeding plumage, the crown and nape are black and the upper parts are pale grey. The throat is white and the breast pale grey, gradually darkening to a black belly. The wings are long, slender and pointed and the tail is deeply forked with sharply pointed tips. The bill and feet are yellow or orange and the iris is reddish brown.Outside the breeding season, the belly is whitish, the tail is reduced in length and the bill has a dark tip.