River Tern

The river tern is also known as the Indian river tern. It has dark gray upperparts; white or very pale gray underparts; a forked tail with long streamers; long pointed wings with pale gray primaries; a stout bill that is bright yellow during breeding and duller yellow with a dusky tip in non-breeding; bright red legs; a black cap in breeding extending below the eye, that lightens to grayish white flecked and streaked with black in non-breeding; a dark mask through the eye and the two longest outer tail feathers are also lost in non-breeding, giving it a shorter tail.  

River terns in breeding season in Ranthambore NP, India, Zone 3.

A breeding bird illustration from Birds of the World.

A non-breeding bird illustration from Birds of the World.

Range map from Birds of the World. 

It is found almost exclusively on freshwater, rarely venturing even to tidal creeks. It is found along inland rivers and lakes. We saw these in Ranthambore NP, Zone 3, on the edge of a small lake. There were only a few of them and they did not seem particularly active. They are listed as Vulnerable by the IUCN and is uncommon.