This bird has been recently recognized as a distinct species and added to the Sri Lankan endemic list. Sparrow sized and stockier than our other swallows, it is unmistakable with purple-blue glossed upperparts and rusty underparts and rump. Both sexes are alike. Young are duller.
The species is well distributed throughout the island up to about 1500 metres elevation. The birds associate in pairs or more often in scattered groups and spend their time flying after the insect prey they feed on. The usual habitat is open areas such as paddy fields, roadsides, grasslands, grass covered hillsides etc. The flight is typical swallow type with the wings being open and shut at the wrist joint. The birds flutter the wings rapidly and then glide gracefully before fluttering the wings again. The flight is however not as fast as the other swallows’. This species commonly associates with other swallows as well as swifts. They fly high as well as within a few feet from ground level. When not flying the birds sit in an open perch like a bare twig or power cable and preen themselves. The call is a pleasant muffled t’lee easily recognized when once heard. The birds also utter a loud twitter accompanied by a shuffling of wings.
The nest is made out of mud pellets and stuck to the underside of a disused flat roof, cave, bridge or culvert generally about three metres from ground level. It is a bottle gourd shaped structure with a long entrance on one side. The nest chamber is within the half dome and consists of feathers and fibre. Both sexes collect mud from the ground, mix with saliva and mould it to worm-cast like pellets and use these to build the nest. The two or three eggs are pure white in colour. The young continue to use the nest for roosting for sometime even after fully fledged. The adults too often use the same nest to breed again. The breeding season is generally from March to July but some birds nest again later in the year.