The adults have very long, flexible tail streamers and orange-red legs.

This idea was tested in 1994 in barn swallows, a species where males have long tail streamers.

They are gull-sized birds have white plumage and long tail streamers.

The adult male of this species is about 17 cm long, but the long tail streamers nearly double the birds length.

The female is duller and lacks the tail streamers.

Females have shorter, thicker tail streamers than males, but the sexes are otherwise similar.

It can be distinguished from Mosque Swallow by the slightly smaller size and longer tail streamers.

It also lacks the long tail streamers of the adult.

It retains the long tail streamers, and has a black bill.

Juveniles lack the tail streamers, are greyer-backed, and have a yellow bill.