A very small, slender swift with long, narrow, sickle-shaped wings and very long deeply-forked tail, which, when folded, looks thin and pointed; dusky brown above, with paler rump; lighter below, esp. on throat; superficially similar in form and appearance to Crested Treeswift, but smaller, more slender, with darker underparts and browner upperparts; tail correspondingly shorter; Very gregarious; sometimes in mixed parties; mostly associated with palmyra and other palms; nests also in thatched roofs.