A unique dark swallow of lowland rainforest, less commonly seen at forest edge and in montane foothills. The only swallow that can be found flying bat-like under the canopy in closed forest. Overall a dark sooty brown, with some birds, especially adult males, having brighter rufous throats. Small and compact with a short, mostly squared tail. Often found nesting under boulders, in caves, or in similar locations in the rainforest. Very similar to Square-tailed Sawwing, and some individuals are best left unidentified. Note Forest Swallow’s unique, bat-like flight, and in good light, its more brownish plumage and sometimes more rufous throat. Despite its visual similarity to sawwings, this species is most closely related to house-martins. Voice is a short, buzzy call note.