灰腰金絲燕 Collocalia marginata

A small, common swiftlet found over a variety of habitats, even human habitation. Gray below with some dark speckling. Black above with blue gloss, a pale band on the rump with some streaks, and a square tail that is dark under the base. Similar to Pygmy Swiftlet, but Gray-rumped is slightly larger and has a less demarcated rump band. Paler below than Germain’s. Does not echolocate, so chooses well-lit nesting sites. Usually silent, but gives a throaty “churr” near nesting site.