During the day these nocturnal gregarious birds rest on cave ledges. The nest is a heap of droppings, usually above water (either a stream or even in a sea-cave).
The YOUNG become very fat before fledging, weighing up to half again as much as the adult birds do. In times past the Amerindians of Venezuela harvested the almost-fledged young which were killed & rendered by boiling to yield oil for lamps & cooking. The generic name Steatornis translates as "fat bird" referring to the oil-rich squabs.

This image was taken within Dunstan grotto in the grounds of the Asa Wright Centre at a high ISO setting using an f4 500mm IS lens + tripod with light from the AWC guide's small hand-torch. I decided not to photoshop out the red eye as these birds are known locally in Trinidad as "Diablotin" (= "little devil").