oilbird

Nocturnal fruit-eating bird related to the nightjar, genus Steatornis caripensis, family Steatornithidae, order Caprimulgiformes. It is crow-sized and lives chiefly in caverns near the sea, in South America and Trinidad.

The oilbird produces a series of high-pitched pulses of about 6-10 KHz, not unlike those of bats. The sounds maybe the outgoing part of a system of echolocation, the detection of objects by the echoes reflected back from them. The pulses are uttered in the caves, but not outside, even at night.