Guácharo cave is well named. These birds also known as 'Oilbirds' nest in colonies underground in caves. Like bats they are nocturnal feeders and feed on fruit, oil palm and tropicla laurels. They are the only nocturnal flying fruit-eating birds in the world (the kakapo is flightless). They forage at night, with specially adapted eyesight. However they navigate by echolocation in the same way as bats, and are the only birds known to do so. They produce a high-pitched clicking sound of around 2 kHz that is audible to humans.