The oilbirds (Steatornis caripensis), locally known as the guácharo, are birds found in the northern areas of South America (including the island of Trinidad in the Republic of Trinidad and Tobago). Nesting in colonies in caves, they are nocturnal feeders on the fruits of the oil palm and tropical 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.