The oilbird (Steatornis caripensis), locally known as the guácharo, is a bird species found in the northern areas of South America including the Caribbean island of Trinidad. It is the only living species in the genus Steatornis, the family Steatornithidae, and the order Steatornithiformes. Nesting in colonies in caves, oilbirds 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 kākāpō, also nocturnal, is flightless). They forage at night, with specially adapted eyesight. However, they navigate by echolocation in the same way as bats, one of the few birds to do so. They produce a high-pitched clicking sound of around 2 kHz that is audible to humans.
Taxonomy
Oilbirds are related to the nightjars, both being in Strisores, and were previously placed alongside nightjars in the order Caprimulgiformes. However, the nightjars and their relatives are insectivores while the oilbird is a specialist frugivore, and it is now deemed sufficiently distinctive to be placed in its own order Steatornithiformes, suborder Steatornithes, and family Steatornithidae.
The fossil record of the family suggests that they were once more widely distributed around the globe. The first fossil oilbird was described by Storrs Olson in 1987 from a fossil found in the Green River Formation in Wyoming. The species, Prefica nivea, was probably not adapted to hovering flight or living in caves, unlike the oilbird. Some of the same families and genera of plants the present day oilbird feeds on have been found in the Green River Formation, suggesting that prehistoric species may have eaten the same fruit and spread the same seeds. Another species from the Upper Eocene has been discovered in France.
Etymology
The specific name caripensis means "of Caripe", the town in Venezuela in which they were scientifically classified in 1799, and the generic name Steatornis means "fat bird", in reference to the...
