The nocturnal South American cave bird that is the only living species in the order Steatornithiformes is the oilbird.
The oilbird, Steatornis caripensis, lives in northern South America and on Trinidad. It nests in colonies inside caves and feeds mainly at night on oil-palm and tropical-laurel fruits. Unlike most nocturnal birds associated with nightjars, it is a specialist fruit-eater rather than an insect hunter.
Its cave life has produced remarkable adaptations. Oilbirds use high-pitched clicks for echolocation, an unusual ability among birds that helps them navigate in darkness. Their large eyes also support nighttime foraging. The name “oilbird” comes from the former practice of capturing and boiling young birds to extract their fat for oil.
Taxonomists once grouped the species with nightjars in Caprimulgiformes. Modern classifications recognize its distinctiveness by placing it in its own family, Steatornithidae, and order, Steatornithiformes. “Guácharo” is another widely used name, especially in Spanish-speaking regions.