What is "s steatornis"

Guacharo \Gua*cha"ro\, n. [Cf. Sp. gu['a]charo sickly, dropsical, guacharaca a sort of bird.] (Zo["o]l.) A nocturnal bird of South America and Trinidad ( Steatornis Caripensis, or S. steatornis); -- called also oilbird.

Note: It resembles the goatsuckers and nighthawks, but feeds on fruits, and nests in caverns. A pure oil, used in place of butter, is extracted from the young by the natives.