Oilbirds, also called guácharos, are found throughout N South America and on the island of Trinidad. As much as 13 in. (33 cm) in body length, with wingspans up to 3 ft (91 cm), they are rich brown in color with black bars and scattered white spots. They have hooked beaks surrounded by stiff, whiskerlike hairs. The beaks are used to pluck fruit while the bird hovers in the air; it never perches. Oilbirds are also the only nocturnal, fruit-eating birds.
Oilbirds nest in large colonies on high, rocky cave ledges, often a good distance into the cave. The female lays two to four eggs per clutch, which hatch in about 33 days. The naked young are fed on rich, oily fruits and become grotesquely fat, reaching twice the adult weight at their maximum size. They lose this
baby fat when their feathers begin to grow in. In the past, baby oilbirds were captured, and their fat boiled down for torch oil, hence their name.
Oilbirds are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Caprimulgiformes, family Steatornithidae.
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