Nature · Birds

Oilbird

Least Concern · northern South America and Trinidad

Steatornis caripensis — Steatornithidae

A nocturnal, cave-roosting, fruit-eating bird of northern South America and Trinidad, and the only bird in the world that both echolocates and lives entirely on fruit. Alexander von Humboldt described it in 1799 from the Caripe cave in Venezuela; its name records the practice of boiling down the fat nestlings for oil. It navigates in total darkness by clicking at rates of about 250 a second, and finds fruit by smell.

How to spot them

▸Rich reddish-brown plumage spangled with white spots edged black, and a strongly hooked pale bill with long rictal bristles
▸Long wings and a long graduated tail; it hovers and flutters at fruiting palms
▸Enormous dark eyes with a highly reflective retina — eyeshine in a torch beam
▸Colonial in caves and dark gorges; the noise is a deafening mixture of screams, snarls and clicking
▸Audible clicking used as sonar, unlike bats' ultrasound, so a human can hear it

How to know it

The only bird that both echolocates and eats nothing but fruit, clicking audibly at about 250 clicks a second

Oilbird — cave swiftlets echolocate but eat insects.

Humboldt described it in 1799 from a cave in eastern Venezuela, and the specific name records that place

Steatornis caripensis, the oilbird — the 'fatbird of Caripe'.

Its English name records the boiling down of fat nestlings by local people for a clear, odourless oil

Oilbird — nestlings can outweigh their parents.

A nocturnal bird that finds palm and laurel fruit by smell and plucks it while hovering

Oilbird.

Roosts by day in caves and dark gorges, and is the only living member of its family

Oilbird — Steatornithidae.

Trinidad's Asa Wright Nature Centre protects the world's most accessible colony, in Dunston Cave

Oilbird; the Cueva del Guacharo in Venezuela is the type locality.

Quick-fire facts

•Length 40–49 cm, wingspan about 95 cm; the Spanish name guacharo means 'one who cries or moans'
•IUCN Red List: Least Concern, though colonies are vulnerable to disturbance and harvest
•Humboldt visited the Caripe cave in 1799 and formally described the bird as Steatornis caripensis, 'fatbird of Caripe'
•Venezuela's Cueva del Guacharo, the type locality, was made the country's first natural monument in 1949
•Nestlings become extremely fat, reaching up to about 1.5 times adult weight before fledging, which is why they were harvested for oil
•It echolocates with audible clicks at around 2 kHz, and has the highest density of rod cells recorded in any vertebrate eye
•It is a major disperser of palm and laurel seeds, carrying them tens of kilometres from the parent trees
•It is placed in the Caprimulgiformes with the nightjars, frogmouths and potoos, or in its own order Steatornithiformes
•It may forage 100 km or more from its roost cave in a night

Drill it — 8 cards

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Sources

Audubon — The Oilbird