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Oilbird | Steatornis caripensis
Vetvogel | Guácharo
The Oilbird is the only member of its family and the only bird in the world that forages for fruit in flight at night. By day it roosts in colonies in dark caves, finding its way with audible clicks by echolocation. The name refers to the chicks, which on a diet of oily fruit become so fat that they were formerly collected to render oil. In the guide area it is a rare visitor to the montane forests of Costa Rica and Panama, with no known breeding colony.
Voice
At the cave a deafening chorus of harsh screams and shrieks, especially when disturbed. For orientation in the dark a series of rapid, dry clicks that are also audible to the human ear. Wandering birds in the guide area are mostly silent, but sometimes give clicks or a hoarse scream in flight.
Recording: Marcin Sołowiej — CC BY-NC-SA 4.0 · converted to mono · xeno-canto
Identification
40–49 cm. A slender, rufous-brown bird with long, narrow wings, a long, graduated tail and a strongly hooked bill with long bristles at the gape. The eyes are large and dark. The plumage is warm rufous-brown, with white spots on the crown, nape, wing coverts and tail. The underparts are paler cinnamon, with white, black-edged diamond-shaped spots that become larger from throat to belly. The legs are short and weak. The sexes are alike. In torchlight the eyes shine red.
Confusion species
Hardly confusable given its size, colour and habits. Nightjars such as Pauraque Nyctidromus albicollis and Short-tailed Nighthawk Lurocalis semitorquatus are smaller, have a tiny bill and hunt insects. Common Potoo Nyctibius griseus and Great Potoo Nyctibius grandis are mottled grey or grey-brown without white teardrop spots and have a short, broad bill. Owls such as Mottled Owl Strix virgata have a facial disc and a short tail.
Habitat
Breeds and roosts in caves and deep, shady gorges in forested hills and mountains. At night it flies, sometimes tens of kilometres, over forest to pluck fruit, especially of palms, laurels (Lauraceae) and incense trees (Burseraceae); the fruit is torn from the tree in flight and swallowed whole, and the seeds are later regurgitated. In the guide area recorded mainly in cloud forest and montane rainforest and in humid foothill forest where wild avocados and other laurels are in fruit; wandering birds roost by day in dense trees or in a rock crevice.
Where the bird is most at home, classified by the vegetation units of Mexico and Central America.
Range and movements
In Costa Rica recorded fairly regularly, especially since the early 2000s, mainly from July to September in the montane forests around Monteverde and the Cordillera de Tilarán, and more scattered in the Cordillera de Talamanca and on the Osa Peninsula. In Panama rare, with scattered records from Chiriquí and Bocas del Toro to Darién, and odd birds that turn up in and around Panama City. No breeding colony is known in the guide area; the birds probably come from South America. Outside the guide area from Colombia, Venezuela, Trinidad and the Guianas through Ecuador and Peru to Bolivia and Brazil.
- Resident
- Summer visitor (c. Apr–Sep)
- Passage (Mar–Apr, Oct–Nov)
- dark = core range, pale = thinly spread
How and when to look
The best chances are from July to September in the montane forests around Monteverde, at fruiting laurels along trails and forest edges. The birds can then be found on night walks with a torch by their red eyeshine; at a regular day roost they are sometimes seen on several consecutive days.
Conservation status
Not threatened. The world population is considered stable, but its dependence on a limited number of caves makes the species locally vulnerable to disturbance and the harvesting of colonies. In the guide area a rare, irregular visitor.
Scientific name
Steatornis caripensis | Humboldt, 1817
Humboldt described the species in 1817 and placed it straight away in the genus where it still stands. The genus Steatornis was introduced in 1814 by Humboldt. Steatornis is Greek, from stear, steatos 'fat' and ornis 'bird', after the fat nestlings once rendered down for oil. caripensis means 'from Caripe', after the Cueva del Guácharo near Caripe in Venezuela, where Humboldt found the bird. The specimen the first description was based on came from caves of Caripe, Venezuela.