Oilbird Steatornis caripensis Scientific name definitions

While many bird species can be described as "unique" in various measures, the Oilbird is truly exceptional. It is the only volant, nocturnal, frugivorous bird in the world and the sole extant representative of Steatornithidae, a family endemic to the Neotropics, currently classified under Caprimulgiformes.

The Oilbird inhabits evergreen lowland and montane forests from sea level to over 3,000 meters, ranging from northern Venezuela and Trinidad south to Bolivia. It breeds and roosts colonially in caves, sometimes in groups of nearly 10,000 individuals, such as those at Cueva de los Guácharos National Park in Venezuela. Foraging at night, the Oilbird may travel tens of kilometers, sometimes up to 120 km from its home cave, guided by its keen sense of smell. Its diet consists exclusively of oil-rich fruit pulp from plants in three families: Lauraceae, Arecaceae, and Burseraceae. This dietary specialization highlights its crucial role as a seed disperser.

Unlike many nocturnal animals, the Oilbird experiences darkness both at night while foraging and during the day in the near-total blackness of its cave. To navigate, it relies on both vision and echolocation. Its retina has the highest rod density recorded in any vertebrate, with one million rods per millimeter, allowing it to absorb as much light as possible. It echolocates via a series of audible clicks, with each bird in a group clicking at slightly different frequencies.

The Oilbird is a socially monogamous, seasonal breeder that appears to form permanent pair bonds. It lays 2–4 white eggs per clutch and has a lengthy incubation and nestling period, resulting in a complete nesting cycle of about 150 days. Nestlings become exceedingly fat on their diet of rich fruit pulp, at peak mass weighing up to 57% more than an adult. The first Western naturalist to encounter the species, Alexander von Humboldt, described how local indigenous people boiled plump nestlings to extract their oil for cooking and lamps, giving rise to the generic name Steatornis, referring to the fat (Greek stear or steatos) deposits of nestlings.

In some locations, such as Cueva del Guácharo in Caripe, Venezuela, and Dunstan’s Cave at Asa Wright Nature Centre, Trinidad, the Oilbird is a significant ecotourism attraction. Despite its potential economic value, the species' specialized diet and extensive home range make it particularly vulnerable to deforestation. Currently, it is considered Least Concern under IUCN Red List criteria, although there are indications of declines across its range. Fortunately, despite its conspicuously noisy caves, many undiscovered colonies likely exist due to the species' covert nocturnal habits and its remote and inaccessible roost preferences. More accurate population assessments, especially in lesser-known regions, could yield valuable insights into population trends, reproductive success rates, mortality factors, and other measures important to the long-term success of this unique species.