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Which swiftlets can navigate in dark caves by echolocation?

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Illustration of a chestnut-collared swift (Cypseloides rutilus) in flight, showing its dark brown body and wings with a distinctive reddish-brown collar around its neck. — Apodiform Chestnut-collared swift (*Cypseloides rutilus*)

Certain species of swiftlets belonging to the genus Collocalia possess the ability to navigate in dark caves using echolocation.123

While many swiftlets nest in caves, this specific capability is found in those species that nest in total darkness deep within caverns. Conversely, some species of swiftlets lack this ability and are restricted to nesting only in areas of caves where some light can penetrate.3

The echolocation used by these birds consists of a series of audible clicking sounds, typically emitted at a rate of about six per second, which allow them to orient themselves and avoid obstacles in the absence of light. Aside from these swiftlets, the only other bird known to utilize echolocation is the oilbird (Steatornis caripensis).132