From Opus

Genus: Aerodramus, Swiftlets

[edit] Description

28 species of Swiftlets from Asia and the South Pacific. They have non or only slightly glossy plumage and some are capable of echolocation. Most breed in caves, sometimes in big colonies. The nests of several species are harvested for medicinal and culinary causes, leading to population decline. Some species live in very remote areas and virtually nothing is known about them.

[edit] Taxonomy

Aerodramus is a genus in the Family Apodidae.
Together with Hydrochous, Collocalia and Schoutedenapus this genus belongs to the subfamily Collocaliini. Some authorities still merge most or all Aerodramus species under Collocalia.
The relationships of the different Swiftlets are still poorly understood and can be called a taxonomist's nightmare. Further study is needed and will doubtless lead to new species, subspecies or lumping of some taxa.