Range map of the Edible-nest Swiftlet, adapted from HBW (2018).
8 current subspecies are recognized as shown below (with range and comparative descriptions):
Several authors believe that this species should be split into two. In that treatment, ssp amechanus and germani are named Germain’s Swiftlet, while the rest of the subspecies retain the name of Edible-nest Swiftlet. However, taxonomical evidence for splitting the species has been unconvincing to many, and this species page will treat the group as a single species under the Biological Species Concept (see Taxonomy section).
Differences amongst subspecies are often subtle and difficult to distinguish in the field due to variations in lighting as well as difficulty in observing constantly fast-moving subjects.
According to the subspecies range, Edible-nest Swiftlets observed in Singapore should be A. f. germani, but specimens collected appeared identical to the nominate race, likely because colonies in Malaysia and Singapore are of the house farmed variety (see House Farming below), which is suspected to be of Javan origin (ssp. fuciphagus). To complicate matters, their feeding ranges are not known and may overlap.
Edible-nest Swiftlets are aerial insectivores that catch arthropods on the wing. Diet analyses have been conducted by examining regurgitated food boluses; hymenoptera, diptera and ephemeroptera made up majority of the food items, while arachnida, coleoptera and hemiptera made up most of the rest.
Natural populations of the swiftlets nest in caves, such as the Niah and Gomantong caves in Borneo, and on the Andaman and Nicobar Islands in the Bay of Bengal. However, due to the practice of farming swiftlets in nest houses (see below), the Edible-nest swiftlets have adopted nesting in man-made buildings as early as the 1880s. (Lim & Cranbrook 2002).
Breeding has been observed to take place year-round but peak in October and February. (Nigel Langham 1979).
As Edible-nest Swiftlets nest in places which are completely dark, they have evolved the ability to echolocate using clicking sounds, along with many other species from the genus Aerodramus. This ability, however, is not diagnostic of the genus as the Pygmy Swiftlet (Collocalia troglodytes) has been proven to possess this ability too.
Sound recording of an Edible-nest Swiftlet's echolocating clicking calls. (Recorded by Lim Hong Yao, 2018)