A swiftlet resting on the ground near the entrance of the Gomantong Cave in Borneo, Malaysia. The Black-nest Swiftlet is the commonest swiflet in limestone areas of Borneo, but it is indistinguishable from three other species, including the Edible-nest Swiflet, whose white nest is made entirely of hardened saliva and is collected to make birds'nest soup. Black nests, composed of white saliva mixed with feathers, are also harvested but are of less value.

MacKinnon J, Phillips J (1999): A Field Guide to the Birds of Borneo, Sumatra, Java and Bali, Oxford Univ Press, 491 p.