The pygmy swiftlet (Collocalia troglodytes ) is a species of swift in the family Apodidae. It is endemic to the Philippines.
Its natural habitat is subtropical or tropical moist lowland forests. At under 9 cm (3.5 in), it is the world's smallest swift. It weighs only 5 grams.
Swiftlets that nest in complete darkness in caves can use echolocation, the ability to position an object by reflected sound, used by other animals such as dolphins and bats.
