Mossy-nest swiftlet (Yến rêu, Aerodramus salangana) 

The mossy-nest swiftlet (Aerodramus salangana) is a species of swift in the family Apodidae.

As the name apodiforme—meaning "footless" in Greek—suggests, the legs of hummingbirds, swifts and treeswifts (or 'crested' swifts) are rather small and offer limited functional uses.
The family name, Apodidae, is derived from the Greek ἄπους (ápous), meaning "footless", a reference to the small, weak legs of these most aerial of birds.

The genus name combines the Ancient Greek aer meaning "air" with -dromos meaning "-racer" (from trekho "to run").
salangana: Possibly from Salangane was the name given by the inhabitants of the Philippines to a small type of swallow.