The Asian palm Swift (Cypsiurus balasiensis) is a bird that  you can see almost constantly in the Sri Lankan skies. They are a small fast flying bird that breeds in coconut palm trees by glueing nesting material under the leaves of the palms with saliva. In common with most, if not all swift species, most of their needs are catered for on the wing. They don't drink, getting all their moisture from their insect prey, they mate on the wing and sleep on the wing.  The only time that they perch is during the breeding season.