A Thai collector of bird's nests holds a prize specimen after a day's climbing in Payanak cave on the island of Koh Phi Phi Lae. The most sought-after nests, like this, are made entirely of secretions from the saliva gland of the brown-rumped, or edible-nest swiftlet, which nest high on cave walls, normally between 200 and 500 feet. The nests are highly regarded in Chinese cuisine, although almost tasteless, and can be cooked in several ways, but most typically as bird's nest soup..