Swiftlets farming and bird nest business

Swiftlets (http://en.wikipedia.org/wiki/Swiftlet) is a kind of bird that produce edible nest from its salive, as many people especially asean believe that bird's nest soup is nutritional and exortic, the price for its is high.
Due to its high price in the market, many entrepreneur in Indonesia, Malaysia and Thailand now are constructing concrete building with necessary sound system to attract the swiftlets to build their nest inside the building, this is called swiftlets farming and in recent year, this have become a very hot business.