Bird's nest, a delicacy made from the thick, sticky saliva of a swift, is estimated to fund a $450m a year industry across Asia.

Now, criminals in Malaysia are capitalising on demand, converting homes and office buildings into birdhouses to harvest the dried strands that are prized for their supposed healing properties.

As Al Jazeera's Gerald Tan reports from the state of Penang, the illegal operators risk turning the population against the entire industry.

Source: Al Jazeera