In the caves of Thailand's idyllic southern islands lies an unlikely treasure that people are willing to kill for -- the nest of a sparrowlike bird called the Swiftlet.
About a half-dozen companies, which have been granted concessions by local governments to gather Swiftlet nests for the lucrative bird's nest soup market, are protecting their caches with private armies that shoot at "unauthorized" visitors.
They've also been known to bribe authorities to look the other way, charge tourist operators protection money and keep locals suspected of being poachers from their traditional fishing grounds on the coast of the scenic Andaman Sea.
Swiftlet colonies are being depleted to supply Chinese restaurants with edible nests from glutinous globs of dried bird saliva that are cooked in a broth.
The soup is popular because it is believed to help growth, skin complexion and sex drive, prevent lung disease and stave off aging.
When a swiftlet's cup-shaped nest is taken before it can lay eggs, the bird is forced to build another one. In the caves, collectors shimmy up bamboo poles lashed together with liana vines. Death and injury from falls are not uncommon.
The Chinese began eating bird's nest soup about 1,500 years ago.
Today, millions of nests are sent to Chinese communities around the world. Hong Kong is the world's largest market, followed by the United States, mainland China and Taiwan.
Some call it "white gold," because a kilo (2.2 pounds) sells for almost $2, 000.
A bowl of bird's nest soup at a good Hong Kong restaurant can go for as much as $60.
Thailand exports about 19,800 pounds annually, which generates $23.8 million in taxes.