(Chemistry professor Joe Schwarcz)
"Here's a question for you. What is the prime use for birds' nests in China? The answer? For birds to lay their eggs in! Did I get you with that one? Did you say bird's nest soup? Well, that certainly is the second most popular use of birds' nests. Believe it or not, some 200 tons of nests are consumed in the world every year, with Hong Kong diners leading the way.
We're not talking any old bird's nest here. These are very special nests constructed by several different species of swiftlets, birds about the size of swallows, found mostly in Thailand, Vietnam, Indonesia, Borneo and the Philippines. The male builds the nest over about 35 days, using, I kid you not, his saliva! No twigs, no leaves, just the sticky material secreted from the bird's two sublingual salivary glands."