A charming story (by Sarah Andrews of AP) about a language of whistles:
Juan Cabello takes pride in not using a cell phone or the Internet to communicate. Instead, he puckers up and whistles.
Cabello is a “silbador,” until recently a dying breed on tiny, mountainous La Gomera, one of Spain’s Canary Islands off West Africa. Like his father and grandfather before him, Cabello, 50, knows “Silbo Gomero,” a language that’s whistled, not spoken, and can be heard more than two miles away.
This chirpy brand of chatter is thought to have come over with early African settlers 2,500 years ago. Now, educators are working hard to save it from extinction by making schoolchildren study it up to age 14.
Silbo — the word comes from Spanish verb silbar, meaning to whistle — features four “vowels” and four “consonants” that can be strung together to form more than 4,000 words. It sounds just like bird conversation and Cabello says it has plenty of uses.
“I use it for everything: to call to my wife, to tell my kids something, to find a friend if we get lost in a crowd,” Cabello said.
In fact, he makes a living off Silbo, performing daily exhibitions at a restaurant on this island of 147 square miles and 19,000 people.
The story includes a link to an mp3 file of a whistled conversation.
Update. You can now (Aug. 2007) see a video describing the island of Gomera entirely in Silbo (!) at this page. Thanks, Jeremy!
Further update. See also this 2011 LH post.