TreeHugger has this really amusing article about escaped pet parrots teaching what they've learnt while in captivity to their wild counterparts.

From the article:

Across parts of Australia, reports have been pouring in of strange voices chattering high in the treetops -- mysterious, non-sensical conversations in English. But while this phenomenon is certainly quite odd, its explanation isn't paranormal. It turns out that escaped pet birds, namely parrots and cockatoos, have begun teaching their wild bird counterparts a bit of the language they picked up from their time in captivity -- and, according to witnesses, that includes more than a few expletives.