In Germany, orinthologists have determined that birds imitate mobile phone ring tones. I'm very pleased to see this article, as I have noticed birds in my neighborhood imitating car alarms (you know the tune). Bird's songs are a great example of memes occurring outside the human race, and bird's ability to mimic human speech sounds is widely known already; it seemed completely logical that they would begin to imitate urban noises (albeit in a monophonic way, since birds can't sing chords) and incorporate these sounds into their song-vocabulary.
While my girlfriend scoffed at the thought, I insisted it was at least possible - and awfully coincidental that the birds picked up those sounds around the same time a neighbor of ours couldn't keep his car alarm (the ubiquious "song" of the city) from going off for an entire hour at a time. Some are helping to call attention to the similarities with a little clever editing, too.