There is always an urban legend about pet store escapees that then bred. Here in Los Angeles, we have our flock - it comes to visit my pet birds daily!

Do you have feral parrots where you live?

A town where I used to live, along the Thames just to the west of London proper, didn't have feral parrots, but had feral parakeets in large numbers. Various stories about their origins, probably the same urban legends as the LA parrots.