We thought so too, last year, but we've now seen them through two winters and found others living at the far south of our island. I doubt they could get back to wherever they've come from since we're a long way from anywhere. We just heard a story about someone buying a whole crate of them to release at a friend's wedding. That didn't surprise us, knowing the guy. At least they're not aggressive, and despite being quite large, they seem to share at the birdfeeder without problem. We find them beautiful, but they definitely do not belong here.