Many birds stay in the UK through the winter, an obvious example is the robin, this winter hasn't been very cold - but they seem to survive fairly well in sub-zero temperatures.
(I need to have a bit of fun with this one)....How did you know they were Canadian? Did they present their passports as the new rules require?
background to the joke:
There is a "Canada Goose" and there is a "Snow Goose" but I don't believe there is a "Canadian Snow Goose" unless it is a Snow Goose that is a citizen of Canada.
However, I agree that they can indeed be beautiful creatures regardless of citizenship.