The goose you see is not common to Canada but makes it's natural habitat in Asia. This one then either escaped from captivity or was 'dropped off' by someone who no longer wanted to care for it.
Bar-headed geese migrate over the Himalayas and spend their winters in India, Assam, Northern Burma and the wetlands of Pakistan. They are believed to be the highest flying bird having been seen at up to 10175 m (33,382 feet). The fact they have a slightly larger wing area for their weight than other geese may be the reason they are able to fly so high.