While there are several subspecies of Canada geese in North America, only the giant Canada goose (Branta canadensis maxima), the largest subspecies, is known to breed in Illinois. The 2007 spring population estimate of giant Canada geese in Illinois was approximately 105,000. Additionally, geese from other subspecies and breeding populations from as far north as Hudson Bay, Canada pass through during migration or spend the winter in our state. The presence of these Canada geese can add greatly to the numbers of geese in Illinois during these time periods. Contrary to popular belief, while giant Canada geese make shorter and less frequent migrations than other subspecies, they do migrate as the severity of winter weather dictates.