At least 11 subspecies of Canada Goose have been recognized, although only a couple are distinctive. In general, the geese get smaller as you move northward, and darker as you go westward. The four smallest forms are now considered a different species: the Cackling Goose.

Some migratory populations of the Canada Goose are not going as far south in the winter as they used to. This northward range shift has been attributed to changes in farm practices that makes waste grain more available in fall and winter, as well as changes in hunting pressure and changes in weather.

Individual Canada Geese from most populations make annual northward migrations after breeding. Nonbreeding geese, or those that lost nests early in the breeding season, may move anywhere from several kilometers to more than 1500 km northward. There they take advantage of vegetation in an earlier state of growth to fuel their molt. Even members of "resident" populations, which do not migrate southward in winter, will move north in late summer to molt.

The “giant” Canada Goose, Branta canadensis maxima, bred from central Manitoba to Kentucky but was nearly driven extinct in the early 1900s. Programs to reestablish the subspecies to its original range were in many places so successful that the geese have become a nuisance in many urban and suburban areas.

In a pattern biologists call “assortative mating,” birds of both sexes tend to choose mates of a similar size.

The oldest known wild Canada Goose was a female, and at least 33 years, 3 months old when she was shot in Ontario in 2001. She had been banded in Ohio in 1969.