加拿大雁
The distinctions between the two geese have led to a great deal of confusion and debate among ornithologists. This has been aggravated by the overlap between the small types of Canada goose and larger types of cackling goose. The old "lesser Canada geese" were believed to be a partly hybrid population, with the birds named "taverneri" considered a mixture of "minima" with subspecies "occidentalis" and "parvipes", which today remain with the Canada goose proper. Actually however, "taverneri" is one of the larger subspecies of cackling geese. In addition, it has been determined that the barnacle goose ("B. leucopsis") is a derivative of the cackling goose lineage, whereas the Hawaiian goose ("B. sandvicensis") is an insular representative of the Canada goose.