I am not sure exactly what you are asking. The Red-Sided Garter Thamnophis sirtalis parietalis has a wide distribution. It ranges from N Texas up into Canada and as far west as Montana. It is not found in Michigan. There are three members of the genus Thamnophis found in Michigan. These are the Eastern Garter T sirtalis sirtalis, Butler's Garter T butleri and the N Ribbon Snake T sauritus septentrionalis. The Eastern is a close relative of the Red-Sided (same species) and this is probably what you are seeing. Easterns can be geographically variable in their appearance going from drab in some areas to quite striking in others. They have red in some locations but I am not sure about Michigan. Easterns from southern Quebec can be erythristic (high amount of red). These are known as "Flame" Garters. This morph has been bred in captivity to emphasize this trait and they are quite beautiful. These might be the snakes that gave you the impression that "Red-Sided" Garters are only found in S Canada thus causing your confusion.
-----
Randy Hallman

[ Show Entire Thread ]