Aahhh..I think I know where the Northern came from. When the GTF were tads in the pool we had a snake in there too. When I looked it up it was a Northern Water Snake. The site said it feeds on tads, I have since caught and released into the lake across the street. It was around this time, my parents tell me, that I began calling the green frogs, northern green frogs. Mystery solved and correction noted : ).