Only venomous snake in this part of Wyoming is Crotalus veridis, prairie rattler. Down on the Colorado/Utah border there is a Crotalus concolor, faded midget rattler. What I've seen in our yard are brown garter snakes and bull snakes. Seen more of those already this year than I've seen in the last two or three years. But we haven't seen any field mice in the yard or garage this year!Oh, the poor thing. I take it you don't have a lot of poisonous snakes there?