I have no poisonous snakes in my region, and I try to let the garden snakes be. They're small compared to the snakes you guys deal with and certainly not dangerous.
However, if some kind of climate shift forces the poisonous snakes closer... well, I'd kill a coyote if he came sniffing around the chicken coop and I'd kill a viper if he came sniffing around my house. Or the coop.