Get a male outdoor cat and feed him just enough to keep him around. Cats lower the rodent population and occasionally get a snake too.
I saw a documentary on the wild Egyptian desert cats that are the forerunners of domestic cats, and they ate more snakes than rodents, vipers especially.
They showed this Morris-lookalike desert cat taking out a pit viper, and Morris just hung back out of the snake’s striking range, occaisonally lashing out with a paw smacking the snake’s head. After twenty minutes Morris was exhausted and the snake’s head was ribbons of bloody disjointed flesh...bit of a nap and he was watching the sun set enjoying snake sashimi.
#1, No cat can handle rats like a good dog can.
#2, Why on earth would I want snakes killed?