An idea most people wouldn't like would be relocating a native snake, such as a Cali King, or Gopher snake to your shed. I am trying to convince my parents to introduce a couple Black King snakes to our barn for pest control. King snakes are wonderful creatures, and the ones you find in California are gorgeous. Not aggressive. Not venomous. Can reach places the cats can't. And they are very good eaters. They are perfectly harmless. Gopher snakes are relatives to some of my FAVORITE snakes. They too are not aggressive or venomous and perfectly harmless, unless you are a mouse.