Maybe a bigass snake in the shed would help. Or have a heart type live traps, I read that you like to eat strange things...
A snakes smell will run them off for a bit. That and the peanut butter and cement trick are good. No pollution or accidental innocent animals getting killed. You could put a little peanut butter on a board near the shed, with a bit of light. Then ambush them with your bb gun, all green beret vs vc style! I did that at a house that had big rats. I put the peanut butter on a little shelf stuck to the privacy fence. Every ten minutes or so, or tv commercial, and blast one if there was one. After a week the shed stunk cuz they went under the floor to die. A lot. And the hunting got poor, guess I thinned 'em out good. There was rat hair stuck in the fence around a few pellets that stuck after going through their ribcages. It amazed me that they would run off with a big hole in the chest! Im usually against killing animals but shooting rats does bring a sort of satisfaction that poison doesnt have.. And theyre disease ridden so you dont need to feel bad. Wally world has perfect bb guns for under $30. On with the ambush, snake, and peAnut butter. Kill'em all! And get a cat. Maybe a cat in the shed instead of a snake? Naahhh, I like snakes.