Sneaky things aren't they. I had one of my OEGB hens think up above our home under our spare goose house was a good place to nest can't even see under there let alone get anything out her being so tiny she managed to get under there well last year when she did it my husband jacked the house up and we got her and her 11 eggs out and I set her up inside the coop. This year my husband had a heart attack and hasn't been able to do much while recupping and something got up under there and killed her. Most likely a weasel or mink since the space is so tiny. I sure hope yours will be safe nesting under your shop.