Work of a vandal

Today I discovered that a bag of fat balls on the floor of the shed had been opened and more than half of the contents removed and scattered over the floor of the shed.  Further investigation revealed a stash of hazelnut shells, then a nest in the middle of the bag for the leaf vacuum. I don't know if this was a single mouse, or a pair.  I've stopped up the hole they were using to get in.  I rather like having them in the garden and under the shed, but I was not too pleased with the mess and destruction inside the shed.