Mice! I've caught 7 in the little GH since late Oct. There's been a lull over the past two weeks though. I have what I think is a shrew - dark gray body - as opposed to a vole - brownish body? - living in the rocks under my patio water feature. Of course it's right next to my portable cold frame. I sprinkled castor oil granules around my cold frame just in case although it probably won't work on shrews.