french dog 2

to the side of my shed is some newly dug soil, quite a nice pile actually that's great for seedlings, however I don't know what is doing it. It's not ants and there is a hole (I think) difficult to see but about six inches in diameter.. I have night cameras and have hedgehogs and foxes coming and going that get on fine along with the neighbours cat, but no idea what is causing the lovely pile of very fine earth like crumble topping. No sign of rats although I have seen the odd mouse. Any ideas?