What could be digging through the soil in a yard that has dirt covered with gravel? It's never near plants, usually near water, so I don't think it's gophers. The holes are too small for CA gophers anyway. I was thinking mice or a snake. I can't get anyone to pop out by running water down the hole.
What is the best way to get rid of them? I am losing a lot of expensive gravel down the holes.