Nature's lawn mowers. Years ago we moved into a house and I hated the landscaping. My two dogs dug around all the trees and plants for me. When I replanted, I did have to wire off the area.
My backyard is all sand, thankfully because I am renting and I'm sure the rabbits would ruin any lawn or garden if there were one! Plus it's fantastic for them to dig in because they can't ruin anything!