My two bunnies have a house up against a wall outside with an enclosed fence around it. They also get full run of the yard sometimes. Anyway, they have been excavating a winter warren underneath their house. It must be getting really deep, because they have been moving a lot of dirt.
This is really fun to watch! They actually push the dirt up out of the hole, and then spread it around with their faces and front feet. They actually have a few graded roads that they have made. I’ll have to take a picture and post it here. You wouldn’t believe it unless you see it. It looks like a planned construction site.