I have a large fenced in area for my rabbits to play in. I used to have problems with them digging tunnels. I cut down some tree branches, and they enjoyed exploring the branches and chewing on the bark. They also quit digging tunnels. When I left the branches in the same place, after a few weeks they started digging again. When I move the branches around every week to create different patterns on the ground, they don\'t dig tunnels. So I guess the trick is, if you don\'t want your rabbits to dig tunnels, change their exercise area often. If someone else wants to try this, I would be interested in knowing what kind of results you get. Thanks.
Any time a rabbit has access to the ground, their natural instinct is to dig. In a large area, their instincts tell them that to avoid hawks and other predators, dig a hole into the ground and hide. There is nothing you can do to prevent digging except to put wire down in the area to prevent them from digging out or something else from digging in. We have had good luck distracting them from digging by putting large diameter plastic or ceramic type plumbing pipes in the yard so they can crawl in to feel safe. Please consider the safety of your rabbits while they are playing in the yard. Here where we live, it only takes a split second for a hawk or eagle to swoop in and grab them or for the feral dogs or coyotes to jump the fence. We NEVER leave them unattended.
Covered dog kennels can solve a lot of those problems. Covered runs are also not a bad idea. I leave my rabbits in the garden with lots of overhead cover for four hours each day and all day on week-ends and they haven\'t dug tunnels for months!
A correction to my reply, they do dig little depressions to lay in when it is hot like dogs do, but no warrens. I also provide them with cardboard concrete forms to run through. I read somewhere that if you let a rabbit run loose in a fenced in yard, sooner or later the rabbit will dig warrens. I wondered why it took so long for the rabbit to dig? I figured that maybe the rabbit needs to learn the layout of the yard before he decides where to put his warren. So if you keep changing the layout, will that prevent the rabbit from digging? So far it has worked with my rabbits! If you get a chance, test out my theory and see if it works for your rabbits and let me know.