I have a (my guess) one and half year old Dwarf rabbit. We have a completely secure courtyard she runs free in with lots of grass flowers and plants, plus her off ground cage stays open for her to jump in when ever she wants. About six months ago she dug a hole so far we can't see the end. She never really went in it to stay just played around it all the time. Two weeks ago she covered it and has nothing to do with it. Really weird? Today she was back at it, opened it up went in checked it out then she covered it up again?? I have never seen anything like it. She's super friendly, runs up to us when we come out side, loves kids. But I don't know why she covers it up. No animals bother her. We have a small dog who she can care less about. I just find it interesting...any input? I guess I'm worried something is scaring her so she's protecting it? Or just normal?
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Her behavior over her tunnel is indicative of an invader/intruder. Even though your courtyard is secured, small pests can always find their way in. I strongly discourage rabbits having the ability to dig freely because of this reason.
While you might keep out larger predators like coyote or wolves #depending on where you live#, its nearly impossible to keep out other dangers.
Small snakes, spiders #some poisonous#, bees, mice/moles, and even wild rabbits can enter her tunnel. If a wild rabbit from outside the courtyard smells her, that rabbit can dig a tunnel starting quite a distance away and dig underground until he intercepts and enters her tunnel. If that happens, the wild rabbit will kill your domestic bunny almost immediately. Other things such as weasels, shrews, badgers, chipmunk, etc. all have the ability to start a tunnel from the other side and enter your rabbits tunnel.
Her behavior indicates that something foreign was in her tunnel, so she covered it to block whatever it was out. She waited what in her mind was long enough for the intruder to be gone and redug the tunnel and must have come across it, or a different predator, so she reburied it again.
The other thing to remember is that domestic rabbits can easily dig a tunnel of 30 feet deep and over 100 feet long in just a few hours so she might start in the courtyard and end up outside somewhere. If she surfaces in an unenclosed area, she's an easy target for a hawk or crow.
If you are really set on letting her dig, then you should remove about 3 feet of soil from her area, lay down a roll of fencing, then put the dirt back over the fence. This way she can dig a bit, but after a few feet she will hit the fence so there's no risk of her getting out. You'll need to use a fine mesh fence - 1/2" x 1/2" holes at the most to keep out shrews and moles.
Also, monitor her food and food storage area extremely close. Mice are highly attracted to the smell of rabbit food #they love it#. However, mouse droppings #poop# is poisonous to rabbits. If a mouse sits in her food dish #at night - they are nocturnal# and leaves a few droppings behind and your rabbit then eats the food, she will die from it, so monitor carefully. I actually found a litter of newborn mice IN the same nestbox as the litter of baby rabbits my doe was nursing. The mouse must have entered, found the nice warm nest and had the litter. Amazingly the doe was nursing the mice babies. Because of the dangers I removed them - but it was awfully cute to see :)
I hope this helps. Please let me know if you have any follow up questions.