I as my rabbits like lots of space I got them a three level hutch with a run at the bottom. All they do is sit on the top floor and sometimes go to the floor below which is where the litter tray is. It's such a waste as the next floor down is a run 3 feet square and a tunnel for them to run through. Any ideas to help encourage them to use it? There's not a bit for them to hide in. Do you think that would help to make them feel safer? Thanks!