My two foster bunny boys have always used a litter tray and in the 18 months I have fostered them they have never done anything anywhere else. Then this past couple of months the litter tray is clean and they are doing all of it just inside the doorway where they hop in and out so it is really a mess. They have it on their paws and everywhere. I cannot understand why they are doing this. It happened overnight. One day they were using the tray and the next the doorway.The litter tray is spotless! They have ignored the litter tray and no matter what I do they will not go anywhere else. Any one have any suggestions? In all the foster buns I have had none have ever done this. Do I smack their bums and tell them they are naughty boys????