We keep our pet rabbit, Keekum, in a cage that we bought used more than 20 years ago for our first pet rabbit. Although it has served three pet rabbits well, the wood is starting to weaken. So when my DH first showed me this hole in the back of the cage, I thought someone had punched a hole through the wood. On closer examination I could see that Keekum has been chewing on this board.
I am not sure if he is trying to ventilate the back room where his litter box is kept or planning an escape. Either way I think we had better get a patch on it soon because I don't think he would know what to do if he met a predator in the night. He knows he is at the bottom of the food chain. When threaten he totally surrenders.