I have used REAL duct tape to seal some of the holes and stuck steel wool to it. It has to be the real stuff or Gorilla tape or they chew right thru it.I don't know what the deal is,but I found where they had chewed thru the plastic container,storage box,that I store my bird food in and I just put masking tape over the hole and they ate right thru it. I then put a covering of cheapy duct tape over and once again,right thru it. I then bought a roll of the real real furnace duct tape and it's been good for about two years now.