The first time we put a collar on Shadow he "lost" it. Under the futon. So we put it back on. Whereupon he took himself outside and lost the collar more thoroughly. So we replaced it. He spent a happy evening under the futon very carefully removing the bell and making sure that it was in no fit state to be re-attached to the collar. Several years later he's still wearing the collar and we seem to have come to an agreement about not bringing prey into the house.

That said, Kheldar managed to catch a fine specimen of a pigeon whilst wearing a bell. I think we've also come to an agreement about not bringing prey into the house, although that could just be because swallows his whole and there's nothing left to bring in...