Instinctively I think it must be, as hunting comes naturally to them. I don't like the many worms they bring into the house, but can live with it. I really don't like the mice they bring in, dead, alive or somewhere in between, but can live with it. BUT today we found a bird's head, just the head, in the hallway and I think I have reached my limit of tolerance. Would it be OK to put a bell on the cats' collars? Or does anyone have any other ideas please?