I used to have cats that brought the offerings up to the sliding glass door. Yes, I have had a "sacrifice" brought inside before too. I talked to the vet about it and he grinned and told me that they were contributing to the pride. He said to hang a bell around their neck and it would help. But they were indoor/outdoor cats, and the flip side of that coin is that it would be cruel to put an alarm around their neck in the event that they were in the position of being the prey. They were just acting on the nature of their instincts. If you're going to own animals, unless you keep them inside all the time, they are going to do what nature has designed them to do. I did have a Maine Coon who used to make the neighbor mad. He would sit on top of her bird house and wait for a bird to come out.