Sorry that you had to experience that, I unfortunaely have witnessed many chipmunks, mice,birds being caught by my cats, never my greys though. I have bird feeders on the other side of my fence and the squirrels are on them all the time, Sara & Max see them on the feeders but can't get them, they charge the fence and bark but the squirrels fly from tree to tree. I had a cat door and they were bringing all their creatures in to show me and all of them were alive. I saved many birds and chipmunks last summer but paid the price when I got bit by a chipmunk and needed a series of rabie shots I still get upset when a little creature is killed RIP squirrel