Cats are predators.
A few months after we had moved into this house (four years ago) Tiger had been in the attached garage... and when he came back inside he had a mouse in his mouth which he then dropped at Nancy's feet. She went to dispose of this poor dead mouse when it startled her by suddenly running away. She managed to catch it and toss it outside, much to Tiger's annoyance.
Ever since then he has liked to hunt in the garage, although he never again caught anything... until this year...
In late March he began finding mice. He would catch them in the garage and then bring them inside the house. When he put them down they would run and he would chase them. Sometimes a human would intervene and put the mouse out of the house and sometimes the mouse would escape, nowhere to be found until, suddenly, a few hours later, Tiger would go into hunting mode and start chasing the mouse around. Nancy had stored huge amounts of sunflower, etc. seeds in the garage to use in her bird feeder. She discovered the mice had been feasting on her birdseed. Apparently at some point mice (little field mice) got into the garage, found this sheltered and dry (relatively) warm environment with a wonderful food supply, and setup housekeeping. No wonder Tiger kept bugging us to let him into the garage.
In early April I was in Pittsburgh for a week. When I returned I was told there had been at least half a dozen mouse events during my absence. Nancy had bought a have-a-heart trap to try to capture any mice that might have come into the house (or been brought in by Tiger) but she never caught any. Then she moved the trap into the garage and found that although sometimes it had been triggered, she never caught a mouse. The frequency of mouse sightings dropped off and then for weeks we saw none. Tiger even seemed to lose some of his interest in being let into the garage.
When Nancy got home from work today she straightened and cleaned the garage... then we went out shopping. Upon our return the kids informed us that Tiger had caught another mouse and brought it into the house. This one, however, had been badly injured and Sean had put it out of its misery and disposed of the body. Later on Tiger, having been let back into the garage, returned with another mouse. He chased this one all around the living room until Sean captured it and took it outside. Apparently Nancy's garage cleaning had eliminated a lot of mouse hiding places and made it easier for Tiger to catch them.
This hunting activity has upset Jennifer. She was lecturing Tiger, telling him that it was not nice to hunt mice. I don't think she convinced him.
A predator is a predator.