My GF has two cats. Both are very interested in fast-moving toys, but one catches them, holds them, and then releases, waiting for them to start moving again. The other does anything and everything it takes to catch the toy and then immediately starts bunny kicking with her rear claws out doing her absolute damnedest to eviscerate the toy. She also spends her days slowly stalking up to the window chattering at the birds she so desperately wants to murder. Not sure how the first cat would do if he ever got outside, but she’d promptly decimate the bird and mouse population and declare herself god-emperor of what remains. That said, I think even she’d leave full-grown rats alone. Why risk it when there are so many easier targets out there?