So, Sid likes to catch mice. Odd thing though, (a little bit amusing): when we are awake, downstairs, Sid grabs her prey and quickly runs to another room to play with it. She actively keeps it way from us.
At night, when we're in bed, she brings the mouse up ONTO THE BED to play. Other half claims she has actually dropped a mouse on his head. And no, (sigh) they're not dead.
House is over 150 years old, so making it 100% critter-proof isn't going to happen.