Mice are social creatures, I had a problem with them a few years ago even though we also had a mouser cat. I put peanut butter in one of those big traps they can get into but not out of, and put it under my stairs. I caught like 8 in one night. The first one probably alerted the others to the food I had in the bait or they wanted to get together to have a party and make more mice. Whatever it was, they all followed the first one in. I haven't seen any evidence of a mouse inside the house or garage since.