A similar question with crickets - how do they jump with balls that big?
Maybe they're Australian moths and crickets, bodies in proportion to these balls; everything there is designed to kill you so the Oz moths and crickets do it by blunt force trauma to your head.
To the OP:
I was having a smoke (yeah, yeah) in the basement garage at the office when a colleague pulled his diesel Range Rover into a parking space beside me. After he shut down and got out, there was an unusual noise still coming from the car. We looked, puzzled, at each other for a few moments, he opened the bonnet (hood) and, lo and behold, there was a kitten sitting on his air cleaner, mewing. Turns out the little fucker came all the way from Limerick. And survived.
Reckon he's your solution.
Limerick is fondly referred to as "Stab City" so he'd be well hard. "A few small mice? No fuckin' problem, Boy!"