So what happens when a few British house mice jump ship in the South Atlantic? After 150 years you get 700,000 odd giant carnivorous albatross munching mice:

What is horrifying ornithologists is that the British house mouse has somehow evolved, growing to up to three times the size of ordinary domestic house mice, and instead of surviving on a diet of insects and seeds, has adapted itself to become a carnivore, eating albatross, petrel and shearwater chicks alive in their nests.

Probably get stuck in the cracks between your floorboards though. Bash! Bash!