Do Cats Really Help Get Rid of Mice?

In the most-cited urban predator study on this question, Parsons and colleagues (2018, Frontiers in Ecology and Evolution) watched feral cats at a rat-rich Brooklyn waste-recycling facility over 79 days. Across 306 videos, with a colony of more than 100 microchipped rats and up to three cats present daily, cameras recorded only 20 stalking events, three kill attempts, and just two successful kills. The cats' main measurable effect was making rats warier and more hidden — not fewer in number. That's a striking result given how often cats are recommended as rat control.

Cats are energy-economists: they take the easy meal (small birds, insects, the occasional mouse) and generally avoid large, defensive prey. In the study, adult rats averaged about 337 grams — roughly ten times a mouse's weight — which likely explains why cats mostly left them alone. Against mice specifically, a keen individual cat will catch some, but well-fed house cats frequently don't hunt at all, since they're not relying on it for food. Even a highly motivated cat faces a physical limit: mice nest in wall voids, cabinet bases, and attic spaces that no cat can access, so the cat only ever encounters the mice bold enough to cross open floor.

A cat may reduce the occasional mouse crossing the kitchen floor and can add some scent-based deterrence, similar to a dog's presence. That's a real, if modest, benefit — particularly for barn or outdoor cats on rural New Hampshire properties. But it won't eliminate a breeding colony nesting inside your structure, and it won't seal the ¼-inch gaps letting mice in. Use integrated pest management — trapping and exclusion — for the actual fix, and consider the cat a bonus.