I've had great success keeping all forms of rodents out with a combination of hardware cloth and pavers up against the perimeter of the chicken's run. Pavers were laid on top of the hardware cloth and then anchored with plastic landscape pegs. You can kind of see them lining the ground in the left of this picture.
We had plenty of mice and chipmunks getting into the pole barn, but never in the chicken's area!
![20201011_181924.jpg 20201011_181924.jpg](https://www.backyardchickens.com/data/attachments/2419/2419239-8e3b3e8f1db89812a23b3744335b5a3a.jpg)
We had plenty of mice and chipmunks getting into the pole barn, but never in the chicken's area!