Roosters won't keep predators away.I don't have bears, but yeah for me mice are lower on the list of my worries. It's a tossup between raccoons, snakes, bobcats, and raptors. Snakes seem impossible to prevent, but I kept a rooster hoping it'll keep them at bay.
He will tell them all where he is every morning starting around 3 AM.
Snakes and mice can be stopped with 0.25" hardware cloth.
That's if your coop is built on a concrete slab.