Here's why we don't have problems with rodents. Clint keeps this one in his workshop.
As long as they leave the chicken eggs, chicks, and the Barn Swallow's nest alone, we let them hang around.
Blacksnakes (aka black rat snake or pilot snake) are territorial and will keep the venomous snakes away.
Many years ago, I was checking on my quail who were all bunched up in a corner of their pen. As I was bent over looking to see what the issue was, I felt something brush my hair. I figured I had moved too close to the barn wall and swiped my head with my hand to clear away any dust or cobwebs I might have encountered. I felt something brush my hair again and turned my head up and came face to face with a much smaller black snake who was checking out my hair! Well, I figured out why the quail were cowering in the corner!