I'm curious about this too - have been thinking about letting my chickens free range inside a 1-acre fenced in area. The fence is not great, but would easily keep in chickens who aren't too interested in wandering. What does concern me is keeping predators out -- we have already lost one chicken to a predator at night. Even if I tuck free-rangers safely into their coop at night, how can we keep out hawks, neighbor's dogs, etc. during the day?