Train your chickens to come when called, so you can let them out and get them in anytime you want. Also enables you to call them to safety when predators lurk. If you have multiple flocks, you can train each to come to a different call. Very helpful when you have new pullets free ranging with old flock, and need to get each flock to its own coop... Wonder if this works..
A free-range flock is at higher risk of predation than confined birds. Providing natural and artificial cover in the form of bushes, boxes, branches will provide a degree of security and safe-haven when predators are detected.