I read that white chickens are least likely to survive, especially from aerial predators. Seems the darker shades have a better survival rate, being harder to see. CD's and criss-crossed strings/twine seem to have some successes, but not foolproof. For free ranging, no real protection except what cover is there for them to duck under. Even so, hawks have been seen to land and walk in or under something to kill, especially chicks.