My new chicks, mail ordered are all 4 weeks old now and one has taken to pecking other chicks. This started last week, just after we moved them to a bigger pen. We have 2 types , Creme Leg Barrs and Black Copper Marans. One of the BCM's has been pecking the backs of the other chickens, but not her own kind. We thought they may be bored so we've moved them outside so they can do more interesting things and isolated the pecker. After 5 days of being isolated I tried putting her with the flock again and she immediately went to feather pecking again. Everyone else does just fine. Don't know what to do to stop this bad habit.