I have a mature flock of 15 hens and recently got some younger chicks. I have had them separated and tried to put them with the flock today and the older hens instantly started pecking feathers. I had just fed the hens their daily table scraps so that might have something to do with it. I thought they would be ok because I let them free range together with no problems. How old should the chicks be before I put them into general population? Is there a technique to prevent pecking.