A little bit of background information...A dog attacked our chickens and we lost 10 of them which left us with 4. So we got 4 more from a farm store then we got a rooster from family. Then I got 10 more from a farm store so they are all about the same age except the 4 original ones that are a year older. Now they are all mature and laying however the rooster is pecking the 4 original hens heads so bad they have lost feathers and 2 of them are bleeding. I have taken the big girls out of the run most days and let them free range. So my question is how do I get him to stop being mean to these hens?