Our flock: One 5 year old rooster (we have had him since he was a chick), 5 hens ages 1 to 3 yrs. Our rooster has never been aggressive. The past week he has zeroed on one hen and has been attacking her (not mating). The instant he sees her he goes straight for her. I have never seen this type of behavior. We let them free range during the day and poor Millie has to hide from him. Putting them in the coop in the late afternoon is becoming a horror for Millie. She hides in a nesting box or cowers in the dirt to stay away from him. Why would Drumstick start this now? Is this common? Thank you for your suggestions!