I have a 5 month old sebright rooster along with several LF hens also 5 months old that grew up together. He is now attacking them when I let them out in the morning. He will chase and grab onto the side of their necks. I have watched him for a while now and he is normally not aggressive. He seems to continually pick on one or two hens for several minutes and then he is quiet. When they are in the coop together they are all fine, very quiet actually. He is not aggressive towards me or my daughter. Is this normal behavior or is he becoming mean.