I have 5 chickens (1 is a cochin--i think--and is a little over 1 year old and the 4 pullets are supposedly an Easter egger blend that are almost 5 months). I introduced the 4 pullets to the coop with my cochin. After about a week, they were all 5 getting along great. The 4 pullets have grown almost twice the size of my other hen. They've all been together out in the coop and run for over 2 months now. Recently, one of the pullets had started to show aggression toward the cochin hen and chasing her around the run. I assumed it was her trying to reestablish the pecking order. I noticed today that this pullet now seems to he bullying the hen and will chase her and pin her the ground and hold her down and peck at her head, to the point of pulling our feathers and causing blood. At what point do I intervene? Or should I do anything? Posting a couple pics for reference.