I have 5 chickens (three Buff Orpingtons, and two Black Sex-links). They are in a chicken coop 4 x 6 with a run 6 x 14. One day I noticed one of the black chickens is very aggressive and head of the pecking order.. However, she picks on two of the Buff Orpingtons. The black chicken was chasing the small one and suddenly the small chicken squatted down; then the black chicken pecks her on the head. The small chicken is scared of the black chicken. The small Orpington try to stay out of her way..The black chicken won't let the other chicken in the coop when shes laying an egg. Do you suppose that two are scared and stressed, which made them stop laying. All 5 were laying for a short period of time and two Orpingtons suddenly stopped laying. Does anyone have any ideas about the problem?