The only chicken discipline I have ever had to dish out was putting an aggressive/feather picking juvenile in a separate area for a brief time out. (Usually long enough to Blue Kote the butts of her victims) And when a hen pecks at my hand aggressively, I will put my fingers together to make a beak & peck her back. After one of my pullets was attacked by a hawk, she became overly protective of her sisters. When I would go to gently sit a chicken down after handling/petting, the pullet would run up & attack. It only took a few times of me pecking her back to stop it. Funny thing is, she had no problem with me picking up & loving on her. Maybe she had some PTSD?
Abuse of chickens or any animal is horrible!