I was raised with farm animals including chickens, we just threw corn out and let them run free. I am now older trying my hand at back yard raising in a small area where I must keep them penned up with a fenced in run area . I bought a barred rock (we always called them dominecker) she is aggressive toward the others but only when released in the run pen? anyone know why? My other 3 chickens are a california white hen and 2 brahmas, all about same age and size.