In view of the limitation of the online version, I thought you and others might be interested in another passage from Nicol:
p.65 "[Chickens] often prefer to exert a degree of control or influence over events, choosing, for example, to forage for food rather than accept the same food freely given… feral chickens and wild junglefowl have a great deal of behavioural freedom as they can select where and when to forage, which food particles to ingestr, whether to stand in shade or sunlight, and how close to get to other birds or humans. In captivity, individual chickens have much less control… this lack of control will have welfare consequences. It has been known for decades that exposure to uncontrollable aversive events, compared to controllable events or no stimulation, results in ‘learned helplessness’, increased fear, stress and susceptibility to disease.”
This is one of several passages in the book that have revealed to me why - at least in some circumstances - different posters on BYC report such different experiences with their chickens.