I agree with Steve. The place I see the most brutality is on the roosts as they are settling in for the night. It's normally a hen lower in the pecking order picking on an immature chicken. Once they all mature enough to get into the pecking order it usually settles down. I've got a separate roost, a little lower than the main roosts, horizontally separated a bit, and higher than the nests to give them a safe place to go. So Lucky, when she matures a little more she'll find her way into the main roost like her mate.
During the summer mine spread out on the roosts. In the winter they normally sleep crowded up next to each other, sharing the warmth. I'm not there as they are settling in for the night but I do know the weaker ones are the last to go to the roosts. When I go down there to lock them up for the night and turn the lights on, some will start pecking their neighbors until I turn the light back off.
Mary, I don't know of any harm to a chicken that sleeps on the floor. Some Silkies do it all their life since they can't fly. You don't have to schedule her an appointment with Dr. Phil or bring out the big guns and show her reruns of Oprah to work on her psyche. She'll be OK.
Cat I don't have a clue what is going on with yours. Normally they like to roost once they learn how. Something has changed, maybe something you'll never know. Maybe an owl tried to get in through a window and frightened them? Maybe a bat? Maybe a whole lot of things totally different than a predator. You can try putting a few on the roost at night and see if they readjust, or just let it go until something else changes. As I said, I don't know of any harm that comes to them from sleeping on the floor as long as they stay out of the nests.
Usually, that meant I wasn't caring properly for the roost and needed to expand it. She may also need assertiveness training.
