We adopted our 5 hens 20 days ago. 4 of them are 6-8 months old and one, Sunny Side-Up, is 4 years old. We were told ahead of time that Sunny was no longer laying. When she first came to us she was sitting in the nest box a lot, but she didn't put up any resistance when we kicked her off of it from time to time. There's only one nest box so the other hens also kicked her off when they needed to lay. After the first week Sunny was no longer trying to hang out in the nest box all day, but we noticed that her underside was featherless and very red and raw. She seems healthy otherwise, as do the other 4 hens who each lay an egg a day. There's only a small amount of squabbling each night over roost spots. We are unsure if the loss of feathers occurred after coming to us or before. Is Sunny's condition self inflicted from broody-like behavior, did the other hens do this to her, or is it something else completely? When will the feathers grow back, and is there anything we should do help her along?