We have chickens that look just like that ! No roosters, and we have seen the mean chickens pick the feathers right off the poor chickens back - My 22 chickens have a huge run, and coop. I think they do this when they are bored. I sacrificed the garden to them, but now that it has been picked clean they are back to picking each other. I know for us, it is the heat, we are still in the 100's here, and the girls spend most days in the coop. Othter wise my girls are in top shape. I use the rooster booster too, but the poor girls that get picked really hate it, and they will try and pick the rooster booster off of themselves, I have the best luck with giving the chickens lots of food/things to keep them from being bored. Hope this helps!Q