I have had three hens for two and a half years now. They get along fine and have plenty of room; in short, I have never had a problem from them. About two months ago, however, a feral/stray rooster started coming around my yard and preening for the hens. It didn't cause any trouble immediately, but today two of my hens started pecking on and pulling out the feathers of the third! I don't know if the rooster being around has anything to do with it, but it is the only new(-ish) factor I can think of. I have my poor attacked hen in a separate pen for tonight, away from the other chickens, but I can't leave her alone there forever. What is the problem and how can I fix it? Any advice would be greatly appreciated!