Hello, I have five chickens, who have always gotten along smashingly until last week. Four of them are suddenly ganging up on one of the RIR, pecking her and attacking her until she lays down. If I isolate her, she wigs out and makes all sorts of noise for hours, and she always seems to want to hang with the other girls. They free range all day, and are only closed into their (very roomy) coop/run at night, when they put themselves to roost. I've checked her all over for signs of injury or disease, but other than one blood spot she got when I caught the others pecking her (I cleaned it and there are no signs of it anymore), she seems unharmed. ANy ideas as to what brought this on, and what I can do to stop it? Thanks for the help!