If she is out of their sight/sound then basically she is loosing her normal spot in the pecking order and they are treating her as a new hen probably... so if they are that aggressive then you should monitor her when she is out to make sure she isn't hurt. Ours never plucked a broody patch on her belly, at least not a noticable one.well when she was off all the younger roos were attacking her a lot and she was attacking them back so i put her back and i thought she was supposed to keep her broody spot the naked spot on her stomach .. i just didn't want her to get hurt or anything so i put her back all the birds were going at her because she is hidden away in a spot where the other birds can't see her and she is a bantam so she could get hurt by the bigger birds