Do you have a really bossy chicken that's making your other girls stressed out. I had this problem with one of my buff orpingtons, I didn't know there was a solution to the problem, but there is!
1. Buy chicken eyeglasses off ebay, That way, your chickens can still see, but they can't see in front of them, so they can't peck the others.
2. Buy Anti-Peck Spray, All you do is spray a little on your chickens everday, so when the bossy one trys to peck them, the strong taste of the spray will keep them away!
3. Separate the bossy chicken from the others for about a week, when you put the bossy one back with the others, they won't remember it and they will most likely become dominant.
4. If none of these options work, than I suggest getting rid of your bossy chicken, Or butchering it for meat.
Your chickens also might be picking on each other if they are over crowded, Make sure your chickens have plenty of room in the run and some time to free range each day.
I hope this helps you all!! Good luck!