My Wyandotte lost her tail feathers a few weeks ago (moulting I suppose) and not long after that she seems to have turned mean. She picks on two of my buff hens. She usually sneaks up behind them, pins them down and bites them on the neck. No feathers come off but I still don't know what she's doing or why she's doing it. The moulting might just be a coincidence. The Wyandotte is not the head hen either so I really don't get it. Please advise. Pic from a few months ago. (she's pretty!) She pooped on me today when I picked her up.