We lost a chicken (the head hen) to a bobcat a month ago, since then we have noticed 2 of 3 of our hens are losing the feathers at the back of their necks. Woke up this morning to one of them dead in the coop. Not sure if it is related or not. I will check for lice/mites after work, but I'm wondering if I have a bully. How do I stop it? And should I add new girls in before winter really sets in or wait until spring? Thx.