A couple of days ago I noticed several down feathers laying around the coop. At first I thought it was the newer chicks establishing themselves and standing up to the main hen. We have one BR hen who is 1.5 years old--the only one out of the group to survive a neighbor's dog attack last April. We got a dozen new chicks in June, so now they are about the same size as the BR. About a week ago they started sleeping all together in the main coop. So I thought it was one of the newer chicks pecking at her. Well, this morning I saw her plucking her own feathers out. And I've noticed that she hasn't laid an egg in 3 days. Are the two issues related? What would cause her to start pulling out her own feathers?