My one year old Araucana hen has some feathers missing from the base of her tail for several weeks now. I recently noticed both my one year old RI Red hens have feathers missing from the base of their wings - not as big a bare spot as the Araucana, but noticeable. I cannot see any parasites on them. They eat organic layer pellets with supplemental oyster shell calcium, and they free range during the day. There are 6 of them (5 hens and a rooster) living in a good sized coop. I have not noticed anyone pecking at the others. Any suggestions? Thanks!