OK. I have 6 chickens. 2 roosters and 4 hens. One of my roosters and a couple of the hens have started to have missing feathers on there backs close to the tail? The one rooster has none at all and 2 hens are perfect so I don't think it is mites or anything. Is it the rooster? Do I need to get rid of it? Please help! None have open wounds just no feathers and seem a little stressed maybe but still laying well.