Had Chickens 5 or 6 years now. We have brown leghorns & Isa Browns this time round. We did have a Rooster not too long ago, but he was better suited for pot pie than in the yard. Our girls have bald or bare spots on their backs, exactly where their feathers begin to fold upward for the tail butt region. Bald spots definitely began when the rooster was around, but seem to have continued / increased with him gone (Or at very least, NOT gotten any better). I guess the usual suspects are mites, or something like that. Anybody know the best way to fix this issue?