I have never had too many problems with my own birds. It has proven to be a blessing and a curse. I can't diagnose many problems from experience! LOL! I went to a friends farm and she has a flock of birds that are losing feathers on their backs, tails, and bellies, Most are naked below their wings and the skin is bright red. At first, I thought they had been over bred but there is only one roo in with a dozen hens. She has other birds and they don't look like this. Any ideas? Has anyone had this happen with mites or lice? I can't imagine it only affecting one flock of birds when there are others separated only by chain link fence.