I am hoping someone can answer this question, as I have the same problem too. I have 4 hens remaining, one died this morning. Two of them are missing feathers just in from (on the back) of the tail and around and below the vent. The hen that died today was my bully hen and showed no symptoms of illness (other than feather loss). The deceased hen was missing feathers all around the vent and was starting to lose feathers on her back close to the tail. I have checked for mites/lice and do not see anything. Will check again tomorrow in daytime. I do not know if her death is related to feather loss. Also, I noticed on the deceased hen, her vent looked like she was trying to push something out. It looked swollen, oozy (maybe a ting of blood). I felt around and did not feel any abnormalities, like blockage, but it was very strange looking. It actually looked just like birth (when the head starts to crown). Again, do not know if death had anything to do with feather loss, but wonder if it had something to do with what was going on in the vent. Any ideas???