Thanks so much for all your opinions. I will check at night with a flash light, as suggested, but as I mentioned , it doesn't appear to be lice or mites. They are outside daily in an enclosed run. I have shoveled the snow out of the run with each storm (we live in NH) so they can get out. When the snow melts they can free range again. I did buy poultry dust but after reading all the warnings on the package, I'm afraid to use it! I went back to the feed store and bought some "natural" spray to help eliminate parasites. I'll try that. Someone suggested worming them routinely, but on the worming bottle it said that the eggs would not be fit for human consumption for at least 2 weeks. In the spring (it's still not "spring" here---over a foot of snow on the ground) I'll empty out the coop, clean it thoroughly and put down new shavings. I just don't understand the featherless, red bottoms! I do appreciate your help!