this method of curing a sick pigeon is something i discovered years ago by accident when i had tried everything i knew to try and cure my best bird which had gone light treated her for everything but nothing had worked she was so bad i had made up my mind i had to put her down but she struggled out my hands pulling out some tail feathers in the process the thought was in my head well lass you dont want to die today so i left her within a few days she picked up a bit and within two weeks was back to normal this had me thinking that by pulling out the tail feathers did i send the hens immune system into overdrive thus curing the original problem it was the only reason i could think of and had forgotten all about it till you mentioned it