We have just noticed that our hen has a small bald spot at the base of her wing, with no feathers growing out of it. We have another rooster, but we aren't sure if he is the problem. We have read some articles on Backyard Chickens that say it might be due to over-mating. She has also lost a lot of feathers on her back, but there are no bald spots there. Can anyone please give us an explanation on why she has the spot, and what we can do to fix it? Thanks.