Hi one of our chickens has lost her feathers along the centre of her breast (doesn't look sore), she lost the in May. She also has 2 bare spots on top where her wings join her body. These do look sore. I spoke to a friend (a retired vet) he said if it was mites all the birds would show signs but no one else had. She seems healthy and is laying. I noticed her getting bullied at night so have separated her to roost, but out together in the day which seems fine, but not really any feather re growth. Yesterday I noticed one more with slightly bauld but not sore breast. Any ideas? As I said all seem otherwise healthy and laying.