Lost feathers on tummy advice please

[merrymegseggs]

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.

 

[merrymegseggs]

Bump!

 

[SilkiesForEver]

Do you have any roosters? Do you think the hen went broody at any point?

 

[merrymegseggs]

No rooster and not neither broody

 

[sbhkma]

Have you checked her over for mites, even though you're pretty certain that's not it?
Is she getting picked on, having feathers pulled out?
Does her breast/belly area feel exceptionally warm to the touch? She may be "sorta-broody" -- I had a hen do that. She kept laying and seemed fine, but she'd spend extra time in the nest box and she pulled out all her breast/belly feathers. 3 weeks later she went full-on broody so into the broody-buster she went.

If she's got bald spots that seem tender, there is most likely a parasite getting her and if you don't treat her and the rest of the flock, you may lose her.