Any ideas on feather loss

[JohnNJerri]

Originally thought the chickens were molting. They are one and a half years old. Unfortunately the neck feathers have never come back again, very minimal feather loss anywhere else. No mites that we can see. No rooster. They are still laying normally.

 

[sourland]

I'm willing that some of the birds in the flock do not have this problem. Am I right? If so they are feather picking/eating the feathers from the necks of the other birds.