injury? mites? damage from roo?

[spish]

over the past 2 weeks ive noticed the majority of my girls have developed a bald patch on the side of their necks (not the back, the left hand side) its on the same spot on all the girls.
i thought at first it could be lice/mites? but have recently treated for that and cant see any signs on the skin.
then i thought maybe they are catching it on the hen house door as they come out or something but nope? so my last conclusion is its where the roo is 'holding' on, but he's never done this 'damage' before to the girls? (he'z been with them 8 months and its only started in the last two weeks, they have no bald spot anywhere else)

any ideas??

 

[chickensioux]

I have a couple of hens like this too. Just the sides of their necks. I have no idea what caused it on mine either. No lice or mites. These are my older girls that are not laying any longer and the roo is not breeding. So I hope someone else can answer your question.
I do have younger hens (Salmon Faverolles) that would have full head of feathers as well as beards but due to the roo, they don't. They are completely bald.