Scaly red skin, missing feathers

[Stefk]

Hello, something seems to have gotten my flock and it’s spreading. I have 3-4 hens with bare bottoms. I thought it was bullying as these seemed to be my bottom of the pecking order ladies but now im Seeing evidence on other chickens. The areas where the feathers should be are dry and scaly. I have inspected them and see nothing crawling. Like lice or mites. I have attached a couple pictures of what I’m seeing. Any ideas on what this is and how to stop it?

 

[Wyorp Rock]

Do you have a rooster?

How much space do you have and how many birds?

Looks like feather picking and/or mounting/mating damage to me.

 

[Stefk]

We do not have a rooster. We have 17 birds in a 10’x20’ run. Their coop is around 8’x6’.

 

[Wyorp Rock]

Space may be a bit tight, observe your birds, especially when roosting.
Looks like feather picking.
Even without a rooster, dominant hens can mount others and cause damage.