Agressive hen on hen mounting? How to stop this?

[undergroundchickens]

I have 10 hens and am starting to see some behavior problems. I have several hens that will aggresivley mount other hens. These hens that are constantly mounted are loosing feathers and getting bald spots on the back of their heads as well as one loosing feathers on her back. These are all hens....no cocks in the flock. They all lay eggs. This behavior seemed to start with just one hen but has quickly spread so more than half my flock does it to each other! What is wrong here? How can this behavior be stopped? I free range them most of the day so it isn't a crowding issue. I have even kept the most agressive of the girls in the run all day and let the others girls out to free range. This seems to help a little but it seems most of the girls have picked up this behavior and no matter who I let out it seems one will still decided to run around and be mean. I am tired of seeing the poor girls being brutilized. Is there something that can be done to "train" them to stop this behavior?

 

[HEChicken]

In the absence of a roo, sometimes hens will take over the "roosterly role". I have a BO that occasionally mounts one of the pullets and "mates" her. Once the deed is done, the pullet will get up and shake just like the real thing. While it seems unusual that you would have so many that are acting this way, I doubt you can "train" them not to. Your best bet might be to treat it just like a real rooster issue and use hen saddles to protect the girly girls.