What to do with a mean girl?

[AeA19]

I’m looking for some suggestions! I have 5 hens, just over 1 year old. They have been together since they were chicks. Within the past couple of weeks my black maran has turned on my barred rock. She gets after her to pin her down and peck at her head. I separated the injured one out to heal, and then i separated the mean girl out for several days, hoping to shake up the dynamics. It didn’t work.
The coop is 4 X 6 and they have an enclosed run that is 8 X 12 and tall enough to stand up in. There are several roost branches in the run to get up on. The other hens in the middle of the order are RIR and an Easter Egger.

 

[BGcoop]

Can you add places for the picked on hen to ”hide” behind Inside the run? If she is able to stay out of sight from the bully she may fare better.

 

[AeA19]

Can you add places for the picked on hen to ”hide” behind Inside the run? If she is able to stay out of sight from the bully she may fare better.

I have added a couple of places to hide but I worry about her getting cornered. She tends to want to go up to get away, so i have several options for her to do that, too.

 

[springvalley123]

Could they have toys, even a shovelfull of yummy dirt, in case they're stressed? a second feed/water station so the barred rock can avoid the maran? Some people put a small compost bin into their run, and that provides entertainment that might help prevent stress, which could help.

 

[rosemarythyme]

I have added a couple of places to hide but I worry about her getting cornered. She tends to want to go up to get away, so i have several options for her to do that, too.

Try to orient any obstacles so there's at least 2 exit points. For example I have almost nothing against a fence, because that tends to create corners that a bird could get pinned against.