Hens Fighting

[Ginganinja17]

I've looked around the forums and would like some advise or other ways to go about this.
I've had chickens for a while and have had to put some inside from time to time for various reasons but never had this type of problem. I have a flock of 5 hens.

I had a hen, Astrid, that ended up with a sprained leg/foot mid January. Thought it was bumble foot at first and tried treating that but ended up not being the case. Tried putting her outside with the others with a wrapped leg during that period but it wasn't good for her and she was favoring it a lot and couldn't roost. We decided the best course of action was to have her inside on soft bedding. She made a full recovery within a couple of weeks. She's a great chicken and one of the better chicken patients.

This is the part I need some help with.
I have an older hen, Fiona, who I took in years ago after her whole flock was killed. She lays on occasion, I don't expect much from her. She's a great chicken and has such a personality.

I reintegrated Astrid into the flock by putting her in a dog crate in the yard with the others around her. We have a smaller run but the flock gets to free range the yard. Seems like everyone had a small period of hostility towards her but was resolved within a few hours except for Fiona. She would watch Astrid and square up to her and then attack talons out. Astrid would fight back and would only stop when separated. I would have Astrid out in the day then take her in at night. The hostility slowed down to minimal after a couple of days so I started supervised free range time with Astrid outside the cage. They tended to stay away from each other and it wasn't bad. I let Astrid go into the coop at night and then Fiona and Astrid were fighting on the roosting bars.

We decided to take Fiona out and put her inside as she was the instigator. All the other hens were fine with both chickens. This was early Feb.
We kept Fiona inside for a week to hopefully reset her brain about Astrid and then tried the same reintegration method in the dog cage in the yard for multiple days in a row. Still fighting and had to clean up blood. Tried again after another week for a few days, still no success. Tried two weeks and still no success but definitely less fighting. Had a trip planned that we just got back from and I didn't want my sitter to deal with it so kept Fiona inside and no one went out for almost three weeks.

Each time I do reintegration I use plenty of snacks or food around the cage to promote positivity multiple times a day. Generally when they are eating Fiona will not be caring about Astrid. It's only when Astrid stands up does Fiona start having a problem.

The other three chickens have zero problems with the other two and vice versa.
Astrid is a big barred rock and Fiona is a definitely smaller welsummer. Prior to Astrid going inside there were zero problems in the flock and any time anyone need to do time inside they always bounced back into their routine.

I'm thinking that maybe Fiona remembers Astrids leg being wrapped and is targeting her as a weak link in the flock. But Astrid is now back to normal.

I'm going to keep doing all day reintegration, but if anyone has any unconventional or other ideas to help with this I'd love to hear them!

Culling or rehoming is not going to be an option.

 

[BlindLemonChicken]

How much clutter do you have in your run? The best way to stop a chicken fight is for the subordinate chicken to be able to break line of sight with the aggressor. If Fiona has lots of things to get behind and there are several feed and water stations it will help mitigate the agression assuming Fiona tries to get away—she will be able to break Astrid’s line of sight and the issue should resolve itself enough that eventually they won’t need it.