Aggressive pecking

[Kit kat Kate]

I have a Buff Orpington which is permanently broody (& not laying) so I about a month ago I isolated her in some extra fencing in the day to try and break her obsession with the nesting box. I understand what she is doing is natural but she will sit there and lose weight until she is on death's door if I let her. They are back all together now and I've taken to closing off the coop after the three others have laid in the morning to encourage the Buff to roam. There is plenty of space for the four of them. Since the isolating the Buff Orpington the Cream Legbar (who was hatched under the buff in April 2018) has risen to the top of the hen hierarchy and has started jumping on top of the two younger farmyard chickens, pecking them on the head aggressively. The Buff Orpington, who has traditionally been quite peaceful, also pecks the others now too.

Any suggestions on the broody Buff or the aggressive behaviour gratefully received!

 

[aart]

There is plenty of space for the four of them.

Meaning they free range?
Dimensions of coop and run, with some pics, would help here.

 

[Kit kat Kate]

Yes, they have access to 1/3 of an acre in the day and they are in a 3 by 5 feet coop which remains open to a fenced area of 10m by 5meters until they are let out in the morning. The space is not the issue as they were fine with it before. It's the dynamic between them that has changed.

 

[san35]

I have a flock of 8, wyandotte rooster, five barred rock, and two Easter Eggers. My easter Eggers and one barred rock are being injured by aggressive pecking. Recently my one Easter Egger has a huge wound on her back. This happened in the day while they were free ranging. I have noticed her being isolated from the group earlier. I have isolated her and she is healing. How and when do I introduce her back into the flock? I am trying to find out which chicken is the aggressor and I am assuming I will have to get rid of her?