2 bigger chickens pecking on smaller one

[Chickassan]

Could always pinless peeper the bullies until your new coop arrives.

 

[21hens-incharge]

Hmmmmm.....
How old are these birds?

She has nowhere to hide it seems. That run size is very difficult to work on barriers with.

See what you can do to set up barriers she can get behind. No dead ends though. It needs to be done so she can get away if followed into her hidey hole.

 

[apryl29]

I have 2 birds who are jerks. They really went after my rooster. His tail was bleeding and they would not leave him alone. Every time he'd be healed and feathers were back I'd put him in w/ the general population and not long after he'd have a bloody tail again. I eventually just kept him in a separate, but adjacent pen. He could see them, but couldn't get to him. It wasn't the best situation for him, but it worked for a while (he was aggressive, so separating him was the best solution for me). Later after he was gone, those 2 birds would go after a couple other hens, sneaking up behind them & pulling fluffy butt feathers. Last summer I separated those 2 out into the separate but adjacent area. I kept them there until fall came & now everyone's together, but I do see them still feather pecking the others. We get cold winters and I couldn't keep them separated during winter.

My point is.. they're not going to stop doing it. You'll either need to rehome, or keep them separated. It could be that they need more protein in their diets. You could try getting a bag of feather fixer, or a higher protein crumble and see if that helps. I tried it and it didn't do much for my situation, but every bird is different. If putting them all in the larger coop doesn't work, you could always leave the bullied bird in the smaller coop. It may be inconvenient, esp if you get a real winter, but you can keep them near each other and maybe someday they'll learn to leave that one alone.