I'm a first time chicken owner with 4 chickens in a 1/2 acre suburban yard. They're about a year old and have co-existed peacefully until now. In the last few weeks one of my Buff Orpington's pecked a big patch of feathers out of the other Buff's back. We pulled her out and isolated her for a few days and reintroduced her and things got worse. She started aggressively chasing and pecking my docile Barred Rock and was also being ganged up on and pecked by the other two chickens until her head and comb were bloody. We removed her again to isolation for I think 5 days. Tried again and same thing. She's back in isolation. The other three are happy as can be without her. We've tried expanding the run area, adding toys and treats to distract, saddles. I was going to try the pinless peepers but they looked painful and awful. I don't want to get rid of her but we're going on vacation in a week and I can't ask the neighbor to come watch my basement chicken several times daily! We don't have free range options because we're in a suburban neighborhood. And it's winter here so I fear the girls are feeling cooped up because their coop and run are the minimum size required. Any last ditch effort advice?