Long-time lurker, first time poster I'm somewhat new to chickens, so bear with me here. I started my flock last May with 4 newly hatched chicks, two Black Aussies and two Buff Orpingtons. They have been in their coop since the summer, started laying the first of December. Coop is a 2X4X4 hen house with pine bedding and 2 exterior nest boxes in the second story of a 8X4 run with sand as flooring. Fed a layer pellet, oyster shells and grit free choice, water cleaned 2-3 times a week, veggie scraps available when I have them, occasional yogurt and dried mealworms. Free-ranged once a day for 1-3 hours in our neighborhood backyard when weather permits (Rainy Oregon!) In late December I noticed feather loss on the ventral neck (under the chin, above the crop) of my largest Buff. Seeing as they were about 7 months old, I wondered if they were about to start a light molt. Shortly after, she stopped roosting and the other Buff also started with some feather loss. Then Buff #2 (Blondie) started sleeping on the floor as well. Being a vet student with vast amounts of small animal emergency experience, I had given the first a thorough look over at the beginning, no obvious scrapes, swellings, mites, lice, rattles, gurgles, discharge. The same exam was performed when the second Buff started behaving oddly, no significant findings. I spend a fair amount of time outside with them (good study time ) and had not witnessed any bullying. Fast forward a couple months and now all 4 hens are sleeping on the hen house floor and with the feather loss ongoing for 3 out of 4 hens, I realized I probably had a feather picker. She was identified as one of the Aussies, ironically, the third to start sleeping on the floor, not the last. As we started work on adding an additional 4X5 area to their run, and spring has allowed more free range time, a new behavior has come up. The bully is being picked on by the smallest Buff (Blondie). The Buff doesn't seem to be seeking out the Aussie bully (Rizzo). Rizzo puffs up, spreads her tail, lowers her wings and starts clucking when Blondie the buff is close by. Sometimes when Rizzo flees, all is well, other times Blondie jumps on Rizzo's back and almost looks like she is trying to spur her, pulling at her comb and back of her neck. So far, since Saturday, I have only noticed a couple scrapes on Rizzo's comb, no chunks or great feather loss. As I see it, two options exist: isolate Blondie the bully and risk Rizzo picking on her when Blondie the new Buff bully is reintroduced, or monitor the situation with the hope that with the conclusion of coop expansion this weekend the extra space will help. Thoughts? Thank you to anyone that reads this fully. As a vet student + someone primarily small animal experienced + chicken unexperienced I have lots of questions. Hopefully what I lack in experience I can make up for in eagerness to learn and observe behavior!