Hoping for some advice and sorry for the long post! I have a flock of 9 hens. Two are about 4.5 years old. Two are 2.5 and five are 8 months old. We introduced the newer ones to the flock with no issues in July. This past week I noticed my 2.5 year old hen Brownie in the runs away from the rest of the flock. We had snow and our runs are very large so I don’t clear the snow from the whole area just from the predator proof enclosed area by their coops. She was just standing out there in the snow all day long. So after investigating we realized 4 of the 8 month old hens were going after her every time she tried to eat or drink. One was actually perched over the food monitoring her! We separated them. I have two coops, the younger naturally stay in one and the older in another. The older hens don’t fight at all. I thought they might have been freaking out over the snow. It’s melted now and I tried to reintroduce. They were fine for about an hour but as soon as I went in my house the 4 young hens actually attacked Brownie this time all at once and I really think they would have killed her if I hadn’t seen from my window. What causes this behavior out of the blue? Brownie has always been at the bottom of the pecking order but she is bigger than the young hens and perfectly healthy. The young hens don’t dare mess with my other older hens. Should I just keep them apart indefinitely? Thanks I’m advance I’ve never had this problem before!