Last night when I went to close up the girls I found one of my EEs had been apparently attacked by the other chickens and her rear and lower back had been picked raw and she was laying near death in the run. I have moved her into a box in my garage but even with TLC I don't think she is going to make it. 2 hrs prior there were no signs of a problem. Now I went to check the girls (as I do frequently through the day) and one of my Dk Brahmas was dust bathing and the others began attacking her and roughly pulling out her feathers. I have seen them pluck each other at times while bathing but nothing like this. Even after she got up it continued. I have noticed some bare butts on some but as this has happened with my other flock, I didn't pay much mind. I am planning to blu-cote the bare butts tonight when all is calm at dusk but... what is going on? background 12 chickens raised together now 6 1/2 months old. They have a 10x16 sand run with a 8x8 coop. plenty of food and water...no signs of diseases or parasites. ANY advice?