Chickens can be brutal to each other. A few days ago I found a 2 month old pullet that had the back of her neck picked open. A (cursory) inspection looked like her spinal cord was exposed, and I didn't think she would make it, but she was alert, so I too her home to live in a brooder by herself. She not only recovered, but was determined to escape back to her family. Yesterday I moved her back to the farm, but she has to remain in solitary for a while until I am sure she won't get treated the same. She probably will end up with younger chicks. She is an Opal Legbar and they are maybe too docile for their own good sometimes.