I have a 5 week Cucko Marans and a 5 week Buff Cochin that have been really going at it lately. The Marans seems to be the dominate bird in the flock as she routinely runs everyone over, even my 6 week old birds. But she generally will not peck anyone unprovoked. The Cochin, however, routinely chest bumps her, while giving her the evil eye, as if to say, "you wanna piece of me"? Does pecking order behavior start this young? Also, I have my flock of 8 seperated in 2 - 55 gallon bins until my coop is finished (hopefully by next weekend if it doesn't snow all weekend). Today, the pecking was so bad I brought the cochin in the house. She's in a dog crate right now for time out!