I have a mixed flock of only hens who were all raised together and are almost two years old. There seems to be an upheaval in the pecking order and I'm trying to figure out why. The two hens that have been on the top of the pecking order have been fighting. The hen who I would have characterized as the one who picked on others the most is now looking roughed up! I've seen threads about chickens fighting when new hens are introduced to the flock, but I can't find anything to explain why my hens would start flighting for no apparent reason. At first I thought the fighting was due to the cold snowy weather when most of the hens opted to stay in the coop rather than go out into the run, but the weather has warmed and the behavior continues. Any idea as to why this happened and what I can do to get my hens to stop fighting?