started sometime this afternoon, chicks picking on others until they bleed (especially @ base of tail). 3 of 4 picked on are buff orpington (does color have anything to do with it?). i'm sure this has been addressed, but i don't know where to look on this forum to find the why and how to fix. i've separated the bloody ones. they haven't been overcrowded (unusually warm today). i've had the perfect little flock until now & i'm baffled what's happened & why. will i be able to re-introduce these four once healed?