At one week of age, I started finding chicks with their tails being picked at and bloody. We realised we needed more room for the 90 little fur balls. We did find that there was one chick that seemed to always start the pecking. It would even turn up it's beak to starter feed in favor of some one else's tail feathers! This chick was very evasive, hard to catch and I'm not sure I've caught up with it yet. We have them in a larger pen, fed occasional suet, and watch closely. Still last night 2 chicks ended up with bloody tails! What I did discover is: Desitin or generic zinc oxide, diaper rash ointment doesn't taste good and covers the red bloody areas very well. If I catch the one that's doing the damage... Well, it wan't be doing damage much longer.