I hatched a group of 15 chicks 3 months ago. Their brooder was huge but I think they got bored 2 days before I had their outdoor coop ready. I put them out of the brooder at 3 weeks with a heat lamp. (we live in Hawaii so pretty mild weather) Well, 2 days before I moved them outside where there was dirt and grass etc to keep them entertained they started picking. 2 of the chicks had bloody quills. I doctored them, applied all kinds of no pick goo over and over. I moved them to an even bigger pen when they were 6 weeks old. Then when they were 9 weeks old I broke them into two groups so they have tons of room. I give them all kinds of interesting things to eat, mulch to scratch through and on and on. But still bloody quills!!! I figured out that the 8 chicks I moved are where the pickers are. The group left behind is happily growing back their tail and back feathers. So now the picker group... I duct taped their backs all up and they would have their tape off in one day. I kept reapplying the tape but dang it there were still bloody quills. I have been watching them closely and saw who the culprits were. The picker would go around looking for tail feathers to pull out. Not just pecking at the blood but literally eying a quill, grabbing ahold and twisting and yanking till the feather came out or broke off and bled. I mean instead of scratching in the dirt and looking for good stuff they were eyeing each other as a tasty snack. I was about ready to ring me some necks. I remembered that I bought pinless peepers and the tool to apply them awhile back. It was really scary putting on the first one. I didn't want to puncture something in their nostrils. Don't know what the inside of their nose looks like. After a bunch of tries I got one pair on. Of course that bird went nuts. Running around like a cook. The other birds didn't like that weird behaviour and pecked at the peeper wearer. But finally things settled down. I have since applied 2 more pairs of peepers. I hate doing it but it is peepers or the boot for these brats. I am hoping that since they are young they will unlearn this nasty habit. When everyones feathers grow back I will take them off and see what happens.