I know I'm not the first with this problem, but I'm just not sure where to start. We have 4wk old chicks (Black Astralorps, Golden Comets, & Aracauna). Today I found 5 (all Golden Comets) with tail feathers pulled out. One girl's vent area was completed pecked free of feathers & bleeding. I have separated all the injured chicks. The worst is by herself. It was hot here today, almost 90. There are 24 in a 4ftx4ft brooder in our garage. This morning I opened the garage door to get some fresh air to them & cool of the garage a bit before the heat of the day. I shut the garage door after lunch & found the hens injured. There is a lid on the brooder to keep them in & predators out. The thermometer in the garage is reading 80 degrees. I turned back on their red heat lamp but moved it higher. Everyone seemed calmer after I pulled the injured ones out & turned on the lamp. The plan has been to move them to their portable pens this weekend. We are moving that up to tomorrow to see if they are doing this because of overcrowding. I'm not sure who is doing the pecking - I saw the Black Astralorps doing some but couldn't tell which one for sure. I also noticed a couple of chicks eating the broken feathers off the floor of the brooder before I could get them picked up. I would appreciate any ideas as to what to do.