I have 8 2 week old chicks of different breeds. Chicks went outdoors today in the run. I sat outside with them in the run for about an hour, just watching them explore, eat bugs, dust bathe. They happily peeped and seemed to be quite content. I even had their ecoglow in there just in case they got chilled (it was sunny about about 73 degrees). I left them there for about an hour, and kept somewhat of an eye on them from the deck. Didn't hear any distress peeps, they all seemed perfectly happy to be enjoying the outdoors and the sunshine. I went out to bring them back in about half an hour later and found one of them with a nasty, bloody vent. All the others were attacking the vent area. I quickly scooped up the chick, checked the others for bloody vents (there were none) and brought her inside to clean her up and devise a plan of where to keep her while healing. In this time (about 15 minutes) I went back out to find yet ANOTHER chick with a bloody vent. I had checked all chicks before bringing in the first and they were fine, so this happened while I was dealing with the first chick. What happened?? Why did they do this? Were they stressed at being outside for too long? Why would it happen to two different chicks in such a short amount of time? They are all now back in the indoor brooder and seem fine. I put some blue kote on both of them after cleaning them up, and they are now in together in a separate tote with a heat lamp. I am terrified it is going to happen again! When can they go back in the other brooder? You can't see the red wound anymore, just dark purple/blue butts! Ugh, so discouraged that this is going to be an issue.