I hatched 12 chicks out before christmas and they have been fully feathered for 3 weeks now so about 7weeks old. I decided to introduce them to the flock. They seemed to be fine until later today I found one dead by the door of the pen and about half of the 11 remaining bleeding from their tails. I dont know what to do. I keep the chicks in the green house ( which is 14x14 and occupys 3 tortoises) and I can not keep them in there forever, nor do i think the tortoises would like that very much. I took all the pullets out of the pen and returned them to the green house for now. How can I introduce them to the flock outside? I may have done something wrong but im not sure. Help would be greatly appreciated.