I have 6 chicks that are about 5.5 weeks old. 2 australorps (1 cockerel, 1 pullet), 2 white leghorns (both pullets, I think), 2 buttercups (both pullets, I think). I put them out into the new pen (8x8) along with six 4.5 week old cochins.....it is a temporary pen until I finish the larger one. There were some knock down drag out fights going on out there. Mostly between the older age group. The cochins tried to stay out of the way and mostly succeeded. But the australorp cockerel (by far the largest) and one of the buttercups were fighting. Like, pecking at each others faces and then jumping up and striking with their feet. Eventually the buttercup would win and grab the australorp by the back of the neck and pin him down. I ended up removing the australorp (he started the fights)...then the buttercups did the same behaviors at the other australorp (pullet). Even when she would submit and cower in front of them, any time she tried to move, the buttercup would grab her by the back of the neck and just hang on and pin her down. The buttercup will be on the opposite side of the pen and then go running and crash into a group of the others and then start grabbing onto one of them. Is this normal pecking order behavior? Or could it be the excitement of the new space? it seemed a little extreme. These chicks have been kept together since day one......they have been inside the brooder up until today......it has been about 3x3.5 (and 5 feet tall with multiple levels of roost) for the last two weeks. It is a larger shed split in half, with the cochins in the other half, so they have been in the same 'shed' for weeks to get used to each other. Prior to that they were in a rubbermaid tub and I didnt notice anything too crazy.