I still have a couple of large fowl Ameraucana and they run with my pen of mixed breed bantams and large fowl and they do just fine. Both my Ameraucanas are hens and I have large fowl Cochins running with them. I no longer have any bantam Cochins but when I had them I never had any problems but as with adding any new bird be sure to watch them for a few days to make sure they get along.