My four hens are five months old. Two Red Sexlings and two Barred Rocks. I bought two 2 month old Americaunas a couple of days ago. I have kept them seperated for 3 days, but they could see each other. I introduced them this morning. The older hens are terribly mean. They are chasing, cornering and pecking. Do I need to worry that they will kill the new birds. It kills me to see them so picked on. Any suggestions? Should I just let them settle on their own?