So I have two ducks currently that are about 10 weeks old. Just got 5 newbies that are a few weeks younger. I kept my bigger ducks in their coop and let the little ones run around and let them see and hear each other. When I took over a new one to my runner it started breathing heavy and puffing sticking out it's chest...now I'm scared to let then out together. I don't want them to kill one of the littler ones. Tips?