I have a mixed flock. I started with a doz Rhode Island reds and rooster for egg production but I caught the chicken obsession and got hooked on the different colored eggs so I bought two doz hatching eggs which were chickens and ducks. Only one duck made it through so I bought 5 khaki Campbells and added them to the flock, and then sold the roosters. The ones that stayed went in an adjoining stall but were able to share the same pasture but just sectioned off with chicken wire. They were able to see and hear each other before I transitioned them together in the same coop. Now I did two new rounds of incubating and have 5 ducks and 17 chickens that I’ll do the same type of transitioning with. I love my mixed flocks and breeds. It’s a little more work but if you transition them right they’ll be good 
