This spring I bought a "box of ducks" at an auction- turned out to have pekin, magpie, runner, cayuga, mallard ducks- 11 in all. The fox got a few and now I have 7. Later in the year I also picked up 6 muscovy ducks and they are now in the same large covered pen/run. The two groups get along fine but stay separate and even sleep apart if one group sleeps in the coop the other sleeps outside and vice versa. My question is will I need to separate them as they become sexually mature so that I don't get mules. I'm guessing from my understanding of males in general that the drakes are going to be "equal opportunity employers" so I'll probably need to separate them.