Both the Pekins and Mallard are about 2 yrs old. My mallard is a drake and I am not sure he will stick around for our next winter as he has become very friendly with a wild female. I am not sure what sex my Pekins but are or how to tell them apart I do usually get an egg a day and there have been times I got two but very seldom. One does appear slightly larger than the other but not significantly larger. The duck house is 14x16 so I believe they have enough room. I will be getting two female runners and one male. All the ducks are able to free range and go to our large pond all day and only house at night. By the way thank you for your help I am concerned about this upcoming mixing and would welcome any and all advice.