I have three Call Drakes and 22 Hens of all sizes, only three of them are Calls. Two I incubated my Call's eggs and hatched out myself and luckily got two more girls. My Call drakes will mate my Khaki Campbell, large Rouen duck, Mallards and anything else in the pen they can get ahold of. I had someone tell me that theirs mated a Blue Swedish duck and made fertile eggs as it was the only male duck in their pen and the eggs hatched. Mine love to chase all and any of my girls. My two babies that are only a couple of months old are separated from them so that they do not hurt them trying to mate them. Mine were about 6 months old when I first got them and had traded large drakes for them so that my girls would be safer. It works out well for me. I found mine on Craigslist along with my Black East Indies babies that all three turned out to be females. Good luck with yours.