I have 2 drakes and 3 ducks. It's now autumn and they are all from end of May hatch. They are all mating, and drakes are not too aggressive at this point. If one mounts a hen, the other one goes away. I'll be ready to intervene in the spring, if that changes. One of the drakes acts dominant and the other one is very submissive and doesn't even try to argue with the leading drake - in fact, he follows him everywhere even when the hens refuse to do so. The funny thing is, he's more liked among the ladies and especially one is doing her best to show affection all the time. Usually the alpha drake uses that to his own advantage.