My crested ducks are young, about 5 weeks old. They are fully feathered and I'm wondering when I should be able to tell their genders.. There is no curl on neither of their tails, but would it show up by now? Just making sure because I just got a rouen drake today and I don't want any troubles when the crested ducks get older. As for the pitch of the quack, the smaller one sounds more quacky and the larger one still has a higher cheepy voice. Neither don't sound like the drake, who has a deep quacky voice.