It has been a while since I had ducks but I do remember that the females quack and make a lot of noise and the males are rather quiet.
The males will get a curly tail feather. I just don't remember at what age all this occurs.
Well, I was just fooling around with them and I picked one up and it was going peep peep peep... and all of a sudden it's voice went very low and sounded like a honk or quacking sound. Is this a female? One other has a voice that sounds like it has a cold and it's raspy voice. Is this a male most likely?