This is my first experience with any ducks, and like so many others new to ducks, I am anxious to know if I have male or female. I have two groups of Muscovy. The older ducks are about 9 weeks old and the younger are about 4 weeks. How old are they when the males definitely outgrow the females. Some from the older batch were brooded elsewhere. They were exposed to a bacteria or something that stunted their growth making it really difficult for me tell simply judging by size. So, if one hisses at about 9 weeks, can I be sure it's a male? If one the same age squeaks, can I be sure it's a female of will the males still squeak once they've started hissing? Any tips will be greatly appreciated! Thanks!