I am a new duck mama of two Rouen ducklings. They are doing very well and growing faster than I had ever imagined. They came from a straight run and I am anxiously awaiting being able to sex them as I also have chicken hens and want to be prepared to expand my duck hens if the one or both of the babies are drakes. They are starting to change from fuzz to feathers. Both are still peeping but one's peep is starting to get hoarse. It sounds just like the baby peep but like a human boy going through puberty. Any advice whether this is a sex indicator or still too early? They are approaching 4 weeks old.