An easy way to tell male from female (for me) is their quack at a younger age like your two are. The drake will whisper and the females will have more of a pronounced quack. I have raised duck for years so I have gotten pretty good at it. The hens of a Cauyga will have the shine to them as well. Another way to tell is by their tail feathers. Males get the curel.(sp) I am not sure on all domestic brreds if they get that?? I raise flying mallards and have had domestic in the past but love the mallards more.

 

Good luck

Goldy_