I have 3 Khaki ducks. I've been told that I have a female and two males by a friend (only by hearing them) and the seller had ordered a straight run, so she was unsure of the genders. One is crazy vocal (quacks and honks) the other two whisper/hiss. The one that quacks has rounded, dark brown flight feathers while the other two have squared, almost black flight feathers. Is there a trait in the feathers with specific genders?