I have three butterscoth call ducklings I hatched out this summer (around 6 weeks old already!) Two of them are I am giving to a friend, so I want to add a white and malard drake. I would like to incubate 3 eggs of each color and give away what I don't want when they hatch. Is there anyway to sex them when they are young or do I have to wait till they fully feather out and begin to change colors?