I go the opposite way with my ratio, at least early season. I hunt over a 60/40 hen to drake combo. I asked a refuge manager years ago, what is the first duck you see when doing arial surveys? He said a black mallard, which surprised me. But he said nothing is that dark and the contrast sticks out like a sore thumb. He said you can spot a black duck from miles away. So i always throw black ducks out in my spread.