I have observed the same: The young ducks often run around the drakes, head-bobbing until i feel dizzy. And the drakes are more interested in the older ducks.I would be careful letting young females with an adult drake some will leave them alone others won’t we see it often on here so you just never know. My Runners and Buffs were mating at 4 months old laying at 4.5 months. The girls were the ones to go after the drake not him after them.