I will not get into vent sexing as you can hurt the duckling. If you have a good eye you can sex looking at the legs of the ducklings. The males will look like over grown monsters with tree trucks for clumsy legs. The females will be well suited to the size of their legs. Females will grow their wing feathers first. So much so that the males will still have featherless stubs while the females are well on their way to having wings. I hope this helps you all sex your ducklings this fall.