Other Sexing Methods
Step 1Listen to the ducks' voices at one month of age. Females will have a loud quack; males have a softer cluck.
Step 2Check the ducks' tail feathers when they are two months old. The males will have a distinct curled feather at the tips of their tails that will be present even if they have molted for the summer.
Step 3Look for extravagant plumage. Males of the mallard-type northern duck species have brightly colored feathers in the winter, but beware: they molt in the summer, adopting a more feminine appearance.
Annie, have just lifted this off the internet so it looks as though they have to be a month old at the earliest before we can sex them. Fingers crossed they are all girls!