Welsh Harlequin/Silver Appleyard Duckling Genders

[alofthus]

Hi all,
A person near me has 2 month old Welsh Harlequin/Silver appleyard mix ducklings that I am very interested in getting. However, I am only wanting females, and they don't know their gender. Does anyone have any good guesses as to the gender of these guys- if it is even possible to tell from a picture?

Thanks in advance, I am fairly new to ducks and only have three of my own so far