The easiest and earliest way to tell a duck's sex is by the quack it makes.After the 'squeeking' stage'Ducks will begin to get their adult voices-Hens quack LOUDLY while Drakes are MUCH quieter with their low vocalizations.If your duck is LOUD - it's a GIRL! Your's look too young to have developed a 'DRAKE-FEATHER' a tail feather (or two) that curls upward - a SURE sign that he's a boy.