How to Know the Gender of a Duck
Ducks lay eggs nearly every day until the duck feels she has laid enough for a full clutch. A full clutch is between eight and fifteen duck eggs. Once there is a full clutch, the female duck will sit on them until hatched. After hatching, the ducklings are lead to the water. Sexing a duck requires listening and looking. The female and male ducks has a different quack. Also, tail feathers of the drakes are different for male and female ducks.
Get the duck to talk by bribing it with treats. Ducks are vocal creatures, so rewarding the duck for quacking should be fairly easy.
Listen to the sound of the duck's quack when the duckling is 10 weeks old. The female quack is loud and the make is like a whisper.
Look at the tail feathers of the duck. If the duck has curled tail feathers then the duck is male.
Pick up the duck and turn it upside down. Venting is picking up the duck, turning it upside down, looking at its genital vent and making a determination from what you see. Female ducks have cone shaped genitals.