In the first 2 to 3 days after ducklings hatch, you might be able to guess their gender based on the color of their bills. Typically, female ducklings have pink bills with a darker tip, while male ducklings have darker bills overall. However, this difference doesn’t last long. Within a few days, the females' bills darken quite a bit, and the males' bills may lighten slightly. By the fourth day, the bill colors become so similar that it’s nearly impossible to tell them apart by appearance alone.
After that point, the best way to determine their gender is by listening to their voices, which becomes possible around 4 to 5 weeks of age. Female ducks develop a loud and clear "quack," while males usually make a softer, raspier sound. So, voice is generally the most reliable method for telling male and female ducklings apart.
Around 5 to 6 weeks of age, my Welsh Harlequin ducks began developing the bill colors that indicate their gender and maturity. My ducks will be seven weeks old tomorrow.
