Back to the original post, sexing young mallards is not as hard to sex as some other birds. Someone mentioned that ducks will quack. Drakes make a more raspy sound. Additionally, ducks will often develop a mottled colored bill (usually orange and brown) while drakes have a solid green bill sometimes with a balck bean on the end. I knew an older gentleman who would pick up a bird and give it a gentle shake to hear it make a noise and would regularly sex birds by that. It's not that difficult to do. Hope this helps and gets back to topic.