Instructions
Hold the duckling upside down in your right hand so that its feet are pointing away from you. Gently hold the tail up with your left hand.
Press in and upward between the ducks legs to expose the vent area. Gently and carefully apply a small amount of pressure to open the cloaca and expose the genitalia. Be careful not to apply too much pressure and avoid inserting any instruments or fingers into the vent, as this will cause serious harm to the duck's sexual organs.
Determine the gender by observing the genitalia carefully. Generally, a female will have a cone-shaped organ, while the male's will appear more elongated and may not show up until several seconds after the vent has been opened.
How to Tell If a Duckling Is Male or Female
Although it is easier to determine the gender of a mature duck, there are a few ways you can figure out whether your ducklings are males or females. While venting is the most accurate method, it can be quite uncomfortable for ducklings and potentially harmful to their sexual organs if not done properly. Even with venting, it is sometimes necessary to wait until the ducks have matured for at least a few months before attempting to determine their gender; the organs of a younger duck can sometimes appear ambiguous to the untrained eye.