Mallard ducks make hardy, easy-to-keep additions to your backyard pond or poultry yard. Adult males are easy to spot with their bright green heads, and females by their blue wing stripes. Mallard ducklings look identical at first glance, but close observation can give you a clue to gender. Vent sexing, meanwhile, leaves no doubt.
Female ducklings are generally more active and noisy than males. Males tend to hang back, rest more and vocalize in low rasping tones. You can place a piece of colored tape around the legs of your noisiest, most active birds and check your observations for consistency over several days. If the tagged birds are noisy for days, they're likely females.
Each duckling has an "eyeline" in the down that bisects the eye horizontally. The line is less prominent in females; the males' are sharp black. Female down tends to be a bit softer than the males' and may appear brighter in color before the feathers come in.
You can also vent sex mallards by turning them belly-up in your hand and pressing lightly on their stomachs just below the vent and along each side, using three fingers. If you do it correctly, you will be able to discern a male's penis. Wear latex gloves and rub the vent in a circular motion with petroleum jelly prior to pressing, to help the duckling relax. Be careful not to injure the duckling.
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