Ducklings come in many colors, from plain yellow to tones of buff and gray intersected with black markings. With only one exception -- the golden hybrid 300 -- down lends no clue to a duckling's gender. If you order baby ducks from the hatchery, they may come with colored tape on their leg that differentiates the boys from the girls. Ducklings purchased individually at a feed store or hatched them at home display a few natural cues to let you know which are boys and girls.
They'll Tell You Themselves
Listen closely to your ducks to know who's who. Female ducklings tend to be noisier than males and have a higher activity level. By 6 weeks old, females are louder and make distinct quacks while males at this age sound raspy and low key. Put a piece of colored masking tape on the leg of your loudmouths. If they tend to be the loudest in the group over the course of several days, they're most likely females.
Down coloration is usually the same in ducklings of either gender. The exception is a sole breed, the golden hybrid 300, where ducklings are black if they're male and brown if they're female.
By 4 to 6 weeks, male ducklings look significantly larger than female ducklings. Their legs are thicker and they appear to stand taller than females due to their size, especially in breeds with upright body carriage such as magpie and runner ducks. In some species such as mallards and Pekin, a curled tail feather easily differentiate the boys. Pekins also have a single black feather on their white bodies, which you can find on their back under their wings.
Check the Vents
Vent sexing is an accurate way to tell a duckling's gender as early as a day old. The procedure involves extruding a male's penis from the vent opening to tell gender. Have your farm or avian vet show you how to do this before attempting it yourself to avoid accidentally injuring your duck's genitalia.
Consult a Professional
Your avian vet also can perform endoscopic examination of your ducklings fiber-optic imaging equipment. The vet administers anesthetic and inserts the endocope into one of the bird's abdominal air sacs. The sac's membranes are clear, allowing the vet to see a single ovary or pair of testes. A less invasive way to tell sex scientifically is to send a bit of eggshell or a feather to a DNA testing lab. Either method costs more than the price of the average duckling.