Fuzzy yellow ducklings don't have to do anything to be adorable, but once you've watched one run for the water and cannonball in, you're bound to be hooked. It's next to impossible to tell a boy duck from a girl duck when they're babies and, depending on what breed you have, it still might not be obvious once they mature. Thankfully more than one way exist to tell if a duck is a boy or a girl.
The easiest and most obvious way to determine the gender of a duck is by the feathers, providing you're dealing with a breed that displays sex-distinguishing colors. A prime example of this is the mallard breed, in which the females are mostly brownish and gray while the males display a rich chocolate color on their chests, a white "collar" around their necks and distinct dark green feathering on their heads. Another clear example is the long-tailed duck, in which the males and females have dark heads. The male long-tailed duck has gray feathers around his eyes, in contrast with the female's white eye feathers that extend in a fine strip toward her ear. If there is no obvious difference in the coloring of the plumage, feathers can still help indicate if you're looking at a boy or girl duck: Just check out the tail feathers; in some breeds, the males' feathers curl up a bit right at the base of the tails.
If you're unable to distinguish any differences between two or more ducks, take a look at their sizes. Even when there are no plumage variations between sexes, the male ducks tend to be a bit bigger than the females.
Some duck breeds in which the males and females look alike give away their genders during certain seasons, like breeding season. One such breed is the freckled duck. The males and the females have identical feathers, but the male sports a red color on his bill during breeding.
When you can't tell a boy duck from a girl duck just by looking at them, close your eyes and let your hearing make the determination. Young ducks under 6 weeks old pretty much all sound alike. As they mature, however, female ducks develop a more distinct and loud quack, while male ducks quack softer and quieter.
Check the Vent
Ducks' reproductive organs are inside their bodies, so telling the boys apart from the girls takes a little more expertise if you're attempting to make a distinction based on the plumbing. Still, it's possible to roll a duck over and turn its vent outward so you can see the organs. Unless you've had experience doing this, checking a duck's vent to determine gender is best left to the vet.
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