How to tell boy and girl ducks or ducklings apart

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There are lots of reasons you may want to know whether you’ve got male or female ducks or ducklings. In this article, you’ll find out how to definitively tell boy and girls ducks or ducklings apart!

Entering the search query “how to sex a duck” into Google sounds like something that could land you on an FBI watch list. Fear not. When we use the terminology “sexing a duck,” we’re referring to how you can distinguish between a male vs female duckling or duck, nothing nefarious. And, no, we won’t tell the FBI on you for reading this article.

Adorable ducklings taking a nap. One of the most important considerations for pet or backyard duck parents is the sex of their ducks. In this article, you'll find out how to differentiate between male and female ducks from hatch day through maturity.

Adorable ducklings taking a nap. One of the most important considerations for pet or backyard duck parents is the sex of their ducks. In this article, you’ll find out how to differentiate between male and female ducks, from hatch day through maturity.

Sex vs gender: what’s the difference? 

First, a point of clarity: “sex” refers to reproductive organs. “Gender” refers to a critter’s sexual identification, e.g. primarily a function of the brain. Confusingly, these terms are often used interchangeably even though they’re quite different, biologically speaking.

Complex organisms are indeed complex, ducks included. And complex biological organisms don’t always line up into neat binary categories, ducks included.

For instance, our female ducks regularly have sex with each other. They also have sex with our drake. Ducks are not known for their sexual discretion, so don’t be alarmed when you see these behaviors in your mature ducks.

(See: Understanding duck mating and courtship)

Humorously, our duck Mary seems to actually think she’s a drake. She’ll regularly challenge our drake, Sir Winston Duckbill, to a duel. She often wins, sending Winston running for his life.

Mary (who we now jokingly call Marty) even has the secondary sex characteristics of a drake: green head during nuptial plumage, orange feet, and curled drake tail feather. What the heck?

Mary/Marty the transsexual duck. Even though she's biologically female, you can clearly see secondary sex characteristics typical of a male/drake Welsh Harlequin, including orange feet, green head plumage, drake curl, etc.

Mary/Marty the transsexual duck. Even though she’s biologically female, you can clearly see secondary sex characteristics typical of a male/drake Welsh Harlequin, including orange feet, green head plumage, drake curl, etc.

Turns out due to prolific egg laying in years past, Mary/Marty experienced ovarian damage. With non-functioning ovaries, her body stopped producing the hormones that made her female, so she started to revert to the default sex in ducks, which is male.

Mary’s sex is female, based on her reproductive organs and chromosomes. What’s her gender? We have no idea. She’s not saying and she doesn’t seem to care — nor do her flockmates.

See: Can ducks change sex? The curious story of Mary/Marty the duck

Our son (yes, he's been sexed) performing a bill inspection on Mawy/Mawty.

Our son (yes, he’s been sexed) performing a bill inspection on Mawy/Mawty.

Thankfully, when it comes to sexing ducks (or ducklings), most cases aren’t nearly as difficult as Mary/Marty. We’ll teach you how! 

How to sex mature ducks

Sexing certain breeds of ducks at maturity, like Welsh Harlequins, is quite easy to do with your eyes and ears, as you'll read about below...

Sexing certain breeds of ducks at maturity, like Welsh Harlequins, is quite easy to do with your eyes and ears, as you’ll read about below…

Let’s start with the easy part: sexing 6+ week old ducks:

Method 1. Vocalization check

If you’ve ever raised ducklings, you know they mature incredibly quickly. In fact, they look like miniature adults after about six weeks. At that point, you can start to tell the difference between male and female ducks using your ears.

That’s because real duck men don’t quack. Instead, drakes make more of a low, raspy blurp-blurp-blurp sound. A drake could talk as loud as it wanted in your backyard and would likely be unable to let your neighbors in on the conversation — unless you have particularly nosy neighbors.

Only female ducks make the distinctive (and loud) duck vocalizations that you think of with ducks: quack-quack-quack. Granted they actually have a far more varied and nuanced vocabulary than “quack.” When a female duck wants to be heard, your entire neighborhood will know about it.

Vocalizations are an easy way to sex either:

a) Young 6-10 week old ducks who haven’t yet earned their distinctive adult plumage. (*Watch the video “Duckling vocalizations: 12 Days old to 6 weeks old” in our How to raise ducklings guide.)

b) Monomorphic breeds like American Pekins who have nearly identical plumage regardless of their sex.

Method 2: Plumage and other physical features

Feather coloration – For older, mature ducks with dimorphic plumage (e.g. the males look different than the females), the easiest way to sex them is to look at their feathers. Drakes of most mallard-derived breeds have gorgeous green-iridescent head plumage for a large part of the year (nuptial plumage), until they go into their eclipse plumage when they look far less showy.

Female ducks within these breeds do not have green heads. However, for other breeds like Pekins (which are all-white), this distinction does not help in sexing. 

(Learn more about duck plumage and molting patterns.)

Drake feathers – While in their nuptial plumage, drakes also have “drake feathers,” a few curled feathers on the top side of their tail.

Female ducks do not have curly drake feathers on the tops of their tails.

Other physical features – Finally, some breeds — like our Welsh Harlequins — also have other physical differences at maturity. For instance, our Welsh Harlequin drake has bright orange legs and a yellow/orange bull, whereas our females’ legs are more dark grey/green in color as are their bills. These physical distinctions are not universal to all breeds of ducks.

Using the distinctions detailed above (vocalizations, plumage check, & other breed-specific sex differences), you should be able to sex a duck that’s 6+ weeks old. If you’re trying to sex a monomorphic breed, there won’t be a green head to go by, but the voice and possibly the drake feather (if they’re in nuptial plumage) will indicate their sex.

How to sex ducklings

While there may be subtle physical differences between sexes of some duck breeds, physical appearance isn't a reliable method of sexing ducklings.

While there may be subtle physical differences between sexes of some duck breeds, physical appearance isn’t a reliable method of sexing ducklings.

Now comes the harder part: sexing those adorable little duckling fuzzballs that all look nearly identical.

Methods: Down color vs bill color vs vent sexing 

In some duck breeds, there are subtle differences in down coloration between male and female ducklings. There are too many breeds and too much variability (or lack of variability) to list here. Plus, this method is not going to help you definitely sex ducklings.

As for bills: in very young Welsh Harlequin ducklings (days 1-3), a pinkish colored bill with a dark tip likely means female, whereas a darker bill likely means male. However, this method is not definitive either and only applies to one breed of duck.

The only 100% definitive way to sex ducklings of any breed is vent sexing, also called vent checking. However, it’s critical that you know how to do vent sexing safely and correctly before you give it a try. And as John Metzer of Metzer Farms says, vent sexing is best done on 1-2 day old ducklings — after that, it’s more difficult.

Warning: you can permanently injure your ducklings with improper vent check

Before we dive into the how to’s of vent sexing, we need to issue a very clear warning. If a vent check is done incorrectly with too much force or for too long a duration, you can permanently injure your ducklings. Those little parts are quite delicate!

Thus, if you don’t know how to conduct a proper vent check, please do not proceed. Let an expert — such as an avian vet — conduct a vent check for you and possibly teach you how to do it for future reference.

Vent sexing instructional video

There are also excellent online instructional videos about how to sex ducklings. We’d highly recommend watching this Metzer Farms’ video about vent checking before you consider doing the procedure yourself:

*For reference, Metzer Farms sexes tens of thousands of ducklings per year, so they likely have more experience sexing ducklings than anyone else out there.

How to vent sex ducklings:

A duck’s anal vent, aka cloaca, is where their reproductive organs reside. However, in ducks/ducklings, neither the male penis nor the female vagina is visible with a mere surface inspection. Hence the need for a deeper look…

When doing vent sexing, you’re NOT trying to pop the [potential] drake’s penis out by pushing on the area around the vent. Instead, holding the duckling upside down in one hand, use the fingers of your other hand to gently pull back (not pushing or applying pressure) on either side of the vent in order to open the vent and expose the reproductive organs below.  

Note: Your first time out, this process may be easier with two people — one to securely hold the duckling, the other to do the penis hunting (ha!).

If you spot a drake penis (which looks like a small, light-colored worm), you’ve got a male. No penis = female.

If you’re vent sexing a bunch of ducklings, you should end up with about a 50/50 ratio of males to females. If not, you’ve likely not been very accurate your first time around. If so, don’t feel bad – it takes a lot of practice to get really good at vent sexing.

Post-sexing: what next? 

If you want to keep track of your male and female ducklings after sexing them, you can either:

a) separate them into separate flocks immediately after sexing, or
b) keep both sexes together, but place a zip tie around the ankles of one of the sexes, clipping off the excess tie.

Warning: If you use zip ties, you have to pay very careful attention as the ducklings’ ankles grow so you don’t end up cutting into the skin with the ties. Remove and replace zip ties as your ducklings grow.

For backyard or pet duck parents, we recommend either not having any drakes or having no more than 1 drake per every 3-4 females. Or if you’re not interested in eggs and are instead interested solely in having good pet ducks with lower potential for medical problems, having a small, all-drake flock could be a good choice for you.

Read more on this topic in our article: Should I get male or female ducks… or both?

Now you know how to sex male and female ducklings and ducks, regardless of their age or breed!




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  • Reply
    August 26, 2022 at 1:27 am

    Oh good lord. They are ducks. They are male or female. End of story.

    • Reply
      Aaron von Frank
      August 26, 2022 at 10:27 am

      Usually, but not always. Nature throws curveballs as we detail in our article: “Can birds change sex? The curious story of Mary/Marty the duck” –  

      Mary is one of our ducks but lots of other duck and chicken owners have contacted us to tell us they’ve experienced a similar phenomenon in their flock. In Mary’s case, she no longer has a functional ovary, which means no oestrogen release. Since there’s nothing suppressing the male genes on Mary’s Z chromosome, she’s at least partially reverting to the default sex in ducks/birds: male. Biologists have seen this happen to birds in nature as well, with some female birds even developing testis once their vestigial ovary masculinises. According to the BBC, in at least one case, a previously female chicken became a male and sired viable offspring.

      There have also been cases in nature where individual birds are even “gynandromorphic,” meaning they are both male and female within the same body. In such cases, the secondary sex characteristics are split right down the middle of their bodies — one side of the body appears male, the other female. 

      While these conditions certainly aren’t the norm in bird populations (whether wild or domestic) they are a reality. It’s strange to us that some humans get emotionally bent out of shape/angry about such things. Do you mind sharing what it is about these situations that makes you uncomfortable?  

  • Reply
    July 1, 2022 at 4:23 pm

    Rancid waffling about gender dysphoria and a transexual b.s narrative just talk about ducks and not your gay lifestyle please

    • Reply
      Aaron von Frank
      July 2, 2022 at 8:16 am

      I’m sorry this information is upsetting to you. Our article is exclusively about ducks, not humans, and interspecific translations are generally inadvisable between species as different as ours. If you have a better biological explanation than the one provided as to why one of our female ducks who suffered ovarian damage soon began to take on the secondary sex characteristics of a male/drake when her body stopped producing female hormones, you’re welcome to share it here. Was this a transexual “lifestyle” choice for our duck? The abandonment of previous generations’ duck values?          

      When descriptions of real world biological phenomena make you angry enough to leave a comment like this, perhaps it’s best not to lash out and instead reflect on deficiencies within your own understanding. (We all have such deficiencies, but we don’t have to maintain them in the face of new information.) After all, biological facts have no obligation to comport to anyone’s belief system, but we each should continuously mold our belief systems to comport with biological facts.   
      Lastly, I’m not gay (nor do I consider that to be an insult), but the term “gay lifestyle” is about as absurd as the term “heterosexual lifestyle.” What’s the operational definition of a gay lifestyle anyway?

  • Reply
    None your business
    April 17, 2022 at 7:50 pm

    Does nobody else read this as nothing more than a WOKE article – there is really a difference between sex and gender? Are there two brain cells working together here? What morans…

    • Reply
      Aaron von Frank
      April 18, 2022 at 12:00 pm

      Our ducks are politically agnostic, as are we. We don’t generally subscribe to or care much about the various peculiarities of right-left American political binaries, which seem to be getting ever more extreme and inhospitable to other perspectives. Our primary allegiance is to what constitutes measurable, observable reality.

      In this case, we’ve described our experience with a duck in our flock who is exhibiting the secondary sex features of a male despite being (most likely) genetically and chromosomally female. We’ve also offered a best guess hypothesis and supporting evidence for what might be causing this outcome (which is far from unique based on our conversations with other people who raise poultry). If this information is offensive or triggering to you, then you might: a) ask yourself why that is, and b) consider what would then cause you to decide that the best next course of action is to lash out with animus rather than attempting to further the conversation with level-headed counterfactuals or additional data.    

      As for the differences between gender and sex, this is not simply our interpretation. For example, the American Medical Association (AMA) states: 
      “… the terms sex and gender are not synonyms. Sex refers to the biological differences between males and females. Gender refers to the continuum of complex psychosocial self-perceptions, attitudes, and expectations people have about members of both sexes. Even the terms male and female, man and woman are not interchangeable. What it means to be male or female originates from physical characteristics derived from sex chromosomes and genes that lead to certain gonads, internal and external genitalia, and physiological hormones. Being a man or a woman holds broader meaning, with cultural concepts of masculinity and femininity coming into play.”
      Obviously, humans and ducks are different species so a duck’s notion of gender is not directly analogous to a human’s notion of gender given the comparable robustness of our mental circuitry and linguistic capacities. Nature is odd, interesting, and imperfect. Humans and ducks can be born with unambiguous genitalia, hermaphroditic, with odd chromosomal pairings, etc. If discussing or describing these realities makes someone uncomfortable, that discomfort might best be understood as an intellectual deficiency of the discomforted rather than the absence of brain cells of those bringing the information to light in order to further our collective understanding. 

      Also, it’s hard to resist pointing out that “morons” isn’t spelled “morans.” Typically, I wouldn’t point out such errors, but in this case it’s hard to resist the temptation. 

  • Reply
    Jude Crocker
    September 28, 2021 at 9:14 pm

    Hi! I’m Jude and i’m a kid but i do truly love ducks. is it possible that the 2 female ducklings i ordered from Metzer are actually boys?

    • Reply
      Aaron von Frank
      September 29, 2021 at 12:29 pm

      Hi Jude. It is technically possible that Metzer Farms sent you two males instead of two females but it’s VERY unlikely. They’re quite good and experienced at sexing ducklings. We’ve always had 100% sexing accuracy with our Metzer ducks. Is there something happening that makes you think yours are males?

      • Reply
        Jude Crocker
        September 29, 2021 at 11:23 pm

        well, my 6 week old welsh harlequin is developing orange feet and she doesn’t have a black beak yet.

        • Aaron von Frank
          September 30, 2021 at 12:52 pm

          Metzer doesn’t necessarily breed ducks for breed standard, and a secondary sex characteristic such as orange feet in a juvenile doesn’t necessarily indicate the sex of the duck. One thing that will be a dead giveaway for sexing your ducks at 6-8 weeks is the voice. You should be getting some proto-quacks from your ducks if they’re females. The males don’t make the stereotypical duck quacking sound, they sound more raspy and almost frog-like in their vocalizations. Are you hearing the beginnings of quacks in your ducks yet?

        • Jude Crocker
          September 30, 2021 at 5:43 pm

          YES!!! but they dont sound anything like male quack. thank you guys for your attentive looking at comments! You guys are so kind and you helped me SO MUCH with my sweet little ducky girls! God bless you!

        • Aaron von Frank
          October 1, 2021 at 6:52 am

          Glad to hear that, Jude! You’re very welcome. Reach out any time you need duck help. 🙂

  • Reply
    Miranda Rienzo
    July 21, 2021 at 11:03 am

    Hello and thanks for the post, I have a mixed flock of ducks (Rouen , pekin, welsh harlequins and Ancona). We have 2 Ancona and 1 Rouen who are quacking (and I swear the other Rouen was quacking but stopped). All the rest aren’t quacking but don’t sound like the males noise either. They are roughly 7-8 weeks old. Is it possible that they may just develop slower than others or am I unlucky enough to have 7/9 ducks end up being males? One pekin has a drake feather, other one not quite yet, 2 harlequins are completely different colours and can’t tell from feathering. They sound more like they have wheezy peeps still but not that low raspy male sound

    • Reply
      Aaron von Frank
      July 21, 2021 at 12:19 pm

      Hi Miranda! That transitional period is a tough age in which to accurately sex ducklings/ducks. Unfortunately, the only thing you can do at this point (without risking injuring them) is to wait and see. Yes, it is a roll of the dice when you hatch duck eggs or don’t get a sexed run, and some times things don’t come out in your favor. For instance, the very first ducklings we picked out years ago turned out to be 3 males and one female. That’s why it’s often a good idea to order sexed runs unless you actually want to have multiple drakes for some reason (breeding, meat production, etc). Doing so requires separate caged runs and either separate coops or partitions within a coop otherwise they’ll really start going after each other if you have females around to prompt competition for mates. Best of luck!

  • Reply
    May 21, 2021 at 9:10 am

    thanks so much now i know my duckling is male your the best Kevin

  • Reply
    Kevin Scott
    February 1, 2021 at 3:11 pm

    Thanks for the article on sexing ducklings. I have not yet jumped into the pond with ducks yet !
    I currently raise heritage turkeys and chickens.
    I am working towards a small flock of ducks, and while doing my due diligence came upon your site with the article on your bio filtration pond.
    I cannot wait for warm weather – so I can start on the pond.
    I will definitely be following your site.
    Thanks again!

    • Reply
      Aaron von Frank
      February 2, 2021 at 2:06 pm

      Thanks for leaving a note, Kevin! Best of luck in your duck raising ventures, and reach out any time we can be of help. We’re sure looking forward to warmer weather, too.

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