Why Do Ducks Have Corkscrew-shaped Penises?

Duck showing off its corkscrew penis

The duck penis is an unusual physical trait that sets ducks apart from other birds, like chickens, which typically lack such an organ. 

Interestingly, it has a corkscrew shape, which perfectly matches the female duck’s reproductive tract. To learn more about this distinctive trait, check out the rest of this comprehensive guide!

What Do Duck Penises Look Like?

A duck facing backwards with its penis visible

A duck’s penis is spiral-shaped, like a corkscrew. It’s long for a bird, sometimes as long as the duck’s body. When not in use, it’s tucked inside the body and only extends during mating.

The color of a duck’s penis varies from pale to dark, and it typically blends with the duck’s overall coloring. The surface texture is slightly ridged, which enhances its corkscrew shape. 

Most ducks grow a new penis every year. I’ve witnessed this cycle first-hand while working with waterfowl at a wildlife conservation center, 

During mating season, their penises were impressively as long as their bodies. Intriguingly, these organs shrink and degenerate after mating season, only to regrow even more elaborate in shape by the next year. 

Check out this video showcasing how long and quirky-shaped duck penis is:

Explosive eversion of a duck penis.

Why Do Ducks Have Corkscrew Penises?

Duck penises have evolved into corkscrew shapes as a direct response to sexual competition and complex mating scenarios. 

This unique structure is a result of evolutionary pressures over thousands of years, where reproductive success dictated physical traits.

Patricia Brennan, a distinctive evolutionary biologist, reveals key insights into this phenomenon through her research

In environments with high male competition, such as with lesser scaups and ruddy ducks, males adapt by growing longer, more elaborate penises. This adaptation is required for fertilizing eggs amidst intense competition.

To be specific, when lesser scaups were forced to compete, they developed significantly longer penises compared to when paired off. This change was directly linked to the need to outcompete rivals in mating. 

Meanwhile, ruddy ducks, known for their large penis-to-body ratios, showed varied responses. 

In a competitive group of ducks, larger males grew longer penises, while smaller ones sometimes only grew stubs, likely due to stress and hormonal impacts.

How Do Ducks Mate With Their Corkscrew Penises?

Male duck using its penis to mate

When ducks begin mating, the male positions himself on top of the female. He must align himself precisely, as the mating process is quick and requires exact positioning. 

Once in place, the male extends his penis at an astonishing speed to ensure it can effectively navigate the female’s reproductive system.

The female duck’s reproductive tract has its own twists and turns designed to make mating selective. This structure allows females to have more control over which males successfully mate with them. 

As mentioned, the male’s corkscrew penis evolved as a countermeasure to this selective process, which ensures that his genes have a chance to be passed on.

During the actual mating, the male’s penis unfurls into the female’s tract, depositing sperm in an effort to fertilize her eggs. This whole process guarantees that only the most fit and adaptable ducks reproduce.

Fun Fact: While many duck species are monogamous during a breeding season, they’re not the “mate for life” kind. 

Each year, ducks are on the lookout for a new partner and they choose the healthiest and strongest mate to ensure their ducklings inherit the best genes. 

This annual search for the perfect mate is linked to the evolution of the duck’s unique corkscrew penis.

Why Do Ducks Have Penises, Unlike Most Birds?

Unlike most birds, ducks have penises because of their unique mating practices. 

While most birds mate through a brief touch, ducks engage in more physical mating. This difference led to the evolution of the duck’s penis.

Most birds reproduce using a process called “cloacal kissing,” where they briefly press their cloacas together. In this system, there’s no need for a penis. 

Ducks, however, have evolved beyond this method due to their complex mating behaviors and environments.

Ducks often mate in water, which can be challenging. The penis helps ensure successful mating in these conditions. 

Additionally, the elaborate structure of female duck reproductive tracts has driven males to evolve penises to navigate these mazes effectively.

The Role of the Duck Penis in Mating

Duck sideview with its visible penis

In duck mating, the corkscrew duck penis is essential to navigate the complex structure of the female’s anatomy. This design also ensures effective fertilization in their aquatic mating environment.

The corkscrew shape of a duck’s penis facilitates deeper penetration, which is a factor in increasing the chances of successful fertilization. 

In the often turbulent waters where ducks mate, this design ensures that the male can quickly and effectively connect with the female and make the most of the short mating opportunity.

Furthermore, the male’s ability to extend and retract the penis rapidly is an essential aspect of duck mating. 

This rapid action minimizes the time needed for mating, which is important in a natural setting where lingering can expose ducks to predators.

Did this guide answer your questions about duck penises? If you want to share your thoughts about this article or ask questions, feel free to leave a comment below!

Leave a Comment

You may also like