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Duck Birth Control

December 28, 2009

We’re both biologists, but we didn’t pay much attention to ducks until five mallards moved into our pond last spring. At first, the ducks (three males and two females) kept to themselves, each staking out a little smidgen of our puny pond as its own. They ate—sticking their cute little duck butts up in the air—and paddled around quietly, confirming our perception that ducks are cute, but not all that interesting.

And then things got interesting—and ugly. One of the females disappeared, leaving three males and just one female. The randy males chased the seemingly helpless female around the pond, across the lawn and even into the air. For days, they quacked and pecked at her until they finally tackled her in the water. There was a whole lot of splashing and a frenzy of quacking and flailing wings as the males forced the female underwater. This was what duck researchers call “rape flight”—what most people call “gang rape”—and is apparently quite common for mallards.

After the rapes, the ducks disappeared. We were fairly sure the female was dead, but a month later a female mallard with 12 ducklings started traipsing around in the tall grass by the pond. Was it the rape victim? We have no idea, but recent research from Yale University scientists suggests that the ducklings were not the product of rape.

While other species engage in sperm wars, ducks face off in a war of genitalia. Most birds don’t have penises, but ducks…well, ducks are different. To score in rape flight, male ducks have evolved a foot-long penis capable of going from flaccid to erect in less than half a second. To fight back, female ducks have coevolved a spiraled vagina that prevents the “explosive” erection of undesirable suitors (i.e. rapists). Read all about it here.

One Comment leave one →
  1. December 29, 2009 10:20 am

    Very strange and interesting stuff. I heard about this very thing on Radiolab last year. Full disclosure: I’m not trolling for them, I just find their radio show fascinating. The aforementioned episode, called “Sperm” (at exposes other peculiarities about different species and how they have evolved to manage reproduction.

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