An interesting piece of oddity from yesterday’s New York Times.com:

[…]Dr. Brennan was oblivious to bird phalluses until 1999. While working in a Costa Rican forest, she observed a pair of birds called tinamous mating. “They became unattached, and I saw this huge thing hanging off of him,” she said. “I could not believe it. It became one of those questions I wrote down: why do these males have this huge phallus?”

A bird phallus is similar—but not identical—to a mammalian penis. Most of the time it remains invisible, curled up inside a bird’s body. During mating, however, it fills with lymphatic fluid and expands into a long, corkscrew shape. The bird’s sperm travels on the outside of the phallus, along a spiral-shaped groove, into the female bird.

To learn about this peculiar organ, Dr. Brennan decided she would have to make careful dissections of male tinamous. In 2005 she traveled to the University of Sheffield to learn the art of bird dissection from Tim Birkhead, an evolutionary biologist. Dr. Birkhead had her practice on some male ducks from a local farm.

Gazing at the enormous organs, she asked herself a question that apparently no one had asked before.” So what does the female look like?” she said. “Obviously you can’t have something like that without some place to put it in. You need a garage to park the car.”

The lower oviduct (the equivalent of the vagina in birds) is typically a simple tube. But when Dr. Brennan dissected some female ducks, she discovered they had a radically different anatomy. “There were all these weird structures, these pockets and spirals,” she said.

Somehow, generations of biologists had never noticed this anatomy before. Pondering it, Dr. Brennan came to doubt the conventional explanation for how duck phalluses evolved.

In some species of ducks, a female bonds for a season with a male. But she is also harassed by other males that force her to mate. “It’s nasty business. Females are often killed or injured,” Dr. Brennan said.

Species with more forced mating tend to have longer phalluses. That link led some scientists to argue that the duck phallus was the result of males’ competing with one another to fertilize eggs.

“Basically, you get a bigger phallus to put your sperm in farther than the other males,” Dr. Brennan said.

So ducks grow big long, corkscrewy, um, duck dongs, in order to best other male ducks!!! It’s all a quest to be the one to be able to say he blew the back out of some poor female duck.

*I love crispy duck, but in the future, I’m going to be a bit more attentive to those extra pieces of unidentifiable crunchy skin.

NY Times.com: In Ducks, War of the Sexes Plays Out in the Evolution of Genitalia