Arms Race in My Barnyard

by Scott Smith

Our little flock of ducks has been a real education for all of us. The spring has provided a lot of opportunities for conversations about what ‘no’ means (‘no’ means ‘no’). This morning I was surprised by a rather extended glimpse of the male duck anatomy. All I can say is, I had NO idea. I did a quick search and I found this fascinating article by Maggie Fox of Reuters. Apparently even ‘Mother Nature’ believes that females should be able to control their reproductive lives…

Brennan noted that in many species, females choose a mate after he puts on an elaborate courtship display, and breeding pairs are often monogamous.

An exception is ducks — especially mallards. Although mallards pair off to mate, females are often raped by stray males.

Yet studies show that these rapes do not pay off for the males. “Even in a species where 40 percent of the copulations are forced copulations, the ducklings still are mostly sired by the mates,” Brennan said.

There’s an excellent reason for this, or at least a strong theory…

What they found surprised them — corkscrew-shaped oviducts, with plenty of potential dead-ends.

“Interestingly, the male phallus is also a spiral, but it twists in the opposite, counterclockwise, direction,” said Yale ornithologist Richard Prum in a statement.

“So, the twists in the oviduct appear designed to exclude the opposing twists of the male phallus. It’s an exquisite anti-lock-and-key system.”

Brennan believes females evolved convoluted oviducts to foil the male rapists.

Only if the female is relaxed and cooperative can the male’s sperm get anywhere near the unfertilized eggs, the researchers suggest.