Swooning for the Snood

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How do you choose your turkey? It might be by weight. Perhaps it is from a favorite farm. Or it could be a brand that you like. But if you were a female turkey, you’d be looking at the snood.

The snood is a fleshy appendage that attaches just above the beak. When tom turkey is just chilling, his snood can be fairly short, but when he struts for the ladies his snood engorges with blood and hangs awkwardly off his bill. It’s a hen head turner.

This bit of bird bling-bling would probably make Mr. Darwin smile with thoughts of sexual selection. Darwin was first to suggest that mate choice and competition for mates might be a selective pressure that shapes the evolution of populations. If this is true, why would female turkeys prefer a big snood? Is this simply a sexy ornament or is it perhaps a signal of worthiness?

Richard Buchholz, a biologist from the University of Mississippi, pondered these very questions and Wild Turkeys proved to be a perfect study animal. Males mate with multiple females (called polygyny), and the sexes look very different (sexually dimorphic). Buchholz designed some fancy mating tests, checked out the health of the males, and eureka, the answers to snood fashion were discovered.

First, Buchholz found a non-sexual function for the bare parts on the head. They are crucial for cooling down strutting tom when he is exerting himself on a hot day. Snood or no snood, he needs his radiator. So there is a clear physical reason for the bare skin. But that still doesn’t explain the long snood.

He did show that a long snood is indeed selected by females, but males also select for it. Females were attracted to a long snood and males deferred to other males with longer snoods. But what is it about a long snood? What does it signal? Healthy, wealthy or wise?

It turns out that the longer the snood a male has the fewer intestinal parasites he carries. Long snooded males are more resistant to parasitic infections. Buchholz suggests that if this is true, it might be a case of females choosing males with good genes. And males that are free of parasites are probably more dominant over other males. Short snooded males that defer to long snoods might be able to assess the competition before fighting with them and avoid wasting energy in fruitless fights that they are sure to lose to the healthier snood.

Enjoy the snood and have a Happy Thanksgiving.

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