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Summer 2012
Cranes dancing in courtship. Photo by Manjith Kainickara

Sandhill cranes are majestic, iconic birds—a species carefully saved from the brink of extinction through concerted conservation efforts. But with the state population up to more than 20,000, some Wisconsinites are calling for a regulated hunt, citing damage the birds do to the state’s corn crop. State Representative Joel Kleefisch (R-Oconomowoc) and others also tout the quality of their meat, calling sandhills “the ribeye of the sky.”

But a federally funded study led by CALS animal sciences professor Mark Berres suggests that policymakers should look at more than the number of birds. A recent analysis of the crane’s Eastern population—birds that spend their summers from the Midwest to the East Coast—indicates we should also consider the distribution of the bird’s genetic diversity.

“The genetic structure of the entire population is anything but uniform,” says Berres, who used DNA fingerprinting to assess the genetic makeup of cranes across the Eastern population’s range. While Berres found a surprisingly good amount of genetic diversity throughout the population and quite a bit of genetic mixing, there also were a significant number of isolated subpopulations, including some in Wisconsin.

These isolated groups of birds possess unique genes that could prove vital to the species’ longterm resilience, perhaps giving the birds the ability to survive new diseases or adapt to changing environmental conditions, Berres explains. But because these subpopulations are relatively small, they are more vulnerable to hunting pressure.

“If people start harvesting them, I’m not sure how stable these local populations will be,” says Berres. “It’s possible that if hunters are allowed to take 20 percent of the overall population, they could inadvertently take 99 percent of a particular subpopulation.”

From a low of just 25 mating pairs in the late 1930s, as estimated by famed naturalist Aldo Leopold, Wisconsin’s sandhill crane population has rebounded thanks to a number of factors, including habitat conservation, increased farm acreage and protected status.

“We have a pretty good understanding of why the birds are doing so well, but we’re really just starting to figure out the population’s breeding structure,” says Berres. “To me it screams ‘Don’t touch them.’”

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