Small falcons pose danger to piping plover population in Great Lakes

"We haven't been able to synthesize all of the available data to get a broad picture of the piping plover population, until now," said ecologist Elise Zipkin.
By Brooks Hays  |  Jan. 23, 2018 at 10:05 AM
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Jan. 22 (UPI) -- The piping plover is considered endangered in the Great Lakes region, but its population numbers have been rising over the last decade.

It's a slow and steady comeback that was expected to continue, at least according to previous population models. But new analysis by researchers at Michigan State University suggests the endangered shore bird could face increased predation pressure from merlins, a small falcon whose numbers are also rising.

The new projections were made possible by sophisticated modeling techniques.

"Even though they knew a lot about piping plovers, having collected multiple data sources for more than 25 years, we haven't been able to synthesize all of the available data to get a broad picture of the piping plover population, until now," Elise Zipkin, an assistant professor of integrative biology at Michigan State, told UPI.

Ecologists had previously been forced to consider one factor at a time, but the latest modeling capabilities -- buoyed by Bayesian probability theories -- allow scientists to consider a combination of factors, including predation, habitat loss, reproductive rates and more.

The analysis showed mortality rates, or survivability, is the main driver of population health for the piping plover in the Great Lakes. The findings have implications for how conservationists go about protecting the endangered species.

"To get the most bang for your buck, our model shows it wouldn't be as effective to spend more time and money improving reproduction or immigration," said Sarah Saunders, a postdoctoral research associate in Zipkin's research lab. "The best approach would we be to improve survival rates."

Like piping plovers, merlins are threatened in the region, so their increase in numbers is seen as a positive sign.

"You wouldn't want to set out to decrease the number of merlins, but you might think about site specific places for predator management," Zipkin said. "There might be places where plovers are breeding, where there would be an opportunity to do predator control."

The new models can also show how different ecological factors affect demographic groups differently. The latest piping plover analysis suggests the rising mortality rate of juvenile birds is a problem unique from the loss of adult birds.

"We know a lot less about what is affecting juvenile survival rates, we haven't really identified why that's the case," Saunders said.

But with more data and new models, researchers hope to find out.

Having published their most recent work in the Journal of Applied Ecology, Zipkin and Saunders are now deploying similar Bayesian-inspired modeling techniques to better understand the range of ecological factors driving the decline of monarch butterflies.

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