How can we save Ohio’s endangered rattlesnakes?

A recent study led by Ohio State University (OSU) has compared the genetics and relocation patterns among two populations of threatened rattlesnakes in order to guide conservation planning that would give these endangered creatures a better chance of survival.

According to the experts, a collection of six closely situated but isolated populations of Eastern massasauga rattlesnakes in northeast Ohio could increase their numbers if strategic alterations were made to stretches of land between their home ranges. Reconnecting these genetically disparate populations could not only help Eastern massasaugas escape extinction, but also establish a thriving habitat for other endangered prey and predator species.

Eastern massasauga rattlesnakes live in isolated spaces in midwestern and eastern North America and were listed as threatened under the Endangered Species Act in 2016 due to loss and fragmentation of their habitat. The scientists examined two groups of Eastern massasaugas in Ohio – a large, genetically diverse population inhabiting the Kildeer Plains Wildlife Area in north central Ohio, and six small, separate populations clustered near each other in Ashtabula County.

By genetically analyzing blood samples of 109 snakes cohabitating in the Kildeer Plains area, the researchers found that the snakes living in fragmented sites in northeast Ohio were very distantly related, and stopped mingling three generations ago. “Once we knew that they didn’t seem to be moving around, the real question is why aren’t they moving? It’s not that big of a distance – so we focused on finding out what was stopping them from being connected,” said study lead author Scott Martin, a PhD student in Conservation Genetics at OSU.

“It seemed to be about specific features of the habitat. If the snakes in northeast Ohio were moving as far as we would expect them to, based on how the Killdeer snakes move and data on the species’ range, they should be able to move between these little sites. And yet when we look at the genetics and use pedigrees to see if there is any breeding between the sites, there’s just not.”  

According to the scientists, wooded areas, cropland, roads, and housing developments – known as “impervious surfaces” – were the main obstacles to snake relocation. By contrast, wet prairies were an ideal habitat for these snakes, offering them more possibilities to move and intermingle.

“You can imagine two snakes in the same habitat that are probably very genetically similar because they can move easily. And then in this other region you have two snakes near each other, but on either side of a four-lane highway, and they will be genetically different because snakes don’t move across that highway, and over time they’ve diverged,” Martin explained. “That means a highway would have a high resistance value and an open field would have a very low resistance value.”

These findings helped the states of Ohio and Michigan to obtain a $2.3 million grant from the U.S. Fish and Wildlife Service to acquire land that could benefit Eastern massasaugas in both states. 

“To me, this is a clear example of where Ohio State basic research has produced practical results that have then been directly used to help conserve wildlife in Ohio – in other words, achieving one of the goals of a land-grant institution, which is to provide useful, practical knowledge of value to the citizens of the state,” concluded senior author H. Lisle Gibbs, a professor of Evolution, Ecology, and Organismal Biology at OSU.

The study is published in the journal Ecological Applications.

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By Andrei Ionescu, Earth.com Staff Writer

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