Can We Save the Midwest’s Only Rattlesnake?
Five scientists in knee-high galoshes sloshed through ankle-deep water this spring in search of rattlesnakes. The team was one of six on the blitz, an annual event held on 2,000 acres in southwestern Michigan. Over the course of five days in April, the blitzers trudged through terrain known as “quaking wetland” (so named because it bounces as it’s walked on, due to the water flowing below the mud), trying to capture, identify, weigh, and measure as many eastern massasaugas as they could find.
The snakes, also known as swamp rattlers, appear to thrive on these boggy acres owned by the Lowe Foundation, created by the entrepreneur, conservationist, and kitty litter inventor Edward Lowe. They aren’t as lucky elsewhere. According to the U.S. Fish and Wildlife Service (FWS), as much as 90 percent of the populations of eastern massasauga could wink out over the next five decades.
The blitz, now in its ninth year, yields valuable data on the rattlers in this corner of Michigan, the state with the most robust population. “It’s a pretty huge effort, and they’re so dedicated to it,” says Mike Redmer, a FWS habitat restoration coordinator. He’s participated in the blitz every year. “Someday, when I retire, that will make me smile as one of the things I was happy I was involved with,” Redmer says.
Eastern massasaugas once thrived across a patch of North America from Iowa to New York and northward to Ontario, but wherever they slithered, they were never popular with people. A barber once put ads in a local Illinois paper requesting volunteers to come kill massasaugas one day a year to keep them from “coming into town”—likely an unfounded fear. Though they are venomous, these rattlesnakes haven’t killed anyone in more than half a century.
As development and agriculture expanded across the species’ range over the past 30 years, the rattler’s numbers and available habitat shrank. Herpetologists estimate that less than half of the eastern massasauga’s historical population still exists. Where experts once found more than 550 populations, fewer than 270 now remain.
The two-foot-long snakes, beige with dark spots, slither through the region’s bogs, fens, and other isolated wetlands but rarely travel more than two miles from their birthplace. So far, assisting their migration―translocating the snakes from one habitat to another―doesn’t look too promising. Purdue University Fort Wayne herpetologist Bruce Kingsbury tried moving some eastern massasaugas to a study site at Camp Grayling, a National Guard training ground in northern Michigan, but they didn’t do as well as the resident snakes. Kingsbury is unsure why, but he speculates that the rattlesnakes are just partial to the areas where they’re born.
And as the climate warms, some places in the rattlers’ range may become unsuitable. Climatologists predict that with climate change, downpours will be heavier, droughts longer, and temperatures higher in the Midwest. More intense storms could flood the crayfish burrows snakes use for shelter in the winter. Drier winters could mean lower reproductive success. And summer droughts could drive away their prey, which consists mostly of small rodents.
“They make a good threatened species. All things are going against them,” says Jennifer Moore, a massasauga researcher at Michigan’s Grand Valley State University.
To keep the snakes’ populations from plunging further as the climate changes, Moore is looking into what it takes to get the snakes to move on their own into places with the right climate and habitat. Every spring, she treks up to Michigan’s Bois Blanc Island. The island is reminiscent of what northern Michigan used to look like: unlogged forest, rare plants, and bogs—perfect, it seems, for eastern massasaugas. The snakes are everywhere.
Moore is trying to see if the snakes, when given good connected habitat, can (or will) move between patches. If they do, conservationists could create or protect habitat surrounding existing rattlesnake populations elsewhere, giving the snakes space to eventually move around. Moore describes it as an “If you build it, will they come?” approach.
Land managers can help create habitat corridors by conducting controlled burns, since many of the snakes’ wetland habitats evolved with periodic fires. Without those blazes, trees take over, turning a good massasauga home with an open canopy into a shaded ruin uninviting to these cold-blooded sunbathers.
Prescribed burns are a tricky business, though. Conduct them too late in the spring and the conflagrations can kill snakes already emerged from their hibernation burrows. Research conducted a few years ago showed that measuring soil temperature can help land managers determine if the snakes have glided out. The FWS now recommends using soil thermometers to take these measurements before lighting the place up.
None of these approaches, of course, will stop climate change’s march forward. A study published in Global Change Biology in 2014 looked at the potential consequences of climate change on massasaugas and the best ways to protect the rattlers. One conclusion was that snakes living in the eastern and northern parts of the species’ range are more likely to survive than those living in the southern and western extremes because the climate is expected to change less dramatically there. Ultimately, says lead author Lars Pomara, now an ecologist with the U.S. Forest Service, land managers should do what they can everywhere the species still slithers. “That was the most important thing: Don’t wait,” he says.
The folks on the Lowe Foundation property aren’t waiting. They’re not exactly sure what climate change will bring, but they now check soil temperatures to time their burns, give rattlers open areas for basking in the sun, and make sure their lawn mowers keep the grass at just the right height.
Practices that keep the massasaugas comfy vary from site to site, but land managers throughout Michigan are adopting some of the survey practices done at the Lowe site in order to get the information necessary to give other massasauga strongholds a boost. This year, though rain cut the blitz short by a couple of days, the researchers were heartened to find 30 massasaugas on day one, the best single day they’ve ever had.
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