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In Presidio County, An Intrepid Biologist Uncovers the Mysteries, and the Plight, of the Country's Rarest Turtle

photograph by Jennifer Smith. The rarest turtle in the country, the rough-footed mud turtle is found in the U.S. in only a few locations in Presidio County. While new research has raised the profile of this Big Bend creature, its future still hangs in the balance.

Stock tanks are as common as corrals and loading chutes in rural West Texas – this is ranching country, after all, and water for livestock is a high priority. But in Presidio County, a few stock tanks have come to play a second, surprising role – as the last sanctuaries of the rarest turtle in the United States. 

The rough-footed mud turtle – named for the spikes that line its feet and tail – is highly aquatic. It may make brief movements between ponds, but unlike, say, the desert box turtle, it won't set out across open terrain. Water, and mud, are its elements – only the female is known to routinely leave water, for the few hours it takes to excavate a nest and lay her eggs. 

The turtle's historic range extends deep into Mexico – but little is known of its status there. What we do know of this turtle is largely thanks to one scientist. Dr. Jennifer Smith spent a decade studying rough-footed mud turtles – trapping them with sardines, tracking them with radio collars – in remote desert country. Fewer than 200 persist in the U.S., she's found, in five known locations – four stock tanks and a spring-fed stream – in Presidio County. 

And while Smith's work has raised the profile of this unlikely Big Bend native, the forces that have driven it to the brink are still at work.

When it comes to Big Bend fauna, the rough-footed mud turtle is clearly more distinctive than the mountain lion, pronghorn or bighorn sheep. But Smith concedes there are reasons why this turtle – as of yet – hasn't achieved iconic status. 

“They're not flashy,” she said. “They're not warm, fuzzy, bighorn sheep. They're not game animals. And they stink – they put out a musk when you mess with them. Plus the sardines. The whole deal is a stinky deal.” 

How did Smith's life become entwined with this remarkable, if stinky, animal?

An East Texas native, Smith's bond with the Chihuahuan Desert began in the 1980s, as an undergraduate at Alpine's Sul Ross State University. She completed a master's in biology at Sul Ross. And she'd embarked on a PhD at New Mexico State University, in Las Cruces, when marriage and motherhood changed her plans. Twenty years later, she returned to NMSU, to complete the degree. Today she teaches at NMSU-Alamogordo.

While she was brainstorming potential PhD projects, Smith traveled to Alpine, to support her old friend Dennie Miller, after the death of his wife. Miller – a former director of the Chihuahuan Desert Research Center – has an irrepressible passion for the region's fauna, especially its reptiles. He'd done pioneering work on the mud turtle in the 80s. With Smith, he talked up the animal, then the least-studied turtle in the U.S.

“He sold me on it,” Smith said. “Everything was unknown about the turtles, nothing was known about them, and – it was in West Texas, which I love. Those two things combined, and I had a project.” 

All the known turtle locations were on private ranches. Gaining access required building trust with landowners, over months and even years.

“You know, they're suspicious,” Smith said, “and I don't blame them – somebody like me coming and looking for a possibly endangered species. But honestly, I became friends with them, and they took me in like family once they decided I wasn't going to do anything weird, that I was just trying to work on my PhD.”

Smith soon discovered how tenuous the turtle's situation was. 

In 1986, the turtles were known at nine locations. But drought, and landowner management choices, had eliminated several of those tanks. Smith watched four sites disappear during her research. Today, only two of those nine populations endure.

But Smith discovered turtles in two new tanks, including one that didn't exist in the 80s – indeed, it's the one tank where she knows the turtles are successfully reproducing. And she found another new population – in a free-flowing spring-fed stream in Big Bend Ranch State Park.

Smith's research was an odyssey – conducted alone, in remote country, amidst harsh elements. She slept in a hammock, on the patio of an abandoned ranch house. To endure the summer heat, she often joined the turtles in the stock tanks. But her endurance yielded the insights field biologists live for.

She trapped the largest rough-footed mud turtle on record – with a carapace length of 7 and a half inches. One of the most thrilling moments came in June 2016, when she was tracking a female with a radio transmitter.

“I documented the one and only time they've been documented laying eggs,” Smith said. “It was so exciting – she's leaving the water! And I'm out there by myself in the middle of nowhere.”

The turtle dug her nest beneath a mesquite bush, and laid her eggs. Heartbreakingly, the eggs were soon eaten – likely by a raccoon. 

The story of the rough-footed mud turtle is the story of water in West Texas. The tanks where the turtle lives are all in the Alamito Creek watershed, south of Marfa. Like other Rio Grande tributaries here, Alamito Creek was historically a perennial stream – and the turtles likely lived along its full course. With damming and groundwater use, Alamito Creek became intermittent and ephemeral. The tanks – most of which are spring-fed – have become a last redoubt for stranded turtles. 

But the mud turtles are survivors – in DNA analysis, Smith found that, despite their isolation, the turtles are genetically robust.

Smith's work has made a splash, within the scientific community and beyond. That's had a downside – poachers have targeted this rarest of U.S. turtles. But there have also been hopeful outcomes.  

Texas Parks & Wildlife staff – especially biologist Russell Martin – have become champions of the turtles. And other partners have stepped up. 

One of the new populations Smith found was on the property of the Fuentez family. Smith found six turtles here – and they were in bad shape, afflicted with a mysterious infestation. San Antonio Zoo staffers restored the turtles to health, the Fuentez family drained and rehabbed their pond, and in October 2021, the turtles were “repatriated” to their Presidio County home.

But the future of this turtle in the U.S. still hangs in the balance. 

The area where the turtles live is remote – but development is happening, including new homes with swimming pools. Increased groundwater use could kill the springs the turtles depend on. Smith would like to see landowner incentives for wetland restoration, aquifer management, and a captive breeding program for the turtles.

The goal, she said, is to keep the turtles from being listed as an endangered species.

“Everybody agrees that it is in the turtles' and the peoples' best interest not to have them listed,” Smith said, “so we need to work together to get their numbers up, so there just another old mud turtle, so there's so many of them they're a pain. And that's going to take work. It's going to take conscious, intentional action on the part of the state.”

Smith's work had shed light on a unique West Texas creature. But its survival will depend as much on politics as on science.

Drew Stuart is the producer for the Marfa Public Radio series Nature Notes.