By Andrew Stuart
For this episode, Nature Notes is teaming up with “West Texas Wonders” – a new reporting series where listeners ask questions and Marfa Public Radio finds answers.
What kinds of turtles live around Marfa?
The question comes from Nathan Stueve. The answer we found surprised us.
Marfa is surrounded by arid grasslands, stony summits and badland deserts. And yet, the area is home to multiple aquatic turtles – including the rarest turtle in the United States.
The rough-footed mud turtle is a threatened species in Texas. Scientists are working to understand, and preserve, this mysterious creature.
The most familiar West Texas turtle is a land-dweller. Watching a desert box turtle make its slow way across a lonesome road in the Permian Basin or Trans-Pecos is a poignant sight.
But this dry-lander is just the beginning.
Dr. Andy Gluesenkamp is the director of conservation at the San Antonio Zoo.
“Turtles in the desert: it’s a – ‘what?’” Gluesenkamp said. “It’s interesting, because most of the turtles that you have in the Trans-Pecos are aquatic. And you don’t think about the Trans-Pecos really being a haven for aquatic turtle species, but in fact there are turtles that live out there that don’t live anywhere else.”
Turtles live in the Rio Grande, Pecos and Devils rivers – the Big Bend slider, the red-eared slider, the spiny softshell turtle, the Rio Grande cooter.
The rough-footed mud turtle is different. It ranges deep into Mexico, from mountain streams to lowland lakes. But in the U.S., it’s found only in Presidio County, south of Marfa – in a half-dozen sites with perennial water, including stock tanks and spring-fed pools.
Adults reach a length of 7-and-a-half inches. They dine on aquatic vegetation and insects. They rarely leave water.
How does this water-lover persist in a parched land?
With funding from Texas Parks & Wildlife, Gluesenkamp and his team at the zoo have partnered with biologists from Mexico and New Mexico in new genetic research.
With blood samples and toenail clippings from live turtles, and bits of bone from long-dead animals, DNA from across the turtle’s range is being sequenced. Analysis will show whether turtles in Presidio County and southern Mexico are indeed the same species. And – it will shed light on the genetic health of Texas populations.
Reliant on isolated outposts of habitat, turtles may face “genetic bottlenecks.” With low genetic diversity, animals are less healthy, less resistant to disease. In the future, Texas turtles might be bred with Mexican turtles, to improve genetic stock.
Yet, there’s some evidence turtles are finding ways to move among sites.
“It was just shocking to look down in these 3-foot-deep pools in this little bitty creek in a canyon, and to see five of these big old turtles – in the middle of the desert,” Gluesenkamp said. “We’ve got some evidence that individual turtles may have been traveled 7 miles or more, from one site to another. And we don’t know how or when they traveled, because years after they were marked at one site, they were found at another site. That just tells me that this turtle’s got a lot of secrets that we still need to unravel.”
In the future, Gluesenkamp would like to use radio telemetry to track turtle movements.
Gluesenkamp said private landowners here are doing a good job of protecting turtles. And, he said, steps could be taken to support the animals – that would have broader positive effects.
Texas Parks & Wildlife is considering the reintroduction of beaver in places like Alamito Creek. Beaver dams would create permanent pools of water.
“That’s going to be good for turtles,” Gluesenkamp said, “and all sorts of other species, from birds to mule deer.”
There are likely just a few hundred rough-footed mud turtles in Texas, but no endangered species listing is imminent. Gluesenkamp said it’s possible to stabilize populations. The turtle, he said, should be a “point of pride” in Presidio County, and across Texas.
“It’s pretty darn cool to be able to say we have the rarest turtle in the States,” he said. “Even though there are so few populations and so few individuals, and we’re concerned about their stability, this is a great starting point for trying to make improvements to their long-term status. I feel like we finally hopped into the pilot seat of a plane that’s in a dive, and we’re pulling back on the bar to get this thing leveled off.”