As Crystal White finished taking measurements of a snapping turtle on the banks of Pryor Creek on July 14, the Rocky Mountain College student removed the metal research radio tracker from the back of the giant reptile’s shell.
The five-person team spent the morning checking turtle traps along the creek, one of several waterways the group observes in one of the first and most expansive research projects on snapping and spiny softshell turtles in the U.S. high plains.
“We have learned a great deal about the current status and distribution of both turtle species in Montana and especially most recently on the Crow Reservation,” Rocky associate professor Kayhan Ostovar told the Gazette. “Utilizing these two species as biological indicators of aquatic ecosystem health we hope to better understand the effects of anthropogenic activity on aquatic systems.”
Now six years into studying the turtles, the team at Rocky’s Yellowstone River Research Center have learned the elusive species of concern are well established in the state. Through mapping nesting sites and tracking movements, the data also suggests that human alteration of rivers hurts the population’s future.
The shell life
The two turtle species live east of the Continental Divide in North America, with Eastern Montana in the northwest corner of the species distribution. They live in large rivers like the Yellowstone and creeks that flow into it.
They generally have a high mortality rate early in life, as unprotected nests and hatchlings easily fall prey to birds and mammals. But once a turtle becomes an adult after nearly a decade of development, they have no natural predators. They can live for up to 40 years.
Humans, however, are known to eat them. While some states allow the commercial catching of the reptile, Montana has banned it. Snapping and spiny softshells are both a designated species of concern in the state.
The bottom feeders will eat whatever comes their way in shallow water. Snappers can take down larger prey like mice or aquatic birds as they grow. A spiny softshell female (the larger gender) can grow to roughly two feet in diameter.
While a snapper has the same size shell, it is much more bulky, and on average weighs 30 pounds. Both the reptiles breathe through nostrils during their active season, but when the hibernation season starts they do not come up for air during an entire winter.
“They even seek out colder areas to slow their metabolism,” Ostovar said. “This extreme behavior was taken notice of from the science community.”
The Rocky research team is based on the RMC campus at the Yellowstone River Research Center. There the group analyzes samples and writes scientific papers. Most of the summertime is spent outside in the field.
Their students come from a variety of science backgrounds, and are all undergraduates — a rarity in the college research field.
“I sometimes forget this is my job,” biology student Kara Holmlund said as the team walked in between turtle traps.
She and her teammates don waders to set nets at the bottoms of rivers or streams and return two days later to the basic holding cell. A pair of researchers stands in the water and lifts the net from either side, about half the time revealing a thrashing turtle with the occasional catfish.
If they catch a turtle, the group sets up a field lab from the back of a truck or a table they carry for more remote areas. Sometimes it takes two or more people untangle the turtles from the net, wary to stay out of reach from their powerful and sharp jaws.
Usually they record the animal's measurements, take a blood sample and tag its shell with a number and a radio transmitter that can only be picked up from a mile away. The field work, heightened in the summer, goes on year round.
“We drill through the ice of rivers to find a turtle's radio signal while it hibernates,” Ostovar said. “Sometimes it can be quite tedious.”
When Ostovar first started tracking turtles in 2015, the project team consisted of him and two students. Now 10 people strong, they can work four days a week on a growing list of projects.
Researchers have done turtle heath studies on the Yellowstone, Bighorn, Little Bighorn, Clarks Fork and Musselshell rivers. They also study turtle behavior in small flowing streams across the region, much of it on private land with permission.
Recently, researchers searched creeks on the Crow Reservation to see the condition of the snapping and spiny softshell turtle population.
“People are interested in seeing how extensive the turtle ecosystem is,” Ostovar said. “We found a healthy population of both species on three creeks up there.”
Once enough researchers gathered enough data, the team began comparing the turtle health in different rivers. The team concluded that the Yellowstone River has one of the largest and most diverse turtle populations.
“It is the longest undammed river in the continental U.S.,” Ostovar said. “So there are floods and sandbars that move. It creates new habitats for turtles to nest on.”
Turtles prefer these sandy, moist beaches, but will also use gravel and cobblestone patches to lay their eggs. While no river studied is without either turtle species, the data suggest the population will dwindle in the near future.
Larissa Saarel, a veteran turtle researcher, made her focus of study comparing the demographics between the Yellowstone and Bighorn rivers.
“We found there were less juveniles and less hatchlings in the Bighorn,” Saarel said. “There were less areas to nest in because of a lack of river movement.”
Saarel used a drone to map out sections on each river and found the Yellowstone had new nesting areas due to river change. The nesting areas on the Bighorn were often observed crowded with the turtles. The study of dams restricting turtle movement is also a project the team is working on.
At Pryor Creek, the group mounted trail cameras next to an irrigation dam to see if turtles try to cross it. Besides floods that go over the barrier, it is completely unknown how turtles react to human constructed barriers.
“While hundreds of studies have occurred on fish this will be one of the first on turtles,” Ostovar said. “Already we tracked turtles above the dam turning around once they reached the barrier.”
The separation of species on smaller creeks, according to Ostovar, can limit the animals' biodiversity, and make a population at risk for extinction. Many of these projects will be published in peer reviewed scientific papers within the next year.
Though this is the last year of the long-term study, the group did not show it as they worked from trap to trap.
“We have a long way to go,” Ostovar said. “But these long-term studies on long-lived turtles will help us learn more about them and Montana’s prairie ecosystems as well.”