The Tennessee Wildlife Resources Agency (TWRA) and the Nashville Zoo at Grassmere are tracking eastern box turtles (Terrapene carolina carolina) in Nashville to determine how their urban environment affects them. Dr. Brian Flock, TWRA’s Wildlife Diversity and Intern Coordinator, created this tracking project with two goals in mind. “The initial idea was to have something to help students in the Nashville area learn about wildlife conservation in their backyard while gaining important information on urban box turtles,” Flock told REPTILES. The lack of information on these animals was the main reason that Tennessee’s Comprehensive Wildlife Conservation Strategy listed them as a species of Greatest Conservation Need in 2005, and they have remained on this list ever since.
After deciding to launch this project in TWRA’s own backyard, Dr. Flock asked TWRA Wildlife Diversity Aquatic Biologist Anna Dellapenta to conduct the fieldwork. In September 2019, Dellapenta began tracking the population of box turtles at TWRA’s headquarters in Nashville. Another dense population of box turtles thrives at the Nashville Zoo, less than five miles from the TWRA’s headquarters. For years, zoo staff have maintained a photo collection of the box turtles they find on zoo property. When James Flaherty, herpetology keeper II, arrived at the zoo two years ago, he was surprised to find so many box turtles on the grounds. Flaherty has always been interested in local wildlife projects and quickly became fascinated with these animals. Flaherty analyzed the unique patterns on the turtles’ shells as depicted in the photo collection, which enabled him to estimate that 20 individual turtles are included in the photographs. After Flaherty and his boss began developing plans to investigate the zoo’s turtles, his boss happened to mention their plans to Dr. Flock. Dr. Flock provided Flaherty with the equipment, and launching in October 2020, the Nashville Zoo is now the secondary site for the project. Dellapenta and Flaherty use radio telemetry to track their turtles. When they locate a turtle, they glue a transmitter to its shell. When they want to check on a turtle, they carry a receiver and an antenna to pick up the signal from that transmitter. The equipment guides them to the turtle’s exact location. They also rely on scute notching to collect data about these turtles. Scutes are the external bony plate on turtle shells, and Dellapenta and Flaherty use a file to mark a notch of a few millimeters wide in the scutes according to a code. Each scute represents a different letter so they can glance at a turtle’s notches to read the code identifying that turtle. While scute notching does not allow Dellapenta and Flaherty to track turtles to their location, it allows them to include every turtle in the study even if they don’t have the means to track them all.Due to shell damage, Anna Dellapenta could not notch this turtle’s shell and painted three orange dots on it instead for identification. Note the scute notching chart visible in the background.
When finding a new turtle, Dellapenta and her colleague Flaherty gather initial data. They measure the shell’s length, width, and height, weigh the turtle, and estimate its age based on scute growth marks. They also record the perceived sex before releasing the animal. Dellapenta has observed a range of personalities among the turtles. Some retreat into their shells, while others persistently attempt to escape. After over a year of fieldwork, Dellapenta is tracking 25 turtles using radio telemetry and has notched an additional 10 to 15 turtles. Flaherty, who started just before winter dormancy, is tracking seven turtles. Zoo staff have assisted in locating these turtles, with all but one found by other property staff. Telemetry and GPS Tracking: During the active season, Dellapenta and Flaherty locate turtles weekly using telemetry equipment, recording GPS coordinates. They note activities like mating and conduct regular weigh-ins. Weight data for females is crucial for understanding breeding habits and recent egg-laying. Winter Behavior: Turtles go underground for the winter. They dig deep, horizontal burrows that leave no visible surface hole, making them undetectable to a casual observer. Researchers do not disturb or weigh turtles during hibernation to avoid harm. Instead, they use telemetry to locate them and confirm they haven’t moved. Research Goals and Preliminary Use: The team aims to collect several years of data before drawing conclusions. However, the ongoing data collection has immediate applications. It will help determine the turtle population size on each property, including sex ratios—a fundamental aspect of population stewardship. Initial estimates suggest the zoo property could host 40 to 50 turtles. The research will also map the turtles’ home ranges, weekly travel distances, and resource utilization. By identifying key areas for hibernation, foraging, hydration, and nesting, the Tennessee Wildlife Resources Agency (TWRA) and the zoo can better implement protective measures.Researchers are analyzing specific areas to determine what attracts box turtles or what they need to thrive. “We could analyze those areas and try to figure out exactly what about them the box turtles are either attracted to or they need or thriving off of—whatever it is about that area,” Dellapenta says. “We kind of need to know because that may in the future sort of dictate how we manage the species in the state.”
Box Turtle Behaviors in the Blackberry Patch: Dellapenta has already witnessed some of her turtles reacting to changing resources. This behavior reminds her of other box turtle accounts and research indicating they may remember where and when resources are available in their environment. “When blackberries got into season this summer, three of my female turtles just bolted for the blackberry patch,” Dellapenta says. “And it’s hard to say exactly what they’re doing in there whether they are just chowing down or whether they’re like well, ‘I’m going to lay my eggs under all of these thick thorns and brambles so that nothing gets to the nest.’” For her, this close observation is an opportunity to learn the reasons for their behavior as well. Herping The Eastern Box Turtle and Eastern Box Turtle Care Sheet are related topics. These scientists hope to continue this tracking project as long as they have the funding and staff to do so; they have several ideas to develop the project in the future. For example: – They may expand the project to a non-urban site to compare data from urban turtles to those in different environments. – They may investigate how temperature affects the turtles throughout the year. – They may monitor them for potential diseases. – They have discussed studying how exotic plants such as privet or honeysuckle influence turtles’ movement and habitat use. – They may expand to studying whether the turtles are suffering genetically by being confined to their population. There are many possibilities, but as Flaherty says, “We’re taking it sort of a turtle at a time right now.” Maggie Gigandet is a Nashville-based freelance writer.
