“Wood tortoises, like trout, don’t like ugly places, and we need them as part of a healthy, functioning ecosystem,” said Tom Akre, a research ecologist at the Smithsonian’s Front Royal, Virginia facility. “They matter because they are important indicators of our environment, and their presence, or absence, lets us know if there is clean water and clean air.”
Wood turtles lost much of their habitat as streams where they are normally found became polluted by runoff from agricultural uses or encroached by nearby development, experts said.
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In Virginia, experts said, wood turtles have “lost nearly half of their historic range” and are considered “one of the most endangered freshwater turtles in North America.”
The Akre team plans to search for wood turtles in Rock Creek Park in the District using what’s called “environmental DNA” to find how many of them are left. Because their population there can be low, and they’re hard to see in murky waters, researchers take water samples and then filter them in a lab where DNA is extracted to see if it matches that of a wood turtle.
“We are basically using technology similar to crime scenes like markers to detect them,” Akre said.
The researchers placed GPS and radio transmitters on wood turtles they found in northwestern Virginia so they can better understand how far they travel, especially when searching for a mate. In some cases, they have found cases of wood turtles crawling approximately 15 miles over mountains in Northwest Virginia and neighboring West Virginia in search of new streams and mates.
Finding turtles is not an easy task. They live under leaves in brown, cloudy water. Researchers have to carefully tread stream beds. Once they find a turtle, they assign it a number and put indentations in its shell to identify it and track it through time. They also take note of its length, width, height, weight, and any unique markings on its shell before putting it back in a stream.
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It is illegal to harass or possess wood turtles. The public should not disturb them and only watch them from a distance, experts said. Smithsonian researchers can survey wood turtles with state research permits and are trained to handle them carefully with minimal disruption to their habitats.
Adapting to a changing environment has been one of the biggest challenges for wood turtles. Bald eagles, for example, have made a comeback in many areas, including the DC region, as they have made their homes in more populated urban and suburban areas. But for wood turtles, it’s not the same.
“Relative to most mammals and birds, everything wood turtles do is slow,” Akre said. “They grow slowly and reproduce slowly.”
Akre said it takes, on average, 15 years for a wood turtle to grow and mature before it can reproduce. “So the fastest a calf could mature and lay eggs would be about 30 years after its mother was born,” she said.
But because “egg, hatchling and juvenile survival is so low, it can actually take much longer for an average female wood tortoise to be replaced with a mature, reproducing daughter,” Akre said. “By the time an average offspring reaches maturity and successfully reproduces an offspring that survives to successfully reproduce offspring, it could be closer to 60 years.”
Akre said hatchling wood turtles are sometimes called the “M&Ms of wildlife” because they are “small, brown and easy to eat,” making them easy prey for raccoons, herons, ravens, skunks and foxes.
Experts said they believe wood turtles still thrive in about 30 to 40 streams in the DC region, but lost much of their habitat long ago.
In Virginia, Akre said, its entire habitat along the Potomac River in parts of Fairfax and Loudoun counties has almost disappeared. In Maryland, experts said, the wood turtle population has lost about a third to a half of its range and is now mostly in the western part of the state.
By tracking where the tortoises are, Akre said, researchers can protect their landscape for better survival.
“If we don’t track them down and understand them,” Akre said, “then there’s a chance they’re gone.”