On a chilly, gray morning in Forest Park, three St. Louis Zoo scientists switched on 20-inch-long antennas to begin their search for a turtle named Pumpkin.
Pumpkin is one of nine box turtles in Forest Park that scientists have tagged with tracking devices. Researchers at the St. Louis Zoo and St. Louis University are tracking box turtles in the city’s largest park and in a remote area in southwest St. Louis County to study how they thrive in urban and rural environments.
Palmer and her colleagues at the zoo recently reported in the journal Frontiers that the three-toed box turtles in the park have a higher mortality rate than the ones they tracked in the woods near Washington University’s Tyson Research Center.
Every month, researchers try to locate the turtles using antennas, said Maris Brenn-White, a research fellow at the zoo.
“It’s like tuning in to a radio station,” Brenn-White said, as she adjusted the dials on the antenna. “Each turtle has its own channel. Our turtle that we’re going to be tracking first is going to be on channel three.”
Like many other land turtles, box turtles are declining in North America as their habitats disappear because of human development and climate change. They’re also threatened by people who collect them for the international pet trade. Missouri has three-toed and ornate box turtles, which live in many parts of the Midwest. Zoo researchers estimate that there are likely hundreds of them in Forest Park.
Studying land-dwelling turtles can help indicate to scientists that an environment is healthy, said Jamie Palmer, a St. Louis Zoo ecologist.
“They live long lives, and they’re low-lying animals. They’re in contact with the environment in a way that other animals may or may not be. So if turtles are healthy, we can often times assume other species are just as healthy,” Palmer said.
As the scientists tracked the turtles, they found that a fair number of them were being killed by lawnmowers. Researchers shared their findings with Forest Park Forever’s maintenance workers in 2018 and recommended setting the height of blades on their mowers to six inches. Since the turtles are small enough to fit in the palm of a hand, workers could not see that they were running over the turtles.
“If you keep your blades above six inches, it’ll just ideally glaze over a turtle and not harm them in any way,” Palmer said.
Forest Park's workers had already been setting the lawnmower blades to six inches for many areas of the park and the zoo's finding gave them another reason to do so, said Forest Park Forever ecologist Amy Witt.
The researchers also say it’s possible that some of the box turtles in Forest Park were found elsewhere, kept as pets and then later dropped off at the park. That could explain the higher mortality rate of turtles in the park, as adopting turtles could disrupt their ability to hibernate, Palmer said.
“If you take a turtle that's been accustomed now to eating food regularly out of a dish, and not hibernating and always having warmth, and then you throw them back in Forest Park, sometimes they don't know how to hibernate,” she said. “It’s a process they come back to, or they just don’t survive it. It kind of messes with them in a way that we can't even begin to understand.”
As she conducted the research, Palmer met several people who’ve taken turtles from the park. Animal rescue operations in other cities also advise against taking box turtles home.
“It's not something that they feel like is bad,” she said. “They're not embarrassed of it, because that's what people did around here for a long time.”
In their study, researchers found that more of the Forest Park box turtles died in winter than during other seasons. That was not the case for the rural turtles. The Forest Park turtles may be more susceptible to emerging from hibernation on unseasonably warm days, said Sharon Deem, director of the St. Louis Zoo’s Institute for Conservation Medicine.
“Sometimes they'll come up because it's five nice days in Missouri in December, and then they'll get caught up above ground and it'll go freezing real quickly,” Deem said.
Deem started the St. Louis Zoo’s research on box turtles seven years ago after a friend, a Central West End resident, showed her a sick pet turtle. The box had been “rescued” from Forest Park and had also been taken along on a family vacation to Florida. Since Deem’s friend thought turtles belonged near the ocean, she sat the turtle on the beach, which caused its illness.
“If somebody who lives right on the border of Forest Park doesn't know that a Missouri box turtle is not a sea turtle, we need to educate people about our amazing turtles here in Missouri,” she said.
While the scientists do their research, they take students from nearby schools with them to look for turtles in the park. It’s an effective way to educate city residents about box turtles, Deem said.
“I have adults come up to me in grocery stores and say, 'It's the turtle lady,’ and that their kid came home and said, ‘Did we know about box turtles?’” she said.
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