Tracking project aims to save turtles from CT road hazards
Why did the turtles cross the road?
Their reasons aren’t as important as them being able to do it safely, and a statewide project is hoping to help them do that.
On top of habitat loss and illegal collection, conservationists say road mortality is a real threat to Connecticut’s turtles.
But for the northern diamondback terrapin, help might be on the way. If a statewide conservation effort succeeds, those road crossings could be assisted by vertebrate-friendly culverts, road barriers and street signs warning drivers they could cross paths with the shelled critters.
Researchers from Western Connecticut State University are teaming up with the Maritime Aquarium at Norwalk and the state Department of Energy & Environmental Protection to track terrapins along coastal roadways this summer and determine which spots could benefit from road mortality mitigation.
Once a week, volunteers for the “terrapin tracking” project will walk along assigned half-mile stretches of road and look for signs of terrapins, dead or alive. They also will look for nests and eggs, photographing what they find and recording their observations in an online data form.
Researchers will use that information to pinpoint locations where road mortality rates are high, said John Michael Arnett, a graduate student at WCSU who is working on the project.
“Road mortality in general for vertebrate species is extremely high,” he said.
Once researchers find
those problem spots, they can implement mitigation strategies such as shortterm road closures and signs that read “turtle crossing,” Arnett said.
There’s another solution, too — and it’s one that wouldn’t require drivers to take any detours.
Culverts — large pipes often seen beneath roadways and bridges — can accommodate traveling turtles, according to Arnett.
“Turtles can easily go back and forth between them and it’s pretty much just an easy highway tunnel for them,” he said.
Yet most culverts are not designed in a way that is beneficial to terrapins, Arnett said.
Because installing new culverts costs money, he said, researchers need to determine where they are most needed.
Wildlife-friendly culverts
benefit not only turtles.
“All sorts of organisms can use them,” said Brian Hess, a DEEP wildlife biologist involved with the terrapin tracking initiative. “Having appropriatelysized culverts is really important for fish, as well.”
Culverts that are submerged at high tide but are above water at low tide, for example, are not conducive to wildlife passage, according to Hess.
“If you do have an appropriately-sized passage for animals, then the next step is to have some sort of barrier that directs them to that and keeps them off the road surface,” he said.
The state Department of Transportation also is a partner in the turtle tracking program, according to a release from the Maritime Aquarium at Norwalk.
“CTDOT has a Natural Resources Planning Team that is heavily involved in the planning and design of construction projects,” CTDOT spokesman Josh Morgan said in a statement. “We’ll continue sharing roadway data, ideas, and mitigation strategies with the Department of Energy and Environmental Protection throughout this project. Protecting natural resources and wildlife are always priorities in our work.”
The northern diamondback terrapin, the only United States turtle that lives in brackish water, is a state-listed species of special concern.
Turtles’ reproductive strategy can be a challenge for conservationists, said Hess.
“Their population structure is based on a small number of individuals reaching adulthood and living and reproducing for a long time,” he said.
Terrapins take eight to 10 years to reach reproductive age, Hess said, and like other turtles, their hatchlings and eggs suffer high mortality rates.
“Adult mortality can be a really big problem,” he said. “Ongoing success of a turtle population often depends on adult survival.”
Meanwhile, terrapins face human-driven threats such as habitat fragmentation, subsidized predators and illegal collection for the pet trade.
Studies show predators like raccoons can dig up almost 100 percent of terrapin nests in a given area, according to Hess.
In developed shoreline areas, “we often see higher populations of these predators” because of human food resources, Hess said. Biologists call those animals “subsidized predators.”
“They might not be there in the same concentrations, in the same numbers, if they didn’t have the resources that people are providing,” Hess said. “Then those (turtle) nests might have more of a chance.”
Given the numerous threats terrapins face, Hess hopes the tracking project will offer “actionable” data to guide conservation efforts.
Terrapins hibernate in mud during the winter, Bridget Cervero, senior education manager for the Maritime Aquarium at Norwalk, told Hearst Connecticut Media. They emerge in April and head for brackish waters, she said. That’s why Connecticut’s terrapin trackers will be on the roads between April and August.
In addition to identifying road mortality hotspots, their work will aid WCSU’s terrapin research.
Arnett is setting out to prove a hypothesis about road mortality’s impact on migrating females.
“If the females are constantly getting hit by the cars, then that will lead to a skewed sex ratio where there are more males than there are females,” he told Hearst Connecticut Media.
To test the theory, he will catch terrapins at nine sites across the state, including in an area isolated from the road, he said, noting the latter will act as a control.
The trackers’ efforts will complement his work.
“We don’t know what areas have road mortality,” Arnett said. “Without their data they’re acquiring the project won’t be a success.”
The volunteer turtle trackers, whom drivers might see wearing reflective vests and walking the side of the road, also could save turtle lives.
“These turtles are one of a kind. They are the only species in the U.S. that lives in brackish water, and their habitat is decreasing every single day, and with climate change, with urbanization … these turtles just are getting hit left and right,” said Arnett. “They can’t defend themselves, they can’t do anything, so we’re just trying to do the most we can for them.”
The Maritime Aquarium at Norwalk will host another virtual training session Tuesday. To sign up, visit www.maritimeaquarium. org/community-science and select the “Terrapin Tracking Team” icon.