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News Track: Despite efforts to save Blanding’s turtles on Highway 100, species in decline
The species could become ‘federally threatened’ in the coming months
Nov. 24, 2024 6:00 am, Updated: Nov. 25, 2024 9:25 am
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A decade after biologists and environmental advocates worked to mitigate the losses along a soon-to-be-constructed section of Highway 100 of Blanding’s turtles — a threatened species in Iowa — the overall population of the turtle throughout the Midwest and Northeastern states has declined, leading to the possibility that its protections will be increased.
Background
As Highway 100 in Linn County was being extended west, biologists and environmental advocates worked to mitigate Blanding’s turtle mortality before the construction began.
Terry VanDeWalle, a senior biologist with Stantec Consulting Services, which focuses on environmental and sustainable engineering issues, was one of the biologists who spearheaded the work.
VanDeWalle worked with the Iowa Department of Transportation to build barriers alongside the highway to keep the turtles off the four-lane road to reduce the risk of mortality. VanDeWalle and his team also added a human-made pond to the area and an underpass for turtles and other wildlife connecting that and two other ponds together.
“We built the pond and put up some exclusion fencing to keep the turtles away from where the road would eventually be,” VanDeWalle said. “Then we built an underpass the next year.”
That section, between Edgewood and Covington roads, opened to traffic in December 2016, according to Jim Schnoebelen, a district engineer for the Iowa DOT. The remaining 4 miles of the extension, from Covington Road to U.S. 30, opened in December 2018.
VanDeWalle began working on the Highway 100 project with the Iowa DOT in 2002, trapping Blanding's turtles, placing transmitters on each of them and tracking their travels in and around the Rock Island Botanical Preserve near the alignment of the highway project.
During that period in 2002, VanDeWalle said he and his team trapped about 12 Blanding’s turtles. Fast forward about 10 years, he said they found only eight turtles.
Blanding’s turtles have distinct yellow throats and hinged lower shells. Unlike other turtle species, Blanding’s require larger landscapes and are known to travel longer distances than other aquatic turtles in search of habitats suitable for breeding and feeding. The turtles help control populations of insects, snails and small fish.
VanDeWalle said the turtles started using the underpass “immediately” after its construction.
“The new overwintering pond and the barrier and underpass are critical to the survival of the population. Without them, the small population would certainly have been lost,” VanDeWalle said. “There is no way to quantify how many turtles. However, if you consider all three species — painted, snapping, and Blanding's — it has to be a lot over the years.”
What’s happened since
VanDeWalle said he and his team haven’t monitored the turtles by Highway 100 since 2018. But despite those efforts from biologists and environmental advocates, the Blanding’s turtle populations are continuing to decline in Iowa and elsewhere.
The Blanding’s turtle, which is a state threatened species in Iowa, might be getting a new ranking: federally threatened.
Jeff Tamplin, a biology professor at the University of Northern Iowa and longtime turtle biologist, is one of the biologists in Iowa who contributes data to the U.S. Fish and Wildlife Service.
“Based on the data, my personal, informed opinion is that I would anticipate some level of federal protection,” Tamplin said, adding that an announcement isn’t likely to be released before 2025.
Under the Endangered Species Act, all states have their own laws for endangered and threatened species. If a species is granted federal protection, all states will have the same laws in place for the species. The “threatened species” label means a species is likely to become endangered in the foreseeable future.
Tamplin said the status assessment for the Blanding’s turtle is completed and the population numbers are crunched but he couldn’t share the service’s decision since it is not publicly released yet. Tamplin said since there will be a new president coming into the White House in January, there isn’t a timeline to announce the new rankings.
The Blanding’s turtle
Tamplin, who has been studying various turtle species for over 20 years, said that 52 to 56 percent of all turtle species, including the Blanding’s turtle, are vulnerable.
“They’re imperiled,” Tamplin said. “They’re near-time extinction.”
Tamplin said researchers have been seeing “low recruitment rates” for turtles across the board, meaning they aren’t finding new hatchlings or juvenile turtles added to the population each year.
Tamplin, who especially specializes in the woodland turtle, said there have been several surveys he has conducted where the recruitment rate is zero.
The Blanding’s turtle — like many other turtle species — can live up to 80 year and don’t reach sexual maturity until about 15 to 20 years old. Tamplin said that Blanding’s turtles, once they do hit sexual maturity, continue to lay eggs “as they get older and older.”
Since it takes so long for many species of turtles to mature and only a few of their eggs hatch, Tamplin said very few turtles survive to reproductive age.
Tamplin said that habitat loss and climate change play a factor as well.
He said that although a 40-year change in habitat can be long for some animals, for turtles it’s “a blink of an eye” given how long they live.
“When habitats that have historically been stable all of a sudden become unstable, over the course of 30, 40 or 50 years, that's really only one generation of turtles,” Tamplin said.
Two key habitat changes that have affected turtle populations — the Blanding’s as well — have been due to flooding events and an uptick in raccoon populations in the state.
Tamplin said turtles often use the same nesting spots year after year, but floods have wiped out many of the spots. He added that turtle eggs can survive underwater for only one to three days before they are no longer viable.
Tamplin said raccoons are a primary predator — both for adult turtles and their eggs. He said the number of raccoons in Iowa has “skyrocketed” over the past few years.
“Raccoon abundances have never been higher in recorded history,” he said.
Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.
Comments: (319) 398-8370; olivia.cohen@thegazette.com
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