Notes on a Blanding’s turtle reintroduction project in the Assabet River National Wildlife Refuge
Biologist Jared Green stands at the edge of a swamp on a picture perfect summer day, and scans the forest of drowned trees and duckweed-covered water that stretches out in front of him.
He dials a frequency on the radio receiver he’s holding and wades into the foot deep water. His rubber chest waders keep him dry and protect him from mud, and submerged logs and branches.
He’s looking for turtle 3776, a juvenile Blanding’s turtle released two years ago at the Assabet River National Wildlife Refuge as part of a Blanding’s turtle introduction project. The 2,230-acre refuge is located about 20 miles west of Boston in the towns of Sudbury, Stow, Maynard and Hudson, Massachusetts.
Green spots a turtle basking on a log, but he says it’s a painted turtle, not a Blanding’s. Adult Blanding’s turtles have dark, high-domed shells about six to nine inches long, and bright yellow throats that help biologists differentiate them from other turtles.
“All these downed logs provide good cover,” Green says. He pauses and slowly sweeps a large radio antenna back and forth in front of him and listens. The receiver makes a steady beeping noise.“I think she’s over here,“ Green says, pointing to a spot in the water about 100 feet away.
A semi-aquatic species, the Blanding’s turtle hibernates underwater, burrowing itself in the muddy bottom of water bodies from late fall through early spring when it returns to land to nest or move from one body of water to another. Habitat fragmentation and road mortality (as a nomadic species, the turtle will wander and cross roads to get from one body of water to another) have severely depleted this shy North American turtle’s numbers throughout much of its range. It is listed as an endangered species on the IUCN Red List and in some US states, and as either threatened or endangered throughout Canada. While it has no federal protection in the United States.
A graduate student in wildlife management at the University of Georgia, Green and his fellow biologists from the US Fish and Wildlife Service, are attempting to establish a new population of Blanding’s turtles at Assabet River by trans-locating hatchlings from a large, stable population at nearby Oxbow National Wildlife Refuge in Devens, in order to bolster the survival prospects for the turtle, which is listed as a threatened species in Massachusetts. This June, the biologists marked a milestone when they released their thousandth Blanding’s turtle at Assabet River.
“It was very exciting,” Green says. “It is a testament to all the hard work of the many partners and collaborators associated with this project.”
And if releasing a thousand turtles wasn’t enough cause for celebration, on June 30 the US Fish and Wildlife Service announced they were reviewing Blanding’s turtles, along with several other amphibian and reptile species, for possible endangered species status. The USFWS is currently conducting a 90-day review to decide if the species warrants a further review for possible ESA listing.
A petition by the conservation group, Center for Biological Diversity, triggered the endangered species review, says Meagan Racey, spokesperson for the USFW’ northeast regional office in Hadley. “Based on an initial look at the information in the petition, we determined a closer look at the species was necessary,” Racey wrote in an email interview. “We have requested the latest information on the species for a thorough status review. After that, we will determine if the turtle warrants Endangered Species Act protection.”
Racey says that because of the USFWS’s agreements to complete other reviews and their need to address species in more urgent conditions, it could be years before they decide on the status of the Blanding’s turtle.
Despite that, Green says he and his fellow researchers’ efforts concerning the Blanding’s turtle have gained even more significance because of the USFWS’ announcement. “Regardless of that outcome, it is a good feeling to know that so many people have worked very hard to help slow the decline of a threatened species. »
Those involved in the effort include biologists, interns, and volunteers from the USFWS’ Eastern Massachusetts National Wildlife Refuge Complex, as well as from Oxbow Associates, an environmental consulting firm in Boxborough.
“The project has been a resounding success,” Brian Butler, president of Oxbow Associates, said in a phone interview. “It’s nice to have that happen in life once in a while.” Butler said the success of the project is in large part the result of a fortuitous collision of people who are creative, willing and motivated.
These persons include Stephanie Koch, a USFWS biologist at Assabet River.
“Releasing the thousandth turtle is really remarkable, because I still vividly remember when we began with just a handful of turtles in the first year ,” Koch said via email. “It’s been exciting to watch the project gain momentum each year, gain partners each year, and of course, get us closer to our overall objective. We saw this as a great opportunity to contribute to the protection of this species, and help ensure it with a permanent place on the landscape.”
Biologists hope that building a strong population of Blanding’s turtles at Assabet River will help offset population losses being experienced by the turtles elsewhere.
Although there are some big Blanding’s turtle populations in the Midwest, most populations in the Northeast are less than 50 turtles, Butler says. The only large population is at Oxbow NWR, where an estimated several hundred Blanding’s turtles make their home. “That’s virtually unheard of east of the Mississippi,” explains Butler.
The open swampy and marshy wetlands at Assabet River provide good Blanding’s turtle habitat. And because it’s a protected wildlife refuge, future development that might threaten the turtles isn’t a concern.
Green joined the project in 2011, but researchers began introducing Blanding’s turtles at Assabet River in 2007, and have now released more than 500 direct-release hatchlings, and 500 head starts. Direct-release hatchlings are newly hatched turtles that are transported directly to the river and released. Head starts are baby turtles that are collected after hatching and distributed to schools and other organizations, like zoos and aquariums, where the tiny Blanding’s turtles are raised during the fall and winter, then released at the wildlife refuge in the spring.
Female Blanding’s turtles dig nest holes where they typically lay 10 to 12 eggs. Biologists try to protect at least 50 nests each year at Oxbow by putting metal screening over them so predators like skunks and raccoons can’t dig up the eggs. When the eggs hatch, researchers release several hundred hatchlings at Oxbow, and bring several hundred hatchlings to Assabet, where about half of them are distributed to groups that raise the head starts.
Head starting is thought to increase turtle survival rates because the head started turtles are significantly larger than wild turtles of the same age – about the size of a three or four year old turtle – and therefore less likely to fall victim to predators like raccoons, herons, and snapping turtles. Surprisingly, even chipmunks eat Blanding’s turtle hatchlings.
Blanding’s turtles are also at risk from habitat loss. Because they wander widely across the landscape between wetlands during the warm weather and while looking for open areas to dig their nests, many get run over by vehicles when crossing roads.
Green says chain link fences have now been built along some stretches of Route 2, a highway that runs through Blanding’s turtle habitat, in order to prevent turtles from trying to cross the road where many had been struck and killed by vehicles. The fencing has reduced Blanding’s turtle road mortality by 95 percent, but had to be built eight to nine feet tall, because the researchers discovered that Blanding’s turtles could actually climb over a three or four foot high fence.
Thirteen schools are involved in the head start program, including Bristol County Agricultural High School in Dighton, Mass., which head starts the largest number of turtles.
Brian Bastarache, chairman of the Natural Resource Management Department at Bristol County Agricultural High School, says that he and his students have been head starting Blanding’s turtles for seven years. The school has a 1000 square foot lab where last year they head started 200 turtles, including 70 Blanding’s turtles. Other head started turtle species, such as Plymouth red-bellied cooters, were destined for release on different projects.
Hatchlings are raised over the fall and winter, and are weighed and measured every week, Bastarache says. Baby Blanding’s turtles arrive weighing about 9 grams (less than 1/3 of an ounce) and grow to 60 to 100 grams (about 2 to 3 ounces) by the time they’re released.
“We trick them into thinking it’s a never ending summer,” Bastarache says. “The baby turtles keep eating and growing all winter.”
Bastarache says working on the turtle project gives students real world experience as part of the natural resource management program. “They apply what they’ve learned,” he says “Our kids … collect data, analyze data, and do an actual research project.” The best day of the school year, he says, is the annual Blanding’s turtle release day in the spring.
“All the kids’ work comes to a culmination that day,” he says. “They hear ‘you did a great job’ from other people. The kids feel a big sense of pride and accomplishment..”
Green agrees that the program offers a great educational experience for the students, teaching them about animal husbandry, the science of conservation biology, and its importance in protecting threatened species.
Also, though juvenile turtles have a high mortality rate, Green’s research has shown head started hatchlings are surviving at a much higher rate than direct-release hatchlings. A previous long-term study of Blanding’s turtles in Michigan found that first-year hatchling survival is only about 26 percent. “That is the number that we are hoping to improve upon through the process of head starting,” he says.
Back at the swamp, the beeping on Green’s receiver gets louder as he gets closer to turtle 3776. “I think she’s right in this area,” he says, as he wades near a partially submerged log. “Oh no,” he sighs, as he unexpectedly discovers an empty turtle shell on a small, grassy island. “Not what I wanted to see.”
The radio transmitter is still attached to the shell of the dead turtle, which Green suspects was probably killed and eaten by a mink or otter. The unanticipated find shows that even larger head started turtles sometimes fall victim to predators.
“That’s nature,” Green says. “But it drives home the point that we want the turtles to get to a larger size so predation is decreased.”
Turtle 3776 was one of their head starts.
“Even if it’s only got a number and not a name, you still get attached to them,” he says.