Maine Audubon is calling for volunteers to collect data on how many turtles are killed by cars. Vehicle mortality is the largest threat to the state’s turtle population second only to habitat loss.  Photo courtesy of Maine Audubon

BATH — The mere act of crossing a road is causing trouble for some of Maine’s already threatened and endangered turtle species.

Maine Audubon is calling for volunteers for its third annual Maine Turtle Roadkill Survey project later this month. The project collects data on how many turtles are killed by cars, giving an insight into which roads have the highest turtle mortality rates so they can find ways to reduce the deaths.

In 2018 alone, the first year of the study, 31 volunteers surveyed a total of 105 routes across 11 counties. Fifty-five of those routes had observations of roadkill or wildlife crossing or attempting to cross the road, and 26 of these routes had a total of 99 turtle observations representing five species.

Biologists are working especially hard to protect box turtles and Blanding’s turtles, which are considered endangered and protected under the Maine Endangered Species Act; as well as spotted turtles, which are classified as threatened.

“The issue with turtles, especially, is that they are long-lived, and often take years – over a decade in Blanding’s turtles – to reach sexual maturity, plus nest mortality can be 90-100% some years … so they can’t take much mortality on the adults without hurting the population,” said Jeff Parmelee, a biology professor at the University of New England.

According to Sarah Haggerty, a conservation biologist at Maine Audubon, habitat loss and vehicles are the biggest threats to Maine’s turtle population. That threat will only increase, especially in parts of the state that are growing.

The human population of Cumberland County alone grew by about 12,000 between 2010 and 2018, according to the U.S. Census.

“(Turtles’) shells worked great against predators in evolutionary time but it’s no match for a car tire,” said Parmelee. “Especially in southern Maine, development is rampant and with each new housing development or shopping center comes more roads and more traffic.”

Haggerty said whenever a new road is built, it fragments a turtle’s habitat and creates new barriers turtles must cross to get from one habitat to another.

Maine is home to seven species of turtles, all of which live in marshy wetlands and ponds. During the summer, females move to warm, sandy areas to lay their eggs, forcing them to cross roadways.

While the distance turtles must travel depends on the environment, Haggerty said Blanding’s turtles are known to travel a kilometer or more.

While snapping turtles can lay up to 50 eggs per year, making it one of Maine’s most common turtles, box turtles only lay 10 to 15 eggs annually.

“If you only lay a dozen eggs and it took you 10 years to do it, if you die it’ll take 10 years to make up for that population loss,” said Haggerty.

Sharon Martel of Dayton volunteered for the survey because she was tired of seeing animals killed on the road and wanted to be a part of the solution.

“(Volunteering) is a small time commitment but I know I’m contributing to conservation science,” said Martel. “It’s a small way you can help but make a big difference.”

Volunteers are trained on how to identify turtle breeds and data collection methods. That information is sent to the Maine Department of Transportation, and local municipalities will then determine whether infrastructure such as a fence or culvert should be installed to keep turtles and other wildlife off the road.

The next volunteer training session will be from 8:30 a.m. to 12:30 p.m. Saturday, March 28, at Grace Episcopal Church in Bath.

Haggerty urged people to watch the roads when they’re driving in the summer when turtles, especially the females, are moving to their nest sites.

“We don’t tend to notice the smaller critters like turtles and other reptiles, but there’s reason to believe they’re hit more than mammals,” she said. “If you see a turtle crossing the road, you can help them, but always move them in the direction they were going. If you put them on the wrong side of the road, they know where they’re going, so they’ll just turn around and have to cross again.”