Each turtle is radio-tracked one time over the winter. During warm weather, researchers capture turtles three times, measuring and weighing them, taking notes on their health, and changing transmitter batteries when needed.
Another reason for radio-tracking turtles is to follow adult females to their nesting sites in spring. Some will nest in agricultural areas, like corn fields, but about two-thirds of the Great Meadows turtles nest in people’s yards.
“They tend to pick the warmest spot to dig their nests,” said Windmiller, “such as an open patch of garden or lawn next to asphalt or a sidewalk, because they retain heat and increase hatching success.
“Sometimes we knock on doors at 9 or 10 at night when we’ve found a turtle nesting in someone’s yard, and ask, ‘Do you mind if we hang out?’ Most people are pretty engaged in helping turtles, even moving their flowers so we can put a cage around the nest.”
Windmiller said the members of his conservation project put hardware-cloth screening over nests early in the season to keep out raccoons and skunks.
Eggs used to hatch in mid-September, but with warmer summers in recent years, they are now hatching in late August and early September.
Another result of hotter summers is more female hatchlings, researchers say.
Blanding’s, as well as many other turtle species, undergo temperature-dependent sex determination, where warmer nest temperatures tend to produce female offspring, and cooler temperatures produce males.
Windmiller said participants in the conservation project put screening around nests in August to protect the hatchlings and allow them to be collected for head-starting. Scarcely larger than a quarter, the tiny turtles may eventually grow as large as 10 inches long and weigh up to 3 pounds.
John Berkholtz, the senior keeper at the Stone Zoo, has been assisting the Blanding’s conservation project since 2006. Berkholtz said in an e-mail that about 10 turtles a year are given a head start at the zoo, where hatchlings from the wild are raised in a captive setting for nine months, then released .
“Head-starting increases survivorship in two major ways,” Berkholtz explained. “The increase in size . . . at release makes them too big to be easy prey for predators such as herons, bullfrogs, and raccoons. Also, they are better able to withstand changeable environmental conditions such as heat and dry conditions, and are able to locate water and food sources, especially in preparation for hibernation.”
“Mink and otters kill some of the released head starts,” Windmiller said, “and some drown. But overall, the head-start turtles have an 80 to 90 percent survival rate. Head-starting increases the survival rate about 20 times over wild hatchlings.”
Windmiller said the US Fish and Wildlife Service typically allows him to keep 50 hatchlings for head-starting, and the remainder are turned loose.
After recording the data for turtle 3300, Windmiller headed off across the open ice, following the signal of a head-started Blanding’s turtle that was released last fall.
Don Lyman is a freelance science writer and adjunct instructor in the biology department at Merrimack College. He can be reached at email@example.com.