By Marcia Anderson

The seasonal vehicular migration that we humans make to the shore coincides with the beginning of diamondback terrapin nesting season in the northeast, often causing hundreds of turtle fatalities. Most of the terrapins squashed under car tires are pregnant females looking for a high, dry place along the shoulder of the road, above the high tide line to dig their nests and lay their eggs.

Diamondback Terrapin hatchlings rescued along the Mass. coastline by volunteers. Photo: Barbara Brennessel

Terrapins are relatively small, harmless turtles that live in salt marshes along the Atlantic and Gulf coasts. They are closely related to freshwater turtles and are the only turtles that are adapted to living exclusively in the brackish waters of coastal salt marshes. Their range extends along the Atlantic coast from Cape Cod to Southern Texas. These terrapins are true ‘home bodies’ and inhabit creeks within marshes very near where they were born. In Massachusetts and Rhode Island, diamondback terrapin populations are considered “critically imperiled”.

Barbara Brennessel of Wheaton College in Norton, Mass., author of the natural history of diamondback terrapins “Diamonds in the Marsh,” calls the diamondback terrapin “another example of a “turtle in trouble.” This elusive estuarine species is the focus of conservation efforts on Cape Cod, she said.

Up along the Connecticut and Massachusetts coastlines, terrapin nesting starts right about now. The Mass Audubon Society in Wellfleet has been monitoring diamondback terrapins for over 30 summers. They look for nesting terrapins and protect hatchlings from predators in Wellfleet Bay. The organization has countered the loss of nesting habitat, partly due to development, by creating nesting habit for the terrapins in places called turtle gardens, according to Audubon’s David Prescott. Last year the Audubon released about 3,000 hatchlings from turtle gardens. 

Terrapins are a predator of not only invasive green crabs, but of periwinkle snails that feed on salt marsh grass and are known to destroy thousands of acres of salt marsh, converting marsh meadows into mudflats. The destruction of wetland habitats may lead to increased flooding, ultimately affecting coastal property values.

Terrapin habitat destruction caused by coastal development has led to large numbers of road kills from Memorial Day Weekend through mid July. Female terrapins are killed trying to cross coastal roads in search of suitable nesting habitat.

Students from the Wetlands Institute, a part of New Jersey’s Stockton State College, and local volunteer residents patrol roads during the terrapin nesting season to minimize road kills. They also remove potentially viable eggs from the carcasses of the killed turtles. These eggs are incubated and, after hatching, are raised at a “turtle farm” for at least four months. The young turtles are tagged with an embedded a microchip and released back into the salt marsh. This successful conservation project has been conducted in the Cape May Peninsula since 1969.

Photo courtesy of Wetlands Institute; Stockton State College

 After much experimentation with barriers and fences, the Wetlands Institute found six-inch corrugated plastic drainage pipe was an effective, inexpensive, and easy way to install barriers. In June 2010 over 7,000 feet of corrugated tubing was installed, and shortly after, road kills were reduced along the entire length of this barrier.

Terrapins are in serious trouble throughout the coastal northeast. It is up to us to ensure their survival. When you see a terrapin crossing the road: slow down, stop, pick her up, cross her in the direction she was traveling, and wish her good luck. Contact the Wetlands Institute or the Massachusetts Audubon Society for more information on the diamondback terrapin conservation projects: Also read The Northern Diamondback Terrapin Habitat, Management and Conservation booklet.

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Marcia Anderson, who has a doctorate in environmental management, works with EPA’s headquarters on issues related to pest management in schools. She formerly worked in pesticides for EPA Region 2 and has a home in Lyman, Maine.