Diamondback Terrapin Survey

December 2024

The Diamondback Terrapin Survey, initiated in 2019, engages volunteers to count basking terrapin in the Inland Bays. Diamondback terrapins are an ecologically and culturally important species for the Inland Bays. Along the Atlantic Coast, terrapin populations have declined dramatically, and face many serious threats from habitat loss, vehicle and boat collisions, increased predation, and drowning in fishing gear. In the Inland Bays, one source of morality is crossing Coastal Highway, which disproportionately kills adult females in search of nesting habitat. State Parks installed the turtle-proof fence in 2005 as a result of Center surveys documenting the scale of this mortality event.

Terrapins can live for 25-30 years and can continue to reproduce for two decades. They need sandy beach habitat, easy access to clean brackish water, and healthy salt marshes. But, these habitats are becoming more rare as shorelines are hardened with bulkheads and stone. As an alternative, the Center recommends installing a “living shoreline” that can reduce wave energy, trap sediment, and filter runoff, while maintaining (or increasing) beach or marsh habitat. Such habitat can protect diamondback terrapin populations by providing areas for feeding and growth.

Currently, no long-term population data exists for terrapins in the Inland Bays. The first step to protection is building a fundamental understanding of terrapin abundance, how that abundance fluctuates naturally between years, and the spatial distribution of terrapins within the bays. The results of this survey can provide optimal locations for terrapin enhancement projects such as beach nesting habitat creation or derelict crab pot removal efforts.

What’s it like to do a Survey?

There are two types of terrapin surveys: water-based and land-based. The water-based surveys use kayaks to paddle transects through large marsh areas of the Inland Bays (all paddling routes are less than three miles round trip). Pairs of volunteers count and record the GPS location for each terrapin or group of terrapins seen. Land-based surveys are performed from stationary locations throughout the bays. The paddling transects and stationary point count locations are pre-selected and serve as long-term stations for the survey.

The survey takes place from the last week of May through the first two weeks of June which corresponds to the peak adult population. Adults have come out of dormancy, and are not seeking nests onshore and it is before the newly hatched and difficult-to-spot young become part of the population. Weather conditions need to meet specific criteria for wind, cloud coverage, air temperature, and tide.

Volunteers involved in data collection are trained annually in survey protocols and safety. Survey training is also hosted virtually and recordings are made available after on the Center’s website.

Survey Protocols

Watch the Virtual Diamondback Terrapin Survey Training

Get Involved

Interested in helping out with this year’s survey season? Contact the Center’s Manager of Community Science, Nivette Pérez-Pérez, at volunteer@inlandbays.org and join the Diamondback Terrapin Survey mailing list.

As the season approaches, additional information will be sent to all potential volunteers regarding assignments, tides, and other important details. Then, you will be able to participate in the survey training, sign up, and start counting terrapins!

All volunteers must fill out the Center’s Volunteer Waiver.

Click HERE for more information about other volunteer opportunities. Another way to support our mission is by donating HERE!