Diamondback Terrapin Survey

Each year, just as people are heading to the beaches, so are female diamondback terrapins. Terrapins live in Delaware’s Inland Bays, but females lay their eggs in the soft sands of the beach dunes. Mid-May to mid-July is their nesting season.

Some are killed crossing Coastal Highway. Unfortunately, nearly all the terrapins that are killed are adult females. Because they can live for 25-30 years and can continue to reproduce for two decades, every female lost is also a loss of all her potential offspring. One solution is more sandy beach habitat on the Bays. But, these are becoming rarer and rarer as shorelines are hardened with bulkheads and stone. As an alternative to bulkheads and stone, the Center recommends installing a “living shoreline” that can reduce wave energy, trap sediment, and filter runoff, while maintaining (or increasing) beach or wetland habitat. Such habitat can protect diamondback terrapin populations by providing areas for feeding and growth.

Diamondback terrapins are an important salt marsh predator and are an iconic species for the region. Little is known about their long term population status, and how that changes year to year and place to place. Terrapins also face a number of serious threats including habitat loss and collisions with motor vehicles. To answer questions about terrapin population status, and ultimately to help with conservation efforts to increase terrapin numbers the Center is beginning a citizen science-based survey to count terrapins annually at multiple locations throughout the bays.

Learn more about diamondback terrapins and the importance of this work in the video below:

What’s it like to do a Survey?

Volunteers can perform surveys by kayaking a predetermined route (performed in pairs with another volunteer) or counting from a chosen land-based location. The survey can occur anytime from the last week of May through the second week of June (May 25 to June 14) but must be performed when weather conditions meet specific criteria for wind, cloud coverage, air temperature, and tide. All paddling routes are less than three miles round trip. Volunteers performing the paddling surveys must have their own kayaks and be comfortable paddling the chosen route without a guide. Observers will count the terrapin heads they see while performing the survey, and provide a GPS point for each terrapin (phone GPS points are accepted). Volunteers must attend training in order to participate in the survey.

Get Involved

Interested in helping out with the 2023 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 2023 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 2023 Volunteer Waiver.

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

STEP 1: Attend or Watch the Virtual Diamondback Terrapin Survey Training

Watch it here

STEP 2: Review the Frequently Asked Questions

What is the difference between the land and water-based surveys?

Where are the survey locations?

When does the survey occur?

How long does each survey take?

Can I bring my kids or grandkids to a land-based survey?

Can I bring my kids or grandkids to a water-based survey?

Can more than one person/group survey a specific site?

Do I need my own boat/kayak?

Can I survey more than one location?

What do I need to bring?

What if I don’t have a GPS?

Will I be kept informed on how the survey is going?

STEP 3: Determine which type of survey works best for you, using the 2022 Diamondback Terrapin Protocol, Tide Calendars, and Survey Locations Maps

Land-Based Surveys

Survey site maps:

Survey Protocols:

Water-Based Surveys

Survey site maps:

STEP 4: Complete the Sign-Up Form

Register HERE!

STEP 5: Complete the Volunteer Liability Waivers

Volunteer Waiver-Digital App

STEP 6: Let’s Count Some Terrapins!

Thank you for your support of the Center’s mission. The season kicks off in April of each year, then runs from May to June. This survey is weather dependent and it does not have a set schedule with possible last-minute notices to participants.

Volunteer Resources/Documents

• 2023 Volunteer Waiver
• Diamondback Terrapin Factsheet
• Volunteer Timesheet
• Land-based survey data sheet
• Water-based survey data sheet
• Surveys’ Protocols
• Rehoboth and Indian River Bays Survey Sites
• Little Assawoman Bay Survey Sites
• Land-Based Tide Calendar
• Water-Based Tide Calendar 
• Tide Calendars for Little Assawoman (land and water based)
• Beaufort Wind Scale
• Beaufort Wind Scale (PDF)
• GPS App Links
  • iOS (Apple) Devices
  • Android Devices
  • Google Maps (no app download required)
  • Windows Devices

Terrapin Gardens

The Center installed a turtle garden for nesting diamondback terrapins located in Delaware Seashore State Park. The nesting site provides suitable habitat that will allow female terrapins to lay their eggs. The project came from the understanding that suitable nesting habitats are difficult for terrapins to locate due to habitat loss and limited accessibility. Efforts have already been made in Delaware to bring attention to this species and implement ways to help limit roadway fatalities. In addition, this project will serve as an educational site for the general public to learn about the importance of this species and its role in the Inland Bays ecosystem. There has been reported success of this same project in New Jersey and we expect similar results in Delaware. For more information, visit our Terrapin Gardens project webpage.

Check out this cool article on
Terrapins featured in our Summer 2019 Inland Bays Journal!