Northern Diamondback Terrapin

Mordecai Island’s cove is home to a small population of Northern Diamondback Terrapins (Malaclemys terrapin terrapin), a New Jersey protected brackish water species that is indigenous to coastal marsh regions. The island’s safe and diverse habitats attract terrapins to bask, feed and nest. Nesting occurs from late May through July on sandy, sunny, non-vegetated areas that are above the high tide line. However, erosion, rising sea levels and urban development have created fewer suitable nesting habitats for successful egg incubation. Terrapins are now navigating over bulkheads, crossing busy streets and nesting further from the marsh in less desirable substrates, which has impacted the population’s survival. 


In 2016, a Terrapin Garden was established on an elevated sand mound at the southwest corner of Mordecai island. In partnership with Project Terrapin and Terrapin Nesting Project, eggs from at-risk nests within Holgate, NJ were relocated to this site and allowed to incubate. The conservation goal of this project was to create a habitat for natural and artificial nesting, establish site fidelity, and repopulation of the species.

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2020 Report

Coming soon. See the 2019 report below for the most up-to-date status.

2019 Report

Following the 2018 installation of Oyster Castles and Marsh Sills breakwater structures along the island’s southwest coastline, an elevated sand mound formed behind the old Terrapin Garden, which successfully supported natural and artificial Northern Diamondback Terrapin nesting.

In accordance with NJDEP Wildlife Scientific Collecting Permits 2019-1825 and 2019100; and US Fish and Wildlife Permit 2019-020, three Northern Diamondback Terrapin clutches, totaling 30 eggs, were renested at the site and covered with nest exclosures to protect the eggs from predators.  Hatchling emergence of the relocated eggs occurred from incubation day 63-86, with an 80% success rate (Table 4).  An overall 71% hatchling success rate was achieved for both natural and relocated egg nesting at this new site.

Learn more about Project Terrapin at:

Learn more about Terrapin Nesting Project at:

2017 Status

The IRS  has determined that the Mordecai Land Trust is tax-exempt under section 501(c)(3) of the Internal Revenue Code of 1986 (“Code”) and not a private foundation pursuant to sections 509(a)(1) and 170(b)(1)(A)(vi) of the Code. Mordecai Land Trust was established in 2001.

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