The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Malaclemys terrapin
Malaclemys terrapin
(Diamond-backed Terrapin)
Native Transplant

Copyright Info
Malaclemys terrapin (Schoepff, 1793)

Common name: Diamond-backed Terrapin

Taxonomy: available through www.itis.govITIS logo

Native Range: Along the Gulf and Atlantic coasts from Texas to Florida and north to Massachusetts (Ernst et al., 1994).

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Malaclemys terrapin are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CA196620022California Region; San Pablo Bay
MA192419924Cape Cod; Charles; Merrimack River; Virginian
PA196619661Lower Delaware

Table last updated 10/17/2021

† Populations may not be currently present.

Means of Introduction: Stocked in Massachusetts at Scusset Marshes in Sandwich and the Slocum River in Dartmouth. Unknown in other locations.

Status: Reported in Massachusetts and Pennsylvania.

Impact of Introduction: No impacts are reported.

Remarks: Terrapins may be sold illegally as food in Chinatown, Boston (Cardoza et al., 1993). Terrapin mortality most commonly stems from being caught in crab pots (Ernst et al., 1994).

Habitat: Coastal salt marshes, tidal creeks and estuaries (Ernst et al., 1994). Life History: During April to July, nests containing up to 18 eggs are excavated in dunes and shoreline soil, often proximal to vegetation (Ernst et al., 1994).

Scientific and standard English names follow Crother (2008).

References: (click for full references)

Babcock, H. L. 1926. The diamond-back terrapin in Massachusetts. Copeia. 150: 101-104.

Benavides, G., D. Renoud, and K. Wasson. 2002. Least wanted aquatic invaders: Diamond-back Terrapin (Malaclemys terrapin). The Elkhourn Souugh [online]

Conant, R. and J. T. Collins. 1998. A field guide to reptiles and amphibians. Eastern and Central North America. Third Edition, Expanded. Houghton and Mifflin Co. Boston.

Crother, B.I. (chair). Committee on Standard and English and Scientific Names. 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and  Reptiles Herpetological Circular. No. 37. iii + 86p.

Ernst, C. H., J. E. Lovich, and R. W. Barbour. 1994. Turtles of the United States and Canada. Smithsonian Institution Press, Washington and London.

McCoy, C. J. 1982. Amphibians and Reptiles in Pennsylvania: Checklist, bibliography, and atlas of distribution. Special puplication of Carnegie Museum of Natural History. Volume 6. Carnegie Museum of Natural History, Pittsburgh.

Author: McKercher, E.

Revision Date: 10/28/2009

Citation Information:
McKercher, E., 2021, Malaclemys terrapin (Schoepff, 1793): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1246, Revision Date: 10/28/2009, Access Date: 10/17/2021

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2021]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [10/17/2021].

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