View source for Diamondback terrapin

{{Short description|Species of reptile}}
{{Speciesbox
| image = Diamond terrapin turtle reptile malaclemys terrapin.jpg
| image_caption = Photographed in the wild
| status = VU
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=Roosenburg, W.M. |author2=Baker, P.J. |author3=Burke, R. |author4=Dorcas, M.E. |author5=Wood, R.C. |date=2019 |title=''Malaclemys terrapin'' |volume=2019 |page=e.T12695A507698 |doi=10.2305/IUCN.UK.2019-1.RLTS.T12695A507698.en |access-date=12 November 2021}}</ref>
| status2 = CITES_A2
| status2_system = CITES
| status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus = Malaclemys
| parent_authority = [[John Edward Gray|Gray]], 1844<ref name=Rhodin1/>
| species = terrapin
| authority = ([[Johann David Schoepff|Schoepff]], 1793)<ref name=Rhodin1/>
| synonyms = {{collapsible list|
|''Malaclemys terrapin terrapin''
|''Testudo terrapin'' <small>Schoepff, 1793</small>
|''Testudo concentrica'' <small>[[George Kearsley Shaw|Shaw]], 1802</small>
|''Testudo ocellata'' <small>[[Johann Heinrich Friedrich Link|Link]], 1807</small>
|''Testudo concentrata'' <small>[[Heinrich Kuhl|Kuhl]], 1820</small>  ''([[ex errore]])''
|''Emys concentrica'' <small>Gray, 1831</small> (<small>[[André Marie Constant Duméril|Duméril]] & [[Gabriel Bibron|Bibron]], 1830</small><ref name="retiledb">[http://reptile-database.reptarium.cz/species.php?genus=Malaclemys&species=terrapin Malaclemys terrapin (SCHOEPFF, 1793)] - The Reptile Database</ref>)
|''Testudo concentrica'' var ''polita'' <small>Gray, 1831</small>
|''Emys terrapin'' <small>[[John Edwards Holbrook|Holbrook]], 1842</small>
|''Emys macrocephalus'' <small>Gray,1844</small><!-- non Sphix 1824, Gunther 1864, -->
|''Malaclemys concentrica'' <small>[[John Edward Gray|Gray]], 1844</small> (<small>1863</small><ref name="retiledb" />)
|''Emys macrocephala'' <small>LeConte,1854</small>
|''Emys terrapene'' <small>LeConte,1856</small> ''(ex errore)''
|''Clemmys terrapin'' <small>Strauch, 1862</small>
|''Malaclemmys concentrica'' <small>Gray, 1870</small>
|''Malacoclemmys terrapen'' <small>[[George Albert Boulenger|Boulenger]], 1889</small>  ''(ex errore)''
|''Malaclemys centrata concentrica ''<small>[[Doris Mable Cochran|Cochran]], 1932</small><ref name="retiledb" />
|''Malaclemys terrapin'' <small>[[Outram Bangs|Bangs]], 1896</small>
|''Malaclemmys centrata concentrica'' <small>Hay, 1904</small>
|''Malaclemys terrapin terrapin'' <small>Lindholm, 1929</small>
|''Malaclemys terrapene'' <small>Stephens & Wiens, 2003</small>
|''Malaclemys terrapin centrata''
|''Testudo centrata'' <small>Latreille, 1801</small>
|''Emys centrata'' <small>Schweigger, 1812</small>
|''Emys concentrica'' var ''livida'' <small>Gray, 1831</small>
|''Clemmys (Clemmys) centrata'' <small>Fitzinger, 1835</small>
|''Malaclemmys centrata'' <small>Lönnberg, 1894</small>
|''Malaclemmys terrapin centrata'' <small>Mittleman, 1944</small>
|''Malaclemys terrapin centrata'' <small>Mittleman, 1945</small>
|''Malaclemys terrapin centra'' <small>Highfield, 1996</small>  ''(ex errore)''
|''Malaclemys terrapin littoralis''
|''Malaclemmys littoralis'' <small>Hay, 1904</small>
|''Malaclemys centrata littoralis'' <small>Siebenrock, 1909</small>
|''Malaclemys pileata littoralis'' <small>Stejneger & Barbour, 1917</small>
|''Malaclemys terrapin littoralis'' <small>Lindholm, 1929</small>
|''Malaclemys terrapin macrospilota''
|''Malaclemmys macrospilota'' <small>Hay, 1904</small>
|''Malaclemys centrata macrospilota'' <small>Siebenrock, 1909</small>
|''Malaclemys pileata macrospilota'' <small>Stejneger & Barbour, 1917</small>
|''Malaclemys terrapin macrospilota'' <small>Lindholm, 1929</small>
|''Malaclemys terrapin pileata''
|''Emys pileata'' <small>Wied, 1865</small>
|''Malaclemmys pileata'' <small>Hay, 1904</small>
|''Malaclemys centrata pileata'' <small>Siebenrock, 1909</small>
|''Malaclemys pileata pileata'' <small>Stejneger & Barbour, 1917</small>
|''Malaclemys terrapin pileata'' <small>Lindholm, 1929</small>
|''Malaclemys terrapin rhizophorarum''
|''Malaclemys tuberculifera'' <small>Gray, 1844</small> ''([[nomen oblitum]])''
|''Malaclemmys littoralis rhizophorarum'' <small>Fowler, 1906</small> ''([[nomen protectum]])''
|''Malaclemmys terrapin rhizophorarum'' <small>Carr, 1946</small>
|''Malaclemys terrapin rhizophorarum'' <small>Carr, 1952</small>
|''Malaclemys terrapin rhizophararum'' <small>Anderson, 1985</small>  ''(ex errore)''
|''Malaclemys terrapin tequesta''
|''Malaclemys terrapin tequesta'' <small>Schwartz, 1955</small>}}
| synonyms_ref = <ref name="retiledb"/><ref name="Fritz2007">{{Cite journal |journal=Vertebrate Zoology |title=Checklist of Chelonians of the World |year=2007 |author=Fritz Uwe |author2=Peter Havaš |volume=57 |issue=2 |pages=190–192 |doi=10.3897/vz.57.e30895 |doi-access=free }}</ref>
}}

The '''diamondback terrapin''' or simply '''terrapin''' ('''''Malaclemys terrapin''''') is a [[species]] of [[terrapin]] native to the [[Brackish water|brackish]] coastal tidal marshes of the [[East Coast of the United States]] and the Gulf of Mexico coast, as well as in [[Bermuda]].<ref name="Parham2008">{{cite journal| last1 = Parham |first1=J.F.| last2 = Outerbridge |first2= Monika. E. | last3 = Stuart  |first3= B.L. | last4 = Wingate |first4= D.B.| last5 = Erlenkeuser |first5= H.| last6 = Papenfuss |first6= T.J.| year = 2008 | title = Introduced delicacy or native species? A natural origin of Bermudian terrapins supported by fossil and genetic data| journal =Biol. Lett.  | volume=4 | issue = 2| pages=216–219 | doi= 10.1098/rsbl.2007.0599|pmid=18270164|pmc= 2429930}}</ref> It belongs to the [[monotypic]] genus ''Malaclemys''.  It has one of the largest ranges of all turtles in North America, stretching as far south as the [[Florida Keys]] and as far north as [[Cape Cod]].<ref name="Seigel">{{cite journal| last = Seigel |first=Richard A.| title = Nesting Habits of Diamondback Terrapin (''Malaclemys terrapin'') on the Atlantic Coast of Florida|journal=Transactions of the Kansas Academy of Science| jstor = 3628414| volume=83|issue=4| pages=239–246|year=1980|doi=10.2307/3628414}}</ref>

The name "terrapin" is derived from the [[Algonquian languages|Algonquian]] word {{transliteration|alg|torope}}.<ref name="MW">{{Cite web|url=https://www.merriam-webster.com/|title=Dictionary by Merriam-Webster: America's most-trusted online dictionary|website=Merriam-webster.com|access-date=30 January 2022}}</ref> It applies to ''Malaclemys terrapin'' in both [[British English]] and [[American English]]. The name originally was used by early European settlers in North America to describe these brackish-water turtles that inhabited neither freshwater habitats nor the sea. It retains this primary meaning in American English.<ref name="MW"/> In British English, however, other semi-aquatic turtle species, such as the [[red-eared slider]], might also be called terrapins.{{citation needed|date=September 2017}}

==Description==
[[File:Diamondback turtle adult female.jpg|thumb|200px|Adult female]]
The common name refers to the diamond pattern on top of its shell (carapace), but the overall pattern and coloration vary greatly. No two diamondback terrapins look alike.<ref>{{Cite web |title=Diamondback Terrapin |url=https://aqua.org/explore/animals/diamondback-terrapin |access-date=2023-04-22 |website=National Aquarium |language=en}}</ref> The shell is usually wider at the back than in the front, and from above it appears wedge-shaped. The shell coloring can vary from brown to grey, and its body color can be grey, brown, yellow, or  white. All have a unique pattern of wiggly, black markings or spots on their body and head. The diamondback terrapin has large webbed feet.<ref name="CT Gov">{{cite web|url=http://www.ct.gov/dep/lib/dep/wildlife/pdf_files/outreach/fact_sheets/dmbkterp.pdf|title=Northern Diamondback Terrapin ''Malaclemys t. terrapin''|last=State of Connecticut Department of Environmental Protection|archive-url=https://web.archive.org/web/20120610150450/http://www.ct.gov/dep/lib/dep/wildlife/pdf_files/outreach/fact_sheets/dmbkterp.pdf|archive-date=10 June 2012|url-status=dead|access-date=25 October 2011}}</ref> The species is [[Sexual dimorphism|sexually dimorphic]] in that the males grow to a carapace length of approximately {{convert|13|cm|in|frac=2|abbr=on}}, while the females grow to an average carapace length of around {{convert|19|cm|in|frac=2|abbr=on}}, though they are capable of growing larger. The largest female on record was just over {{convert|23|cm|in|frac=2|abbr=on}} in carapace length. Specimens from regions that are consistently warmer in temperature tend to be larger than those from cooler, more northern areas.<ref>Davenport, John (1992).[http://www.britishcheloniagroup.org.uk/testudo/v3n4diamondback.htm "The Biology of the Diamondback Terrapin ''Malaclemys Terrapin'' (Latreille)"] {{webarchive|url=https://web.archive.org/web/20091017142425/http://www.britishcheloniagroup.org.uk/testudo/v3n4diamondback.htm |date=2009-10-17 }}, Tetsudo, '''3(4)'''</ref> Male diamondback terrapins weigh {{convert|300|g|oz|0|abbr=on}} on average, while females weigh around {{convert|500|g|oz|0|abbr=on}}.<ref>{{Cite web |url=http://www.dep.state.fl.us/coastal/sites/stmartins/pub/SMM_Terrapin_Report.pdf |title=The Status and Demography of the Ornate Diamondback Terrapin (Malaclemys terrapin macrospilota) within the Saint Martins Marsh Aquatic Preserve |access-date=2012-04-04 |archive-date=2016-09-28 |archive-url=https://web.archive.org/web/20160928193051/http://www.dep.state.fl.us/coastal/sites/stmartins/pub/SMM_Terrapin_Report.pdf |url-status=dead }}</ref> The largest females can weigh up to {{convert|1|kg|oz|abbr=on}}.<ref>{{cite book|url=https://books.google.com/books?id=jWH9F-w5e8UC&q=diamondback+terrapin+grams&pg=PA21 |title=Diamonds in the marsh: a natural history of the diamondback terrapin - Barbara Brennessel - Google Boeken |access-date=2013-04-22|isbn=9781584655367 |last1=Brennessel |first1=Barbara |year=2006 }}</ref>

Diamondback terrapins can live up to 40 years in captivity, but scientists estimate they typically live for about 25 years in the wild. <gallery mode="packed" heights="140">
File:Malaclemys terrapin diamondback terrapin turtle animal.jpg|The diamond pattern of the turtle's back
File:Diamondback Terrapin.jpg
File:Line4228 - Flickr - NOAA Photo Library.jpg|A tub full of diamondback terrapins of various colours
</gallery>

===Adaptations to their environment===
Terrapins look much like their freshwater relatives, but are well adapted to the near shore marine environment.  They have several adaptations that allow them to survive in varying salinities. They can live in full strength salt water for extended periods,<ref>{{cite journal | last1 = Bentley | first1 = P.J. | last2 = Bretz | first2 = W.L. | last3 = Schmidt-Nielsen | first3 = K. | year = 1967 | title = Osmoregulation in the diamondback terrapin, ''Malaclemys terrapin cetrata'' | journal = Journal of Experimental Biology | volume = 46 | issue = 1| pages = 161–167 | doi = 10.1242/jeb.46.1.161 | pmid = 6032170 | bibcode = 1967JExpB..46..161B }}</ref> and their skin is largely impermeable to salt.  Terrapins have lachrymal salt glands,<ref>{{cite journal | last1 = Cowan | first1 = F.B.M. | year = 1971 | title = The ultrastructure of the lachrymal "salt" gland and the Harderian gland in the euryhaline ''Malaclemys'' and some closely related stenohaline emydids | journal = Canadian Journal of Zoology | volume = 49 | issue = 5| pages = 691–697| doi=10.1139/z71-108| pmid = 5557904 }}</ref><ref>{{cite journal | last1 = Cowan | first1 = F. B. M. | year = 1981 | title = Effects of salt loading in salt gland function in the euryhaline turtle, ''Malaclemys terrapin'' | journal = Journal of Comparative Physiology | volume = 145 | pages = 101–108 | doi=10.1007/bf00782600| citeseerx = 10.1.1.494.4703 | s2cid = 574410 }}</ref> not present in their relatives, which are used primarily when the turtle is dehydrated.  They can distinguish between drinking water of different salinities.<ref name="Davenport, J 1990">{{cite journal | last1 = Davenport | first1 = J. | last2 = Macedo | first2 = E. A. | year = 1990 | title = Behavioral osmotic control in the euryhaline diamondback terrapin ''Malaclemys terrapin'': responses to low salinity and rainfall | journal = Journal of Zoology | volume = 220 | issue = 3| pages = 487–496 | doi=10.1111/j.1469-7998.1990.tb04320.x}}</ref> Terrapins also exhibit unusual and sophisticated behavior to obtain fresh water, including drinking the freshwater surface layer that can accumulate on top of salt water during rainfall and raising their heads into the air with mouths open to catch falling rain drops.<ref name="Davenport, J 1990"/><ref>{{cite journal | last1 = Bels | first1 = V.L. | last2 = Davenport | first2 = J. | last3 = Renous | first3 = S. | date = 1995 | title = Drinking and water expulsion in the diamondback terrapin ''Malaclemys terrapin'' | journal = Journal of Zoology (London) | volume = 236 | pages = 483–497 | doi = 10.1111/j.1469-7998.1995.tb02726.x }}</ref>

Terrapins are strong swimmers. They have strongly webbed hind feet, but not flippers like [[sea turtles]] do.  Like their relatives (''[[Graptemys]]''), they have strong jaws for crushing shells of prey, such as clams and snails.  This is especially true of females, who have larger and more muscular jaws than males.<ref>{{cite journal | last1 = Tucker | first1 = A. D. | last2 = Fitzsimmons | first2 = N. N. | last3 = Gibbons | first3 = J. W. | year = 1995 | title = Resource partitioning by the estuarine turtle ''Malaclemys terrapin'': trophic, spatial and temporal foraging constraints | journal = Herpetologica | volume = 51 | pages = 167–181 }}</ref>

===Subspecies===
Seven subspecies are recognized, including the [[nominate race]].

*''M. t. centrata'' ([[Pierre André Latreille|Latreille]], 1801) – Carolina diamondback terrapin (Georgia, Florida, North Carolina, South Carolina)<ref name=Rhodin1>{{cite journal
  | last1 = Rhodin | first1 = Anders G.J.
  | last2 = van Dijk | first2 = Peter Paul
  | last3 = Inverson | first3 = John B.
  | last4 = Shaffer | first4 = H. Bradley
  | title = Turtles of the world, 2010 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status
  | page = 000.101 | date = 2010-12-14
  | journal = Chelonian Research Monographs | volume = 5 
  | url = http://www.iucn-tftsg.org/wp-content/uploads/file/Accounts/crm_5_000_checklist_v3_2010.pdf }}</ref>
*''M. t. littoralis'' ([[William Perry Hay|Hay]], 1904) – Texas diamondback terrapin (Texas)<ref name=Rhodin1/>
*''M. t. macrospilota'' (Hay, 1904) – ornate diamondback terrapin (Florida) <ref name=Rhodin1/>
*''M. t. pileata'' ([[Prince Maximilian of Wied-Neuwied|Wied]], 1865) – Mississippi diamondback terrapin (Alabama, Florida, Louisiana, Mississippi, Texas)<ref name=Rhodin1/>
*''M. t. rhizophorarum'' [[Henry Weed Fowler|Fowler]], 1906 – mangrove diamondback terrapin (Florida)<ref name=Rhodin1/>
*''M. t. tequesta'' Schwartz, 1955 – East Florida diamondback terrapin (Florida)<ref name=Rhodin1/>
*''M. t. terrapin'' ([[Johann David Schoepff|Schoepff]], 1793) – northern diamondback terrapin (Connecticut, Delaware, Maryland, Massachusetts, New Jersey, New York, North Carolina, Rhode Island, Virginia)<ref>{{Harv|Conant|1975|p=}}</ref><ref>{{Harv|Smith|Brody|1982|p=}}</ref><ref name="retiledb"/><ref name="dtwg" >{{Cite web | author = Butler, J.A. | author2 = Seigel, R.A. | author3 = Mealey, B.K. | name-list-style = amp | title = ''Malaclemys terrapin - Diamondback Terrapin'' | date = 2006 | url = http://www.dtwg.org/Bibliography/Publications/Butler%20et%20al.,%202006.pdf | access-date = 2020-12-19 | archive-date = 2021-01-24 | archive-url = https://web.archive.org/web/20210124103553/http://www.dtwg.org/Bibliography/Publications/Butler%20et%20al.,%202006.pdf | url-status = dead }}</ref>

The isolated [[Bermuda]]n population, which arrived in Bermuda on its own rather than being introduced by humans, has not yet been officially assigned to a subspecies but, based on [[mtDNA]], it is closely related to the population from the Carolinas.<ref name="Parham2008"/>

==Distribution and habitat==
[[File:Malaclemys terrapin, Galveston Co., Texas; 8 May 2008.jpg|thumb|Texas diamond-backed terrapin (''Malaclemys terrapin littoralis''), [[Galveston County, Texas]] (8 May 2008)]]
Diamondback terrapins live in the very narrow strip of coastal habitats on the Atlantic and Gulf Coasts of the United States, from as far north as [[Cape Cod]], [[Massachusetts]], to the southern tip of [[Florida]] and around the [[Gulf Coast of the United States|Gulf Coast]] to [[Texas]]. In most of their range, terrapins live in ''[[Spartina]]'' marshes that are flooded at high tide, but in Florida they also live in mangrove swamps.<ref>{{cite journal | last1 = Hart | first1 = K. M. | last2 = McIvor | first2 = C. C. | year = 2008 | title = Demography and Ecology of Mangrove Diamondback Terrapins in a Wilderness Area of Everglades National Park, Florida, USA | journal = Copeia | volume = 2008 | pages = 200–208 | doi=10.1643/ce-06-161| bibcode = 2008Copei...1..200H | s2cid = 84316908 }}</ref> This turtle can survive in freshwater as well as full-strength ocean water, but adults prefer intermediate salinities. Despite its preference for salt water, it is not a true [[sea turtle]] and is not fully marine. They have no competition from other turtles, although [[common snapping turtle]]s do occasionally make use of salty marshes.<ref>{{cite journal | last1 = Kinneary | first1 = J. J. | year = 1993 | title = Salinity relations of ''Chelydra serpentina'' in a Long Island estuary | journal = Journal of Herpetology | volume = 27 | issue = 4| pages = 441–446 | doi=10.2307/1564834| jstor = 1564834 }}</ref> It is unclear why terrapins do not inhabit the upper reaches of rivers within their range, as in captivity they tolerate fresh water. It is possible they are limited by the distribution of their prey.<ref>Coker, R. E. 1906. The natural history and cultivation of the diamond-back terrapin with notes of other forms of turtles. North Carolina Geological Survey Bulletin. 14:1-67</ref> Terrapins live quite close to shore, unlike [[sea turtle]]s, which wander far out to sea; however, a population of terrapins on [[Bermuda]] has been determined to be self-established rather than introduced by humans.<ref name="Parham2008"/> Terrapins tend to live in the same areas for most or all of their lives, and do not make long-distance migrations.<ref name="Gibbons, J. W. 2001">{{cite journal | last1 = Gibbons | first1 = J. W. | last2 = Lovich | first2 = J. E. | last3 = Tucker | first3 = A. D. | last4 = Fitzsimmons | first4 = N. N. | last5 = Greene | first5 = J. L. | year = 2001 | title = Demographic and ecological factors affecting conservation and management of diamondback terrapins (''Malaclemys terrapin'') in South Carolina | journal = [[Chelonian Conservation and Biology]] | volume = 4 | pages = 66–74 }}</ref><ref name="Tucker, A. D. 2001">{{cite journal | last1 = Tucker | first1 = A. D. | last2 = Gibbons | first2 = J. W. | last3 = Greene | first3 = J. L. | year = 2001 | title = Estimates of adult survival and migration for diamondback terrapins: conservation insight from local extirpation within a metapopulation | journal = Canadian Journal of Zoology | volume = 79 | issue = 12| pages = 2199–2209 | doi=10.1139/z01-185| bibcode = 2001CaJZ...79.2199T }}</ref><ref>{{cite journal | last1 = Hauswaldt | first1 = J. S. | last2 = Glen | first2 = T. C. | year = 2005 | title = Population genetics of the diamondback terrapin (''Malaclemys terrapin'') | journal = Molecular Ecology | volume = 14 | issue = 3| pages = 723–732 | doi=10.1111/j.1365-294x.2005.02451.x| pmid = 15723664 | bibcode = 2005MolEc..14..723H | s2cid = 1897746 }}</ref>

==Life cycle==
Adult diamondback terrapins mate in the early spring, and clutches of 4–22<ref>Brennessel, Barbara. "Diamonds in the Marsh," Hanover: University Press of New England, 2006</ref> [[egg (biology)|eggs]] are laid in sand [[dune]]s in the early summer. They hatch in late summer or early fall. Maturity in males is reached in 2–3 years at around {{convert|4+1/2|in|mm|order=flip|round=5|abbr=on}} in length; it takes longer for females: 6–7 years (8–10 years for northern diamondback terrapins) at a length of around {{convert|6+3/4|in|mm|order=flip|round=5|abbr=on}}.{{Citation needed|date=April 2021}}

===Reproduction===
{{More citations needed section|date=April 2021}}
Like all reptiles, terrapin fertilization occurs internally. Courtship has been seen in May and June, and is similar to that of the closely related red-eared slider (''[[Trachemys scripta]]'').<ref>{{cite journal | last1 = Seigel | first1 = R.A. | year = 1980 | title = Courtship and mating behavior of the diamondback terrapin, ''Malaclemys terrapin tequesta'' | journal = Journal of Herpetology | volume = 14 | issue = 4| pages = 420–421 | doi=10.2307/1563703| jstor = 1563703 }}</ref>  Female terrapins can mate with multiple males and store sperm for years,<ref>Barney, R.L.  1922.  Further notes on the natural history and artificial propagation of the diamondback terrapin.  U.S. Bureau of Fisheries.  Economic Circular No. 5, rev.  91-111</ref> resulting in some clutches of eggs with more than one father.

Like many turtles, terrapins have temperature dependent sex determination, meaning that the sex of hatchlings is the result of incubation temperature. Females can lay up to three clutches of eggs/year in the wild,<ref name="Feinberg, J. A 2003">{{cite journal | last1 = Feinberg | first1 = J. A. | last2 = Burke | first2 = Russell L. | year = 2003 | title = Nesting ecology and predation of diamondback terrapins, ''Malaclemys terrapin'', at Gateway National Recreation Area, New York | journal = Journal of Herpetology | volume = 37 | issue = 3| pages = 517–526 | doi=10.1670/207-02a| s2cid = 59038338 }}</ref> and up to five clutches/year in captivity.<ref>{{cite journal | last1 = Hildebrand | first1 = S. F. | year = 1928 | title = Review of the experiments on artificial culture of the diamond-back terrapin | journal = Bulletin of the United States Bureau of Fisheries | volume = 45 | pages = 25–70 }}</ref>  It is not known how often they may skip reproduction, so true clutch frequency is unknown.

Females may wander considerable distances on land before nesting.  Nests are usually laid in sand dunes or scrub vegetation near the ocean<ref>{{cite journal | last1 = Roosenburg | first1 = W. M. | year = 1994 | title = Nesting habitat requirements of the diamondback terrapin: a geographic comparison | journal = Wetland Journal | volume = 6 | pages = 9–12 }}</ref> in June and July, but nesting may start as early as late April in Florida.<ref name="Butler, J. A. 2004">{{cite journal | last1 = Butler | first1 = J. A. | last2 = Broadhurst | first2 = C. | last3 = Green | first3 = M. | last4 = Mullin | first4 = Z. | year = 2004 | title = Nesting, nest predation and hatchling emergence of the Carolina diamondback terrapin, ''Malaclemys terrapin centrata'', in Northeastern Florida | journal = American Midland Naturalist | volume = 152 | pages = 145–155 | doi=10.1674/0003-0031(2004)152[0145:nnpahe]2.0.co;2| s2cid = 86042069 }}</ref>  Females will quickly abandon a nest attempt if they are disturbed while nesting.  Clutch sizes vary latitudinally, with average clutch sizes as low as 5.8/eggs/clutch in southern Florida<ref>Baldwin, J.D., L.A. Latino, B.K. Mealey, G.M. Parks, and M.R.J. Forstner.  2005.  "The diamondback terrapin in Florida Bay and the Florida Keys: Insights into Turtle Conservation and Ecology".  Chapter 20 In: In: W. E. Meshaka Jr., and K. J. Babbitt, eds. ''Amphibians and Reptiles: status and conservation in Florida''. Krieger Publishing Company, Malabar, Florida</ref> to 10.9 in New York.<ref name="Feinberg, J. A 2003"/>  After covering the nest, terrapins quickly return to the ocean and do not return except to nest again.

The eggs usually hatch in 60–85 days, depending on the temperature and the depth of the nest. Hatchlings usually emerge from the nest in August and September, but may overwinter in the nest after hatching.<ref name="Baker, P.J. 2006">{{cite journal | last1 = Baker | first1 = P.J. | last2 = Costanzo | first2 = J.P. | last3 = Herlands | first3 = R. | last4 = Wood | first4 = R.C. | last5 = Lee | first5 = R.E. Jr. | year = 2006 | title = Inoculative freezing promotes winter survival in hatchling diamondback terrapin, ''Malaclemys terrapin'' | journal = Canadian Journal of Zoology | volume = 84 | issue = 1 | pages = 116–124 | doi=10.1139/z05-183| bibcode = 2006CaJZ...84..116B }}</ref> Nest predation is a large threat to Diamondback Terrapins. A study was done on 3159 nests finding that the greatest predator was racoons and predated nests were completely emptied of egg.<ref name="Feinberg, J. A 2003" /> Hatchlings sometimes stay on land in the nesting areas in both fall and spring and they may remain terrestrial for much or all of the winter in some places.<ref name="Butler, J. A. 2004"/><ref>{{cite journal | last1 = Pilter | first1 = R | year = 1985 | title = ''Malaclemys terrapin terrapin'' (Northern diamondback terrapin) Behavior | journal = Herpetological Review | volume = 16 | page = 82 }}</ref> Hatchling terrapins are freeze tolerant,<ref name="Baker, P.J. 2006"/> which may facilitate overwintering on land.  Hatchlings have lower salt tolerance than adults and Gibbons et al.<ref name="Gibbons, J. W. 2001"/> provided strong evidence that one- and two-year-old terrapins use different habitats than do old individuals.

Growth rates, age of maturity, and maximum age are not well known for terrapins in the wild, but males reach sexual maturity before females because of their smaller adult size.  In females at least, sexual maturity is dependent on size rather than age.<ref>{{cite journal | last1 = Hildebrand | first1 = S. F. | year = 1932 | title = Growth of diamond-back terrapins: size attained, sex ratio and longevity | journal = Zoologica | volume = 9 | pages = 231–238 }}</ref>  Estimations of age based on counts of growth rings on the shell are as yet untested, so it is not clear how to determine the ages of wild terrapins.

===Seasonal activities===
Because nesting is the only terrapin activity that occurs on land, most other aspects of terrapin behavior are poorly known. Limited data suggest that terrapins hibernate in the colder months in most of their range, in the mud of creeks and marshes.<ref>{{cite journal | last1 = Yearicks | first1 = E. F. | last2 = Wood | first2 = R. C. | last3 = Johnson | first3 = W . S. | year = 1981 | title = Hibernation of the northern diamondback terrapin, ''Malaclemys terrapin terrapin'' | journal = Estuaries | volume = 4 | issue = 1| pages = 78–80 | doi=10.2307/1351546| jstor = 1351546 | s2cid = 84411783 }}</ref>

==Diet==
The diamondback terrapin typically feeds on [[fish]], crustaceans (such as [[shrimp]] and [[crabs]]) [[marine worms]], [[Sea snail|marine snails]] (especially the [[Littoraria irrorata|saltmarsh periwinkle]]), [[clam]]s, [[barnacles]], [[mussel]]s, other [[Mollusca|mollusks]], insects, carrion, and sometimes ingest small amounts of plant material, such as algae.<ref>{{cite web |url=https://www.tortoisetown.com/diamondback-terrapin-care-sheet/ |title = Diamondback Terrapin Care Sheet Freshwater Pet Terrapin Care Guide|website=Tortoisetown.com}}</ref><ref name="aqua.org">{{cite web |url=https://aqua.org/explore/animals/diamondback-terrapin |url-status=dead |archive-url=https://web.archive.org/web/20120423150124/http://www.aqua.org/explore/animals/diamondback-terrapin |archive-date=2012-04-23 |title=Diamondback Terrapin}}</ref><ref>{{Cite web|url=https://www.ncwildlife.org/Portals/0/Learning/documents/Profiles/diamondback_091611.pdf|title=Diamondback Terrapin North Carolina Wildlife Profiles|website=Ncwildlife.org|access-date=30 January 2022}}</ref><ref>{{cite web |url=http://blogs.thatpetplace.com/thatreptileblog/2014/08/12/diamondback-terrapin-care-keeping-usas-unique-turtle/#.X7CXuvkwi9I |title = Diamondback Terrapin Care |website=Blogs.thatpetplace.com|date = 12 August 2014 }}</ref><ref>{{Cite web|url=https://www.chesapeakebay.net/S=0/fieldguide/critter/diamondback_terrapin|title=Diamondback Terrapin &#124; Chesapeake Bay Program|website=Chesapeakebay.net|access-date=30 January 2022}}</ref> At high densities the terrapin may eat enough invertebrates to have ecosystem-level effects, partially because periwinkles themselves can overgraze important marsh plants, such as [[Spartina|cordgrass]] (''Spartina alterniflora'').<ref>{{Cite web|url=https://wetlandsinstitute.org/conservation/terrapin-conservation/20-years-of-terrapin-conservation-and-research/|title=25 Years of Terrapin Conservation and Research|website=Wetlandsinstitute.org|access-date=30 January 2022}}</ref> Gender and age can greatly affect the diet of the diamondback terrapin, males and juvenile females tend to have less diversity in their diet. Adult females, due to their powerful, defined jaw, will occasionally feed on crustaceans such as crabs and are more likely to consume hard-shelled mollusks.<ref>{{Cite web|url=http://www.dtwg.org/Bibliography/Theses/Tulipani%202013.pdf|title=Foraging ecology and habitat use of the northern diamondback terrapin (''Malaclemys terrapin terrapin'') in southern Chesapeake Bay|website=Dtwg.com|access-date=30 January 2022|archive-date=22 January 2021|archive-url=https://web.archive.org/web/20210122024347/http://www.dtwg.org/Bibliography/Theses/Tulipani%202013.pdf|url-status=dead}}</ref>

==Conservation==
{{More citations needed section|date=April 2021}}
[[File:Diamondback Terrapin. Taken by CITES.png|thumb|A juvenile diamondback terrapin]]

===Status===
In the early 1900s, the species was considered a [[delicacy]] and was hunted almost to [[extinction]].<ref name="The diamondback terrapin: The biolo">{{cite journal | last1 = Hart | first1 = K.M. | last2 = Lee | first2 = D.S. | year = 2006 | title = The diamondback terrapin: The biology, ecology, cultural history, and conservation status of an obligate estuarine turtle | journal = Studies in Avian Biology | volume = 32 | issue= 32 | pages = 206–213 | bibcode = 2006SAvBi..32..206H }}</ref>  The population also decreased due to the development of coastal areas, terrapins being susceptible to wounds from the propellers on motorboats.

Another common cause of death is the trapping of the turtles in recreational [[crab trap]]s, as the turtles are attracted to the same bait as the crabs.<ref>{{Cite web|last=Miller|first=Matthew L.|date=2018-03-27|title=Saving Terrapins From Drowning in Crab Traps|url=https://blog.nature.org/science/2018/03/27/saving-terrapins-from-drowning-in-crab-traps/|access-date=2021-03-26|website=Cool Green Science|language=en-US}}</ref> [[The Wetlands Institute]] estimates that a minimum of 14,000 to 15,000 terrapins drown in crab traps annually set along the New Jersey coast alone.<ref>{{Cite web|title=Terrapins and Traps - The Wetlands Institute|url=https://wetlandsinstitute.org/conservation/terrapin-conservation/terrapins-and-traps/|access-date=2021-03-26|website=Wetlandsinstitute.org}}</ref> Countless more drown or starve to death in [[Ghost net|ghost traps]], abandoned or lost crab traps along with discarded nets, throughout their habitat.<ref>{{Cite web|last=Kim|first=Josh|date=2019-11-27|title=Ghost pots imperil terrapins|url=https://www.oceancitytoday.com/news/ghost-pots-imperil-terrapins/article_650f399a-1138-11ea-be43-7fd183ad0558.html|url-status=live|access-date=2021-03-26|website=Ocean City Today|language=en |archive-url=https://web.archive.org/web/20220409184539/https://www.oceancitytoday.com/news/ghost-pots-imperil-terrapins/article_650f399a-1138-11ea-be43-7fd183ad0558.html |archive-date=2022-04-09 }}</ref> Among two such abandoned crab pots in a tidal marsh in Georgia, a study found 133 dead terrapins, according to the [[Center for Biological Diversity]].<ref>{{Cite web|last=Bennett|first=Elise|date=2020-02-05|title=International Turtle Experts Urge Florida to Protect Diamondback Terrapins From Drowning in Crab Pots|url=https://biologicaldiversity.org/w/news/press-releases/international-turtle-experts-urge-florida-protect-diamondback-terrapins-drowning-crab-pots-2020-02-05/|url-status=live|access-date=2021-03-26|website=Center for Biological Diversity|language=en|archive-url=https://web.archive.org/web/20210307121201/https://biologicaldiversity.org/w/news/press-releases/international-turtle-experts-urge-florida-protect-diamondback-terrapins-drowning-crab-pots-2020-02-05/ |archive-date=2021-03-07 }}</ref>

Further, an increase in [[seawall]]s and [[Bulkhead (barrier)|bulkheads]] being built for storm and erosion control, exacerbated by [[climate change]] and [[sea level rise]], inadvertently eliminate terrapin's nesting habitat on beaches and upland areas with soft shorelines.<ref>{{Cite journal|last1=Witherington|first1=Blair|last2=Hirama|first2=Shigetomo|last3=Mosier|first3=Andrea|date=2011-05-31|title=Sea turtle responses to barriers on their nesting beach|url=http://dx.doi.org/10.1016/j.jembe.2011.03.012|journal=Journal of Experimental Marine Biology and Ecology|volume=401|issue=1–2|pages=1–6|doi=10.1016/j.jembe.2011.03.012|bibcode=2011JEMBE.401....1W |issn=0022-0981|url-access=subscription}}</ref><ref>{{Cite web|title=Enhancing nesting habitat for northern diamondback terrapins in New Jersey - Turtle Gardens - Great Bay Terrapin Project - Wildlife Conservation - Conserve Wildlife Foundation of New Jersey|url=http://www.conservewildlifenj.org/protecting/projects/terrapin/garden/#:~:text=Northern%20diamondback%20terrapins%20are%20an,of%20salt%20and%20fresh%20water.&text=To%20help%20provide%20suitable%20areas,of%20sand%20in%20these%20areas.|access-date=2021-03-26|website=Conservewildlifenj.org}}</ref>

Due to these factors, the diamondback terrapin is listed as an [[endangered species]] in [[Rhode Island]], a [[threatened species]] in Massachusetts and is considered a "species of concern" in [[Georgia (U.S. state)|Georgia]], [[Delaware]], [[Alabama]], [[Louisiana]], [[North Carolina]], and [[Virginia]]. The diamondback terrapin is listed as a "high priority species" under the South Carolina Wildlife Action Plan. In [[New Jersey]], it was recommended to be listed as a Species of Special Concern in 2001. In July 2016, the species was removed from the New Jersey game list and is now listed as non-game with no hunting season. In Connecticut, there is no open hunting season for this animal. However, it holds no federal conservation status.<ref>{{Cite web |title=ECOS: Species Profile |url=https://ecos.fws.gov/ecp/species/2073 |access-date=2022-11-07 |website=ecos.fws.gov}}</ref> In 2021, a terrapin was hatched in Massachusetts with two heads, two gastrointestinal systems, and two spines that are fused together.<ref>{{Cite web|date=2021-10-14|title=A rare two-headed turtle is alive and thriving, surprising scientists|url=https://www.popsci.com/science/two-headed-turtle-born-massachusetts/|access-date=2021-10-17|website=Popular Science|language=en-US}}</ref>

===Conservation status===
The species is classified as [[Vulnerable species|Vulnerable]] by the [[IUCN]] due to decreasing population numbers in most of its range.<ref>Roosenburg, W.M.; Baker, P.J.; Burke, R.; Dorcas, M.E.; Wood, R.C. (2019). "Malaclemys terrapin". [[IUCN Red List|IUCN Red List of Threatened Species]]. '''2019''': e.T12695A507698. [[Doi (identifier)|doi]]:10.2305/IUCN.UK.2019-1.RLTS.T12695A507698.en. Retrieved 12 November 2021.</ref>  There is limited protection for terrapins on a state-by-state level throughout its range; it is listed as Endangered in Rhode Island and Threatened in Massachusetts. The Diamondback Terrapin Working Group <ref name="Diamondback Terrapin Working Group">{{Cite web|url=https://www.dtwg.org/|title=Home|website=Dtwg.com|access-date=30 January 2022}}</ref> deal with regional protection issues. There is no national protection except through the [[Lacey Act]], and little international protection.{{citation needed|date=September 2016}}

Diamondback terrapins are the only U.S. turtles that inhabit the brackish waters of estuaries, tidal creeks and salt marshes. With a historic range stretching from Massachusetts to Texas, terrapin populations have been severely depleted by land development and other human impacts along the Atlantic coast.{{citation needed|date=September 2016}}

[[Earthwatch Institute]], a global non-profit that teams volunteers with scientists to conduct important environmental research, supports a research program called "Tagging the Terrapins of the Jersey Shore." This program allows volunteers to explore the coastal sprawl of New Jersey's Ocean County on Barnegat Bay, one of the most extensive salt marsh ecosystems on the East Coast, in search of this ornate turtle. On this project, volunteers contribute to environmental sustainability in the face of rampant development. Veteran turtle scientists Dr. Hal Avery, Dr. Jim Spotila, Dr. Walter Bien and Dr. Ed Standora are overseeing this program and the viability of terrapin populations in the face of growing environmental change.<ref>{{Cite web|url=http://www.earthwatch.org/exped/avery.html|title=Earthwatch: Tagging the Terrapins of the Jersey Shore|website=Earthwatch.org|access-date=30 January 2022|archive-date=29 June 2013|archive-url=https://web.archive.org/web/20130629215121/http://www.earthwatch.org/exped/avery.html|url-status=dead}}</ref>

===Threats===
The conservation status was heavily impacted by the consumption of diamondback terrapins in the 1900s when their sweet meat eventually became a multi-million dollar industry for gourmet restaurants.<ref name="The diamondback terrapin: The biolo"/> Around the 1920s, with the enforcement of prohibition, the consumption of diamondback terrapins declined.<ref name="The diamondback terrapin: The biolo"/> Since then, however, the population has never fully recovered. Another threat is exposure to paralytic shellfish toxins (PST), such as [[saxitoxin]]s, which may contaminate mussels and other shellfish in terrapins' diets and are a result of the [[harmful algal bloom]]s that have been prominent along the coastline where diamondback terrapins reside.<ref name="The role of a PSP-producing Alexand">{{cite journal|last1=Hattenrath-Lehmann|first1=T.K.|last2=Ossiboff|first2=R.J.|last3=Burnell|first3=C.A.|last4=Rauschenberg|first4=C.D.|last5=Hynes|first5=K.|last6=Burke|first6=R.L.|last7=Bunting|first7=E.M.|last8=Durham|first8=K.|last9=Gobler|first9=C.J.|date=2017|title=The role of a PSP-producing Alexandrium bloom in an unprecedented diamondback terrapin (Malaclemys terrapin) mortality event in Flanders Bay, New York, USA|journal=Toxicon|volume=129|pages=36–43|doi=10.1016/j.toxicon.2017.02.006|pmid=28209476|bibcode=2017Txcn..129...36H |s2cid=26225689}}</ref> Gastrointestinal studies have identified the presence of ingested PST in their tissues which causes the muscle weakness, paralysis, etc. that eventually lead to death.<ref name="The role of a PSP-producing Alexand"/>

The major threats to diamondback terrapins are all associated with humans and probably differ in different parts of their range.  People tend to build their cities on ocean coasts near the mouths of large rivers and in doing so they have destroyed many of the huge marshes that terrapins inhabited.<ref>Ner, S, and R.L. Burke.  2008.  Direct and indirect effects of urbanization on Diamondback terrapins of New York City: Distribution and predation of terrapin nests in a human-modified estuary.  J.C. Mitchell, R.E. Jung, and B. Bartholomew (eds.).  Pp. 107-117 In: Urban Herpetology.  Herpetological Conservation Vol. 3: Society for the Study of Amphibians and Reptiles</ref>  Nationwide, probably >75% of the salt marshes where terrapins lived have been destroyed or altered. Currently, ocean level rise threatens the remainder.

Traps used to catch crabs, both commercially and privately, have commonly caught and drowned many diamondback terrapins,<ref name="Gibbons, J. W. 2001"/> which can result in male-biased populations, local population declines, and even extinctions.<ref name="Tucker, A. D. 2001"/><ref>{{cite journal | last1 = Dorcas | first1 = M. E. | last2 = Wilson | first2 = J. D. | last3 = Gibbons | first3 = J. W. | year = 2007 | title = Crab trapping causes population decline and demographic changes in diamondback terrapins over two decades | journal = Biological Conservation | volume = 137 | issue = 3| pages = 334–340 | doi=10.1016/j.biocon.2007.02.014| bibcode = 2007BCons.137..334D }}</ref>  When these traps are lost or abandoned ("ghost traps"), they can kill terrapins for many years.  Terrapin-[[Bycatch reduction device|excluding devices]] are available to retrofit crab traps; these reduce the number of terrapins captured while having little or no impact on crab capture rates.<ref>{{cite journal | last1 = Guillory | first1 = V. | last2 = Prejean | first2 = P. | year = 1998 | title = Effect of a terrapin excluder device on blue crab, ''Callinectes sapidus'', trap catches | journal = Marine Fisheries Review | volume = 60 | pages = 38–40 }}</ref><ref>Roosenburg, W.M. and J.P. Green. 2000. Impact of a bycatch reduction device on diamondback terrapin and blue crab capture in crab pots" ''Ecological Applications'' 10:882-889</ref> In some states (NJ, DE, MD), these devices are required by law.

Nests, hatchlings, and sometimes adults<ref>{{cite journal | last1 = Seigel | first1 = R.A. | year = 1980 | title = Predation by raccoons on diamondback terrapins, ''Malaclemys terrapin tequesta'' | journal = Journal of Herpetology | volume = 14 | issue = 1| pages = 87–89 | doi=10.2307/1563885| jstor = 1563885 }}</ref> are commonly eaten by raccoons, foxes, rats<ref name="Feinberg, J. A 2003"/><ref name="Hay, W.P 1917. Pages 3-21">Hay, W.P.  1917.  Artificial Propagation of the diamondback terrapin.  Department of Commerce Bureau of Fisheries Economic Circular No. 5, revised.  Pages 3-21</ref><ref>{{cite journal | last1 = Draud | first1 = M. | last2 = Bossert | first2 = M. | last3 = Zimnavoda | first3 = S. | year = 2004 | title = Predation on hatchling and juvenile diamondback terrapins (''Malaclemys terrapin'') by the Norway rat (''Rattus norvegicus'') | journal = Journal of Herpetology | volume = 38 | issue = 3| pages = 467–470 | doi=10.1670/29-04n| s2cid = 85682505 }}</ref> and many species of birds, especially crows and gulls.<ref name="Butler, J. A. 2004"/><ref>{{cite journal | last1 = Burger | first1 = J | year = 1977 | title = Determinants of hatching success in diamondback terrapin, ''Malaclemys terrapin'' | journal = American Midland Naturalist | volume = 97 | issue = 2| pages = 444–464 | doi=10.2307/2425108| jstor = 2425108 }}</ref> Density of these predators are often increased because of their association with humans.  Predation rates can be extremely high; predation by raccoons on terrapin nests at Jamaica Bay Wildlife Refuge in New York varied from 92 to 100% each year from 1998 to 2008,<ref name="Feinberg, J. A 2003"/> Burke unpubl. data).

Terrapins are killed by cars when nesting females cross roads<ref>{{cite journal | last1 = Szerlag | first1 = S. | last2 = McRobert | first2 = S.P. | year = 2006 | title = Road occurrence and mortality of the northern diamondback terrapin | journal = Applied Herpetology | volume = 3 | pages = 27–37 | doi=10.1163/157075406775247058}}</ref> and mortality can be high enough to seriously affect populations,<ref>{{cite journal | last1 = Avissar | first1 = N.G. | year = 2006 | title = Changes in population structure of diamondback terrapins (''Malaclemys terrapin terrapin'') in a previously surveyed creek in southern New Jersey | journal = Chelonian Conservation and Biology | volume = 5 | pages = 154–159 | doi=10.2744/1071-8443(2006)5[154:cipsod]2.0.co;2| s2cid = 85345195 }}</ref> especially during active periods, such as the breeding season. <ref>{{Cite journal |last1=McRobert |last2=Szerlag |date=2006 |title=Road occurrence and mortality of the northern diamondback terrapin |url=https://brill.com/view/journals/ah/3/1/article-p27.xml |journal=Applied Herpetology |volume=3 |issue=1 |pages=27–37 |doi=10.1163/157075406775247058 |issn=1570-7539|url-access=subscription }}</ref>Terrapins are still harvested for food in some states. Terrapins may be affected by pollutants such as metals and organic compounds,<ref>{{cite journal | last1 = Holliday | first1 = D. K | last2 = Elskus | first2 = A. A. | last3 = Roosenburg | first3 = W. M. | year = 2009 | title = Impacts of multiple stressors on growth and metabolic rate of ''Malaclemys terrapin'' | journal = Environmental Toxicology and Chemistry | volume = 28 | issue = 2| pages = 338–345 | doi=10.1897/08-145.1| pmid = 18788897 | bibcode = 2009EnvTC..28..338H | s2cid = 12542492 }}</ref> but this has not been demonstrated in wild populations.

There is an active casual and professional pet trade in terrapins and it is unknown how many are removed from the wild for this purpose.  Some people breed the species in captivity<ref>{{cite journal | last1 = Szymanski | first1 = S | year = 2005 | title = Experience with the raising, keeping, and breeding of the diamondback terrapin (''Malaclemys terrapin macrospilota'') | journal = Radiata | volume = 14 | pages = 3–12 }}</ref> and some color variants are considered especially desirable. In Europe, ''Malaclemys'' are widely kept as pets, as are many closely related species.

==Relationship with humans==
[[File:Testudo 2.jpg|thumb|University of Maryland's Testudo statue]]
In [[Maryland]], diamondback terrapins were so plentiful in the 18th century that slaves protested the excessive use of this food source as their main protein. Late in the 19th century, demand for [[turtle soup]] claimed a harvest of 89,150 pounds from [[Chesapeake Bay]] in one year. In 1899, terrapin was offered on the dinner menu of renowned [[Delmonico's Restaurant]] in New York City as its third most expensive item. Either Maryland or Baltimore terrapin was available for $2.50 ({{Inflation|US|2.50|1899|2018|r=2|fmt=eq|cursign=$}}). Although demand was high, over-harvesting diminished capture to a mere 823 pounds by 1920.<ref>{{Cite web |url=http://www.turtletrack.org/Issues03/Co01252003/CO_01252003_Partridge_Whistle.htm |title=Turtletrack.org |access-date=2007-03-31 |archive-url=https://web.archive.org/web/20030212144704/http://turtletrack.org/Issues03/Co01252003/CO_01252003_Partridge_Whistle.htm |archive-date=2003-02-12 |url-status=usurped }}</ref>

According to the [[FAA]] National Wildlife Strike Database, a total of 18 strikes between diamondback terrapins and civil aircraft were reported in the US from 1990 to 2007, none of which caused damage to the aircraft.<ref>{{cite web |url=http://wildlife.pr.erau.edu/BASH90-07.pdf |title=Archived copy |website=wildlife.pr.erau.edu |access-date=30 June 2022 |archive-url=https://web.archive.org/web/20080828152603/http://wildlife.pr.erau.edu/BASH90-07.pdf |archive-date=28 August 2008 |url-status=dead}}</ref> On July 8, 2009, flights at [[John F. Kennedy Airport]] in [[New York City]] were delayed for up to one and a half hours as 78 diamondback terrapins had invaded one of the runways. The turtles, which according to airport authorities were believed to have entered the runway in order to nest, were removed and released back into the wild.<ref>[http://www.nypost.com/seven/07082009/news/regionalnews/queens/turtles_delay_flights_at_jfk_178237.htm Turtles Delay Flights at JFK] at the ''[[New York Post]]'' website</ref> A similar incident happened on June 29, 2011, when over 150 turtles crossed runway 4, closing the runway and disrupting air traffic. Those terrapins were also relocated safely.<ref>[http://www.cnn.com/2011/TRAVEL/06/29/new.york.turtles.airport/index.html?hpt=hp_t2 Mating turtles shut down runway at JFK] at [[CNN.com]]</ref>  The Port Authority of New York and New Jersey installed a turtle barrier along runway 4L at JFK to reduce the number of terrapins on the runway and encourage them to nest elsewhere.<ref>{{cite news|last=Prendergast|first=Daniel|title=Shell of a save: JFK barriers to block runway turtles|url=http://www.nypost.com/p/news/local/queens/shell_of_save_6RTJtcfQFbl27yHTgUMrQM|access-date=15 June 2013|newspaper=New York Post|date=15 June 2013}}</ref>  Nevertheless, on June 26, 2014, 86 terrapins made it onto the same runway, as a high tide carried them over the barrier.  Their population is controlled by the raccoon population; it has been shown that as the raccoons decrease in number, mating terrapins increase, leading to increased turtle activity at the airport.<ref>{{cite web |last1=Schweber |first1=Nate |title=Studying What Lures Turtles to a Tarmac at Kennedy Airport |url=https://www.nytimes.com/2014/07/04/nyregion/diamondback-turtles-terrapins-takeover-jfk-kennedy-international-airport.html |work=[[The New York Times]]|date= 3 July 2014|access-date=11 February 2019}}</ref>

Many human activities threaten the safety of diamondback terrapins. The terrapins get caught and drown in crab nets that humans put out, are [[suffocated]] by [[Water pollution|pollution]] that humans greatly contribute to, and lose their marsh and estuarine habitats because of [[urban development]].<ref>{{Citation | last = Conant| first = Therese| title = Diamondback Terrapin| url = http://www.ncwildlife.org/Portals/0/Learning/documents/Profiles/diamondback_091611.pdf| access-date = October 20, 2011| publisher = Division of Conservation Education, N.C. Wildlife Resources Commission}}</ref> Recent anthropogenic habitat modification, such as the construction of docks, roads, and housing developments, as well as activities such as crab-trapping, likely play a role in low annual survivorship. <ref>Witczak, L. R., Guzy, J. C., Price, S. J., Gibbons, J. W., & Dorcas, M. E. (2014). Temporal and spatial variation in survivorship of diamondback terrapins (Malaclemys terrapin). Chelonian Conservation and Biology, 13(2), 146-151.</ref>

===History as a delicacy{{anchor|Cuisine}}===
{{Rquote|right|Part of the pleasure of eating terrapin when the fashion was at its height, however, was its outré, bizarre, even monstrous essential nature...Killing, cleaning, and preparing terrapin is not easy...|Paul Freedman<ref name="freedman"/>}}Diamondback terrapins were heavily harvested for food in colonial America and probably before that by Native Americans. Terrapins were so abundant and easily obtained that slaves and even the Continental Army ate large numbers of them.

In the 19th century, a dish called {{anchor|Terrapin à la Maryland}}"Terrapin à la Maryland", a stew with cream and sherry, was a canonical element, along with [[Canvasback|canvasback duck]], of the elegant and regional "Maryland Feast" menu, an "elite standard...that lasted for decades".<ref name="freedman">Paul Freedman, "Terrapin Monster", p. 51–64 of Dina Khapaeva, ed., ''Man-Eating Monsters: Anthropocentrism and Popular Culture'', {{isbn|9781787695283}}, p. 59</ref>

By 1917, terrapins sold for as much as $5 each ({{Inflation|US|5|1917|2017|r=2|fmt=eq|cursign=$}}).<ref name="Hay, W.P 1917. Pages 3-21"/>  Huge numbers of terrapins were harvested from marshes and marketed in cities. By the early 1900s, populations in the northern part of the range were severely depleted and the southern part was greatly reduced as well.<ref name="Coker, R. E 1931. pp. 219-230">Coker, R. E. 1931. The diamondback terrapin in North Carolina. In (ed) H. F. Taylor, Survey of Marine Fisheries of North Carolina. University of North Carolina Press, Chapel Hill, NC pp. 219-230</ref>  As early as 1902 the U.S. Bureau of Fisheries (which later became the U.S. Fish and Wildlife Service) recognized that terrapin populations were declining and started building large research facilities, centered at the Beaufort, North Carolina Fisheries Laboratory, to investigate methods for captive breeding terrapins for food.<ref>Wolfe, Douglas A. 2000. A History of the Federal Biological Laboratory at Beaufort, North Carolina 1899-1999.</ref> People tried (unsuccessfully) to establish them in many other locations, including San Francisco.<ref>{{cite journal | last1 = Brown | first1 = P. R. | year = 1971 | title = The story of California diamondbacks | journal = Herpetology | volume = 5 | pages = 37–38 }}</ref>

===Use as a symbol===
Maryland named the diamondback terrapin its official [[List of U.S. state reptiles|state reptile]] in 1994. The [[University of Maryland, College Park]] has used the species as its nickname (the [[Maryland Terrapins]]) and mascot ([[Testudo (mascot)|Testudo]]) since 1933, and the school newspaper has been named ''[[The Diamondback]]'' since 1921. Accordingly, the athletic teams are often known as "Terps" for short.<ref name="Maryland 2010">{{cite web | url = http://www.msa.md.gov/msa/mdmanual/01glance/symbols/html/reptile.html | title = Maryland state reptile—diamondback terrapin | access-date = January 21, 2011 | date = March 8, 2010 | work = Maryland manual on-line: a guide to Maryland government | publisher = Maryland State Archives | archive-date = January 11, 2012 | archive-url = https://web.archive.org/web/20120111152618/http://www.msa.md.gov/msa/mdmanual/01glance/symbols/html/reptile.html | url-status = dead }}</ref> The Baltimore baseball club entry in the [[Federal League]] during 1914 and 1915 was called the [[Baltimore Terrapins]]. The terrapin has also been a symbol of the [[Grateful Dead]], upon the release of their studio album, ''[[Terrapin Station]]''; as a result, many images of the terrapin dancing with a tambourine appear on posters and t-shirts in Grateful Dead memorabilia. Inspired by the song, the [[Terrapin Beer Company]] also uses a terrapin as its namesake and logo on its packaging.<ref>{{Cite web|last=Ogletree|first=Owen|date=2007|title=An interview with the owners of Terrapin Beer Company, Athens, Georgia.|url=http://www.classiccitybrew.com/terrapin07.html|access-date=2020-12-16|website=Classiccitybrew.com}}</ref>

==References ==
{{Reflist}}

==Bibliography==
* {{Cite book|last=Conant|first=Roger|title=A Field Guide to Reptiles and Amphibians of Eastern and Central North America|edition=2nd|publisher=Houghton Mifflin|location=Boston|year=1975}}
* {{Cite book|last1=Smith|first1=Hobart Muir|last2=Brody|first2=E.D.|title=Reptiles of North America: A Guide to Field Identification|publisher=Golden Press|location=New York|year=1982}}

==External links==
{{Commons category|Malaclemys terrapin|Diamondback terrapin}}
* [http://www.diamondbackterrapin.com/ Jonathan's Diamondback Terrapin World]
* {{usurped|1=[https://web.archive.org/web/20030304010241/http://www.chelonia.org/malaclemmysgallery.htm Malaclemys Gallery]}}
*{{EMBL species|genus=Malaclemys|species=terrapin}}

{{Emydidae}}

{{Taxonbar|from=Q569170}}
{{Authority control}}

[[Category:Fauna of the Eastern United States]]
[[Category:Reptiles of the United States]]
[[Category:Symbols of Maryland]]
[[Category:Malaclemys]]
[[Category:Reptiles described in 1793]]
[[Category:Taxa named by Johann David Schoepff]]