Editing Tuatara (section)

===Distribution and threats===
Tuatara were once widespread on New Zealand's main North and South Islands, where [[subfossil]] remains have been found in sand dunes, caves, and Māori [[midden]]s.<ref>{{cite journal |author1 = Towns, D.R. |author2 = Daugherty, C.H. |author3 = Cree, A. |title=Raising the prospects for a forgotten fauna: A review of 10&nbsp;years of conservation effort for New Zealand reptiles |journal=Biological Conservation |year=2001 |volume=99 |issue = 1 |pages=3–16 |doi=10.1016/s0006-3207(00)00184-1 |bibcode = 2001BCons..99....3T |url=http://www.claudius-r-us.com/forum/download/file.php?id=77 |access-date=11 March 2012|archive-url=https://web.archive.org/web/20140424131734/http://www.claudius-r-us.com/forum/download/file.php?id=77 |archive-date=24 April 2014}}</ref> Wiped out from the main islands before European settlement, they were long confined to 32&nbsp;offshore islands free of mammals.<ref name="DoC"/> The islands are difficult to get to,<ref>{{Harvnb|Lutz|2005|pp=59–60}}</ref> and are colonised by few animal species, indicating that some animals absent from these islands may have caused tuatara to disappear from the mainland. However, ''kiore'' (Polynesian rats) had recently become established on several of the islands, and tuatara were persisting, but not breeding, on these islands.<ref>{{cite journal |author=Crook, I.G. |year=1973 |title=The tuatara, ''Sphenodon punctatus'' {{small|(Gray)}}, on islands with and without populations of the Polynesian rat, ''Rattus exulans'' {{small|(Peale)}} |journal=Proceedings of the New Zealand Ecological Society |volume=20 |pages=115–120 |jstor=24061518 }}</ref><ref name=cree_etal1995>{{cite journal |author1 = Cree, A. |author2 = Daugherty, C.H. |author3 = Hay, J.M. |year = 1995 |title = Reproduction of a rare New Zealand reptile, the tuatara ''Sphenodon punctatus'', on rat-free and rat-inhabited islands |journal = Conservation Biology |volume = 9 |issue = 2 |pages = 373–383 |doi = 10.1046/j.1523-1739.1995.9020373.x|bibcode = 1995ConBi...9..373C }}</ref> Additionally, tuatara were much rarer on the rat-inhabited islands.<ref name=cree_etal1995/> Prior to conservation work, 25% of the distinct tuatara populations had become extinct in the past century.<ref name = "Daugherty_1990">{{cite journal |author1 = Cree, A. |author2 = Daugherty, C.H. |author3 = Hay, J.M. |date=1990-09-01 |title=Neglected taxonomy and continuing extinctions of tuatara (''Sphenodon'') |journal=Nature |volume=347 |issue=6289 |pages=177–179 |doi=10.1038/347177a0 |bibcode=1990Natur.347..177D |s2cid=4342765}}</ref>

The recent discovery of a tuatara hatchling on the mainland indicates that attempts to re-establish a breeding population on the New Zealand mainland have had some success.<ref name=bergner>{{cite news |title=Rare reptile hatchling found in New Zealand |newspaper=[[The Guardian]] |date=20 March 2009 |url=https://www.theguardian.com/environment/2009/mar/20/tuatara-reptile-new-zealand }}</ref> The total population of tuatara is estimated to be between 60,000<ref name=encyclo /> and 100,000.<ref>{{cite encyclopedia |author1 = Daugherty, C. |author2 = Keall, S. |title = Tuatara islands |encyclopedia = Te Ara – the Encyclopedia of New Zealand  |url = http://www.teara.govt.nz/TheBush/FishFrogsAndReptiles/Tuatara/2/en}}</ref>

==== Climate change ====
Tuatara have temperature-dependent sex determination meaning that the temperature of the egg determines the sex of the animal. For tuatara, lower egg incubation temperatures lead to females while higher temperatures lead to males. Since global temperatures are increasing, climate change may be skewing the male to female ratio of tuatara. Current solutions to this potential future threat are the selective removal of adults and the incubation of eggs.<ref>{{Cite web |date=2017-02-06 |title=A Threat to New Zealand's Tuatara Heats Up |url=https://www.americanscientist.org/article/a-threat-to-new-zealands-tuatara-heats-up |access-date=2022-12-12 |website=American Scientist |language=en}}</ref><ref>{{cite journal |last1=Hoare |first1=J. M. |last2=Pledger |first2=S. |last3=Keall |first3=S. N. |last4=Nelson |first4=N. J. |last5=Mitchell |first5=N. J. |last6=Daugherty |first6=C. H. |title=Conservation implications of a long-term decline in body condition of the Brothers Island tuatara ( Sphenodon guntheri ) |journal=Animal Conservation |date=November 2006 |volume=9 |issue=4 |pages=456–462 |doi=10.1111/j.1469-1795.2006.00061.x|bibcode=2006AnCon...9..456H |s2cid=86412390 }}</ref>