Establishing a New Wild Population of Tuatara (Sphenodon guntheri)

Abstract

Translocations of reptiles and amphibians have been questioned as a conservation tool because they generally have not been successful. However, translocation is the only method by which many species can be restored to parts of their former range, which increases their conservation security. Tuatara ( Sphenodon spp.), sole surviving members of the reptilian Order Sphenodontia, are restricted to offshore islands of New Zealand. Dispersal into former habitat on the mainland or other islands, following removal of the causes of extinction, is unlikely. Captive rearing of reptile hatchlings from eggs collected in the wild to produce founders for new populations is also a conservation technique that has had mixed success. However, captive incubation and rearing are techniques that allow large numbers of tuatara to be produced to start new populations without detrimental effects on small source populations. We document the first contemporary translocation of S. guntheri, providing details on selection of release sites and founders. Release sites were chosen on a rodent‐free island that provided a variety of habitats for tuatara as well as abundant food and shelter. The release propagule comprised 18 wild‐caught adults and 50 captive‐reared juveniles. Four separate release sites were established to separate adults from juveniles during the establishment phase. Five years of monitoring indicate that at least 57% of tuatara survived translocation and that reproduction has occurred on the new island. All tuatara increased in weight and length, demonstrating that tuatara have an indeterminate growth pattern. The 56% of recaptured juveniles represented a cross section of the sizes released. We evaluated the use of head‐started juveniles as founders, based on survival and growth data. Because tuatara are long‐lived, late‐maturing reptiles with slow reproduction, establishment of a self‐sustaining population will take decades of monitoring to confirm.

Predicting the fate of a living fossil: how will global warming affect sex determination and hatching phenology in tuatara?

“…The greatest chance for the future survival of tuatara, other than reducing the magnitude of global warming, lies in their translocation to other islands or protected mainland areas predicted to have thermally suitable micro-sites for nesting (Nelson et al 2002a). Several translocations aimed at restoring tuatara to parts of their former range have occurred since the mid-1990s, including three translocations of S. guntheri.…”

Temperature-Dependent Sex Determination and Contemporary Climate Change

“…Translocation has met with mixed success when applied to reptiles of conservation concern, but the successful establishment of translocated reptiles [e.g. Nelson et al, 2002b;Cook, 2004;Germano and Bishop, 2009] demonstrates that it could be an important tool for allowing species to persist under a changing climate. Translocation to more southern reserves has been proposed for the Brothers' Island tuatara (S. guntheri) as a means of mitigating the impact of climate change -in this case, translocated populations already occur for this species and proposed translocation sites are potentially within the species' historic range [Mitchell et al, 2008].…”

Ecology and Dynamics of the Blood Parasite, Hepatozoon Tuatarae (Apicomplexa), in Tuatara (Sphenodon Punctatus) on Stephens Island, New Zealand

“…Small individuals with more ticks are more likely to be exposed to, and to ingest, an infective tick. Although tuatara have indeterminate growth, and size is not necessarily related to age (Nelson et al, 2002a), smaller individuals are probably younger than larger individuals and may be sufficiently naïve to the blood parasite to permit higher infection intensities. This is supported by the higher frequency of Ht observed in leukocytes among larger hosts.…”

“…However, we consider this explanation unlikely because bloodparasite infections in reptiles are rarely lethal (Eisen, 2001;Brown et al, 2006), and we found no association between blood-parasite infection and body condition. Furthermore, estimated annual survival rates of adult tuatara are relatively high (.95%; Nelson et al, 2002b).…”