Establishing a New Wild Population of Tuatara (Sphenodon guntheri)

• Published in: Conservation biology 2002-08, Vol.16 (4), p.887-894
• Main Authors: Nelson, Nicola J., Keall, Susan N., Brown, Derek, Daugherty, Charles H.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Conservation biology; Conservation in Practice; Conservation, protection and management of environment and wildlife; Eggs; Female animals; Fundamental and applied biological sciences. Psychology; Habitat conservation; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Population growth; Population size; Reptiles; Wildlife conservation; Young animals; Zoology
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1046/j.1523-1739.2002.00381.x

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.