Research Profile

Returning Tuatara (Sphenodon spp.) to the New Zealand Mainland

Tuatara

Tuatara (Sphenodon spp.), endemic to New Zealand, have been confined to offshore islands since last century. Island populations are now stable but represent only a small portion of their former range, largely due to the impact of introduced predators.

Tuatara have been translocated to islands to increase their range, but the mainland offers greater diversity of habitat, and the potential for range expansion in response to climate change. This is important for long-term population persistence as tuatara have temperature-dependent sex determination, making them particularly vulnerable to the affects of global warming with males produced at warm incubation temperatures.

Tuatara research enclosure at Karori Wildlife Sanctuary

The translocation of a population of tuatara back to the New Zealand mainland into a mouse proof area at Karori Wildlife Sanctuary (KWS) occurred in December 2005. This allowed the opportunity to test ideas on a threatened species that are not usually possible. For example, investigation into what level of mouse control is necessary for tuatara to succeed on the mainland. This is valuable information as mice on the mainland remain a problem due to frequent reinvasions through fences.

Investigation into territory development has also been facilitated; tuatara are territorial animals, and territory acquisition is competitive, especially where they occur in high densities. Little is known about territory development, especially in juveniles and in new locations. Translocations have been conducted previously, but little information is available on factors that affect dispersal post-translocation. Dispersal is important for tuatara as females only mate every 4 years, and finding a mate in new habitat is important for population establishment and persistence.

This aim of this project is to successfully return tuatara to the New Zealand mainland. This is addressed within three research questions.

1. Can tuatara coexist with mice? This is investigated by monitoring a test group of 10 animals placed outside the mouse proof enclosure in KWS daily using radio telemetry.

2. Stephens Island

   How do tuatara develop territories? Firstly, two blocks of densely populated habitat on Stephens Island were cleared to monitor territory establishment in the gaps. Secondly, pre-dug burrows in KWS were arranged in two groups; those with the same layout as Stephens Island and those in a random layout. The aim is to test if knowledge of neighbours limits dispersal. Finally, territory size will be monitored by recording spot locations of animals in KWS to assess if territories differ in new habitats with competitive release.
3. Can tuatara survive on the mainland? The data gathered from the above questions will be collated to assess whether tuatara can survive on the New Zealand mainland.

Profile Kate McKenzie Kate did her undergraduate degree in Ecology and Zoology through Massey University in Palmerston North, and moved to Wellington to begin her Masters degree at Victoria University due to the active herpetology group established there. Kate has broad research interests including all aspects of reptile ecology, the use of translocation as a restoration tool and behavioural ecology particularly territoriality, resource use/defence and mating systems. Photo by Nicola Nelson.

Biological knowledge of tuatara has been used in the past to contribute to a successful conservation programme. However, there is still much to be learnt, especially with respect to the effects of restoring species to parts of their former range. Research will contribute to ecological knowledge on threatened species. These translocations will establish procedures for translocations to the mainland, an important step in the conservation of this biologically and culturally significant species.

Project completion will be mid 2007.

Papers & presentations

• Kate McKenzie & Nicola Nelson. Returning the tuatara (Sphenodonspp.) to the New Zealand mainland and investigating co-existence with mice (Mus musculus). New Zealand and Australia Joint Ecological Societies Conference, Ecology Across the Tasman, Wellington, July 2006.

More about Tuatara

• Tuatara restoration at Karori Wildlife Sanctuary
• Tuatara visitor experience at Karori Wildlife Sanctuary
• Tuatara fact sheet
• Information about tuatara on the Department of Conservation's website

Article Ref #0010
Published Mar 12, 2007
All photos by Kate McKenzie, except where indicated.