Research Profile

Tuatara mating and nesting behaviour

Captured on camera – the first ever image of tuatara mating in the wild on mainland New Zealand, at Wellington’s Karori Sanctuary Photo by Tom Lynch

Gail Porter, BSc (Biochemistry)
Nicola Nelson, PhD (supervisor)
School of Biological Sciences
Victoria University of Wellington
New Zealand

This research project is part of a broader study of tuatara (Sphenodon spp.) being undertaken by the School of Biological Sciences at Victoria University of Wellington. The overall aim is to establish whether tuatara populations can be self-sustaining on New Zealand’s mainland.

Gail’s research focuses on two of the factors necessary for tuatara self-sustainability – mating and nesting. A third factor (hatchling survival) will be studied separately, as a future project.

Although male tuatara mate every year, the females mate only once every four years. Courtship and mating take place in late summer (February to March), and nesting happens about 8 or 9 months later (October to November). Observations of tuatara on Stephens Island in Cook Strait – the source of the Karori Wildlife Sanctuary tuatara – show that males compete for the right to mate with females.

Gail’s field work during the mating period (February-March 2007) identified 23 individual tuatara – 15 males and 8 females out of the 35 males and 35 females transferred into Karori Sanctuary.

On Stephens Island (which has 2000 tuatara per hectare), 40 matings were observed in 2007. With 60 tuatara per hectare at the Sanctuary, Gail expected to see one or two matings there. She saw none, but three matings were observed by others. Two of these were at night. All three matings involved the same pair – and this pair was also seen “courting” on five other occasions.

The courtship behaviour was lengthy and slow, taking two to three hours for the pair to get within half a metre of each other. The male would move towards the female’s burrow in very gradual stages, and then position himself side-on to her and make a circuit around the burrow. The female would then respond – by rejecting the male or appearing to show interest.

Gail will study tuataras’ nesting behaviour later this year (October and November), when the females prepare for nesting.

The research project will be completed by the end of 2007.

Papers & presentations

• Gail Porter, Nicola Nelson, Jennifer Moore & Katherine MacKenzie. Density-dependence in the mating system of tuatara. Biolive Conference for Teachers, Victoria University of Wellington, July 2007; and The Biodiversity Extinction Crisis Conference, University of New South Wales, July 2007.

More about tuatara

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

Acknowledgements

• The Allan Wilson Centre
• Royal Society of New Zealand
• Victoria University of Wellington
• Nicola Nelson