Where were you during the 1969 moon landing? What about at the turn of the century when the world was bracing for the Y2K Apocalypse? Or during the 2020 Covid-19 pandemic?
What if I told you that there are world record-breaking geckos in Canterbury that were here through it all? That two geckos in particular, ‘Antoinette’ and ‘Brucie-Baby’, recently celebrated their 60th and 64th birthdays? That might seem unimpressive compared to a human lifespan, but most geckos are lucky to live 10-15 years elsewhere in the world.
So, what’s their secret? And how do we know this? It’s not like you can just ask a gecko its age (that would be rude! as well as difficult…). If you’ve worked with geckos or other lizards like I have, you’d also know that they’re elusive at the best of times and all look the same to an untrained eye. Well, like all great scientific breakthroughs, this story involves good record keeping, a bit of fancy maths, and, of course, Lincoln ecologists!
The Beginning
Let me take you back to the summer of ‘67. Staff from the Department of Scientific and Industrial Research (DSIR) are tramping across Motunau Island, which lies 64 km north of Ōtautahi Christchurch and 1 km off the Canterbury coast. Weeds, fire, and rabbits had drastically changed the island’s vegetation since the 1850s, but rabbits were eradicated in 1962 and Motunau had otherwise never seen an introduced mammal. That absence makes the island a decent refuge for native lizards and seabirds.
Under the leadership of ecologist, Tony Whitaker, a team of DSIR staff surveyed lizards there every summer until 1975. As part of this, they caught Waitaha Geckos (Woodworthia brunnea) along a 20 x 20 m grid using pitfall traps, which are essentially baited holes in the ground that lizards fall into trying to get a sweet treat (don’t worry , this doesn’t harm them!).
Back then, Whitaker’s surveys had two main goals. The first was to test what kind of bait the lizards liked the most and the second was to figure out how to find nocturnal geckos in the dark. In case you were wondering, they found that lizards LOVE canned pear and that you can find geckos at night by spotlighting because their eyes reflect light like cats. For this story, though, the basic measurements taken from individual geckos over the years turned out to be far more interesting…
An Exciting Realisation
Fast forward several decades to the late 1990s and enter our Lincoln ecologists: Masters student Carol Bannock and Senior Lecturer Graham Hickling! Together with Tony Whitaker himself, they were going through Whitaker’s notes and realised that because geckos caught in the 1967-75 DSIR surveys were permanently marked by a unique combination of toes being clipped, they may be able to identify some of the same individuals 30 years later*. They also realised that because each individual had its snout-vent length (SVL) recorded, they could use growth rates to figure out how old each gecko was when first captured.
* Side note: I know toe clipping sounds brutal. We’ll unpack that later… For now, understand that although this method of identifying individuals is not used anymore, it was the best method for ecologists at the time because lizards shed their skin and therefore can’t be permanently marked by things like paint or dye.
With no time to lose, the trio raced back to Motunau! With some searching, they found the original lizard grid from old survey pegs (who needs modern GPS?) and diligently caught and measured geckos between December 1996 and February 1997. Overall, they found 61 new geckos and recaptured 16 of the 133 toe-clipped between 1967-1975 (~12%).
To determine the growth rates of Motunau’s Waitaha Geckos, Bannock, Whitaker, and Hickling used the average SVL of one-year-old geckos caught in 1996-97 (identified by their small size) and the differences in SVL length for geckos caught 12 months apart in 1967-75 to create a growth curve. They then used that curve to estimate how old each gecko was when first caught in 1967-1975 (large geckos were categorised as 6+ years because Waitaha Geckos tend to stop growing after this). Next, they calculated the age of the 16 geckos recaptured in 1996-97 by adding their estimated ages to the number of years since first capture. The modelling for this is a little tricky, but it’s thoroughly explained in this paper by Ebert (1980), if you are interested. What you really need to know is that 10 of those 16 geckos turned out to be at least 36 years old!! The remaining 6 were between 29 and 34.
2025 and Beyond
In 1999 when Bannock, Whitaker, and Hickling published their paper, finding 30+ year-old geckos was huge news. It proved that Waitaha Geckos on predator-free Motunau could live equally as long in the wild as they do in captivity and added at least 15 years to the previously estimated maximum age for the species (or any gecko species in the world for that matter!).
The discovery was so exciting that it also prompted the Department of Conservation to immediately take charge of regular surveys on Motunau. In fact, it was in their most recent 2024-25 survey that ‘Antoinette’ and ‘Brucie-Baby’ were rediscovered (named in honour of Tony Whitaker and his co-worker, Bruce Thomas, in 1967 and 1969).
That is not the end of Lincoln’s gecko searching though! Since 2021, our very own Dr Jennifer Gillette has been testing photography as a technique to identify individuals and to, hopefully, replace toe clipping in long-term studies. Together with her summer students, she has taken 1000s of photos of Waitaha Gecko iris and dorsal patterns around Akaroa Harbour and tested the ability of a pattern-recognition software called I3S to correctly match new photos with existing individuals in her database.
According to Jennifer, the research on Motunau’s geckos has significantly impacted the way we understand and manage gecko populations in Aotearoa today. Because they live so long, Waitaha Geckos have evolved to be K-selected species, which means they mature slowly and have very few offspring. This strategy worked well before humans arrived, but today, most gecko populations in Aotearoa don’t have the luxury of living on predator-free islands like Motunau. This means that many geckos may be eaten before they are old enough to have babies, and their populations may take decades to recover from predation.
That is why being able to identify individuals like Antoinette and Brucie-Baby is so important! It’s also why no pest species can be overlooked in conservation and environmental management efforts!!
The author, Sam Dryden, is a postgraduate student in the Master of Science at Te Whare Wānaka o Aoraki Lincoln University. This article was written as an assessment for ECOL 608 Research Methods in Ecology.
Article reference: Bannock, C. A., Whitaker, A. H., & Hickling, G. J. (1999). Extreme longevity of the common gecko (Hoplodactylus maculatus) on Motunau Island, Canterbury, New Zealand. New Zealand Journal of Ecology, 23(1), 101-103.