TOSSI – The quest for Duvaucel’s geckos

Searching for a small reptile in dense bush may seem like an impossible task, but when you’re grovelling about with experienced hunters it is amazing what can be discovered.

Late in the summer I was in my element, scratching away at kikuyu grass, attempting to locate tracking tunnels that would prove the existence of Duvaucel’s geckos at Tāwharanui Open Sanctuary. Until recently, I didn’t know geckos were much of a thing in New Zealand, and I was intrigued when I met a fellow TOSSI volunteer who frequently goes on monitoring escapades.

Duvaucel’s geckos are New Zealand’s largest native gecko, measuring up to 32 centimetres from snout to tail-tip, and they are well camouflaged in tree hollows, under logs, rocks and bush litter, or in petrel burrows.

I begged to join the gecko seekers, and they let me tag along with a small troop to far-reaches of the park, where researchers had reintroduced 80 Duvaucel’s geckos in 2016.

Like many native species, they do well on sanctuary islands, but they are no-longer part of mainland ecosystems. Releasing these reptiles at Tāwharanui was a first for the mainland and was only possible because the park is surrounded by a predator proof fence and has a trapping programme.

The research collaboration involving Dr Manuela Barry from Massey University, Auckland Council and TOSSI aims to identify any effects of mice on the native gecko. For example, can Duvaucel’s geckos successfully establish in the presence of mice, do bigger groups of mice make geckos move from an area, stop breeding or will mice even eat the juveniles? The study could help develop the plans for further reintroductions of Duvaucel’s geckos throughout New Zealand, thus improving the nation’s biodiversity. It will also identify the impact of mice, should they find their way on to predator-free islands.

Last year, Covid restrictions kept volunteers at home and when we resumed monitoring tasks this year, the tracking tunnels were buried in the overgrowth. Experienced guides explained what I was looking for and then I was crawling about under harakeke (flax) to strike the researcher’s jackpot.

Inside the tracking tunnels are white cards with a central black inky strip that reptiles and mammals scurry across and consequently, leave their mark. There was genuine excitement for everyone when we saw the five-toed footprints of Duvaucel’s geckos. Brilliant! The reptiles were still alive, and we had the proof. There were also prints from mice and some cards had foot and tail prints of native skinks wanting to get in on the action. Each tracking card has a date and location, and the monitoring team returns these to the researchers. We reloaded the tunnels with new cards and some enticing morsels to continue luring both reptiles and mammals to take a wander across the inky strips.
Seeing really is believing, and now I’ve seen the footprints of our largest native gecko – I am keen to see the critter itself. That really will be a thrill.

Jackie Russell, TOSSI
www.tossi.org.nz