Our Changing World: Bringing back lizards in Central Otago

5:48 am today

By Karthic SS for Our Changing World

On the rock tors of Central Otago, herpetologist Carey Knox scans the schist ledges for lizards. He's looking for a grand skink, or an Otago skink.

Both are endangered lizard species that became extinct in this area due to introduced pests and habitat destruction.

Now, the skinks have returned to these outcrops near Alexandra with the help of the Central Otago Ecological Society (COET).

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The Mokomoko Dryland Sanctuary is the first sanctuary protecting dryland habitat in New Zealand. Pioneered by COET, it was established with a 1.6km long fence enclosing a 14-hectare area, creating a relatively safe haven for endangered reptiles.

A man in a stripey t-shirt and wide-brimmed hat crouches in dry brown grass in front of a large flat rock formation.

Herpetologist Carey Knox looking for skinks. Photo: Karthic SS

'A Rolls Royce' fence

Before the full fence was installed, Dr Grant Norbury, chair of COET, and James Reardon, scientist at the Department of Conservation (DOC), tested a small predator-proof enclosure.

One day, a group of visiting students witnessed a mouse attacking large lizards inside the pilot enclosure. "That confirmed for us if we're going to be successful with this work, we need to build up a bigger fence," says Grant.

For the sanctuary proper, COET opted for the "Rolls Royce" fence - better at keeping mice out, but more expensive. "But mice still get in fences, so you need to be very vigilant," says Grant.

A man in a cap, sunglasses, black pufferjacket and brown pants sitting on a rock in a dry scrubby hillscape dotted with rocks. The sky is blue with puffy clouds.

Dr Grant Norbury of the Central Otago Ecological Trust. Photo: Karthic SS

Finally, after more than a decade of preparing, 150 endangered skinks and geckos were introduced into the sanctuary in 2018.

The grand and Otago skinks, unique to the Otago region, are known as giant skinks due to their impressive size - up to 30cm long for Otago skinks.

Another striking resident, the jewelled gecko is "probably one of New Zealand's most beautiful reptiles," says Carey. They're bright green with white or yellow diamond patterns adorning their back.

A bright green lizard with yellow diamond patterns on its back sits on the spiky-leaved branches of a shrub surrounded by bright red berries.

A jewelled gecko (Naultinus gemmeus). Photo: Carey Knox

How the skinks are doing now

To check how the lizards are faring in their new home, DOC organises an annual skink survey in the sanctuary in collaboration with COET, Wellington Zoo, and independent herpetologists like Carey.

When Carey finds a skink, he photographs both its left and right sides, because the scaly patterns on a skink's side are like a "fingerprint".

"All of the skinks we find get catalogued. We also record whether it's an adult or a juvenile, what rock we found it on, and what time we saw it," he explains.

A shiny brown speckled skink sunbathing on a lichen-covered rock.

Grand skink. Photo: Karthic SS

The past two surveys have detected a steady increase in juveniles, indicating that the skinks are doing well and breeding. In 2020, there were five newborn skinks spotted for both species. In 2023,19 juvenile grand skinks and 20 juvenile Otago skinks were recorded.

Climate change threats

A couple of years ago, a huge wildfire tore through the tussocks of the Lammermoor Range, near Middlemarch in Central Otago. Carey reckons the fire killed thousands of skinks and jewelled geckos.

"That was quite devastating," he says. "About 4,500 hectares of lizard habitat burnt. I definitely think that climate change, just general drying out of the habitat, is going to increase the fire risk."

He hopes people will be a bit more careful about lighting fires around tussock grassland habitats.

A landscape photo taken from high on a hill showing dry brown hills studded with rocky tors, patches of scrub, and a green grass valley floor and lake in the distance.

The rocky landscapes of Central Otago are ideal habitat for lizards. Photo: Karthic SS

Fascinating and endangered

There's also a hope that through the sanctuary, more people will learn about New Zealand's 125 lizard species - which are often rare, and mostly out of sight.

Anna Yeoman, a science communicator and trustee of COET, hikes the sanctuary regularly.

"I've become so aware that a lot of New Zealanders don't know about their lizards," she says. She's hoping to change that with her book sharing the stories of these fascinating but endangered animals.

A man with headphones around his neck takes a selfie with a woman smiling and wearing a backpack. They are standing in a dry grassy field with a high, mesh predator proof fence in the background below a rolling brown hill beneath a blue sky.

Tune into Nature presenter Karthic SS in the field with Anna Yeoman, science communicator and trustee at the Central Otago Ecological Trust. Photo: Karthic SS

Grant is hopeful that the sanctuary will be a home to more rare lizards in the coming years.

"The vision for the future is to allow the public to come in here, walk around these beautiful schist rocks, and see these native lizards out on these rocks - or in the shrubs, in the case of jewelled geckos," he says. "Just seeing their beautiful colours and getting an idea of what used to be once here."

Listen to the episode to learn more about the Mokomoko Dryland Sanctuary and New Zealand's lizards.

The Tune into Nature podcast is produced and presented by Karthic SS. It is funded by the Lotteries Environment and Heritage Fund administered by Te Tari Taiwhenua the Department of Internal Affairs. The podcast is supported by Otago Access Radio and Science Communication, University of Otago. You can find it on Facebook, Instagram, Youtube and on podcast providers.

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