Sasha Roselli and Nicole Sutton from DOC Alexandra scour the rock outcrops for grand skink, Nov 2019. Credit: Anna Yeoman
Establishment: 2016 - now
The pilot project had proven successful. Important translocation lessons had been learnt. It was finally time to establish the full sized Mokomoko Dryland Sanctuary.
The 14 ha fence
Pest-proof fences are expensive and require specialist building skills. They must be high enough to prevent cats leaping over them, strong enough to withstand deer rubbing their antlers on them, and contain no holes or cracks large enough to allow a baby mouse to squeeze its flexible body through. They must also allow water courses to flow through, watercourses which when in flood will be carrying logs and other debris, without letting any pests in. A further challenge at Mokomoko Dryland Sanctuary is the difficulty of the terrain, the steep hills and gullies covered with great outcrops of schist rock.
To build the 1.6 km pest proof fence that would enclose the 14 ha of Mokomoko Dryland Sanctuary, the Central Otago Ecological Trust had to raise $539 000.
In November 2014 work on the fence began, and by March 2015 it was complete. It was given six months to settle in, ensuring the concrete culverts and the posts bedded in without any cracks or gaps opening up, before work began to eradicate the pests from the interior.
As they had done with the small fence, COET removed pests using a mixture of poisons and kill-trapping, in consultation with the Department of Conservation and the Ministry of Health, and using methods that would minimise both animal suffering and the risk of poisoning non-target species. The most difficult species to eradicate was the hares, but eventually they were all removed.
By 2016 the Mokomoko Dryland Sanctuary was pest-free and ready to receive lizards. However, the western grand and Otago skinks were not ready, as their low breeding success in captivity meant COET was looking at 2018 as the earliest date for introduction.
A further challenge was the difficulty of the terrain, the steep hills and gullies covered with great outcrops of schist rock.
Mokomoko Dryland Sanctuary fence-lines, the 14 ha fence on the left, the 0.23 ha fence on the right. Credit: Anna Yeoman
Jewelled geckos
While COET waited for the captive grand and Otago skink population to slowly increase, they followed up other potential lizard introductions. Jewelled gecko were identified as a possibility. Before human arrival in Central Otago, these striking green geckos were common in the dense vegetation such as Coprosma, Corokia and kanuka, but for many decades now they had been extinct from the region. Lizard experts Tony Jewell and Carey Knox were consulted to follow up this possibility.
The mountain ranges of eastern Central Otago have a reasonable sized population of inland Otago jewelled gecko whose habitat was being degraded by land use changes. So beginning in March 2018, with the help of Carey Knox from Wildlands Consultants, 86 jewelled gecko were translocated from these ranges into Mokomoko Dryland Sanctuary.
Carey Knox returned a number of times through 2019 to survey the jewelled gecko population in the sanctuary to see how well they had survived their first year. These lizards are very cryptic, meaning that they are well camouflaged, and can be very difficult to see. However, 36 of the original founders were re-sighted, along with eight juveniles born in Mokomoko Dryland Sanctuary, a result that is very encouraging and suggests the population is doing well so far.
Carey Knox and helpers release a jewelled gecko into Mokomoko Dryland Sanctuary 2018. Credit: COET
Grand and Otago skinks
In November 2018 the western Otago and grand skinks were ready to be released into the large Mokomoko Dryland Sanctuary. Thirty three grand skinks and 36 Otago skinks were released onto the large rock outcrops. Heeding the lessons learnt during the pilot translocations, the grands and Otagos were released into separate areas of the sanctuary. If a pair of skinks had been getting on well in captivity they were released next to each other on the same outcrop. The schist outcrops within Mokomoko Dryland Sanctuary offer numerous prime spots for these lizards, with great numbers of cracks for refuge, and fruit-bearing native vegetation around them. It was hoped that the population would thrive here, but the western animals had proved difficult and slow breeders in captivity, so the outcome of this translocation was far from certain.
Watch a video of the translocation here:
An Otago skink eyes us from its safe retreat. Credit: Anna Yeoman
A promising start
During 2019, several skink surveys using volunteers re-sighted a good number of grand skinks, but only three of the 36 Otago skinks, which was cause for concern. So in November 2019 a team consisting of Carey Knox along with lizard experts from DOC Macraes and Dunedin, carried out a full survey. They found 16 Otago skinks and 14 grand skinks, a very encouraging result. It’s normal to re-sight only a portion of the released lizards as some individuals remain very elusive, some disperse widely, and some die - three have been found dead so far. But these numbers suggest a successful first stage of re-establishing the skinks in the sanctuary. Quite a few animals were found in pairs, boding well for seeing babies later in the summer.
"It’s a fantastic result and a tremendous relief."
Grant Norbury, Nov 2019
Watch a video of the skink survey here
Babies!
Jewelled gecko newborns began to be seen the summer following translocation, in early 2019. By the end of 2020, 13 juvenile jewelled geckos had been found. These tiny twists of green are incredibly hard to spot amongst the vegetation, especially with their diamond patterning, so finding this many suggests there will be a good number more out there, happily evading searchers.
To see the first grand and Otago skink babies, COET had to wait a little longer, until the following summer, as none of the skinks were pregnant when translocated into the fence. Finally, in February, 2020 Grant Norbury was thrilled to spot a newborn Otago skink happily basking on the rock, and a month later a newborn grand skink. Others were soon added to the tally.
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Seeing the population begin breeding is a major milestone and a very encouraging indicator. Like the jewelled geckos, they are generally even more elusive than their parents, so there are likely to be more hidden away in the tangle of bluffs and vegetation.
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Carey Knox, Pat Liddy and Amanda Salt discussing tactics for the skink survey Nov 2019. Credit: Anna Yeoman
And then there were seven
In December 2023, the long awaited introduction of Otago green skinks took place. Carey Knox led the collection of 61 skinks from a number of sites in the Hawkdun Range, and one site near Kokonga. A good number of the skinks were pregnant females. It’s wonderful to have a population of Otago green skinks protected in the sanctuary, as like many of New Zealand’s lizards, their numbers have been declining in the wild. They’re a strongly-built, 20 cm long skink with a shiny-green back and a feisty disposition. They like damp sites with a mixture of rock and vegetation, and have been released in the main gully of the sanctuary. This makes seven lizard species now living at the sanctuary, getting us close to the full lizard community that once populated these dry hills.
Trustee Tom Lamb releases a green skink at Mokomoko Dryladn Sanctuary. Credit: Anna Yeoman
Young Otago skink. Credit: Anna Yeoman
Big skinks on the rise
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2024 season brought two exciting milestones. The tally of grand and Otago skinks born in the sanctuary topped 100 animals. Again, actual numbers will be higher than this, as some individuals will be happily eluding us. The second milestone was that our first sanctuary-born grand skinks began contributing to the breeding population, having reached four years of age. In January 2025, the first sanctuary-born Otago skinks also reached breeding age.
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By the end of summer, 2025, 59 young grand skinks, and 57 young Otago skinks had been spotted in the sanctuary. After these lizards had such difficulty breeding in captivity, this healthy growth of the population is wonderful to watch.
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Don't forget the little guys
Before the fence was built, three smaller lizard species were already living at the site – McCann's skinks, southern grass skinks and schist geckos. In 2020, Masters student Samantha Turner, supervised by Grant Norbury, compared their numbers both inside and outside the fence, from before and after the fence was built. Results showed that these species have also benefited hugely from the pest-proof fence. Their numbers had close to doubled five years after the fence went up. Tail loss was much lower inside the fence, indicating the absence of predation by introduced mammals.
Three schist geckos (and some tasty slaters) in an Onduline retreat used for monitoring. Credit: Anna Yeoman
