NZTA said it was hard to predict lizard numbers - but they would likely be ornate skinks and northern grass skinks (pictured). File picture. Photo: Supplied / Andy McKay
A four-hectare section of forest and grassland near Levin will soon become home to a population of native lizards.
The 24km highway from Ōtaki to north of Levin will link up to the rest of State Highway One, north of Wellington at a total cost of $2.1 billion.
NZTA project director Glen Prince said, during the consenting phase, protected native skinks and geckos were found, and to accommodate them, a predator-proof fence was built and a habitat developed near the highway at a cost of $900,000.
"Anyone that's visited Zealandia and those sorts of places might be familiar with the fencing structures that are used to keep predators out, so we've used something similar here," he said.
The fence itself went 100mm down into the ground to prevent burrowing predators - similar to the design at Wellington's Zealandia wildlife sanctuary.
Construction had been underway since April and the fence was made secure in July, allowing pest eradication to start.
NZTA said predicting actual lizard numbers - likely ornate skinks and northern grass skinks - was hard, because they were "very cryptic and sparse in the region".
Lizard translocations typically released 30-60 individuals, sufficient for establishing a new population, and as the sanctuary already had a resident ornate skink population, any further influx would boost that baseline number.
The goal was to release 30 at a minimum, but the sanctuary had capacity for 1000.
A predator-proof fence has been built and a habitat developed near the highway. Photo: Supplied
Under the project's Resource Management Act consent conditions, lizards needed to be safely located inside the fence, before construction work could begin in certain areas.
The lizards could live in the protected area beyond the end of the road construction project.
Prince said NZTA had worked closely with iwi partners, councils and the Department of Conservation on its design. A fenced area could be pest-controlled easier than an open area, so it was the most cost effective solution.
There was an area of remnant bush at the southern end, other areas were planted with native trees and plants, and habitat features put in, including log stacks, lizard hides and natural stone piles.
A plan showing the location of the predator-proof fence. Photo: Supplied
The earliest lizards could be moved was mid-October, Prince said. Under the Wildlife Act Authority (WAA), they could not be relocated during colder months between May and September.
Being cold-blooded, they were less active during this period, and therefore harder to locate and settle into their new home.
Even then, the daily conditions muset still be right to avoid overly stressing the lizards - above 12 degrees, with less than 5mm of rain and light winds, he said.
Before any lizards could be moved, 30 days of predator-free monitoring were required within the fence. That was about halfway through now, meaning the first lizards would be relocated about the middle of October.
According to the Department of Conservation, they lived in forests, deep leaf litter, rock piles or thick vegetation. They preferred damp, humid conditions and the species was very secretive.
Adults had a small home range, often only a few metres, if the habitat was suitable, and would exclude other adults.
Northern grass skinks were often more abundant in coastal locations and were avid baskers for warmth. They loved sunny rock piles and tumbles that had plenty of crevices.
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