Region’s rare reptiles facing growing threats

A fire that began at the edge of the Te Papanui Conservation Park near Middlemarch in early November last year tore through more than 4500ha of land, including in the Deep Stream area. The massive blaze also killed many distinctive endemic reptiles and dramatically highlighted the climate change risks faced by Otago’s 23 endemic lizards. Reporter John Gibb spoke to the president of the Society for Research on Amphibians and Reptiles in New Zealand, Jo Monks, about the future for Otago reptiles.

Climate change and soaring fire risks are posing big threats to Otago’s distinctive reptiles, including nine recently discovered lizard species.

Dr Jo Monks is the Dunedin-based president of the Society for Research on Amphibians and Reptiles in New Zealand and a Department of Conservation science adviser. She gave a talk on Friday on efforts to save the country’s reptiles, at the ninth World Congress of Herpetology, which attracted 874 people, mostly from abroad, to the University of Otago’s Dunedin campus.

Dr Monks is keen to raise community awareness of the growing threats to Otago’s endemic reptiles.

Dr Monks said a huge fire which broke out at the edge of the Te Papanui Conservation Park near Middlemarch last November killed many lizards, and highlighted the growing fire risks in Otago arising from climate change.

"The Middlemarch fire was a warning that New Zealand and its precious conservation areas and species are not immune to risk from fire.

"This risk is only going to increase as climate warms, particularly in eastern New Zealand."

Jewelled geckos, cryptic skinks, McCann’s skinks, southern grass skinks, korero geckos, Burgan skinks and possibly other species were affected by the Middlemarch fires.

Some individual lizards initially survived the fires, but their long-term prospects were poor "due to decreased food resources and increased risk of predation, such as from birds, in the blackened landscape".

A less direct threat from climate change was that higher temperatures meant Otago’s alpine zone was increasingly suitable for a broader range of introduced mammalian predators, such as rats and weasels as well as mice and stoats, for longer each summer.

Several Otago lizards had been seen only in the alpine zone and could come under increased pressure from warming climate.

Climate change threats to Otago reptiles were "mostly underappreciated", Dr Monks said.

However, Prof Alison Cree’s research group at the University of Otago zoology department was "actively working on understanding these impacts".

New Zealand is home to more than 100 reptiles which are found nowhere else in the world.

Otago has 23 endemic lizard species and also, at the Orokonui Ecosanctuary, a reintroduced tuatara population.

Of those 23 lizard species, 10 are geckos and 13 are skinks, and 12 of the lizard species are found only in Otago.

Most of the Otago reptiles are either threatened or at risk.

Recently discovered species in North Otago, including the southern black-eyed gecko, were particularly distinctive, as were the better-known grand and Otago skinks, Dr Monks said.

"The biggest risk to native lizards in Otago associated with climate change is probably increased risk of fire, with warmer temperatures predicted."

Species most susceptible were those with very small distributions, and which had been adversely affected by habitat destruction and predation by introduced mammals.

For example, Burgan skinks were considered nationally critical and occupied only a small range near Middlemarch.

Recently discovered species such as the southern black-eyed gecko in the Oteake Conservation Park — an upland area west of Omarama — were also vulnerable, Dr Monks said.

Fire risk was expected to more than double throughout the country by the end of the century, and this was more pronounced in eastern areas.

"In coastal Otago, severe fire weather duration is expected to increase up to three-fold by 2040."

Prof Cree said more awareness of reptiles was needed when considering possible land use change, to ensure crucial habitat was not destroyed, and she also highlighted concerns about growing fire risks, including in Central Otago.

"The message I want to get out to the people of Otago is to protect the lizards’ habitat."

"They need secure habitats," Prof Cree said.

Dr Monks said the existence of several reptile species was threatened by climate change.

A climate change-related boost in the frequency and severity of storms posed risks for coastal reptile species on the West Coast, and increased fire risk threatened species with small distributions in Otago.

In 2016, Department of Conservation staff captured the remaining 38 "cobbled skinks" from a storm-swept beach at Granity, in northern Westland, and transferred them to the Auckland Zoo, shortly before the last of their distinctive cobblestone habitat was destroyed by storm surges.

One of the ironies of climate change is that as Otago reptiles come under growing pressure, nine new species have been discovered in the region over the past decade.

Four new species have been discovered in about the past three years — all in North Otago: the North Otago black-eyed gecko, Oteake skink, rockhopper skink and alpine rock skink.

Invercargill herpetologist Tony Jewell deserved "full credit" for these discoveries, Dr Monks said.

A further five species had been discovered through improved genetic techniques, in the last decade.

Further action on climate change was urgently needed, Dr Monks said.

"As a nation we need to be more aware of the uniqueness of our biodiversity and the threat posed to it by climate change on top of other threats."