Archey's frog population numbers are in question after a mining company has released new research. Photo / NZME
Archey's frog population numbers are in question after a mining company has released new research. Photo / NZME
Under leaf and twig in the Coromandel bush creeps a cryptic critter, one experts thought numbered in their thousands.
But new research estimates there could be as many as 50 million.
The research, released by a mining company looking to expand its operations at Waihī, claims wild populations of Archey'sfrog could actually be more than 50 million, up from the previously thought 5000 to 20,000.
Gold mining company OceanaGold has consent applications lodged with Thames Coromandel District Council, Hauraki District Council and Waikato Regional Council for its proposed Waihī North Project. This includes a new underground mine north of Waihī.
The amphibian that lives there has sensitive feet and there have been concerns raised the proposed activity will be damaging to the species, particularly with vibrations.
The Department of Conservation lists Archey's frog as endangered. It is one of four remaining species of native frog, and the only terrestrial frog found on mainland New Zealand.
Lloyds Ecological Consulting's Dr Brian Lloyd prepared the research for OceanaGold to find out what impact the proposed new mine would have on the small and nocturnal frogs.
The research draws from 381 sightings of the frog which provided a preliminary estimate of its distribution range in the Coromandel Peninsula.
Population estimates were obtained from five areas and seven habitat types within the species' Coromandel distribution range as well as from the predicted vibration footprint of the proposed Wharekirauponga mine.
He said its best estimate for the total Coromandel Archey's frog population was 54.8 million frogs, "several orders of magnitude greater" than the previous estimate.
In his summary, Lloyd said: "Although our population estimate is based on sparse data and untested assumptions, it is the best estimate possible with available data and is more credible than the 5000 to 20,000 estimate."
He says a more reliable estimate would require a well-designed study programme with extensive and intensive fieldwork.
Coromandel Watchdog of Hauraki has been vocal in its opposition to the proposed mining activity on public conservation land.
Chairwoman Catherine Delahunty said she read the report and noted it had not been peer-reviewed.
"It has been produced by a reputable scientist, but for a mining company,'' she said.
She said the estimate was based on small areas and extrapolated to others.
In her opinion: "They admit themselves the data is very sparse and a lot more work needs to be done, and yet they are making a very big claim."
Even if the population health was increasing, she said the area should not be mined particularly because of the associated vibrations.
She said the frogs were a "tiny, amazing 200 million-year-old species", that don't have ears.
"They feel everything by vibration through their feet."
The green-brown creatures move about 1sq m in their entire lives.
When asked about his research, Lloyd said he had years of experience in population estimation, including with the Department of Conservation.
Archey's frogs live only in a few areas of the North Island, including the Coromandel. Photo / NZME
He was aware the findings would cause a "fair bit of conflict", and he said he would be discussing the findings with the Watchdog in the coming months.
"I put a lot of caveats in the report about that 50 million. I would not be surprised if it was only 5 million, but it's definitely not 20,000."
The work was done in January and he said a major project was to be undertaken later this year.
"Getting a population estimate for a critter like Archey's frogs isn't easy."
In response to concerns the research had not been peer-reviewed, he said he would look at getting it peer-reviewed after the coming summer's data collection.
OceanaGold proposed to set up and fund an annual independent research fund to further study the native species. It was also working on a large-scale biodiversity enhancement and predator control programme for the Coromandel.
A report by Babbage Consultants Limited senior ecologist/herpetologist Dylan van Winkel for OceanaGold concluded due to a lack of evidence for or against the adverse effects of vibration, a precautionary response to assessing the effect of vibrations with amplitudes higher than 2–4mm/s was warranted.
Department of Conservation Hauraki operations manager Avi Holzapfel said the organisation was aware of the findings and several specialists had begun reviewing them.
He said it would welcome research convincingly demonstrating Archey's frogs occur in greater numbers than originally thought.
But he said the department remained cautious about these results and it was important to note it was a consultant's report, not published or peer-reviewed.
He said that with the figures estimated the department would expect to find the frogs everywhere in the potential Coromandel habitat it is found in, which was not seen in its observations.
Research into the Coromandel Archey's frogs' distribution and population began in the 1950s, and long-term fieldwork in the 1980s.
Holzapfel said studies at Coromandel and Whareorino had shown the frogs can be found in high density at specific sites, but it did not mean that density would occur even a short distance away.
OceanaGold Waihi operation sustainability manager Kerry Watson said, as outlined in the report, this was research based on sparse data and was an estimate.
"However, what is exciting to see from this report is that the estimated population is significantly higher than scientists have previously understood."
The report adds to the current understanding of the species, Watson said. But additional research would help them more accurately understand the population in the Coromandel.
"We look forward to building on this initial round of research and hope to continue to share these insights publicly."
A Waikato Regional Council spokeswoman said the application from OceanaGold was received on June 23 and formally accepted as complete under s88 of the Resource Management Act on July 8.
The application is being assessed as to whether further information was needed.
