Natureland investigating why half its tuatara population died within two years
Natureland is conducting an internal review to figure out how four of its eight tuatara died within a two-year span.
The Nelson zoo's acting director of Natureland Grant Abel said individual tuatara died in August 2017, March 2018, and April 2019, for reasons still unknown.
A fourth animal died earlier this Month in an unrelated accident, when it appeared to have been killed after the burrow it had made for itself collapsed.
Abel said the tuatara was observed to be well in the morning, but was found to have died during the regular afternoon inspection.
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Abel, who took over in March, said the review of the environment and husbandry care for the tuatara began immediately after the death in April.
"An expert review of the necropsy reports and opinion as to whether the deaths are related to anything in particular, is needed to help inform whether environmental or nutritional changes are needed in the husbandry of the tuatara at Natureland."
Due to tuatara having very slow metabolisms, any health issues that arise could be slow to develop and hard to identify, Abel said.
"Reaching out to specialists for expert advice will help to ensure that the tuatara are being provided appropriate care at all times. The health and wellbeing of the animals in our care is always our priority."
The eight tuatara had been given to Natureland by the Ngāti Koata Trust more than a decade ago.
Ngāti Koata Trust cultural manager Louisa Paul said they had been made aware of the first death in 2017 and the most recent one in May, but had not known about the other two before meeting the new manager.
She said communication between Ngati Koata Trust and Natureland had always been "really good".
"I don't know why we weren't alerted about the other two deaths prior to meeting the new manager.
"Four in two years is not normal ... especially in captive care."
For the remaining tuatara, Paul said she wasn't "sitting and hoping the other four are going to be ok", with action being taken to ensure their survival.
"We've got to look after the four that are living, and what that looks like is in discussion."
She said the Trust was working with Natureland and a national tuatara committee, including captive manager Simon Eyre in Wellington, tuatara specialist Dr Nicola Nelson and someone from the Department of Conservation.
Natureland has also reached out to Wellington Zoo's reptile expert David Laux and arrangements are being made for experts to visit Natureland as soon as possible.
The news of the death of the tuatara came to light at a Nelson City Council meeting on Wednesday.
Natureland Wildlife Trust board chair Alan Hinton, with board member Steven Standley and Abel presented their submission to the Nelson City Council's annual plan, reiterating their request for their annual funding to increase to $243,000 per year.
During questioning on the proposal, Councillor Tim Skinner raised the issue, saying he had heard via rumours that four tuatara had died.
This was confirmed by Abel, who said the tuatara habitat had "not had any work done on those areas for a number of years"
He said work had been prioritised on bird enclosures instead.
Tuatara expert Lindsay Hasley, who has worked with the reptiles for the past 30 years at the Southland Museum and Art Gallery, said there were a range of factors that could lead to premature death in captivity for tuatara.
While they were a durable animal capable of living in excess of 100 years, access to UV light, hydration, social dynamics and stress were all factors that needed to be accounted for.
Hasley said being cold-blooded, tuatara didn't catch diseases which required warm hosts, and also had a natural immunity to fungi and other organisms in the soil.
Overheating was one of the biggest killers, which could cause major stress to their immune systems.
He said even one very hot day, if the animals couldn't get away from the heat and their body temperature exceeded 30 degrees, could be life threatening.
"Heat stress destroys their natural immunity, fungus can get under the scales, six months later it migrates to the bloodstream, and that can cause mortality.
"You wouldn't know anything was wrong. They don't die the next day, they don't die the next week – it's not until six months to a year later."