Zoo tuatara release boosts rare population
12 February 2008
Zoo tuatara release boosts rare Cuvier Island population
Two young Northern tuatara of Cuvier Island origin, bred at Auckland Zoo, are today being released back to their ancestral home to help boost this rare population - estimated to be fewer than 30 animals.
The two four-year olds bring to 20 - two-thirds of the total known island population - the zoo has now bred and released onto Cuvier Island since receiving six Cuvier adults from the Department of Conservation (DOC) in 1990. The last release from the zoo (11 animals) was in 2003.
DOC relocated the six adults to the zoo to begin a pest eradication programme on this Hauraki area island, which by 1993 was successfully cleared of the Kiore (Pacific rat) The zoo is the only captive facility in New Zealand breeding Cuvier-origin tuatara as part of DOC’s ‘Headstart’ tuatara breeding recovery programme.
A further 14 zoo-bred young are expected to be relocated to Cuvier Island this spring, provided they reach the required 80grams – the size at which they can adequately defend themselves from natural predators, including adult tuatara. In addition, four tuatara eggs from a clutch laid last December at the zoo, are currently incubating at Victoria University, and are expected to hatch between April and June. Another key partner in the recovery programme, Victoria University’s role in incubating the eggs is enabling it to carry out important research into the influence of temperature on tuatara sex, as well as the effects of global warming.
“There’s nothing fast about a breeding recovery programme with tuatara. It’s the classic ‘good things take time’ with this dinosaur-age species, so every successful birth is really important,” says Auckland Zoo NZ fauna team leader, Andrew Nelson.
“It’s incredibly satisfying to see our adults successfully laying clutches, to rear the resulting young for close to 48 months, and then be able to release fit and healthy animals back onto Cuvier to contribute to the recovery of this Northern tuatara sub-species,” says Mr Nelson.
DOC ranger for the Hauraki Area islands, Rob Chappell, says while DOC could only find a total of six tuatara in 1990 (just prior to the eradication programme), they have since found another seven adults.
“It’s possible there could be up to 30 by now, but they’re extremely difficult to find,” says Mr Chappell, who has worked on the rugged 196ha island since 1972.
“While tuatara reach sexual maturity around 14 years, they’re in no hurry, and can potentially still wait years before deciding to breed. I’m not expecting to see a massive population increase in my life-time! But the great thing about Cuvier is it’s safe – totally pest-free. We know this from the flourishing wildlife we’re now seeing - from moko and shore skinks and Pacific and common geckos, to the return of seabirds such as red-billed gulls, white-fronted terns, fluttering shearwaters and diving petrels that are now confident of nesting back on the island,” says Mr Chappell.
Overall since 1995, Auckland Zoo has released a total of 50 tuatara (Red Mercury Island, Cuvier Island, and Stanley Island) onto their respective islands.
• Found only in
New Zealand, the rare tuatara is the only surviving member
of the order sphenodontia, a lineage that stretches back to
the dinosaur age some 225 million years ago – the
beginning of the ‘Age of Reptiles’.
• Once living throughout the mainland of New Zealand, tuatara are now found only on 37 off-shore islands. Total tuatara population on all these islands is estimated to be between 50,000 and 100,000.
o The two recognised tuatara species are Brothers Island (Sphenodon guntheri) and Common tuatara (Sphenodon punctatus) - comprising Cook Strait and Northern tuatara. The Northern tuatara is found from the Poor Knights group in the North to Moutohora Island in the Bay of Plenty. Tuatara from Cuvier Island, like other island populations Auckland Zoo is working with (i.e. Stanley & Red Mercury islands) are bred separately, as it is thought they could be genetically distinct (though research has yet to confirm this).
• The word tuatara means “spiny back” in Maori
• A tuatara differentiates itself from other lizards: Its skull has extra holes; it has a pineal eye covered by opaque scales; no ear holes (though hears very well); and has serrated jaw bones which work as teeth.
• Longevity: No one knows for certain how long tuatara can live. The oldest recorded tuatara is Henry (Southland Museum), born in the 1880s.
• Cuvier Island, once part of the mainland, became an island about 12,000 years ago as sea levels rose around a coastal mountain, trapping the remnants of its mainland fauna and flora.
• In 1879 Cuvier Island was made a lighthouse station. Farm animals, including goats, were introduced as food for the lighthouse keepers, and cats escaped and became wild. By the later 1950s, the forest had been reduced to open parkland and there were few sea birds. Saddleback, red-crowned kakariki, pied tit, tui and milktrees were extinct on the island and the tuatara population was reduced to seven known animals. In 1957, over half of the island was designated a nature reserve.