Living fossil breeds on New Zealand's mainland
31 Oct 2008
A nest of tuatara eggs discovered at Wellington's world-first wildlife reserve - the Karori Sanctuary - has conservation staff in a state of expectant excitement.
Known as New Zealand's living fossil, the tuatara is a reptile that's unique to New Zealand and the survivors of a species that became extinct about 60 million years ago. The discovery is the first recorded nest of tuatara eggs seen on New Zealand's mainland in at least 200 years.
Leathery white eggs
The discovery came during routine maintenance work near the Sanctuary's unique mammal-proof fence, where staff uncovered the four ping-pong ball sized leathery white eggs.
"This time last year we found a gravid [egg-carrying] female," said Sanctuary Conservation Manager Raewyn Empson.
"We knew of two suspected nests but didn't want to disturb them to confirm whether or not they contained eggs. The nest in this photo was uncovered by accident, and is the first concrete proof we have that our tuatara are breeding. It suggests that there may be other nests in the Sanctuary we don’t know of."
The eggs were photographed, then immediately covered up again to avoid disturbing their incubation.
Although only four eggs were unearthed, it is likely that there are more in the nest as an average clutch contains around 10.
The eggs would have been laid almost exactly one year ago in a shallow trench dug by the female and then backfilled. Other than guarding the nest for a few days afterwards to prevent other females from digging it up, that's the end of a tuatara's maternal responsibility.
All being well, the tuatara could hatch any time between now and March.
The hatchlings will break out of the eggs using a special egg-tooth that will fall off after about two weeks.
For the first six months or so the legendary 'third eye' for which the tuatara is most famous will be visible as a white patch on the forehead. This too will disappear as the tuatara grows.
As with some other reptiles, soil temperature will determine the animals' gender. Warm soil (over 21 degrees) results in males, and cool soil (under 21 degrees) females.
Tuatara are the only surviving members of the order Sphenodontia and endemic to New Zealand. Every other species in this order became extinct about 60 million years ago, leading scientists to refer to tuatara as 'living fossils'.
It is uncertain exactly how long tuatara have been absent from mainland New Zealand but they were already rare by the late 1700s when the main predator was the kiore or Pacific rat.
The establishment of a population at the predator-free Karori Sanctuary in 2005 was a breakthrough in re-establishing this species in the wild on mainland New Zealand. It has also made the species a lot more visible to the public.
Some 70 animals were transferred to the Sanctuary in 2005 from Takapourewa / Stephens Island in the Marlborough Sounds, which lie on the tip of the South Island just south of Wellington. Another 130 animals were released in 2007.
Karori Sanctuary is acknowledged as one of Australasia's top 25 ecological restoration projects.
An inner city slice of native paradise within New Zealand's capital city, the Sanctuary is part of a 500-year vision to return this area of Wellington to its pre-human state.
The multi-million dollar project involves developing 252 hectares of native forest into a predator-free area behind state of the art predator-proof fences. Native flora and fauna have been reintroduced including rare New Zealand flightless birds the weka and kiwi.
The Sanctuary is a unique protected natural area for New Zealand's endangered wildlife. Over 35 kilometres of bush tracks and paths criss-cross regenerating forest, providing walks and other activities for all ages.
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