Friday 20 March 2009 12:25pm
The return of tuatara to their wild habitat in the southern South Island moves a step closer this month with the transfer of 15 juvenile tuatara to an outdoor enclosure at the Orokonui Ecosanctuary near Dunedin.
The tuatara originate from research at the University of Otago aimed at understanding how tuatara from the Cook Strait region will respond to the cooler temperatures of Otago.
Project Leader Associate Professor Alison Cree says tuatara are internationally famous as the only survivors of rhynchocephalian reptiles, a group related to lizards.
"They are native to New Zealand and once lived as far south as Bluff. Since human arrival, they have become restricted to a few dozen offshore islands in Cook Strait and northern New Zealand, most of which offer security from rats.
"As part of a national recovery plan, conservation managers, biologists and community groups are working towards the reestablishment of tuatara within sanctuaries free of mammalian predators on the North and South Islands.
"Orokonui - the first large-scale sanctuary in the South Island - is of particular importance, given concerns about impacts of global climate change on more northerly populations."
Before releasing tuatara in the Orokonui enclosure, the Otago researchers examined the way that tuatara respond to cold temperature. PhD student Anne Besson found that tuatara basked more efficiently as sunlight hours were reduced.
Ms Besson says the tuatara also remained active at temperatures as low as 5°C, a similar temperature range to that of Otago lizards, including native geckos.
Unlike lizards in Otago, tuatara are egg-laying, raising a particular concern about the way that embryos might respond to cool soil temperatures. Warm soil is needed for embryonic development, and only the highest soil temperatures produce males (tuatara have a rare form of temperature-dependent sex determination in which cool soil temperatures produce only females).
Although initial monitoring of soil at Orokonui failed to identify sites warm enough for production of males, Associate Professor Cree says warmer temperatures have been recorded this summer, raising optimism that both sexes can be produced. Several of the tuatara to be transferred come from eggs incubated in the sanctuary, showing that soils there were warm enough for embryos to survive over winter.
The tuatara will initially go into an outdoor rearing closure, not on public display, where they can be closely monitored. Ecosanctuary staff and university researchers are in consultation with the Department of Conservation and iwi including Ngati Koata (kaitiaki of tuatara on Stephens Island/Takapourewa) and Ngai Tahu (Kati Huirapa Runaka ki Puketeraki) regarding the possibility of eventual free-release of tuatara within the sanctuary.
Ecosanctuary manager Chris Baillie says sanctuary staff are delighted to be able to offer a secure facility that assists with the national recovery plan for tuatara.
"We are hopeful that, in the future, a thriving population of tuatara will live in the Ecosanctuary to inspire visitors to assist in the protection of this precious reptile."
For more information, contact
Associate Professor Alison Cree
Department of Zoology
University of Otago
Tel 64 3 479 7482
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