The tuatara has survived ice ages and volcanic eruptions but New Zealand’s last survivor of the dinosaur age may become extinct because of global warming.
The lizard-like reptile, one of the world’s oldest living creatures, is vulnerable to temperature change because temperature determines the sex of its young.
According to Jennifer Moore, a Victoria University researcher investigating the tuatara’s sexual behaviour, a temperature above 21.5 degrees celsius creates more male tuatara while a cooler climate leads to females.
Already male tuatara on a tiny predator- free island near the top of the South Island outnumber females by 1.7 times, she says.
“They’ve certainly survived the climate changes in the past but most of them (past climate changes) have been at a lower rate,” she said.
“So you wouldn’t expect these guys to be able to adapt to a climate that’s changing so rapidly.”
The tuatara, whose Maori name refers to the spines on its back, is the only survivor of a species of reptile that flourished during the age of the dinosaurs, about 200 million years ago. It can grow up to 50 centimetres long and weigh up to one kilogram and like its reptile relative, the turtle, the slow-moving tuatara can live more than 100 years, feeding mainly on insects.
But scientists say its long lifespan as well as its four-year breeding cycle – relatively slow for a reptile – will make the adaptation process more difficult.
Peter Gaze, a senior conservation officer at the Conservation Department, says global warming has become a new challenge for many of New Zealand’s wildlife. “I think the impact of temperature change is widespread and diverse,” he said.
He said rare species such as the rock wren – an ancient, tailless bird found only in the South Island mountain ranges – could become extinct if the warmer climate let predators, such as rats, live in higher altitudes.
The United Nations Intergovernmental Panel on Climate Change, the world’s top authority on global warming, predicted in a report in February that global temperatures would rise by 1.8 to 4 degrees this century.
The group has predicted a severe impact for New Zealand, with forestry and agriculture likely to be hit hard by global warming.
On a global level, the report predicts large numbers of plant and animal species could die out by 2050 because of global warming.
It says billions of people around the world will face floods and famine and millions will die as crops fail and diseases take hold.