Researchers look at role Maori played in moa extinction

October 8, 2009

The role Maori played in exterminating more than 30 native bird species within a few generations of their arrival in New Zealand is being investigated by Otago University researchers.

Anthropologist Chris Jacomb said a $777,000 grant by the Marsden Fund will do more than help understand the behaviour of the voyagers who settled New Zealand.

The research will also be of "international significance" in the high-profile debate on the role of humans in extinction processes.

He said Polynesian settlers found a pristine environment, but through fire, hunting and the spread of their rats and dogs -- brought as food -- burned a third of the nation's forests in just 150 years.

They killed off all the moa and their main predator, the Haast's eagle, and at least 29 other bird species.

A bird expert, at the American Museum of Natural History in New York, Joel Cracraft, has previously argued that moa were probably doomed from the moment Maori arrived.

"The Polynesians who got there were pretty good at trashing the environment and eating everything in their path," he said

And Samuel Turvey, an ecologist at the Zoological Society of London, said Maori hunted -- and ate -- the moa to extinction, almost certainly within a century of settlement. "It seems that (moa) simply couldn't grow fast enough to breed and replenish their heavily hunted population," said Dr Turvey.

Mr Jacomb said that although the "before" and "after" were relatively well documented, little is known about how the extinctions occurred.

His team will use new DNA techniques and analysis of stable isotopes on bone and eggshell, and match the results with radiocarbon dates.

Stable isotopes of carbon and nitrogen in things that were once alive can show what kinds of food a human or animal ate during its lifetime.

Mr Jacomb plans to investigate changes in ecosystems, by analysing the moa eggshells common in archaeological sites of the moa-hunters.

The remains cannot only be easily carbon dated, but the DNA information in them analysed to give the species and family relationships of the moa that laid the eggs.

With enough such measurements, the researchers will build a picture of the diet and environment of individual moa, and how these were affected by forest burning and hunting.

They hope to produce a region-by-region extinction timeline for those moa species involved, and a model of the behaviour of both the Maori and their prey in the changing environment.

Separately, an Australian researcher was using ancient DNA samples from moa to work out how climate change affected the birds before Maori arrived in New Zealand.

Adelaide University researcher Nicolas Rawlence, an expert on ancient DNA, has questioned whether climate change had already put downward pressure on the moa populations before humans arrived.

And there is another theory that though moa numbers may have been between three million and 12 million birds 1000 years ago, they tumbled to just 159,000 before the Polynesians arrived, possibly because of avian diseases brought by migrating birds or local volcanic eruptions.

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