4 ago 2012
Moa feet
The population size of the giant moa remained stable over the past
40,000 years until the arrival of humans in New Zealand around 1280 AD.
The study was undertaken by researchers from the University of
Adelaide's Australian Centre for Ancient DNA, the University of
Colorado, and the University of Waikato and Landcare Research in New
Zealand. The results are published online in the journal Quaternary Science Reviews.
The giant birds -- measuring up to 2.5 metres high and weighing 250
kilograms -- were the largest herbivores in New Zealand's pre-human
environment but were quickly exterminated after the arrival of
Polynesian settlers.
"Until now it has been difficult to determine how megafauna responded
to environmental change over the past 50,000 years, because human
arrival and climate change occurred simultaneously in many parts of the
world," says Dr Nic Rawlence, lead author of the study and a
postdoctoral research fellow from the Australian Centre for Ancient DNA
and the University of Waikato.
"Using ancient DNA, radiocarbon dating and stable dietary isotope
analysis, we have been able to show that before humans arrived, moa
mitigated the effects of climate change by tracking their preferred
habitat as it expanded, contracted and shifted during warming and
cooling events," Dr Rawlence says.
"Moa were not in serious decline before humans arrived, as has been
previously suggested, but had relatively stable population sizes. The
overwhelming evidence suggests that the extinction of moa occurred due
to overhunting and habitat destruction, at a time of relative climatic
stability."
Co-author of the study, Dr Jamie Wood from Landcare Research, says
the results "show that range shifts and minor population fluctuations
observable in the fossil and genetic record are a natural response to
environmental change and do not necessarily lead to extinction."
"Climate change has been blamed for megafaunal extinctions in other
parts of the world, but this is not the case for moa," says co-author Dr
Jessica Metcalf from the University of Colorado.
ACAD Director and project leader Professor Alan Cooper says: "The
very recent extinctions in New Zealand provide a unique opportunity to
examine the extinction of Ice Age megafauna and the relative roles of
human hunting and climate change."
The study was funded by an Australian Research Council (ARC) Discovery Grant.
