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THE first human settlers in New Zealand embarked on a hunting “blitzkrieg”,
wiping out the islands’ 11 species of giant flightless moas in less than a
century. Researchers previously thought that the birds were gradually driven to
extinction over several hundred years.

Richard Holdaway of Palaecol Research and Christopher Jacomb of the
Canterbury Museum, both in Christchurch, say that the latest carbon-dating of
artefacts found on the islands suggests that settlers first arrived around 1280,
300 years later than had been thought. The last firm evidence of living moas
comes less than a hundred years later.

Holdaway and Jacomb believe population dynamics doomed the birds once small
groups of settlers began killing them. Their computer model shows that the
long-lived moas were vulnerable to any increase in adult mortality, and just 100
initial settlers could have wiped out a population of 158 000 adult birds within
80 to 160 years. With 200 initial settlers, the moas could have vanished in as
little as 50 years.

The discovery also supports the idea that early hunters are to blame for the
disappearance of large animals in newly colonised areas such as Australia and
the Americas, says anthropologist Jared Diamond of the University of California
at Los Angeles.