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Fwd: Big moa birds' extinction came at hand of man (4/18/2000)

Thought this was relevant to the dino board.

Susanne Moore
Library Specialist
Processing Services
Michel Orradre Library
Santa Clara University
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Title: Big moa birds' extinction came at hand of man (4/18/2000)

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Science & Technology

Published Tuesday, April 18, 2000, in the San Jose Mercury News

Big moa birds' extinction came at hand of man

New York Times

OVER the last 40,000 years, as anatomically modern but primitive hunters spread around the world, species after species of big animal vanished from the Earth in their wake. ``Blitzkrieg'' has long been scientists' favorite image for these spasms of biological destruction.

Nowhere, perhaps, was the extinction more striking than in New Zealand, where an entire class of large flightless birds called moas, 11 species and an estimated 160,000 individuals in all, once lived. New evidence now suggests that it may have been the most rapid extinction ever brought about by primitive people.

Some moas were about as big as turkeys, but others were awesome ostrich-like creatures, the largest weighing more than 500 pounds and standing 10 feet tall. Skeletons show that they were built remarkably like some dinosaurs. They had never encountered anything like the stone age Polynesians who colonized their islands in the late 13th century, and the big birds presumably had no fear of them.

So by the time the ship of British explorer James Cook first brought Europeans to New Zealand in 1769, every last one was gone. The conventional view has been that the Polynesians, ancestors of today's Maori people, hunted and otherwise drove the moas to extinction in a thousand years or so.

But now scientists say evidence from the early Polynesian settlements, plus new calculations based largely on the birds' reproduction profile, indicate that on the scale of geological time, the extinction required 160 years at most and probably considerably less. The scientists say the destruction of the moas by club and snare was the fastest extinction of big animals -- what scientists call mega-fauna -- so far.

It was apparently even more rapid than the swift rate at which some scientists believe large creatures like mammoths, mastodons, camels, ground sloths and giant beavers were exterminated by prehistoric hunters in a North American blitzkrieg about 13,000 years ago. The cause of those extinctions has been hotly debated and remains unsettled.

The extermination of the moas ``is probably the clearest instance of the extinction of a whole fauna of large animals'' in a short time by hunter-gatherers, said Dr. Richard N. Holdaway, the chief author of the new study, which appears in the current issue of the journal Science.

A paleobiologist specializing in the biology of extinctions, Holdaway runs a private research company called Palaeocol Research in Christchurch, New Zealand. His co-researcher was Chris Jacomb, curator of archaeology at the Canterbury Museum in Christchurch.

With some exceptions, experts say, large-scale extinction of big animals generally coincided with the arrival of early modern humans in places where they had never been. This did not happen in Africa, they theorize, because people and other animals evolved there together, and African animals were therefore not so naive about humans.

One of the most rapid extinctions was in North America, where not just big plant-eaters but also the predators that depended on them -- including saber-toothed cats, short-faced bears, cheetahs, maned lions and bigger versions of today's wolves -- are believed to have vanished in perhaps 400 years.

Three possible causes have been advanced for this extinction episode. Two are related to the blitzkrieg hypothesis: that humans swept across the continent from Siberia in a ``killing front'' that moved perhaps 100 miles in a decade, and that the animals were killed by diseases carried by people and their dogs from Siberia. The third hypothesis says that rapid climate change played the critical role.

For New Zealand, Madagascar and many Pacific islands, few would deny that the first arriving humans caused mass extinction, said Dr. Jared Diamond, an ecologist at the University of California-Los Angeles, who wrote a commentary on the new study in Science. The only questions, he said, are how fast the extinctions were and whether hunting was the only cause. For New Zealand, he said, the new study ``shows that moa extinctions were very fast and were mainly by hunting.''

Holdaway and Jacomb wrote that ``even minimal levels of human hunting pressure caused an irreversible decline in the moa population.'' The results of their study, Holdaway said, ``reinforce the view that people with even the most basic technologies -- fire, clubs, snares -- can have major environmental effects.''

``Yes, this was a blitzkrieg,'' Diamond wrote in Science. ``Yes, a few people could and did kill every moa.''

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