Moas in decline before humans arrived

12:27 10 November 04

Humans may not be entirely to blame for wiping out moas - the giant
flightless birds that once grazed in New Zealand. A new study by researchers
in the US and New Zealand suggests that a huge moa population existed in the
few thousand years before the arrival of humans.

Skeletal remains and other clues had previously put the moa population in
New Zealand at around 159,000 at the time humans arrived, one thousand years
ago. But the latest research suggests that there were between 3 and 12
million moa. If both numbers are correct, that means something else
decimated the bird population before humans finished it off some 500 years
ago.

Neil Gemmell and his colleagues at the University of Canterbury in
Christchurch and the US Forest Service in Missoula, Montana, reached the new
estimate using published mitochrondrial DNA sequences from bone samples of
58 Dinornis, the largest of the 10 species of moa. The sequence data had
previously been stored in GenBank, the public DNA database.

Genetic variation increases as a population expands. By taking into account
other factors that influence genetic variation, such as estimates of the
rate at which moa DNA mutates, the Gemmell team calculated that between 300
000 and 1.4 million Dinornis lived in New Zealand between one and six
thousand years ago.

>From fossil evidence indicating what proportion of the moa population is of
the species Dinornis, the researchers obtained an estimate of between 3 and
12 million for all moa species.

Full Text at NewScientist
http://www.newscientist.com/news/news.jsp?id=ns99996650

Posted by
Robert Karl Stonjek
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