Dead as a dodo? Not necessarily|jon_downes|jon@cfz.org.uk|12/15/03 at 21:22:58|jon_downes|xx|0|217.44.226.21|Dead as a dodo? Not necessarily
Anna Salleh
ABC Science Online
Thursday, 20 November  2003

Dr David Roberts of the Royal Botanic Gardens, Kew in the U.K. and Dr Andrew
Solow of the Woods Hole Oceanographic Institution, Massachusetts, in the
U.S. estimate in today's issue of the journal Nature that the dodo actually
became extinct nearly 30 years after its last reliable sighting.

Accurately estimating when a species becomes extinct is difficult as rare
individuals can survive undetected for years after they are last seen. While
the idea that an animal is not necessarily extinct just because it hasn't
been seen for a while may seem obvious, extinction dates have traditionally
been set as the date of last sighting.

To estimate the animal's actual point of extinction, Roberts and Solow
applied a statistical test to the last 10 recorded dodo sightings. Their
maths related the probability of an animal still existing at particular
times after it was last seen.

While the extinction of the ungainly bird is commonly dated to 1662, the
last time it was seen on an islet off Mauritius, Roberts and Solow's
calculation put the date as 1690.

Australian biologist Professor Des Cooper of Macquarie University in Sydney
said it would be interesting to test the technique on a number of Australian
animals. Researchers have rediscovered some of these after they thought they
were extinct.

He gave the example of the marsupial Gilbert's Potoroo which, up until 1994,
was thought to have been extinct for 100 or 120 years.

"A graduate student from the University of Western Australia went down to
somewhere in the south west of the state to try to look for brush-tailed
bettongs and to her utter astonishment started trapping Gilbert's Potoroo.
Every one was quite taken aback," Cooper told ABC Science Online.

He also says it could be interesting to apply the statistical test to the
thylacine in Tasmania, the Tasmanian devil, the night parrot in Central
Australia, and even the disappearance of the megafauna in Australia.

To work out the 'new' dodo extinction date the researchers used actual
sightings of the animal but Cooper said that fossil data could be used as a
substitute.

However he said he would "be inclined to raise my eyebrows" at the idea of
applying the concept to the extinction of the dinosaurs because he did not
think there would be accurate enough data.
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