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10 August
2006
Why are some
males faithful, stay-at-home partners while others sleep around, with no strings
attached? In mountain brushtail possums, it turns out to depend on how disturbed
their home is.
Based on
five years of radio-tracking mountain possums or bobucks, Dr Jenny Martin from
Melbourne University’s Department of Zoology found that in neighbouring
populations in northeast Victoria, male possums living in unlogged forest were
promiscuous, whereas those who lived in disturbed habitat paired for life.
“Days of our
Lives has nothing on this real-life soap opera” says Jenny.
The reason
seemed to be a basic one—the need for food and shelter. It turned out that the
key difference between the two sites was the number of hollow-bearing trees.
“Bobucks
sleep in hollows that are only found in big old trees. At my first (disturbed)
site, logging had removed most of these trees. The remaining few were all a long
way from the wattle groves where the possums feed” she says. “At the other site,
which had never been logged, there was plenty of food and shelter in the same
area.”
After
hundreds of hours of possum-tracking during the day and night, she was able to
work out why this difference had such a drastic effect on the possums’
behaviour. In good habitat, she says, many females can live close together and
do not need to spend much time travelling, so males have easy access to them.
The reverse is true in disturbed areas where females occupy and travel through
much larger areas.
Jenny’s
study is the first to reveal the ways in which human changes to habitats can
profoundly affect the social lives of marsupials.
Jenny Martin
is one of 16 Fresh Scientists who are presenting their
research to school students and the general public for the first time thanks to
Fresh Science, a national program hosted by the Melbourne Museum and sponsored
by the Federal and Victorian governments, New Scientist, The Australian and
Quantum Communications Victoria. One of the Fresh Scientists will win a
trip to the UK courtesy of the British Council to present his or her work to the
Royal Institution. | 
