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Threatened possums have just two choices for survival

Tuesday, 24 May 2016


Possum populations in Western Australia’s south-west will continue to decline as climate change and habitat loss take their toll on the region’s marsupial fauna.

Research from ECU’s Centre for Ecosystem Management, published in PLoS ONE, has shown that as climate change impacts on the fragmented landscapes of WA, brushtail possums have two choices to survive: migrate or adapt.    

Lead Researcher Dr Shaun Molloy said the geographic area where the possums (or ‘koomal’ to use their Nyoongar name) can survive is both shifting and contracting due to climate change.

“The clearing of native bush and the effects of jarrah dieback has made the two survival options, migrate and adapt, particularly difficult,” he said.

“In Western Australia we’ve lost a huge amount of native vegetation and what’s left tends to be in small patches or fragments” he said.

“Movement between different habitats becomes very difficult for koomal when the bush is fragmented because they won’t cross open areas.

“Those small patches also make adaptation difficult because small areas of bush don’t tend to support a full range of plant species and natural processes such as access to light, the movement of water and air, and the movement of genetic material, are highly disturbed.”

The research team used species distribution models (SDMs) to predict how climate change will impact the species.

This enabled them to identify important areas of habitat for conservation purposes and to identify areas where conservation activity will be most effective.

“What makes this research special is the addition of field studies. We spent a year observing and radio tracking koomal to see how they survive in a fragmented landscape and used our observations to make our models much more realistic than the normal desktop exercise,” Dr Molloy said.

The result are models which show the geographical area where the species can survive based on the climate, surviving habitats and then modified the maps to include the effects of climate change by 2070.

“Our research shows the koomal will probably split into two distinct groups, much like has been predicted for other species such as the ngwayir, or western ringtail possum," he said.

“One group will be isolated in the Darling Scarp inland from Perth extending south to around Dwellingup while a second group will be confined to a band along the south coast of the South West corner.”

Koomal quick facts:

  • The koomal is a geographically isolated subspecies of the common brushtail possum and is endemic to south-western Australia.
  • Since European settlement koomal have undergone a significant reduction in distribution due to its vulnerability to habitat fragmentation, introduced predators and dieback.
  • It is very different to other brushtails in that it is much smaller, has a more carnivorous diet and is genetically and behaviourally different to other subspecies.

The research was published in PLoS ONE and is available on its website.


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