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Koalas, people and climate change: not a good mix

As Australia gets warmer and drier, koalas will struggle to survive. JSFauxtography

On 22 September, a Senate inquiry released its report, The koala - saving our national icon. The inquiry made 19 recommendations, and called for more funding for koala research. The environment minister is now considering whether to list the species as threatened.

Think back to the summer of 2008-2009. Surprised residents found wild koalas appearing in their gardens displaying abnormal behaviour. Koalas were trying to climb into swimming pools, they were drinking from dogs’ water bowls and they were lying at the bottom of trees, no longer able to climb.

These koalas were dying from a prolonged drought and a number of consecutive days that exceeded 40°C. CSIRO climate change predictions indicate that such extreme climate events will occur more frequently as we go forward.

What is so special about the koala?

The koala is an iconic Australian native marsupial that has a very limited diet. It can only eat certain trees – predominantly eucalypts – that contain particular leaf chemistry (such as high levels of nitrogen) and moisture. The koala’s habitat and food trees have been relentlessly cleared since European settlement. Koalas were also hunted to near extinction in many parts of eastern Australia for the fur trade.

Today’s koalas have many threats to contend with, including the fragmentation of their habitat and loss of their food trees, attacks from dogs, collisions with cars and disease. Yet the koala enjoys no Federal legislative protection.

The heatwaves of 2009 drove koalas out of the trees.

Climate change is now compounding these existing threats.

The koala is recognised by the International Union for the Conservation of Nature (IUCN) as one of only ten species worldwide that is highly vulnerable to climate change.

This is due to increasing atmospheric CO₂ levels that will reduce the nutritional value of their eucalypt leaves. Koalas will also be affected by drought and their very limited capability to adapt to rapid, human-induced climate change.

Along with my co-authors from the University of Queensland, I recently published the findings of a study into the effects of climate change on the distribution of koalas in eastern Australia.

We predicted that, under the current “business as usual” climate change scenario of a high dependence on fossil fuels, current koala distributions will likely contract eastwards and southwards in Queensland, New South Wales and Victoria.

Of considerable concern is that their distribution will contract to regions such as southeast Queensland and coastal New South Wales. These are regions in which koala populations are already significantly declining due to high human population densities, disease, and ongoing threats associated with urbanisation such as habitat loss.

In arid and semi-arid regions such as the Mulga Lands of southwestern Queensland, climate change is likely to compound the impacts of land clearing, resulting in significant contractions in the distribution of this species.

As koalas are pushed into urbanised areas, they come in conflict with people, cars and dogs.

A proactive approach to koala conservation planning is necessary to protect the koala and many other species that depend on eucalypt forests.

Importantly, conserving adequate koala habitat that provides “climate refugia” - that is, an area where koalas may be able to continue to live when their climatic and environmental conditions have changed - is essential to the future survival of this native animal in the wild.

Can koalas and humans co-exist?

Expert witnesses from the Koala Research Network recently told the Senate inquiry into the status, health and sustainability of Australia’s koala population about the significant threats to koalas, including climate change.

We hope the inquiry will result in a positive outcome for koalas, with a federal listing for koalas as “vulnerable” under the Environment Protection and Biodiversity Act.

Giving private landholders financial conservation incentives to help koalas could certainly aid their survival. Landholders could be paid to leave areas of identified koala habitat intact, rehabilitate important koala areas with their food trees and provide adequate connected koala habitats.

These measures, and political will, may mean it is not yet too late for koalas in some regions.

But for some of the rapidly developing coastal areas with dense human populations, it is probably a little too late to prevent local koala extinctions.

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