14 February 2006

Koalas have as much to fear from dogs and busy roads as losing their juicy Eucalypts to tree clearing, according to new research.

A University of Queensland study of koalas in Port Stephens says traffic and dogs are more of a threat to koalas than previously thought.

“In some areas, deaths from dog attacks and cars can be as detrimental to koalas as habitat loss,” study author Dr Jonathan Rhodes said.

“If we are to continue to see this iconic Australian species in our backyards, then we need to protect habitat, but this must be combined with reductions in the number of koalas killed by our dogs and on our roads.”

Dr Rhodes, a PhD graduate from UQ’s School of Geography, Planning and Architecture, studied koalas to show how wildlife survived in fragmented semiurban landscapes and how to prioritise conservation actions.

He said he analysed data on koala distributions, koala radio-tracking data, habitat mapping, traffic volumes and dog densities.

Of 41 koalas radio-tracked in the Tomago Sandbeds in Port Stephens, New South Wales between 1995 and 1997, eight died from dog attacks and one died after being hit by a car. Koalas roughly had an annual 14 percent chance of being killed by a dog.

Last year 34 koalas died on Port Stephens’ roads with one death reported for January, according to the Native Animal Trust Fund.

Port Stephens koala coordinator Geoff Bartlett said there were usually between 20 and 40 road fatalities a year and about six deaths from dogs a year in Port Stephens.

Backburning and tree clearing around powerlines and for new subdivisions also threatened koalas.

Dr Rhodes produced two mathematical models, one to predict the effect of habitat and human interference on koala distributions and another to predict the risk of koala deaths from cars.

He estimated the chance that a car would hit a koala trying to cross a busy road in Port Stephens may be around 20-50 percent, but this would depend on traffic volumes, car speeds, road type, koala behaviour, and time of day.

Koalas crossing roads during peak times would most likely be hit.

He said accommodating increases in traffic volumes on existing roads was preferable to building new roads through koala habitat.

Wildlife crossings, speed reduction zones and wildlife reflectors would also help.

Dr Rhodes said his models could be adapted and transplanted to help form conservation plans for many other wildlife species living in semiurban areas.

The Port Stephens koalas also relied heavily on two Eucalypts, the drooping red gum and swamp mahogany, most likely for food and shelter.

Dr Rhodes conducted his koala research as part of a team that included UQ School of Geography, Planning and Architecture Senior Research Fellow Dr Clive McAlpine, UQ Ecology Centre Director Professor Hugh Possingham, and UQ student Michiala Bowen.

Dr Rhodes is currently a postdoctoral fellow at CSIRO Marine and Atmospheric Research in Hobart working on monitoring and managing marine ecosystems.

MEDIA: Dr Rhodes (03 6232 5113, Jonathan.Rhodes@csiro.au) or Miguel Holland at UQ Communications (07 3365 2619, m.holland@uq.edu.au)