[ASC-media] Media release: cutting roadkill

CRCA Media crcamedia at starclass.com.au
Mon May 30 20:36:05 EST 2005

CRCA Media Release 05/20

May 31, 2005


Dead animals on Australian highways are so common that most drivers don't give them a second glance  - but roads which cut through bush pose a major threat to the animals which live there.

Dr Miriam Goosem of the Cooperative Research Centre for Rainforest Ecology says that roads departments and shire councils are becoming far more aware of the problem.

"With increasing traffic and regular highway upgrades, roads have become a real problem for canopy- and ground-dwelling animals," says Dr Goosem. "In some cases, such as the endangered Cassowary and the rare Lumholtz's Tree-kangaroo, road deaths are so frequent that they are a real threat to species survival. 

"For example, along 2km of highway through rainforest, I found 4,000 animals killed over a 3 year period when checking weekly. This does not include the animals that disappeared between surveys."

While road kills are an obvious and tragic result of the fragmentation of habitat by roads, other consequences may be less obvious but equally serious.

Roads, pipelines, electric power-line easements and other artificial clearings in bushland can create impossible problems for bush dwellers when they are scared of crossing the open area, she says.

"A viable population needs genetic diversity," says Dr Goosem. "An area of forest or bush sliced in two by a road or other clearing can create two distinct and non-viable populations of a once-thriving animal.

"An overpass or an underpass may be the solution to the problem, and if it is included in the planning for road making or road maintenance it becomes a minor engineering project," she says.

Dr Goosem says that while 'fauna underpasses' are not a new idea, with new research they are an idea whose time has come. On the other hand, 'fauna overpasses' in the form of rope bridges that possums can walk across are very new.

One criticism of the provision of animal underpasses was that they would become 'predators' lunch-boxes', as cats and foxes would quickly learn to take up station where there was regular prey traffic.

"This can easily be prevented by providing cover for animals which use the underpass right up to the entrance and exit," she says. "In the underpass itself, we have learned to provide 'furniture' to protect the passing creatures: the tunnel is floored with local soil, there are rocks and logs to provide shelter for small animals, and ropes and branches allow tree-living animals to escape from ground level."

Traffic through the underpasses has been monitored by the researchers using sophisticated sensors, automatic cameras and simple brushed sand floors to record animal footprints.

The researchers found that in forest country, pest species such as foxes and cats (and even cane toads) are more inclined to use road clearings for their own travel, and less likely to penetrate the denser bush.

Many canopy-dwelling species seldom if ever descend to the ground, and for them Rainforest CRC researcher Nigel Weston and National Parks ranger Rupert Russell provided overpasses in the form of rope bridges above busy roads.

"Initially we trialled hanging tunnels made of rope. We found that several rare species of possum quickly learned to use them but preferred walking along the top of the structure, so we changed to a much simpler and cheaper form of rope ladder," says Dr Goosem.

Dr Goosem says that there is encouraging community and official acceptance for achieving the best environmental outcome, and increasing understanding of the effects of man-made structures on animal population dynamics.

This research has been included in a manual of environmental best practice produced by the Rainforest CRC and the Queensland Department of Main Roads. Overpasses and underpasses have been included in many road upgrades in eastern Australia, according to Dr Goosem, and the requirement for natural habitat adjacent to underpass entrances is now emphasised throughout Australia.

There has also been growing international interest in the research project.

"Globally, we lead the world in rainforest road ecology and mitigation of road impacts for rainforest fauna," says Dr Goosem. "This project is not just good science, but it adds significantly to the skills base of Australian road engineers, many of whom are involved in large overseas projects."

This project supports Australia's National Research Priority No. 1, an Environmentally Sustainable Australia.

More information from:

Dr Miriam Goosem, Rainforest CRC, 07 4042 1467 or	0409 965 905
Ms Trish O'Reilly, Rainforest CRC, 07 4042 1246, 
patricia.oreilly at jcu.edu.au						

Prof. Julian Cribb, CRCA Media					0418 639 245
More science stories: http://www.sciencealert.com.au

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