Velocity Web Site - Rainforest animals rescued from road kill


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A Lemuroid Ringtail Possum strutting across a possum bridge over the Old Palmerston Highway. Videocapture: David Thompson

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Not only does animal road kill endanger Australia's wildlife but it has even greater social and economic costs: human injuries and fatalities, loss of biodiversity, passenger distress, motor vehicle damage and high insurance premiums are just a few

The East Evelyn overpass project received a series of awards for innovation and engineering excellence.

Rainforest animals rescued from road kill

If the grass is greener on the other side, Australian rainforest animals can graze to their hearts content thanks to the new wildlife crossings on the North Queensland coast. From Zebra Crossings to Koala Crossings, native animals have good reason to cross the road; it's now simple and safe.

To alleviate road induced problems researchers from the Rainforest Cooperative Research Centre (CRC) have spent eight years producing innovative projects to get animals off the streets.

"Major roads have caused road kill problems for Australia's native animals for decades," said Rainforest CRC member, Dr Miriam Goosem of James Cook University. NSW Wildlife Information and Rescue Service estimates that 7 000 native animals are killed on New South Wales roads every day.

Not only are treasured endangered species reduced to road kill, but road barriers also create habitat fragmentation; isolating animal populations, probably causing in-breeding and, in extreme cases, threatening extinction. "For some animals, such as the endangered Cassowary and rare Lumholtz's Tree-kangaroo, mortality on the roads forms a threat to species' survival," Miriam said.

While a variety of methods to prevent road kill have been trialled, animal crossings have proved most successful.

Before you conjure up images of lolly-pop ladies ushering animals across busy freeways, note that these are not traditional crossings. Animal underpasses and overpasses were developed to allow animals freedom to cross the road as they please.

An operational underpass just after completion, at the East Evelyn Road Upgrade
Photo: Jonathon Munro

Overpasses consist of a rope ladder strung high above the road connecting canopies on one side to the other; their main function is to reduce fragmentation for animals that rarely or never leave the canopy. Underpasses are tunnels under major roads that allow animals to pass under the busy traffic, thereby lowering road kill and enabling animal movement.

But while tunnels are dug and rope bridges hung, how do researchers ensure animals use these new crossings?

The best way to ensure animal use is to guarantee they travel in style. A variety of rope bridges were put to the test to decipher wildlife preferences. The first overpass bridge design was constructed in 1995 across a logging track high in the mountains behind Cairns.

Since then, Rainforest CRC student Nigel Western has used photographic evidence to decipher animal travelling preferences. Nigel used infrared cameras and spotlights to track animal use of bridges.

"The bridge that registered the most possum traffic was a rope ladder version we strung across the Old Palmerston Highway - where we had up to 30 crossings a night," Nigel said. "Species included lemuroid, green and Herbert River ringtails, coppery brushtails and striped possums."

While rope tunnels were created to offer some protection from aerial predators, evidence showed animals preferred the high life, traversing along the top of the structure.

Much research into underpasses was carried out during the upgrade of the East Evelyn road on the Atherton TableLands.


	These canopy bridges were constructed in November 2005, on the Palmerston Highway, near Millaa Millaa and miraculously survived from Cyclone Larry. Photo: Birgit Kuehn

It seems a major underpass attraction for ground dwelling creatures is the chic interior design.

Underpass 'furniture' has been adopted inside these 3.4 metre high tunnels to create habitat constancy. Underpasses are covered with soil and leaf litter, rocks and logs. Not only does this decoration mimic the outside habitat, but it also provides smaller animals protection from predators.

Tracks in the sand inside the underpasses were examined to determine which animals were using the structures. "A variety of animals were found to be using the rainforest corridor however it is not expected that rare target species will use it until it is well established," said Miriam. The rare Lumholtz's tree-kangaroo has used the structure several times.

A major issue was that underpasses might become predator's lunchboxes, as feral animals learned to use the area as a hunting ground. To combat this issue designers created an indoor fun park with large tree branches and thick ropes that swing between the trees providing escape routes from would-be predators.

Monitoring of East Evelyn road has provided evidence that animal crossings work. The area that was once a hot spot for road induced animal fatality now has very few road kills.