Pedestrian fauna opt for shorter underpasses

May 7, 2015 by Rob Payne, Science Network WA
Pedestrian fauna opt for shorter underpasses
A southern brown bandicoots (Isoodon obesulus fusciventer) Credit: Brian Chambers

If anyone ever asks 'why did the bandicoot cross the road?', you would never guess the answer would be 'because the underpass was short', but it seems local researchers have proved just that.

University of Western Australia scientists tagged populations of southern brown bandicoots (Isoodon obesulus fusciventer) and western bobtail lizards (Tiliqua rugosa rugosa) around 10 fauna underpasses in the Perth metropolitan area, including Roe Highway, Mandjoogoordap Dr in Mandurah and Safety Bay.

Using motion-activated and PIT tag readers, they tracked the animals to determine how often they used the underpasses to safely cross major roads to better understand how design can impact native communities.

The underpasses varied in length, width, vegetation density at the entrances and 'furniture' within, such as ledges, logs and branches.

The researchers found none of these characteristics had an influence on bobtail behaviour, though one stood out as significant for bandicoots.

"Bandicoots used shorter underpasses more frequently, suggesting they were incorporating these structures into their home ranges to access resources on both sides of the road," Dr Brian Chambers says.

"The longer underpasses were used infrequently, likely during dispersal events."

Dr Chambers says it appears shorter underpasses allow bandicoot communities to persist in patches otherwise too small to support viable populations.

Pedestrian fauna opt for shorter underpasses
Western bobtail lizards (Tiliqua rugosa rugosa). Credit: Brian Chambers
"They basically stitch together territory on both sides of the road," he says.

While the knowledge is important, certain logistical challenges need to be addressed.

"Minimising the length of fauna underpasses poses a challenge for road designers, as the length of the underpass is usually determined by the width of the ," Dr Chambers says.

He suggests vegetated median strips might be the answer, with two shorter underpasses separated by a patch of scrub instead of one long passageway.

Given that bandicoots in the study were frequent users of a one-hectare patch, the size of this reserve wouldn't need to be large.

Pedestrian fauna opt for shorter underpasses
A bandicoot captured on an infrared camera using an underpass. Credit: Brian Chambers

Not only would this provide habitat, it would increase gene flow between populations, maintaining breeding diversity.

Dr Chambers says the study recorded the identities of individual animals which provided a better idea of how underpasses are used at a population level.

The infrared cameras also allowed researchers to track other species using the underpasses, which included western grey kangaroos, foxes, cats, rabbits, snakes, rats and even a family of ducks at two locations.

They found underpasses frequently used by bandicoots didn't correlate with higher use by predators such as cats and foxes.

Explore further: How smart roads can help koalas beat traffic

Related Stories

Addressing feral cats' diet may help protect native species

February 2, 2015

Because reducing the impacts of feral cats—domestic cats that have returned to the wild—is a priority for conservation efforts across the globe, a research team recently reviewed the animals' diet across Australia and ...

Study suggests new method of identifying native species

February 16, 2012

(PhysOrg.com) -- A radically new way to determine whether an introduced species has become a native species - by observing the reactions of other local species - is outlined in research by the University of Sydney, using ...

Roadkill hot spots identified in California

April 17, 2015

An interactive map shows how California's state highway system is strewn with roadkill "hot spots," which are identified in a newly released report by the Road Ecology Center at the University of California, Davis. The data ...

Bat bridges don't work: study

June 13, 2012

Wire bridges built to guide bats safely across busy roads simply do not work, University of Leeds researchers have confirmed.

Recommended for you

Matter waves and quantum splinters

March 25, 2019

Physicists in the United States, Austria and Brazil have shown that shaking ultracold Bose-Einstein condensates (BECs) can cause them to either divide into uniform segments or shatter into unpredictable splinters, depending ...

How tree diversity regulates invading forest pests

March 25, 2019

A national-scale study of U.S. forests found strong relationships between the diversity of native tree species and the number of nonnative pests that pose economic and ecological threats to the nation's forests.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.