How did the gliding mammal cross the road? Turning power poles into stepping stones

Squirrel gliders are sizing up power poles as dead trees to help them cross busy highways, according to new research from zoologists at Southern Cross University.

The findings by Dr Brendan Taylor and Dr Ross Goldingay, from the University’s School of Environment, Science and Engineering and published in the international journal Restoration Ecology, come after the pair explored novel ways of enabling gliding mammals to cross roads and highways.

“Using the logic that power poles are basically just dead trees, we have been investigating whether similar-sized wooden poles, obviously devoid of powerlines, can be installed to assist squirrel gliders to make glide crossings over roads,” Dr Goldingay said.

The study focused on four dedicated wildlife land-bridges over roads in Brisbane and in the Tweed and Byron shires of northern New South Wales.

The two Brisbane land-bridges, over Compton Road at Kuraby and Hamilton Road in Chermside, each contained eight seven-metre high wooden poles specially installed for gliding mammals to use. The two NSW sites had no poles.

“All four land-bridges were covered in vegetation but only the Brisbane land-bridges, with the wooden poles, were used repeatedly over several years by gliders to move from one side of the road to the other,” said Dr Goldingay.

Specialised infra-red cameras revealed the squirrel gliders were using the wooden poles at least once per week.

“These results are remarkable and important, given that roads not only impact populations of wildlife through road kill but some species show a reluctance or inability to cross the gap in habitat created by the road, thereby isolating populations on either side,” said Dr Taylor.

Since the study was completed a similar crossing rate was recorded at another Brisbane location (over a road at Mansfield), where 12-metre high wooden poles were installed.

Dr Goldingay said the poles proved to be a simple mitigation measure.

“Our research has revealed that these poles can act as stepping stones for gliding mammals.

“The great benefit of using poles is that you are not restricted to just installing wildlife crossing structures as new roads are built. You can look more closely at existing roads where population bottle necks have been created and install poles to reduce the threat of extinction.

"This new conservation tool has relevance not only to our local gliding mammals but relevance elsewhere in the world because most of the 60 or so species of gliding mammals are exposed to increasing levels of habitat fragmentation."

Dr Taylor and Dr Goldingay’s study forms part of Southern Cross University’s research in the field of zoology. SCU’s work in this field was given the highest possible classification of ‘well above world standard’ in the recent Excellence in Research for Australia (ERA) 2012 national report. The University’s zoology research is focused on the impacts of environmental change – both natural and human induced – on animal species, including the impacts of land clearing, road building and urbanisation on marsupials; how Australia’s bird fauna has evolved and adapted over time; the impacts of climate change and ocean acidification on marine organisms. Zoology research is located in the University’s School of Environment, Science and Engineering and in the Marine Ecology Research Centre and the National Marine Science Centre.

PUBLICATIONS:
Taylor, B. D., and Goldingay, R. L. (2012). Restoring connectivity in landscapes fragmented by major roads: a case study using wooden poles as “stepping-stones” for gliding mammals. Restoration Ecology 20 (6), 671–678.

Taylor, B. D., and Goldingay, R. L. (in press). Squirrel gliders use road-side glide poles to cross a road gap. Australian Mammalogy

Photo: Female squirrel glider on a pole installed on a landbridge in Compton Road, Kuraby, Brisbane (Credit: B Taylor & R Goldingay).