Artificial roosts built for ghost bats at risk of homelessness in remote Pilbara mining regions
In the red, rocky hills of Western Australia's remote Pilbara, new 'motels' are springing up.
Looking like rammed-earth FIFO accommodation, the artificial roosts have been built into the hills near the town of Newman to replicate caves for ghost bats that are at risk of becoming homeless from mining.
A project team, involving scientists and mining companies, designed the new accommodation options for ghost bats after finding evidence of their presence at BHP's Mining Area C site near Newman in 2010.
The ghost bat is Australia's largest carnivorous bat and is found across the north, from the Pilbara to central Queensland.
They are listed as a vulnerable species under the Western Australian Wildlife Conservation Act and rely on caves for roosting.
The Threatened Species Scientific Committee estimates the population of ghost bats in the Pilbara is between 1,300 and 2,000, with the Hamersley population alone possibly being as high as 800 bats.
Studying ghost bats
Scientific research on the ghost bats was mostly carried out in Queensland and the Northern Territory until 2011, when a new project began in WA to collect data.
After realising there was insufficient knowledge on the species Macroderma gigas, WA ecologists set about gathering new information.
The eight-year Chasing Ghosts project was undertaken by the Biologic Environment Survey in collaboration with universities, mining companies, the Perth Zoo and pastoral stations.
A number of research techniques such as infra-red motion sensors, handy cams, computerised software and detectors were all trialled, but discontinued before scientists tried different approaches.
DNA used to identify bat populations
Using DNA technology to study bat scats, wing clips, and feeding remains in caves, scientists identified more than 700 potential bat caves across the Pilbara.
"We started off by searching for all the caves that we could, looking to see if there were scats within the cave, and counting the scats within them," the project's technical manager, ecologist Belinda Barnett, said.
"We then realised that new advances in DNA technology would enable us to identify individuals by the DNA in their scats.
"From these data we could count how many individuals used a cave, how many caves they used, how far they moved, and over what time."
Ms Barnett said the study also revealed which caves were essential for the bat population.
"Hormones found in the scats allowed us to determine if females were pregnant, and therefore which caves may be more important during the breeding season."
With the information collected, scientists designed and constructed the new artificial roosts being trialled at BHP's Mining Area C and Cattle Gorge.
The roosts were redesigned for multiple bat species after the first building attempts, using readily available components, proved too expensive and not as effective.
The more complex designs include pigmented concrete to reduce light shine, altered hanging structures on the roofs, and smaller chambers for another significant Pilbara species, the leaf-nosed bat.
The project last month won a 2018 Golden Gecko Award for Environmental Excellence.
Information about the location of the bat population has been made available to the public in a database.
Companies can use the information to check if areas proposed for mining are home to bats and whether artificial roosts need to be built as alternative accommodation to their natural caves.
"The studies have considerably extended knowledge relevant to the management of Pilbara ghost bats," retired zoologist Norman McKenzie said.
It is hoped that, as more studies are done, a more accurate estimate of the number of ghost bats in the region will lead to more targeted land management.
For now, BHP is continuing to investigate how the bats can use artificial roosts instead of caves at various locations in the Pilbara.
The company said 173 hectares of the bats' feeding areas had been retained.