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Australian bat ecologists work to learn about impacts of catastrophic bushfires
Scientists estimate over 1 billion (yes, billion) animals died when fires ravaged Australia’s bushland in late 2019 and early 2020. But that enormous number doesn’t include bat losses, according to Australian bat ecologist Michael Pennay, who is conservation officer for the Australasian Bat Society and a volunteer firefighter. He says scientists don’t know enough about Australia’s bat density to accurately estimate how many perished.
Australia is home to around 80 species of bats, and around 80% of the species roost in trees—typically in hollows that can take 100 years to form. Between June 2019 and March 2020, officials estimate over 42 million acres burned, destroying habitat like tree hollows and impacting food sources like flowers and insects.
“The fires also coincided with maternity season when many species congregate and crèche their pups in communal hollows, likely killing many bats in their tree roosts,” Pennay says. “Sadly, I watched many suitable habitat trees as they were consumed by fire and did not see any bats flee to safety.”
While wildfires (called bushfires in Australia) are not unusual in the country, in recent years, climate change has caused these fires to become extraordinarily large and severe. In November and December 2019, Australia experienced the lowest-recorded amount of rainfall in its history. Along with the severe drought came extremely high temperatures—the average maximum temperature in Australia on December 18, 2019, was over 107°F, with temperatures in some areas up to 122°F. The extreme drought and record-setting temperatures meant lightning strikes and other fire ignitions quickly grew into immense firestorms.
Pennay says many wildlife species, including bats, succumbed not just to the flames, but also to starvation, thirst, injury, and heat stress well beyond the extent of the fires.
Bat ecologists are working to learn about the fires’ toll. They found 48% of the Golden-tipped bat’s (Phoniscus papuensis) habitat burned. The Grey-headed flying fox (Pteropus poliocephalus) is another species in danger, suffering from food loss as well as heatwave-induced mass mortality events, which can kill tens of thousands of flying foxes at a time. Both species are now on the Australian government’s list of animals in need of urgent management attention.
One study found over 40% of the habitat of the Greater broad-nosed bat (Scoteanax ruppellii) and the Eastern false pipistrelle (Falsistrellus tasmaniensis) burned. A study in Kosciuszko National Park found about half the normal number of tree-dwelling bats, but not a single Eastern false pipistrelle—before the fires, scientists found this species at 80% of study sites. Bat ecologists want to learn more, but their field work has been delayed due to the pandemic.
“Unfortunately, our terrible summer has been followed almost immediately by another terrible event: the current COVID-19 pandemic,” Pennay says. “Widespread travel restrictions have hampered efforts to begin monitoring and assessing the impacts of the fires.”
Pennay and fellow researchers plan to get out into the field when they can to learn more about how the fires affected bats. They are also working toward a landscape-scale monitoring program for Australia to learn more about the continent’s bats, how bushfires impact them, and how to help protect them.