It was a story that seemed too good to be true, and indeed it was: During the devastating 2019–20 Black Summer bushfires in southeastern Australia, false reports circulated that wombats had protected other animals by herding them into their burrows.
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But the reports did contain a grain of truth; it turns out that the Wombat burrows do serve as fireproof shelters for small mammalsbirds and reptiles during and after extreme fires.
Dale Nimmo, an ecologist at Australia’s Charles Sturt University, was asked to verify the reports. “There was quite a bit of evidence that species other than wombats were regularly using their burrows,” Nimmo said.
He decided to explore the role of their burrows in forest ecosystems affected by fire. His colleague Grant Linley went looking for wombat burrows in Woomargama National Park and Woomargama State Forest. About 180 of their combined 310 square kilometres had burned during the 2019–2020 fires. When Linley arrived there in the summer of 2021, vegetation had already begun to grow back.
Wombat burrows are impressive feats of underground infrastructure. “They have multiple entrances and multiple chambers,” Nimmo said. “They are wide. They have temperatures that are well below the surface temperature, so they are cool when it’s hot.”
Wombats can grow to more than a metre long and weigh up to 40 kilograms. They can be territorial and aggressive towards each other and other large mammals. But because wombats are not predators, “it’s a little bit safer for other species, small mammals and small lizards and so on, to cohabitate with them,” Nimmo said.
In a paper published in the Journal of Mammalogy, the team described how Linley set up cameras in 28 wombat burrows in areas that had varying degrees of charring from wildfires, including some that had not been burned. The cameras took photographs of burrow traffic from June 2021 to April 2022, producing hundreds of thousands of photographs.
The images showed that burrows are a hub of activity. Fifty-six vertebrate species were observed, and several endemic species were seen more frequently in burrows than at nearby sites without burrows, including bush rats and the agile antechinus (a marsupial related to the Tasmanian devil), the 2-metre-long tree monitor and birds such as the spotted torillo and the grey woodpecker.
A wombat burrow can last for decades, potentially providing a “multigenerational refuge” for many species, Linley said.
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