NEW STUDY: WOMBAT BURROWS PROVIDE CRITICAL SHELTER FOR MANY SPECIES FOLLOWING WILDFIRE

A new study, published in the Journal of Mammalogy, found wombat burrows boost native mammal richness, provide critical shelter for numerous species following severe wildfire, and may even be an important source of water.

It states “wombat burrows play a valuable and underappreciated role in Australia’s fire-prone forests”.

Native species such as bush rats, agile antechinus, lace monitors, painted button-quails, and grey shrike-thrush were more prevalent around burrows compared to similar sites without burrows.

The research, supported by the World Wide Fund for Nature-Australia, focused on the burrows of common wombats (Vombatus ursinus) in Woomargama National Park and Woomargama State Forest in southern New South Wales.

More than 18,000 hectares of the national park and state forest burnt between 29 December 2019 and 18 February 2020.

Scientists set up sensor cameras in front of 28 wombat burrows situated amid varying degrees of fire severity and at 28 control locations nearby with the same fire severity but without burrows.

Between June 2021 and April 2022, the cameras recorded more than 15,000 individual animals. Of the 56 species identified, 47 were native and nine introduced.

The cameras recorded 30 species inspecting a burrow, 11 foraging at a burrow, 10 entering or leaving a burrow, four drinking from a flooded burrow, and one bathing in a flooded burrow.

Lead author Grant Linley, an ecologist and PhD Candidate with Charles Sturt University’s Gulbali Institute, said “burrow sites had higher native mammal species richness”.

“Wombats alter the soil, topography and vegetation around their burrows. They turn over tonnes of soil constructing a burrow and their scats increase nitrogen levels which boosts herb cover.

“We think these changes increase the foraging opportunities for small insectivores and omnivores, such as bush rats, agile antechinus, grey shrike-thrush, and painted button-quails and that’s why we see more activity by these species around burrows.

“More small vertebrates hanging around wombat burrows could then be drawing in larger native predators, such as lace monitors, so the impact of burrows may be cascading through the system,” Mr Linley said.

Co-author, Professor Dale Nimmo from Charles Sturt University’s Gulbali Institute, said aside from better foraging opportunities, the use of burrows as a refuge from predators may also be attracting small animals.

“Many resources critical for species survival, such as logs, were destroyed by severe fires. We found associations between species and burrows were often strengthened in fire impacted habitat. For example, agile antechinus, bush rats, and painted button-quails – all smaller-sized animals – were most active at burrows subject to high severity fire.

“Wombat burrows are potentially aiding in the survival, persistence, and recovery of animal populations following severe wildfire events,” Professor Nimmo said.

Co-author Dr Kita Ashman, a conservation scientist with WWF-Australia, said wombat burrows could help some species deal with the challenges of climate change.

“Wombats extensive burrow systems can create microhabitats that enhance water retention, assist in nutrient cycling, and contribute to overall ecosystem resilience. In an increasingly unstable climate, wombats can be valuable agents in adapting to and mitigating some of the impacts of climate change,” Dr Ashman said.

The study found smaller species were more active around burrows and larger species less active, with larger animals excluded from utilizing the available shelter and foraging potential due to the size of the burrow openings.

It also noted that 19 burrows filled with water at least once. A range of species drank this water, suggesting that in periods of low water availability, burrows could possibly provide a critical service.

“Common wombats are in decline, their range is contracting, and we need to turn that around. They’re the only surviving native species capable of digging deep, wide burrows. Their value as providers of shelter and a refuge for numerous species is only going to increase as fires become more intense in the future,” said Mr Linley.