Published: Saturday, May 18, 2020
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The Conversation, by Grant Linley and Dale Nimmo
Credit: Pixabay/CC0 public domain
The Black Summer bushfires that swept Australia in 2019-20 provided ideal conditions for spreading misinformation, from the subtle to the absurd.
In this context, a bizarre social media story became viral.
It was a story about heroic wombats who herded other animals into their burrows that were fireproof to save them from flames. We explained at the time that this story was mostly inaccurate. We’ve now done a more thorough investigation and found that there may be some truth to the story.
They are complex and deep. The burrows of common wombats can be up to 15 meters in length with multiple chambers and entrances. Even if they don’t bring wildlife into their burrows, wombats can still use their burrows as “fire refugia” – providing shelter, food and drinking water in the event of a bushfire.
Not only wombats use burrows
In the forests that burned during Black Summer bushfires, north of Albury in New South Wales we installed 56 cameras. We chose sites with varying levels of severity because some areas were more severely affected than others.
The cameras were placed in two areas: one with similar plants but no burrows, and the other with the same type of plants but without burrows. We then monitored the burrows between June 2021 and April 2022 in order to determine which animals used them and how.
The wombat burrows were home to 56 different animal species (19 mammal, 33 bird species and four reptile species).
In and around burrows, native species like bush rats, agile Antechinus, lace-monitors and birds, such as painted button-quail were more numerous than nearby control sites. Even a threatened species like the heath monitor was seen emerging out of a burrow.
Barbara Triggs – a wombat expert who literally wrote the “book on wombats” – had observed several species “scurrying from burrow entries” and emerging “from tiny crevices in walls” of the wombat burrows. Our results are confirmed by her and other observations.
Overall, burrows are hotspots for mammal activity. More mammal species were recorded in burrows compared to control sites. The smaller mammals were more common, possibly because they could use the burrows with the wombats.
The burrows were avoided by larger animals like kangaroos, wallabies and emus. It is possible that they were afraid of a wombat. Wombats have been known to defend territory.
Images show that wombat burrows are safe refuges in the event of a fire. Credit: Charles Sturt University
Wombat burrows showed some interesting behavior. Total, 31 species interacted with the burrows. The species found included 30 species that were inspecting the entrance to the burrow, 11 species foraging in the burrow or around its lip and 10 species entering or emerging.
After rain, we also observed animals bathing and drinking in temporary pools that filled up at the entrances of burrows.
This suggests that even though water was abundant during our study period wombat burrows provide a valuable eco-system function which could help other wildlife. This is an interesting observation and warrants further research.
The highest use of burrows by native wildlife was in the areas that had burned most intensely. This is consistent with the notion that wombats burrows provide a refuge for native wildlife following a fire.
Underground networks
Our results are only the tip of the Iceberg. Many burrowing species around the world provide habitat to other species. Burrows are a source of resources and shelter for many species, from the American badger to giant armadillos.
Sand goanna burrows are home to at least 28 different animal species. The bilby burrows are described as “outback oasis”, because they provide shelter for birds, reptiles, and mammals.
Animal burrows are not the only ones that offer shelter after a fire. In a US study published in 2018, gopher tortoise nests found in burned areas contained 8.5 times as many wildlife species as burrows located in unburned areas.
Wombats can help other people.
Our research focuses on the bare-nosed wombat. Although not listed as endangered, their numbers have decreased markedly since European settlement.
Our research is part of a growing body evidence suggesting that protecting wombats would benefit a variety of species in many Australian eco-systems.
Our wildlife, including the wombat burrow, will need help as large and severe forest fires are becoming more common across southeast Australia.
This article was republished by The Conversation, under a Creative Commons License. The original article can be read.
Source: Phys.org