Wombats, known for their compact bodies and dense fur, dig extensive underground burrows that can offer safe shelter during fires. /Grant Linley
Photo: Grant Linley
Between 2019 and 2020, fire from several wildfires in Australia devastated more than 10 million hectares of forests in the southeast of that country, including a record amount (1.8 million hectares) burned with high severity, affecting almost 3 billion vertebrate animals. During those weeks, a curious animal story went viral: wombats (small, robust, short-legged marsupial mammals) that supposedly pushed other animals into their burrows to protect them from fire.
The story, which depicted a small, caring animal becoming the hero of the forest, was false. But even so, some elements of truth can be extracted from that picturesque story that can be very important for conservation. This is suggested by new research published in the Journal of Mammalogy. (Can see: Elon Musk’s SpaceX achieves its first landing after four attempts)
But what truth could that story have? Well, wombats happen to be the largest burrowing marsupials on the planet. They excavate and use multiple burrows that consist of a large network of underground tunnels that can be over 15 meters long, with multiple entrances. These small animals are active in forests after a fire, so they have the ability to maintain burrows in burned habitats. The researchers then asked a simple question: could these burrows provide shelter to other animals from the impacts of fire?
To answer it, they monitored the activity of a variety of native vertebrates around wombat burrows in habitats that burned with varying severity during the 2019 and 2020 wildfires, and in nearby, but unburned, areas. The camera traps they installed recorded 746,674 images containing 370,845 images of wildlife. In them, 15,723 individual animals of 56 species appeared, made up of 19 species of mammals, 33 of birds and 4 of reptiles.
Excluding the wombat, present in almost all the images, the researchers identified 48 species in the burrows and 43 in control sites. The presence of burrows in the environment was associated with an increase in the activity of many native animal species. Smaller species were more active around these burrows, compared to larger species. After severe wildfires, many species remained associated with these burrows, which the research says supports the idea that burrows act as refuges in difficult times.
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Numerous examples of smaller species using wombat burrows were detected, including the bush rat, black rat, short-beaked echidna, gray shrike, white-throated treecreeper and lace monitor. “Our study method may have even underestimated the activity of some of these species, as camera traps are typically less effective at capturing smaller species of mammals, birds, and reptiles,” they write. In fact, other researchers have documented small mammals entering and exiting burrows.
And why is size so important? Of course, larger species may not fit in the burrow. But not only that: common wombats are large and robust mammals, with occasional displays of aggression. They are known to compete for resources. “It is therefore possible that the common wombat actively discourages larger competitors from its burrows, or that macropods avoid burrows to reduce the risk of a negative encounter, as the common wombat vigorously defends its territories against non-intruders. desired,” the scientists write.
Now, do burrows protect from fire? For small vertebrates that are vulnerable to predators, many flammable shelters, such as logs, are consumed by severe fires. Wombat burrows, in contrast, survive fire and can persist for decades, potentially providing important post-fire shelter. The study found that although the fires did not affect some species much, they did cause more animals to gather near burrows. This way they could interact, look for food and feel safer from predators.
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“The importance of ecosystem engineers in providing critical refuge to other species highlights the often overlooked risk of co-extinctions due to burrow loss,” they write.
The burrows could not only protect from fire, but could even be a source of water. The scientists observed several cases of wombat burrows filling with water, “indicating that water supply may be another ecological function they perform,” it read. Animals such as the eastern gray kangaroo, red-necked wallaby and swamp wallaby were captured drinking from their burrows, suggesting that the burrows could provide an important water resource for the animals, although they may only provide services during periods of low availability of water.
All of this makes it possible, they conclude, that “the value of burrowers as shelter and shelter providers is likely to increase following disturbance in a variety of ecosystems.” With the prospect of wildfires becoming larger and more severe around the world, researchers believe it is crucial to understand how animals survive and recover after these extreme events. So while the social media story wasn’t 100% true, science does have evidence that wombat burrows were very important in Australia’s forests that often suffer fires. And they could continue to be so. (Can see: After coal: what was left of the mining exploitation in Cesar)
