Animals Can Influenece Fires As Either Firefighters Or Inadvertent Arsonists

Grazing animals such as kangaroos were among the many victims of the Australian bushfires. Depending on the location they may have reduced these fires' likelihood, or made them even worse. stockpexel/Shutterstock.com

Following the astonishing expansion of fires in the Amazon, Arctic, and Australia recently scientists are considering where animals fit in. Besides being victims to an utterly horrifying extent, animals can reduce the circumstances under which fires reach such terrifying intensity, but sometimes they can also create those very conditions.

Many local councils use grazing animals such as goats to keep down grasses that turn to fuel in a dry spell. Dr Claire Foster of the Australian National University notes it's not just animals specifically employed for the task who fill this role. In Trends in Ecology and Evolution, Foster gives examples of creatures as diverse as termites and elephants that contribute to hazard reduction.

"One of the most amazing examples is from savanna ecosystems with termites," Foster in a statement. "They create massive structures where a huge variety of other animals choose to live. These 'nutrient islands' attract large herbivores that preferentially graze around the termite mounds, making them less likely to burn and creating a safety zone during moderate-severity bushfires."

On the other hand, Foster notes, some animals have the opposite effect. “A lot of the things that make a plant good to eat are the things that make it hard to burn. When you take out all the nutritious, palatable plants, those left over tend to be drier and more flammable."

Grassland habitats are safest when grazed by large beasts, but alpine areas are often the opposite, Foster reports. Foster explained to IFLScience that grazing animals usually suppress fires in high productivity environments, but in places with less productivity, which usually includes alpine regions, removing the grasses “can lead to shrub or forest encroachment,” making for greater fire danger. “[Flatlands] have lots of grazing-resistant grasses, so they tend to stay as grasslands,” she said.

"It's very clear that when used strategically, and in the right ecosystems, mammals like goats and cattle can have strong fire-suppressive effects, but I've also seen many examples where they actually do the opposite and increase the risk of severe fires," Foster said.

Foster also describes a few species with more distinctive consequences. Certain Australian birds have been observed deliberately spreading fires to flush out prey, while beavers maintain ponds and wetlands that act as firebreaks, protecting areas downwind. Animals trails can prevent the spread of low-intensity fires, and astonishingly this even includes ant trails, with areas around leafcutter ants' nests less likely to be burnt than other parts of the same ecosystem. Vizcacha, rabbit-like South American creatures collect wood for their courtship displays. The areas around occupied vizcacha burrows don't tend to burn because the inhabitants keep the grasses down, but once abandoned, these sites become particularly fire-prone.

A lot more research is required to identify better ways to use animals for fire control, but Foster told IFLScience some lessons could be applied immediately. “In Australia we have a lot of ground-dwelling animals (including bandicoots, bettongs, and Malleefowl) that turn over leaf litter, mixing it with soil to make it less flammable. Many have been killed by cats and foxes and their reintroduction could bring big benefits,” she said.

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