Vent d'Autan

According to a recent study, vulnerable quokkas avoid prescribed burn areas for months, but unburned patches provide critical refuge for the displaced marsupials.

A new study published by Povh and colleagues in the International Journal of Wildland Fire has revealed how individual quokkas, a threatened marsupial species, respond to prescribed burns in the forests of southwest Australia. Researchers from Murdoch University and the Department of Biodiversity, Conservation and Attractions tracked the movements of 20 quokkas before and after controlled burning of sections of forest. They found that while quokkas can survive the low-intensity fires, they avoid burned areas for months afterwards, shifting their home ranges to unburned patches. Understanding these impacts of prescribed burning is vital for managing the habitat of this vulnerable species.

The Quokka is a small, cat-sized marsupial that is endemic, meaning it is found nowhere else in the world except southwest Australia. Unfortunately, quokka populations have declined over the years due to habitat loss, invasive predators like foxes, and disease. They are now classified as “vulnerable” on the IUCN Red List of Threatened Species.

Quokkas rely heavily on riparian vegetation, the plant life along rivers and streams, for both food and shelter. They are habitat specialists, preferring areas with dense understory in this riparian zone. Quokkas browse on shrubs and woody vegetation in these habitats. The thick vegetation also provides protection and refuge for them.

A problem for the Quokka is that thick vegetation can also be a fire hazard. Without fire, the vegetation can become a tinderbox for massive, uncontrollable fires.

Prescribed burning is commonly used in southwest Australia to reduce fuel loads and hopefully decrease the severity of intense wildfires. However, the impacts of these controlled burns on wildlife like the Quokka are not well studied or understood. The researchers wanted to understand how quokkas respond when parts of their habitat are burned since this has important implications for managing and conserving this threatened species.

Between July 2018 and September 2019, the team humanely trapped quokkas. If they were over a couple of kilograms, they were given a VHF collar with a GPS. This had to be done without anaesthetic so that the scientists could be sure that the collars wouldn’t cause problems for the animals. 

The animals were released and tracked to identify their home ranges. The scientists then looked at the quokkas’ activity on five sites southeast of Perth. One was a control site with no burn, three had prescribed burns, and one was burned after the experiment.

The good news is that the quokkas survived the burns. Of the twenty quokkas collared, eighteen survived to the end of the experiment. One died of natural causes before the burns, and one sadly was roadkill.

The tracking data revealed that quokkas avoided the burned areas for at least six months after the prescribed fires. Instead, they found new home ranges. Povh and colleagues write:

“The new home ranges established in fire-exclusion areas by quokkas in the present study were in the same habitat, with well-developed riparian vegetation structure providing refuge and forage. This result shows the species’ high fidelity to riparian ecotype with dense understorey, as previously reported.”

Povh et al. 2023

The researchers found that having unburned “fire exclusion” areas near the controlled burns was critical for quokka persistence and survival. These unburned patches provided refuge during the fire as well as habitat afterwards once quokkas moved away from the burned zones. Without these intact areas of habitat, the quokkas may have struggled to find suitable resources after being displaced by the fires. Povh and colleagues emphasise the importance of long-term support.

“Planning should consider appropriate area for the total population that is likely to use the fire-exclusion site while surrounding burned habitat regenerates. We found that quokkas did not use burned areas for at least 6 months post-burn, so fire-exclusion areas will be critical for providing refuge, foraging resources, and protec­tion from predators for at least this time period. Identifying when regrown vegetation becomes used again by quokkas was beyond the scope of the present project, but is imperative for future planning.”

Povh et al. 2023

This research has meaningful implications for wildlife conservation and habitat management in fire-prone landscapes. By tracking quokkas’ detailed response to prescribed burns, the study highlights the critical importance of unburned patches and planned fire exclusion areas. It provides valuable insights that directly inform habitat management practices to support threatened species vulnerable to fire, like the Quokka. The findings reveal that unburned areas must be strategically located close to burn sites and contain the necessary resources to shelter displaced wildlife. The researchers emphasise that ongoing monitoring of fire exclusions is needed to evaluate their effectiveness and adapt plans accordingly.

Finally, this research establishes a useful model for understanding both short and long-term fire impacts using animal movement data. Povh and colleagues conclude:

This study shows the importance of mon­itoring each of these fragmented populations before and after prescribed burns, both in burn and fire-exclusion areas, to define appropriately sized and located fire-exclusion areas to ensure the persistence of populations into the future.

Povh et al. 2023

READ THE ARTICLE
Povh, L.F., Willers, N., Shephard, J.M. and Fleming, P.A. (2023) “A conservation-significant threatened mammal uses fire exclusions and shifts ranges in the presence of prescribed burning,” International Journal of Wildland Fire. Available at: https://doi.org/10.1071/wf22196.