John Woinarski¹, Sarah Legge^2,6, Chris Dickman³, Hugh McGregor⁴, Bronwyn Hradsky⁵, Tida Nou⁶

¹Charles Darwin University, ²The Australian National University, ³The University of Sydney, ⁴The University of Tasmania, ⁵The University of Melbourne, ⁶The University of Queensland

The 2019-20 bushfires have been extensive and—in some areas—-of very high severity. Many threatened species have had most of their distributions burnt, and the fires are likely to have imperilled many species not previously considered threatened. One of the post-fire challenges to population recovery that many native species will face is increased risk of predation, including by introduced foxes and cats. Researchers from the National Environmental Science Program’s Threatened Species Recovery Hub have been examining interactions between fire and predation by cats and foxes, and options for management in these complex and challenging circumstances.

Many cats and foxes will, like many native animals, have been killed in the extensive and severe wildfires. However, the cats and foxes that survive will compound the toll taken by fire on native wildlife. This is because fire will have removed much of the shelter (e.g., shrubs, grass cover, hollow logs) that was previously available for many native animals, rendering cats and foxes much more efficient predators. Both cats and foxes are generalist predators, able to survive on whatever prey has made it through the fire, and also able to scavenge off dead animals (although cats prefer not to). Finally, they are both able to move large distances to capitalise on wherever prey has survived and can be hunted.

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Image: Camera trap image of a fox prowling a burnt area in the Otway Ranges, Victoria. Credit: Bronwyn Hradsky.

Reducing cat and fox densities across intensely burnt landscapes may help the native animals that survive in those areas. This could potentially be achieved with broadscale poison-baiting programs. Even cats, which normally avoid taking poison baits, may be more likely to consume baits after fire, if they are hungry due to a lack of prey. However, if cats do not take the baits, the removal of foxes is likely to advantage cats, and neutralise any benefit from fox reduction. In addition, it is unclear how much fox and cat density would need to be reduced, and for how long, after such a fire event to achieve measurable outcomes for native species. It is unclear also whether native species such as dingoes or goannas will be more likely to take the baits if their other food sources have become scarce post-fire. Monitoring these varied outcomes of feral predator control following the 2019-20 fires presents an opportunity to fill these knowledge gaps.

Alternatively, strategic, intensive fox and cat control carried out at specific locations will be critical for protecting key populations of native species that have been badly fire-affected. Strategic locations could include places where threatened species are known to have persisted through the fire, perhaps because the fire intensity at that location happened to be lower, or because the location acts as a fire-protected refuge, such as a rocky area (e.g., Brush-tailed Rock wallabies, Mt Kaputar Rock Skink).

Priority strategic locations include the unburnt patches in an otherwise burnt landscape, which may contain most of the post-fire survivors of some species. Finding these patches as quickly as possible, and then protecting the inhabitants of these patches from predation by cats and foxes (as well as other threats) is a critical action for supporting post-fire recovery, because cats and foxes are likely to concentrate on unburnt patches once they have exhausted their hunting opportunities in the burnt landscape. Some unburnt patches could be quite small, supporting only low numbers of any one species, and those numbers could quickly be reduced to zero by just a handful of predators.

There is a range of options for undertaking strategic control, including intensive shooting and trapping, and localised poison-baiting (including the use of Felixer traps). Not all options involve killing cats and foxes. For example, constructing artificial shelters may help some species evade capture from predators, and excluding predators from remnant populations of native species with
predator-proof fencing is also possible, as has been done recently to protect surviving Kangaroo Island dunnarts.

As many cats and foxes will have been killed by these fires, there is an opportunity, if post-fire pest control is strategic and maintained, to achieve meaningful reductions in the numbers and impacts of introduced predators in our environment, at least at strategic sites if not in the landscape more broadly.

Kangaroo Island in late February 2020, six weeks after the fires. All of the vegetative cover has burnt leaving native spe-cies with no shelter from predators. Credit: Nicolas Rakotopare.

There is an immense outpouring of community willingness and intent to support the recovery of wildlife following the bushfires. Many different groups including private land managers will be involved in the recovery process. Outcomes will be maximised when actions are collaborative, well-coordinated and strategic. Developing a post-fire recovery plan which identifies management options and recovery priorities, and stakeholder responsibilities and resourcing is a valuable process. It will also help to ensure precious resources are best used and important actions are not missed.

Along with other concerned conservation biologists, researchers from the Threatened Species Recovery Hub have developed a ‘blueprint’ for management responses to the 2019-20 fires. It is hoped that the blueprint will provide valuable evidence-based guidance to a wide range of individual agencies, conservation NGOs and other groups. You can find it here: Chris Dickman, Don Driscoll, Stephen Garnett, David Keith, Sarah Legge, David Lindenmayer, Martine Maron, April Reside, Euan Ritchie, James Watson, Brendan Wintle, John Woinarski (2020) After the catastrophe: a blueprint for a conservation response to large-scale ecological disaster, Threatened Species Recovery Hub, January 2020.

For further information, contact the Threatened Species Recovery Hub here.

Read more from the March 2020 ESA Bulletin.