The feral catastrophe

By Dr John Kanowski, AWC Chief Science Officer

Australia has been an island for tens of millions of years. As a result, our country supports globally distinctive biota. The arrival of people at least 50,000 years ago resulted in substantial changes to the ecology of the continent; however, over time, a human-natural order was established, and a multitude of native species flourished.

The arrival of Europeans and other settlers in the last few centuries has resulted in a profound set of changes to the prevailing order, through the dispossession of the Traditional Owners, the conversion of native ecosystems to agriculture or their modification through pastoralism, and the introduction of species from other parts of the world.

Two of the most destructive introductions were the cat and fox. Cats arrived with the First Fleet and within a century had spread across the entire continent and most large islands. The fox was introduced 150 years ago; it spread throughout southern and central Australia, and to many islands. Both species are highly effective predators of native vertebrates. They are the primary cause of extinctions of native mammals, and of their continuing decline, and a major cause of decline of other vertebrate groups. Cat predation alone is a factor in the decline of 85% of Australia’s threatened mammals, over 50% of Australia’s threatened birds and reptiles, and 40% of Australia’s threatened frogs.

“With well over 2 million feral cats roaming every corner of Australia’s mainland, and with every cat predicted to kill over 1,000 animals each year, this adept predator continues to be an unrelenting ecological threat to native Australian fauna.  Feral cats know no boundaries and they need to be managed over large areas and across landscapes. Effective, resource-efficient and humane management, like that carried out by Australian Wildlife Conservancy (AWC), is critical in tackling this pervasive problem.”

Susan Hunt AM PSM, Chair, WA Feral Cat Working Group and AWC supporter

AWC

Recent papers have estimated that feral cats and foxes kill around 1.5 billion native vertebrate animals a year in Australia, with another 250 million native animals killed by domestic cats. This is higher than the number of animals killed annually by land clearing, or by the 2019–20 ‘megafires’ in south-east Australia. The ‘average’ feral cat is reported to eat over 600 native vertebrate animals a year, as well as a large number of insects.

WHAT IS AWC DOING?

For more than 30 years, AWC has been leading efforts to conserve native wildlife threatened by feral cats and foxes.

Safe havens

AWC has established the largest network of fenced feral predator-free areas on mainland Australia – which, together with a fenced area on Kangaroo Island, and the entirety of Faure Island in Shark Bay, Western Australia – comprise 10 cat- and fox-free sites, with a total area of just under 50,000 hectares.

We have reintroduced a total of 23 locally extinct mammal species (including 19 nationally threatened species) to these feral predator-free areas, increasing the number of secure populations and their global population size. These reintroductions have ensured species are exposed to selective pressures across the extent of their range (in particular, returning species to semi-arid environments), and have helped restore ecological processes at reintroduction sites. The establishment of feral predator-free areas also benefits populations of resident animals, especially terrestrial mammals, ground-active birds such as Malleefowl, and larger reptiles such as the Great Desert Skink, which are preyed-upon by cats and foxes.

AWC

‘Outside the fence’ projects

In the last few years, we have increased efforts to establish populations of native mammals susceptible to cats and foxes outside fenced areas. While this has long been part of AWC’s practice, technological developments – such as cat-baits, grooming traps and canid pest-ejectors – have improved our capacity to suppress densities of feral predators to levels where some vulnerable native mammals can persist. ‘Outside the fence’ reintroductions are currently active at Mt Gibson, Western Australia. Here, we have successfully re-established populations of the Brushtail Possum and Chuditch (Western Quoll) in a circa 70,000-hectare predator-suppression area, and will attempt releases of the more predator-susceptible Woylie in 2024. The project is underpinned by a research program looking at: the response of cats and foxes to baiting; the survival, movements and habitat preferences of reintroduced mammals; and behaviours associated with the survival or mortality of reintroduced mammals.

Garry Mason/AWC

Landscape-scale management

In northern Australia, AWC’s fire management program – delivered over more than 7.5 million hectares – coupled with the ongoing control of feral herbivores, helps to reduce the intensity of cat predation over the vast areas of savannas and spinifex ecosystems we manage alone and with our partners in the Kimberley, Northern Territory and North Queensland. Research by AWC and collaborators has shown that cats prefer to hunt in open habitats, such as areas burnt by wildfire or grazed heavily by cattle. Our land management aims to maintain areas of dense ground cover to provide refuge for cat-susceptible species across the sanctuaries we manage.

SILVER BULLETS?

AWC continues to engage with researchers investigating the potential of ‘synthetic biology’ (gene-drives and related methods) to create continental-scale, humane and safe methods of feral predator control. Although this is a rapidly growing field of science, boosted (like many) by recent advances in Artificial Intelligence and machine learning, realistically we are still decades away from a technical, socially acceptable ‘silver bullet’ type of solution.

AWC

GOING FORWARD

For the foreseeable future, it is critical that AWC continues to implement its existing, proven methods of conserving threatened native animals, through establishing and maintaining feral predator-free areas, progressing work on ‘outside the fence’ reintroductions (coupled with improved methods of feral predator control), and landscape-scale management of fire and feral herbivores in northern and central Australia.

Beyond our own sanctuaries, AWC is contributing to the development of sensible, national- and state-level policy on the control of feral predators, for example, recently making a submission to a review of the Federal Government’s Feral Cat Threat Abatement Plan.

AWC also regularly engages with state governments, conservation groups, Indigenous organisations and private individuals interested in establishing feral predator-free safe havens, providing advice based on our experience on a pro-bono or ‘fee for service’ arrangement, depending on the means of the other party. We anticipate ongoing development of safe havens by this range of groups, and aim to improve conservation outcomes across Australia, regardless of tenure.

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