Solving the feral cat problem: AWC submission to parliament

AWC is a national leader in the establishment of feral cat-free areas, with a total of eight fenced areas and one entire island supporting populations of 15 nationally-threatened mammals.

We undertake extensive research on the ecology of feral cats, with a view to better controlling them in the broader landscape; and we are currently collaborating on work to develop gene drives for feral cat control.

Recently our Chief Science Officer, Dr John Kanowski, shared AWC’s knowledge, experience and scientific findings in a formal submission to the House of Representatives Standing Committee on the Environment and Energy, as part of the Inquiry into the problem of feral and domestic cats in Australia.

Summary of key points

• Feral cats occur throughout the Australian mainland and on many islands.
• Feral cats are a major and ongoing threat to Australian wildlife, being the primary driver of extinction for Australian mammals.
• At present, there are no methods of direct control that can effectively, reliably and permanently eradicate feral cats from the Australian mainland or large islands, sufficient to restore threatened species.
• Conservation fences are a proven effective means of permanently excluding feral cats, when properly designed and maintained, allowing the conservation and reintroduction of native wildlife.
• AWC is the leading proponent of the establishment of feral cat-free areas in Australia, with a total of 8 fenced areas (and one island in its entirety) supporting populations of a total of 15 threatened mammal species. AWC is continuing to expand our network of fenced areas and the species protected by them. We have demonstrated the outstanding success arising from this network, with ongoing exclusion of feral cats (and other pests) and consequent recovery of many threatened species.
• Secure populations of threatened species established in fenced areas have the potential to seed releases to the broader landscape, provided feral cats can be effectively controlled outside the fence.
• Gene drive technology has the potential for continental-scale control of feral cats, but long-term research is required to develop and deploy gene drives safely and effectively.

Recommendations

The value of conservation fencing in effectively controlling feral cats and facilitating the recovery of threatened species should be recognised in the Commonwealth’s Threatened Species Strategy, in Recovery Plans, in State Government regulations, and in the design and funding of specific conservation programs.

The network of conservation fences (and feral cat-free islands) should expand so that there are multiple secure populations of all species currently threatened by introduced predators.

Investment in developing more effective methods for the control of feral cats, and in potential long-term solutions such as gene drive, should increase, with the aim of safely returning threatened species to the broader landscape over the medium-long term.

The impact of feral and domestic cats including on native wildlife and habitats 

Cats are the primary cause of mammal extinctions in Australia and a leading threat to remaining mammals (Smith and Quin 1996; Burbidge and Manly 2002; Woinarski et al. 2011, 2014; Fisher et al. 2014; Ziembicki et al. 2015; Doherty et al. 2017). Cats are particularly serious predators of small- to medium-sized mammals (native rodents, dasyurids, bandicoots and bettongs); nevertheless, mammals up to the size of small wallabies (~4 kg) are readily taken, as are juveniles of larger species (e.g., Abbott et al. 2014; Fancourt 2015). 

Cats also prey heavily on rabbits and mice, where present: these introduced species can maintain cat densities at high levels, increasing rates of predation on native species (Smith and Quin 1996; Denny and Dickman 2010). We note also that there is no compelling evidence that feral cats can effectively reduce the population size of pest species such as rabbits and house mice at a landscape scale. 

Although mammals are favoured prey of cats, a wide range of prey including birds, lizards, frogs and insects are taken (Denny and Dickman 2010; Doherty et al. 2015; Woinarski et al. 2017, 2018; Murphy et al. 2019; Woinarski et al. 2020). 

Evidence shows that each feral cat typically kills numerous animals in a single night. Estimated consumption rates, based on inspection of the stomach contents of cats, are five to 35 animals killed per night (Read and Bowen 2001; Kutt 2012). Video footage collected on AWC sanctuaries in the Kimberley have shown that, on average, feral cats prey on seven native animals per 24 hours (McGregor et al. 2015). Based on the estimated population size of feral cats in Australia (Legge et al. 2017), it is calculated that feral cats kill over 1 billion native animals each year (approximately 460 million native mammals, 270 million birds, 466 million reptiles, and 92 million frogs: Woinarski et al. 2017, 2018; Murphy et al. 2019; Woinarski et al. 2020). 

Feral cats are a major and ongoing threat to conservation of Australian wildlife, with estimated kill rates noted to be “substantially higher than … land clearing” (Murphy et al. 2019). The impacts are particularly severe for small- to medium-sized native mammals, of which 89 species are (or were) considered to be ‘extremely’ or ‘highly’ vulnerable to cat predation; in fact, 26 of these species are now extinct (Radford et al. 2018). 

Primarily as a result of predation by feral cats (and foxes, in southern Australia), vast tracts of the continent have lost most of their small- to medium-sized mammal fauna. This has consequences, not only for the conservation of the affected species, but for ecosystem processes. Australian ecosystems have evolved in the presence of a diverse assemblage of small- to medium-sized mammals, which participate in a number of important ecological processes including herbivory, seed and spore dispersal, soil engineering and predation (e.g., Eldridge and James 2009; Fleming et al. 2014). For this reason, effective conservation in Australia means more than converting tenure to the protected area estate – it means active management of feral cats and other introduced species, the restoration of ecologically-appropriate fire regimes, and – where feasible – the reintroduction and recovery to former abundance of regionally-extinct species.