Predation by cats and European red foxesPredation by cats and European red foxes

Predation by cats and European red foxes

Feral predators can have rapid and catastrophic impacts on populations of threatened rodents (Tuft et al. 2021). While there is limited direct evidence of the consumption of Pookila by feral predators (records in dog scats; Hoskins 1997; Davis et al. 2015; Lock & Wilson 2017; MidCoast Council NSW 2024. pers comm 13 February), it is recognised in the Threat Abatement Plan for Predation by Feral Cats 2024 that the Pookila is likely highly susceptible to predation by cats (and/or in some cases by foxes) (DCCEEW 2024a) and that cats and foxes can significantly impact population numbers (Seebeck et al. 2003; Burns 2019a).

Like many other Pseudomys species, Pookila are docile and display poor awareness of exotic predators (P. Burns, pers. obs.). In such species, selective predation can occur (as reported, for example, on the broad-toothed rat, Mastacomys fuscus; Green 2002), leading to a disproportionate impact of predation on the vulnerable species even when co-occurring species (for example, the house mouse) are at greater abundance. Furthermore, communal burrowing and small local population densities mean that predation events at burrow entrances can cause rapid local declines (Burns 2019a).

The relative impact of predation by feral cats and foxes on the Pookila is not yet understood. Based on factors such as small body size, lower breeding output, and occupation of open habitat, some researchers have identified the Pookila as having a high threat rating from feral cat predation (Dickman 1996; Stobo-Wilson et al. 2021). Radford et al. (2018) reported the cat and fox threat to Pookila to be approximately the same based on expert opinion, although with weak evidence. While foxes are currently absent from the Tas mainland and Flinders Island (DNRE Tas 2022), and fox control is in place in other parts of the species’ range, effective cat control in open, non-insular systems beyond the local scale is not yet possible and potentially counterproductive (Lazenby et al. 2015; Lazenby et al. 2021; see Predator management).

The density and predatory impact of cats and foxes can be altered by competitive interactions with other predators. For example, reduced numbers of foxes via fox control can increase cat density, alter cat behaviour, and ultimately increase the impact of predation by feral cats (Risbey et al. 2000; Rees et al. 2023). Tasmanian devils have been shown to alter the behaviour and abundance of feral cats (Hollings et al. 2014; Lazenby & Dickman 2013), and cats have a much higher predatory impact on small mammals compared to devils (Hollings et al. 2014). The decline of devils caused by Devil Facial Tumour Disease (DFTD) is likely to have increased the predatory impacts of feral cats in Pookila habitat on the Tas mainland.