Introduction

Native terrestrial mammal species are experiencing rapid and significant declines across the globe (Di Marco et al. 2014; Woinarskiet al. 2015; Brodie et al. 2021). In many cases, protected areas are providing the last population strongholds (Geldmann et al. 2013; Pacifici et al. 2020). However, altered fire regimes and invasive species, amongst other disturbances, continue to result in mammal decline even within protected areas (Lawes et al. 2015; McCain 2019; Rija et al. 2020; Tedeschi et al. 2022). Therefore, understanding which habitat attributes are important for mammal persistence and how disturbances, like invasive species and fire, affect mammal activity and habitat use is critical for developing effective management strategies to facilitate their persistence within protected areas (Driscoll et al. 2010; Maxwell et al.2020).
Topography and vegetation productivity are important attributes influencing terrestrial mammal occurrence and diversity (Dorph et al. 2021). Topographic variation can create heterogeneous habitats varying in microclimate and resource availability, providing habitat for mammals with diverse niches (Dormann et al. 2010). Similarly, areas with high vegetation complexity and productivity offer more food and shelter than less productive areas and support larger and more diverse mammal communities (Sukma et al. 2019). Small mammals, in particular, favour these productive habitats due to food availability—such as invertebrates, seeds, and fungi—as well as shelter from terrestrial and aerial predators (Hanser et al.2011; McCain et al. 2018; Swan et al. 2020).
Invasive mammalian predators, such as the feral cat (Felis catus ), stoat (Mustela erminea ), small Indian mongoose (Urva auropunctata ), and European red fox (Vulpes vulpes ) are major threats to native mammals globally (Doherty et al.2016; GISD 2023). These species are highly adaptable and opportunistic, and can thrive across a range of landscapes, including within large remnant forests, along edges of fragmented forests, in agricultural and urban environments, and many other ecosystems (Nichols et al.2019; Alexandre et al. 2020; Louppe et al. 2020). Activity of these predators can increase in response to prey abundance (Scroggieet al. 2018), anthropogenic features—like tracks and farms—that provide efficient movement and foraging opportunities in structurally complex environments like forests (May and Norton 1996; Colón 2020; Schwemmer et al. 2021), and time since fire (Nalliahet al. 2022; Doherty et al. 2023). Understanding how invasive predators respond to these factors can assist land managers in developing more targeted strategies to effectively mitigate their impacts (e.g., McGregor et al. 2020).
The response of mammals to fire is commonly driven by how fire alters their food and shelter resources (Morris et al. 2011; Griffiths and Brook 2014; Lees et al. 2022), rather than direct mortality (Hale et al. 2021; Shaw et al. 2021). Some small mammals, like the Trowbridge’s shrew (Sorex trowbridgii ) in North America, decline after fire in response to a loss of food or an increased predation risk (Greenberg et al. 2007; Culhane et al.2022), while other more generalist species, like the cliff chipmunk (Tamias dorsalis ), can be largely unaffected by fire (Morandiniet al. 2023). The abundance of large herbivores, such as the red-flanked duiker (Cephalophus rufilatus ) in Cameroon, can increase in recently burnt areas, as the regenerating vegetation is typically more palatable (Klop et al. 2007; Reid et al.2023). Fire can also create preferable hunting habitat for meso- and apex predators, such as the coyote (Canis latrans ) and Florida panther (Puma concolor coryi ) in the U.S.A, which benefit from the increased exposure of their prey (Dees et al. 2001; Cherryet al. 2017).
Fire-driven changes in predator-prey interactions are especially likely to be detrimental to native fauna when they benefit invasive mammalian predators (Geary et al. 2020; Doherty et al. 2022). Fire can increase the activity invasive predators, such as feral cats (hereafter ‘cat’) and European red foxes (hereafter ‘fox’), by removing vegetation which normally provides prey with refuge (McGregor et al. 2015; Leahy et al. 2016; Hradsky 2020; Miritis et al.2023). Climate change is increasing the occurrence of fire in many parts of the world (Canadell et al., 2021; van Oldenborgh et al., 2020; Jones et al. 2022) and may facilitate range expansions for both cats and foxes (Aguilar et al. 2015; Elmhagen et al. 2017), thus increasing the likelihood of negative impacts on native fauna. This highlights the need for well-informed management strategies that account for the effects of fire, vegetation, and anthropogenic features on the activity of cats, foxes, and native mammals, so the effectiveness of protected areas for conservation can be optimised.
Australia serves as one of the most prominent global examples where the potential for the interaction between fire and invasive predators carries a great risk for native mammals (Doherty et al. 2023). Since European colonisation, many overlapping threats have contributed towards the decline of Australia’s mammal community (Woinarski et al. 2019a; Ashman et al. 2021; Legge et al. 2023). The cat and fox have played a particularly damaging role, contributing to the extinction of >25 mammal species and killing an estimated 556 million native mammals each year (Kearney et al.2019; Woinarski et al. 2019b; Stobo-Wilson et al. 2022). Not all studies have found that cat and fox activity increases after fire (e.g., Hradsky et al. 2017b; Bliege Bird et al. 2018; Lothian et al. 2022), and a quantitative review found that—should this phenomenon be observed—it was most likely to occur shortly after fire (e.g., weeks to months; Doherty et al . 2023). This indicates that there may be a critical period immediately post-fire when prey is most vulnerable to an elevated risk of predation, although Doherty et al. (2023) emphasised that further studies that begin sampling shortly after fire (i.e., <1 month) are necessary to better understand the generality of this response.
In this study, we tested whether the activity of cats, foxes, and the native mammal community could be predicted by fire, vegetation, topography, and proximity to anthropogenic features within a high-value conservation reserve. We used camera traps to quantify mammal activity across 30 sites, both before and immediately after a prescribed burn at burnt and unburnt sites. We fitted generalised linear mixed models to test the following predictions:
  1. Cats and foxes will be more active at sites burnt by the prescribed fire (McGregor et al. 2016b; Hradsky et al. 2017a), near anthropogenic features (Hradsky et al. 2017c; Schwemmeret al. 2021), and where mammalian prey activity is higher (Geary et al. 2022).
  2. The macropod community (large herbivorous marsupials) will show increased activity in areas burnt by the prescribed fire, due to the availability of regenerating vegetation preferred for grazing (Klopet al. 2007; Reid et al. 2023).
  3. The activity of the small mammal (<2 kg) community will be negatively influenced by the prescribed fire due to fewer resources and an increased predation risk and be positively influenced in riparian and highly productive areas (Lawes et al. 2015; Swanet al. 2015; Mariani et al. 2022).