Predation in Australian tropical savannas: a missing piece in the ‘mesopredator release’ puzzle

Extensive research has explored whether the removal of apex predators leads to a ‘release’ of smaller, mid-level predators, with subsequent effects to prey species, formalised as the ‘mesopredator release’ (MPR) theory. The MPR theory has been widely applied as both: (1) a theoretical framework to explain the cascading ecological impacts caused by the loss of apex predators; and (2) a practical foundation for management that leverages the ecological role of apex predators for conservation and economic outcomes. Two introduced mesopredators – the cat (Felis catus) and red fox (Vulpes vulpes) – have had catastrophic impacts across Australia, causing widespread decline and extinction of native fauna. There has been much attention on harnessing the potential suppressive role of Australia’s apex predator, the dingo (Canis familiaris), on invasive mesopredators, to benefit native fauna. However, there is ongoing debate surrounding the potential conservation benefits of dingoes. Here, we reiterate the complexities of understanding the ecological role of apex predators, and how such complexity has often been compounded by study design limitations. Consequently, the equivocal evidence base regarding the suppressive role of dingoes is not necessarily surprising. While inferentially robust studies have demonstrated evidence against the suppressive role of dingoes on mesopredators, such studies remain rare and representative of a select few habitat types. Hence, expanding the breadth of ecological settings in which robust MPR research is conducted would significantly progress our understanding of how predators function in Australian ecosystems. Given (1) their reasonably intact state, (2) the ongoing impact of cats on native species, and (3) the absence of the red fox, we propose that the tropical savannas of northern Australia represent a useful opportunity to progress our understanding of the ecological role of dingoes. We advocate for experimentally manipulative research where possible and appropriate, supported by a broader correlative research program that capitalises on large-scale variation in cat density and habitat degradation. Such research would not only address key knowledge gaps currently hindering management efforts to conserve native species across northern Australia but progress our understanding of the generality of the MPR theory, and its applicability for conservation.