Influence of landscape structure on invasive predators: feral cats and red foxes in the brigalow landscapes, Queensland, Australia

Abstract

Context Invasive mammalian predators are often associated with fragmented landscapes, and can compound the impacts of habitat loss and fragmentation on native fauna. Knowledge of how invasive predators are influenced by different landscape structures can assist in the mitigation of their impacts. Aims The aim of the present study was to investigate the influence of landscape structure and site-scale habitat attributes on the frequency of feral-cat and red-fox detections in fragmented agricultural landscapes. Methods Field surveys of the frequency of red-fox and feral-cat visitation at a site scale were stratified for six different habitat types in six study subregions. The habitat types were large remnant patch interior, large remnant patch edge, small remnant patch, roadside verge, regrowth patch and open agricultural land adjacent to a remnant patch. Sites were centred in a 1-km buffer area from which landscape composition and configuration were calculated. We applied a generalised linear model and an information-theoretic approach to determine the effect size and importance and rank of the explanatory variables on red-fox, feral-cat and pooled cat and fox detection rates. Key results The most important factors influencing detection rates had a positive effect and included: the dominance of cropping in the landscape (cat, fox, pooled cat and fox); and the density of vegetation at a site scale (fox, pooled cat and fox). The number of native habitat patches was also an important factor in the models of red foxes and pooled invasive predators. Conclusion Spatially heterogeneous cropping landscapes incur higher rates of invasive-predator detections than do intact native-woodland and pasture landscapes at the 1-km scale. At a site scale, elevated invasive-predator detections occurred at sites with dense vegetation, characteristic of narrow woodland and the edges of large woodland patches. Implications The research findings highlight that vertebrate pest management needs to target highly fragmented agricultural landscapes that are more likely to have elevated levels of invasive-predator activity. Landscape restoration efforts need to consider the redesign of landscapes to make them less suitable for predators and more hospitable for native wildlife.