Laying low: Rugged lowland rainforest preferred by feral cats in the Australian Wet Tropics.

Invasive mesopredators, particularly feral cats, are responsible for the decline of many species of native mammals worldwide. In Australia, there is currently limited understanding of the drivers of feral cat occupancy in tropical rainforests, the most biodiverse ecosystem in the continent. We carried out camera-trapping surveys at 108 sites across eight study sites. Camera-trap pairs were placed at 2.2km intervals along roads, with one camera-trap facing the road and another 50m into the forest to ensure that individuals who prefer or avoid roads could be detected. Single-species occupancy analysis was implemented to investigate how environmental factors influence feral cat distribution in the Australian Wet Tropics. There were 524 independent feral cat detections, 11 times higher than previously recorded in the Australian Wet Tropics. The main environmental factors influencing feral cat distribution were a positive association with terrain ruggedness, a negative association with elevation, and a higher affinity for rainforest than eucalypt forest. These findings were congruent with global studies on feral cat ecology but disagreed with similar surveys within Australia. Understory complexity is reduced in rugged terrain, which could improve feral cats’ hunting efficiency, while increasingly harsh and consistently wet weather conditions at higher elevations drive their preference for lowland rainforest. Feral cats were heavily associated with roads, supporting the theory that roads facilitate access and proliferation of feral cats within more remote parts of the rainforest. Higher elevation rainforest with no roads could act as refugia for native prey species within the critical weight range. Regular monitoring of existing roads should be implemented to monitor feral cats, and new linear infrastructure should be limited to prevent encroachment into these areas. This is pertinent as climate change modelling suggests that habitats at higher elevations will become similar to lower elevations, potentially making the environment more suitable for feral cat populations.