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.