Occupancy of the Invasive Feral Cat Varies with Habitat Complexity

Abstract

The domestic cat (Felis catus) is an invasive exotic in many locations around the world and is thought to be a key factor driving recent mammal declines across northern Australia. Many mammal species native to this region now persist only in areas with high topographic complexity, provided by features such as gorges or escarpments. Do mammals persist in these habitats because cats occupy them less, or despite high cat occupancy? We show that occupancy of feral cats was lower in mammal-rich habitats of high topographic complexity. These results support the idea that predation pressure by feral cats is a factor contributing to the collapse of mammal communities across northern Australia. Managing impacts of feral cats is a global conservation challenge. Conservation actions such as choosing sites for small mammal reintroductions may be more successful if variation in cat occupancy with landscape features is taken into account.

Habitat as a mediator of mesopredator‐driven mammal extinction

“…A similar pattern was observed in a region of northern Australia, where feral cat occupancy was significantly lower in topographically complex habitats than in neighboring simple habitats (Hohnen et al. ). Further, in the same region, McGregor et al.…”

Moving in complex environments: a biomechanical analysis of locomotion on inclined and narrow substrates

“…Dingoes were never observed on the rocky hills during this study, suggesting that the locomotion of dingos may be compromised in these habitats relative to open areas. Similar strategies have been shown in feral cats, which occupy open habitats more frequently than complex ones (Hohnen et al, 2016) and display better hunting success in these open habitats when compared to complex ones (McGregor et al, 2015).…”

Declines in the mammal assemblage of a rugged sandstone environment in Kakadu National Park, Northern Territory, Australia

“…This compounding interaction of two threat factors may be responsible for the decline that we report for this study area, however the incidence of cats, and change in this incidence over time, was not evaluated in our study. There is some evidence from other regions that cat densities may be lower, and/or their predation impacts may be less, in rugged areas than nearby lowland areas (Hohnen et al 2016b;Legge et al 2017). Much of the recent decline in the mammal fauna of northern Australia has occurred in relatively featureless lowland areas (Woinarski et al 2001), with the fauna of more rugged sandstone areas showing more resilience (Hohnen et al 2016a).…”

“…Far less attention has been paid to the rugged sandstone ranges that contrast sharply with the relatively featureless lowlands, although some monitoring data indicate declines of some mammal species in these environments, albeit less drastic than for lowland sites (Woinarski et al 2004(Woinarski et al , 2010. These sandstone areas support a diverse set of mammal species, many of which are endemic to them (Woinarski et al 2009); and their topographic complexity has been presumed to offer refuge from some threatening processes that may pervade the lowland environments (Freeland et al 1988;Radford et al 2014;Hohnen et al 2016b). For example, whereas vegetation change due to extensive pastoralism has been posited as a possible contributory agent for faunal change in the lowlands (Woinarski et al 2001;Woinarski and Ash 2002;Woinarski and Fisher 2003;Legge et al 2011), cattle and feral livestock generally are largely absent from more rocky and rugged areas, and hence this factor would be unlikely to be involved in any change in the fauna of the sandstone uplands.…”