The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. II. A field experiment

Abstract

The hypothesis that predation by feral cats and introduced foxes reduces population sizes of small, native vertebrates was supported by results of a predator-removal experiment at Heirisson Prong, a semi-arid site in Western Australia. The methods of control used against cats and foxes to protect native mammals reintroduced to Heirisson Prong produced three broad ‘predator zones’: a low-cat and low-fox zone, where foxes were eradicated and spotlight counts of cats declined after intensive cat control; a high-cat and low-fox zone where spotlight counts of cats increased three-fold after foxes were controlled; and a zone where numbers of cats and foxes were not manipulated. Small mammals and reptiles were monitored for one year before and three years after predator control began. Captures of small mammals increased in the low-cat and low-fox zone, but where only foxes were controlled captures of small mammals declined by 80%. In the absence of cat and fox control, captures of small mammals were variable over the sampling period, lower than where both cats and foxes were controlled, yet higher than where only foxes were controlled. The capture success of reptiles did not appear to be related to changes in predator counts. This study presents the first experimental evidence from mainland Australia that feral cats can have a negative impact on populations of small mammals.

Keystone effects of an alien top-predator stem extinctions of native mammals

“…Similarly, feral cats did not, on average, respond to dingo removal. Given that both dingoes and foxes are predators of rabbits and cats, it is plausible that interactions with both dingoes and foxes could have influenced their abundances (Newsome et al 1989;Risbey et al 2000). Another alternative is that rabbit and cat populations may be determined by other factors such as the availability of food resources and recent rainfall events more than by the presence of dingoes (Letnic et al in press).…”

Predator-baiting experiments for the conservation of rock-wallabies in Western Australia: a 25-year review with recent advances

“…Basically, the input into the box is 'lay baits', and the output is 'more prey'. Critical questions remain unanswered principally because exotic predatormarsupial relationships are cryptic predator -prey systems that remain immeasurable without access to appropriate remotesensing electronic aids (Molsher et al 1999;Risbey et al 2000). Recent developments have made this goal feasible, and we conclude the present paper by describing some enabling technology that is now available for field trials.…”

“…In 1982, they launched a predator-baiting experiment that was designed to test the hypothesis that red fox predation was limiting population growth of five endangered RW populations living on isolated rocky outcrops in the WA Wheatbelt. The red fox has long been considered an important limiting factor on Australian vertebrates (Hoy 1923;Wood Jones 1923-1925Finlayson 1961;Christensen 1980;King et al 1981;Copley 1983;Newsome et al 1989;Friend 1990;Risbey et al 2000;Short et al 2002).…”

Annual variation in prey composition of domestic cats in rural and urban environment

“…In terms of overall proportions, they have been estimated to kill 2-7% of all birds in southern Canada (Blancher 2013) and to be responsible for at least 30% of sparrow deaths in an English village (Churcher and Lawton 1987). Introduced cats are responsible for the decline of native mammals in Australia (Risbey et al 2000;Wheeler and Priddel 2009;Moseby et al 2009;Frank et al 2014), and several island studies have documented strong negative effects by cats on local endemic fauna (e.g., Fitzgerald and Veitch 1985;Medina and Nogales 2009;Bonnaud et al 2012). These examples show, without a doubt, that both feral and free-ranging house cats should be considered a serious threat to biodiversity.…”