Mesopredator Management: Effects of Red Fox Control on the Abundance, Diet and Use of Space by Feral Cats

Abstract

Apex predators are subject to lethal control in many parts of the world to minimize their impacts on human industries and livelihoods. Diverse communities of smaller predators—mesopredators—often remain after apex predator removal. Despite concern that these mesopredators may be 'released' in the absence of the apex predator and exert negative effects on each other and on co-occurring prey, these interactions have been little studied. Here, we investigate the potential effects of competition and intraguild predation between red foxes (Vulpes vulpes) and feral cats (Felis catus) in south-eastern Australia where the apex predator, the dingo (Canis dingo), has been extirpated by humans. We predicted that the larger fox would dominate the cat in encounters, and used a fox-removal experiment to assess whether foxes affect cat abundance, diet, home-range and habitat use. Our results provide little indication that intraguild predation occurred or that cats responded numerically to the fox removal, but suggest that the fox affects some aspects of cat resource use. In particular, where foxes were removed cats increased their consumption of invertebrates and carrion, decreased their home range size and foraged more in open habitats. Fox control takes place over large areas of Australia to protect threatened native species and agricultural interests. Our results suggest that fox control programmes could lead to changes in the way that cats interact with co-occurring prey, and that some prey may become more vulnerable to cat predation in open habitats after foxes have been removed. Moreover, with intensive and more sustained fox control it is possible that cats could respond numerically and alter their behaviour in different ways to those documented herein. Such outcomes need to be considered when estimating the indirect impacts of fox control. We conclude that novel approaches are urgently required to control invasive mesopredators at the same time, especially in areas where apex predators are absent.

The diet of the feral cat (Felis catus), red fox (Vulpes vulpes) and dog (Canis familiaris) over a three-year period at Witchelina Reserve, in arid South Australia

“…This study represents another contribution to an increasingly comprehensive set of detailed assessments of the diet of introduced mammalian predators in Australia (Dickman et al 2014;Doherty 2015;Doherty et al 2015;Kutt 2011;Kutt 2012;Molsher et al 2017;Paltridge 2002;Pavey et al 2008;Read and Bowen 2001;Yip et al 2014), all demonstrating substantial levels of predation on many native species. The main results of this study are largely consistent with this body of previous studies: foxes and cats take a very broad range of vertebrate and invertebrate prey; the diets of both species show substantial flexibility as some prey items change in abundance seasonally (or in response to management and other factors); there is a high dietary overlap between cats and foxes, but cats tend to take a higher proportion of birds and reptiles than do foxes; for all three predator species (but especially so for dogs), rabbits may comprise a high proportion of the diet; and cats tend to take smaller mammalian prey than do foxes and dogs.…”

Incorporating disturbance into trophic ecology: Fire history shapes mesopredator suppression by an apex predator

“…Feral cats are also major predators of rodents and other small mammals in Australia . We did not record feral cats frequently enough to analyse their relationships with fire, dingoes and foxes, but these relationships are likely to be complex given evidence that cats are known to be drawn to recently burned areas and to avoid both dingoes (Brook et al, 2012) and foxes (Molsher, Newsome, Newsome, & Dickman, 2017). If foxes suppress cats to a greater extent than dingoes, then it is possible that cats at times benefit from the suppression of foxes by dingoes.…”

Evaluation of camera placement for detection of free‐ranging carnivores; implications for assessing population changes

“…In Australia, feral cats Felis catus and red foxes Vulpes vulpes have contributed to declines in many native bird and reptile populations (Doherty et al, 2016), and together have been implicated in most of the thirty mammal extinctions that have occurred since European settlement (Woinarski, Burbidge, & Harrison, 2015). This has triggered the development of various management approaches aimed at mitigating their impacts, such as predator free fencing (Legge et al, 2018), translocation to predator free islands (Abbott, 2000), guardian animals (van Bommel, 2010;van Bommel & Johnson, 2012) and lethal control (Doherty & Ritchie 2017;Doherty, Driscoll, Nimmo, Ritchie, & Spencer, 2019;Hunter, Lagisz, Leo, Nakagawa, & Letnic, 2018;Molsher, Newsome, Newsome, & Dickman, 2017). Each of these management approaches vary considerably in cost, spatial extent and effectiveness.…”