Not all predators are equal: a continent-scale analysis of the effects of predator control on Australian mammals

Introduced predators pose threats to biodiversity and are implicated in the extinction of many native species. In Australia, considerable effort is spent controlling populations of introduced predators, including the dingo Canis dingo and the red fox Vulpes vulpes, to reduce their effects on native species and livestock. Studies describe different outcomes of controlling dingo and fox populations on native species, making biodiversity management decisions difficult for conservation managers. We conduct a meta-analysis to compare the impacts that control programmes targeted towards dingoes and foxes in Australia have on introduced predators and on other mammal species, including native species and prey species. Our results provide evidence that lethal control of dingoes and foxes has different outcomes for different mammalian species. Dingo removal had a negative effect on the abundance of native mammals weighing less than the critical weight range (CWR) of 30-5500g, and a positive effect on the abundance of mammals above the CWR. Fox abundance increased in response to dingo control, but confidence intervals were large. Fox removal had strong positive effects on ground-dwelling and arboreal mammals. Lethal control of dingoes did not have a significant effect on cats, but where dingoes were removed there was a tendency for foxes to increase, and where foxes were removed there was a tendency for cats to increase. Our results highlight unintended and perverse outcomes of lethal predator control on Australian mammals. Lethal control of dingoes significantly increases abundances of above CWR mammals and significantly decreases abundances of under CWR mammals. Lethal control of foxes significantly increases the abundances of CWR mammals. These findings show how removing dingoes and foxes alters mammal assemblages and provide comprehensive and objective information for conservation managers. We recommend that land management agencies take the results of this study into consideration when planning lethal control programmes targeting dingoes and foxes because, depending on the target canid, these programmes result in different outcomes for other mammal species. Removal programmes targeting dingoes and/or foxes can result in increased abundances of introduced predators and, ultimately, have far-reaching effects on many mammal species.