Feral cat management key to saving threatened species: Deakin ecologist

Dr Tim Doherty, a Research Fellow in Deakin's Centre for Integrative Ecology within the School of Life and Environmental Sciences, said Australia suffered some of the worst impacts of feral cats, the primary driver of the nation's mammal declines and extinctions.

In his new research paper: Impacts and management of feral cats Felis catus in Australia, published in Mammal Review today, Dr Doherty outlines the far-reaching impacts of the invasive species and lays out priorities for their management.

Dr Doherty said feral cats dined out on at least 400 of Australia's vertebrate species and many invertebrates, but their damage wasn’t just confined to predation.

"Right now the critically endangered woylie (a small marsupial), mountain pygmy possum, kangaroo island dunnart, central rock rat and western ground parrot are all facing imminent extinction thanks to feral cats and other threats," he said.

"The worst hit areas are up around northern Australia, and in arid desert areas where species have less protection from predators.

"Feral cats are preying on some of our most at risk species here in Australia, but they can also cause harm through disease transmission and competition with natives for habitat and food.

"They can have socio-economic impacts as well, mostly as disease vectors, transmitting infectious pathogens that can affect agricultural production and human health, with 36 pathogens or diseases so far recorded from Australian feral cats.

"Animal extinctions also lead to an overall decrease in biodiversity, upsetting important ecological processes. For example, the loss of digging mammals (a favourite prey for feral cats) can lead to an increase in leaf litter accumulation and hence fire risk."

But Dr Doherty said controlling feral cats was challenging and eradication from mainland Australia was currently impossible.

He said poison baiting programs that commonly target foxes have been less successful for cats because cats have a preference for live prey.

Dr Doherty said management programs had to be tailored to local conditions and draw on both lethal and non-lethal approaches.

"Priorities for future research and management are to prevent further extinctions, test new management tools, trial options for control via ecosystem management, and increase the potential for native fauna to coexist with feral cats," he said.

"Options for managing feral cats range from eradication on islands and complete exclusion from small fenced areas, to population reduction over areas of varying size.

"Feral cat eradication is currently being attempted on Dirk Hartog and Christmas Islands, with future projects proposed for Kangaroo, French and Bruny Islands."

One out of the box solution Dr Doherty touches on in is using "guardian dogs", similar to the Maremmas that protected Warrnambool's little penguin colony from foxes and inspired the film Oddball.

"One possibility would be to explore whether guardian dogs could likewise reduce the impacts of feral cats by extending this model to wider ranging, solitary and nocturnal prey," he said.

Dr Doherty also stressed the importance of broader ecosystem management.

"Some options involve killing feral cats, while others focus on reducing impacts by modifying features of their environment," he said.

"Maintaining habitat through appropriate fire and grazing practices can promote ecological refuges that protect native fauna from cat predation."

The paper was a collaborative effort between researchers from Deakin University (Dr Tim Doherty and Dr Euan Ritchie), the University of Sydney (Professor Chris Dickman), the University of Tasmania (Professor Chris Johnson), the University of Queensland (Dr Sarah Legge) and Charles Darwin University (Professor John Woinarski).