A new book co-authored by a Charles Darwin University (CDU) environmental scientist has identified that pet and feral cats together are killing more than two billion mostly native reptiles, birds and mammals a year in Australia.
The book, “Cats in Australia: Companion and killer“, compiles key findings from hundreds of studies and management experience about cats across Australia.
It describes the origins, spread and ecology of cats; the impacts of feral and pet cats on Australian wildlife; the impacts of cats on human health and livestock productivity; the legal and moral context for their management; and options for managing feral and pet cats to reduce the toll they take on biodiversity.
The authors, CDU Professor John Woinarski, The Australian National University’s Professor Sarah Legge and The University of Sydney’s Professor Chris Dickman are also leaders of a major research program investigating the impacts of feral cats on Australian wildlife through the Threatened Species Recovery Hub of the Australian Government’s National Environmental Science Program.
Professor Woinarski said the book investigated one of Australia’s most complex and controversial conservation management dilemmas: what to do when a loved one turns bad?
“Cats tamed humans about 4000 years ago and since then they have cunningly used humans to provide food, comfort and safety, and to aid their dispersal across, and conquest of, most of the world,” Professor Woinarski said.
“We want to alert and inform all Australians to the threat cats pose to our wildlife. Our community and leaders need to manage this threat far more effectively if we want to conserve Australia’s unique wildlife.
“With almost four million pet cats in Australia, this is also a call for those with pet cats to help contribute to this conservation effort, by being responsible with the cats that own them.
“Some may think that cats work to keep down the numbers of introduced rabbits, rats and mice, but actually these introduced species are a food source, boosting the number of cats and hence increasing their impact. Cats aren’t an effective control on introduced pest animals,” he said.
Professor Legge said people had very deep and conflicting opinions about cats, but there was no denying they were a catastrophic problem for Australian wildlife, which evolved without cats.
“Australia’s mammal extinction rate is by far the highest in the world and cats have been a leading cause of at least 20, or two-thirds, of our mammal extinctions over the last 200 years,” Professor Legge said.
“On average, each feral cat in the bush kills a whopping 740 animals per year. In a year with average conditions there are about 2.8 million feral cats, but that figure can double when good rain leads to an abundance of prey animals.
“On average each pet cat kills about 75 animals per year, but many of these kills are never witnessed by their owners.
“While each urban cat kills fewer animals on average than a feral cat in the bush, in urban areas the density of cats is much higher (more than 60 cats per square kilometre). As a result, cats in urban areas kill many more animals per square kilometre each year than cats in the bush,” she said.
The University of Sydney’s Professor Dickman said that each day cats killed more than 3.1 million mammals, 1.8 million reptiles and 1.3 million birds in Australia.
“Many of Australia’s native species cannot withstand these high levels of predation and will become increasingly at risk of extinction unless the problem of cats in Australia is solved,” Professor Dickman said.
The Threatened Species Recovery Hub is a collaboration of leading Australian research institutions to undertake science to support the recovery of Australia’s threatened species. It receives funding from the Australian Government’s National Environmental Science Program.