Don’t be under any illusions, cats are killers and have caused the extinction of dozens of Australian native species. The problem continues today.
CATS ARE APPEALING. I quite like the way they purr, and play, and look contented or haughty; and mostly they’re fine-looking animals. They can deliver companionship and pleasure to many.
But in many places, including the Australian bush, they are an environmental disaster.
Our recent analysis of the fate of all Australian mammal species concluded that predation by feral cats was the single factor that contributed to most extinctions since European settlement of Australia, and also the factor most implicated in the endangerment of remaining mammal species.
This biodiversity loss and ongoing decline has been extraordinary. Thirty species of Australian endemic mammals have been made extinct over the last 200 years, far more than for any other continent over this period.
The losses entirely or largely attributable to feral cats include the pig-footed bandicoot, desert bandicoot, lesser bilby, desert bettong, Nullarbor dwarf bettong, desert rat-kangaroo, broad-faced potoroo, kuluwarri (central hare-wallaby), crescent nailtail wallaby, white-footed rabbit-rat, Capricorn rabbit-rat, lesser stick-nest rat, short-tailed hopping-mouse, long-tailed hopping-mouse, large-eared hopping-mouse, Darling Downs hopping-mouse, broad-cheeked hopping-mouse, long-eared mouse, blue-grey mouse and Gould’s mouse.
Don’t know them? Well, now you never will. These species were an integral, indeed quintessential, part of Australia’s extremely distinctive mammal fauna, and had lived successfully on this continent for tens of thousands, probably millions, of years. Many of these species were ecologically important, delightful, beautiful, culturally significant, abundant and widespread.
Feral cats have now eliminated them, subverting our natural heritage. The damage continues unabated, as feral cats are driving the decline of very many still existing mammal (and bird and perhaps reptile) species.
Feral cats are now ubiquitous across continental Australia, from the most extreme deserts to the tropical north, and they also occur on many islands. The problem that they present is pervasive.
The evidence for causation is compelling. On the mainland and on islands, many native mammals (and birds) disappeared rapidly soon after the arrival of feral cats; where cats have been exterminated from islands, some native mammals have recovered; experimental and other studies have demonstrated that where cats have been excluded (by fences) or effectively controlled (by baiting), native mammal populations have recovered, often dramatically; dietary studies of feral cats show high rates of consumption of mammals; and radio-tracking studies have shown that cat predation is a major cause of mortality for many native mammal species.
We have long been unaware of, or ignored, this problem. But if we care about the fate of our wildlife, we cannot afford to ignore it any longer.
However, the management of cats is a formidable challenge. There is no single immediate solution, but instead a need for action on many fronts. Our society should be more broadly aware of the deconstruction of our fauna, and of the pernicious role of feral cats in this loss. We may need to re-think the extent to which we care for and value species that have an innate belonging to our country relative to those that we have brought here for our own satisfaction. Cat-owners and local governments should be more effectively regulating the keeping and management of pet cats.
We need to recognise more the value of islands to Australian biodiversity — to enhance biosecurity for those biodiversity-significant islands that currently have no cats, to attempt to eradicate cats where practicable from islands where they are present, and to ‘maroon’ on cat-free islands some highly threatened species that, because of the impacts of cats, may not persist on the mainland. For other highly-threatened mammals, there is a need to establish a mainland refuge network of large cat-proof exclosures.
There has been some progress recently on increasing the effectiveness of baiting for feral cats, and baiting programs need to be more extensively trialled (to ensure that there is no significant loss of native species), and then extended over larger scales and longer timeframes. And there is need to understand and implement over large scales those management actions that can indirectly influence cat abundance and impact, such as fire, dingoes and grazing – there is now substantial evidence that impacts of cat predation are magnified in extensively burnt areas and in heavily grazed areas (because these offer less shelter for native species from predation), and in areas in which dingoes and wild dogs have been ‘controlled’. And, over a longer-time period, there is a need to develop a biological control agent for cats, that is adequately humane, that has no significant risk for native species or for felid species elsewhere in the world.
Sometimes, we see simply what we want to see. Many in our community see cats as inoffensive and desirable pets. It is an illusion.
Professor John Woinarski currently works in part for the North Australian Hub of the National Environmental Research Program atCharles Darwin University and as an advisor to Pew Charitable Trusts. He has been engaged in conservation research and management for more than 40 years, mostly in northern Australia.
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