Feral cats are devastating our wildlife, so we need a long-term, sustainable solution. This is where Australia’s natural predators come in.
A few moments on the internet will reveal that, as companion animals, cats are rivalled only by dogs. Our love affair with them is hardly surprising: they are elegant, graceful and affectionate animals. But they are also highly adaptable and successful hunters. Sadly our soft spot for them brings with it disastrous consequences for smaller wildlife species, particularly mammals, birds and reptiles.
Cats are wreaking havoc on our native wildlife, from northern Australia’s Kimberley to southern Australia’s Alps: nowhere is unaffected. Along with other threats such as habitat loss and fire, cats are pushing many native animals to the brink of extinction.
How serious is the cat problem? It’s been estimated that there may be as many as 15 million feral cats in Australia, each killing about five native animals per night: a nightly total of around 75 million native animals. And it’s not just feral cats doing the damage; that adorable Fluffy has a sinister side too. It often isn’t recognised that there is abundant and diverse native wildlife in and around many Australian cities and towns, including bandicoots, sugar gliders, quolls, koalas, parrots, water dragons and snakes. The development of remotely triggered camera traps has provided ample evidence that such wildlife frequently falls victim to domestic cats on their nightly excursions.
For a long time our other invasive predator of note, the European red fox, was seen as enemy number one to our wildlife, particularly mammals, but there’s a growing realisation that its many meals are eclipsed by those of cats, both feral and owned. Globally, cats are rated at 38th and red foxes at 99th on the IUCN’s list of 100 of the World’s Worst Invasive Alien Species.
And it’s not just cats’ appetites that are doing the damage. Cats are the primary host of the parasite Toxoplasma gondii, which can infect most mammals and birds, causing the potentially fatal disease toxoplasmosis (toxo). Even when not lethal, toxo can impact wildlife populations indirectly, through effects that include impaired vision, disorientation, loss of coordination, anorexia, lethargy, fever, skewed offspring sex ratios and abortion. Most bizarrely, animals infected with toxo are often attracted to the smell of cats and hence are more likely to be killed and eaten by them; a kind of parasite-driven mind control.
So what can we do to reduce the damage done by cats and mitigate this national conservation disaster? The most urgent needs are for vigorous education and awareness campaigns about the impacts of cats on wildlife, and tighter regulations and enforcement around responsible cat ownership. This should include mandatory desexing, the imposition of night-time curfews and containment of cats within pet owners’ properties at all times.
In addition, a number of on-ground solutions are already available or under consideration; there is no doubt that a range of measures will be essential. These include the development of cat-specific poison baits and release of a cat-specific virus. However cat control through disease and poison programs are unlikely to be effective long-term, as natural selection will favour disease-resistant and cautious cats which will result in rapid population bounce-back. After all, cats are known for their smarts, being more attracted to moving prey and suspicious of foreign objects. Under good conditions, furthermore, they can reproducequickly and bountifully.
Fencing can effectively exclude cats from habitats and provide wildlife refuges, and they play a critical role in holding the line for species such as bilbies, already teetering on the edge of extinction. However the use of fencing as a regular and ongoing strategy for wildlife conservation in our vast country will not only be logistically challenging (perhaps impossible) but also forbiddingly expensive. More fences will also result in it becoming harder and harder to see bilbies, bandicoots and many other native species in the wild. What a sad outcome for our nation and what an indictment of our allowing cats to reign supreme and unchecked!
Cue the predator
Why are cats able to run rampant? A significant reason is the lack of balance that now characterises our ecosystems. A crucial step is likely to be returning native top predators, in particular dingoes and Tasmanian devils, to landscapes, so that they can resume their important ecological roles. Scientific research (pdf) is strongly suggesting that dingoes not only kill cats but also instill fear in them, which means that they avoid areas and times where dingoes are active. Hence dingoes can provide a 24-hour-a-day, seven-day-a-week, cat control service.
If we want to conserve our iconic and globally unique wildlife then we need to work with, rather than against nature, and supporting more positive management of dingoes and returning Tasmanian devils to mainland Australia for their biodiversity benefits (pdf)would be one of the best and most cost effective things policy-makers could do now. Non-government conservation organisations such as the Australian Wildlife Conservancy are already leading the way.
In 1995 the USA and Canada worked together to reintroduce wolves to Yellowstone for their ecosystem benefits. The success of this bold step is now the stuff of legend. Isn’t it time we had our ‘Yellowstone moment’ and began restoring Australia’s ecosystems to some of their former glory?