In North America, the feral cat poses no threat to the native ecosystem because predation from the Coyote has kept it confined to urban areas. In Australia, the feral cat inhabits the entire continent from the snowy highlands to the arid interior and is pushing Australian birds, reptiles and marsupials towards extinction.

But Australia was not always the cat paradise that it is today. It is quite probable that over the last 10,000 years, the cat was introduced by successive waves of Indonesian, Chinese, Portuguese and Dutch mariners. However, it seems that the cat found it difficult to take hold in an ecosystem containing Devils, Thylacines (Tasmanian Tigers) and nomadic Humans.

When the English introduced the cat in 1788, it was into an ecosystem in which Devils and Tigers had recently become extinct, and the local Humans were soon to stop living a nomadic existence. This allowed the cat to enter near the top of the food chain with few competitors or other animals hunting it.

As well as being aided by a lack of competitors, the cat was aided by Humans deliberately releasing them into the wild in order to control rabbits and mice. Although the cats did quite a good job keeping the rabbits and mice under control, they also preyed upon native birds, marsupials and lizards that had not evolved defences to it. This led to mainland Australian suffering a significant decline in ecological biodiversity.

Thankfully, the island state of Tasmania had the Devil, and this helped the local ecosystem resist some of the negative attributes of the cats. The Devil is primarily a scavenger. It has evolved a good sense of smell to find dead animals, and powerful jaws to chase any other carnivore off the carcass. In Tasmania, Tiger Quolls do most of the hunting of live animals, only to then find the Devil following their trail, and then chasing them off their kills. Since being introduced to Tasmania, the cat has found itself in a similar position to the Quoll. It hunts, and is then chased off its kill by Devils. Cat remains have also been found in Devil stomachs. This may indicate that the cat's lack of endurance has been exploited by Devils.

Being constantly chased off their kills, and possibly eaten, has resulted in Tasmania having by far the lowest cat concentrations in Australia. As a consequence, Tasmania has not lost a single marsupial, with the exception of the Thylacine, since colonisation.

On mainland Australia, significant money has been spent on cat eradication programs. The use of 1080 is a favoured method. 1080 is a synthetically produced substance that is a replication of a naturally occurring poison found in plant species such as poison bush, kite leaf poison bush, poison pea, and wallflower poison bush. Although native animals can eat the foliage, seeds and flowers of the plants with no ill effect, it is deadly on the feral animals that have not evolved alongside it.

Despite the impressive science behind it, it is very expensive, and for a country of 7,600,000 square kilometres, it has zero chance of success. It simply can't overcome the vacuum effect. Once cats are removed from a region, more simply migrate in.

There are also large areas of Australia where poisoning can not be used. These areas include farming land, urban communities and any area when poison bush doesn’t occur naturally. Farmers don't want local cat populations eradicated because to do so would result in plague populations of rabbits and mice. Although constant poisoning and warren ripping regimes are in an ecologist's interests for they bring with them funding, they are not in a farmer's interests as they are expensive and time consuming. The cats do a better, cheaper, and more sustainable job.

As is to be expected, different agendas have led to some heated division between ecologists and farming communities. Ecologists refer to the farmers with all manner of unsavoury insults, while farmers tell the ecologists to do something useful with their lives.

Recognising the futility of the poisoning regimes promoted by some ecologists, some scientists have taken a more holistic approach to the issue. Professor Chris Johnson, from James Cook University, has argued in favour of reintroducing Dingos, Quolls and the Devils to the various mainland ecosystems that humans have eradicated them from. Professor Johnson has stressed that native predator communities need to be rebuilt because they have the ability to remain in balance with native prey. As native predators replace the feral predators, or reduce their numbers, native prey is able to rebound.

Rebalancing Australia's ecology?

Wednesday, 03 October 2007

By Chris Johnson

Dingo may save Australian wildlife

In regards to how the Dingo would go against the fox and the cat, Professor Johnson has some interesting research backing up his proposal. He has found that in places where Dingoes are rare or absent, and foxes and cats are abundant, 50 per cent of ground-living mammals have vanished. Where Dingoes remain abundant, the rate of local disappearance is 10 per cent or less.

In regards to how the Devil would go when put up against a fox, and a Dingo, the proposal shifts to one of hypotheticals. Palaeontologist Stephen Wroe has analysed how they would go in a one-on-one battle and found:

"In one-to-one situations, our results suggest that the devil would easily prevail and even give dingoes [wild dogs] a run for their money."

Even though Devils would be more than capable of holding their own in a fight against a dog, fox or cat, some concerned citizens fear that if the Devils were reintroduced, they would prey on native fauna. One of these concerned citizens is Sarah Hartwell, who wrote:

"In 1995, the wildlife issue became more urgent with a rabbit calcivirus outbreak causing predators in previously rabbit-infested areas to turn more and more to native animals. New South Wales National Parks and Wildlife Service stepped up the use of poison bait (not trapping and destruction) to kill foxes, feral cats and dogs, but at the same time, some scientists spoke of reintroducing the Tasmanian Devil into mainland Australia in the hope that it will prey on fox cubs, kittens etc. It was not stated how Tasmanian Devils would be trained to kill only introduced species and not kill native species. Many would question the wisdom of (re)introducing any predator likely to prey on already "decimated" fauna."

As Ms hartwell quite rightly feared, a wild animal can’t be trained to kill one animal and not another. It will kill what it is capable of killing. In Tasmania, Devils are scavengers because they are slow and cumbersome. They do; however, have powerful jaws and a keen sense of smell. Baby foxes are potential prey because, unlike marsupials which are carried in pouches, they are left in dens.  Cats are also potential prey because they have no endurance. Even a human can catch a cat just by following it.

Contrary to stereotypes, the cat fares poorly when compared to native predators. It has very weak jaws and very little endurance. Furthermore, whereas the pouch allows marsupial predators to be very mobile with their young, the cat is forced to leave their kittens unprotected as it goes to hunt. The cat’s main advantage is a symbiotic relationship with humans. Because it lives in the family home, or on the family farm, if it is ever eradicated from the wild due to a drought or other changes in conditions, the urban landscape acts as an oasis until the good times return. It can then recolonise. Furthermore, the urban cats can breed with the feral cats to increase genetic diversity and strengthen the species as a whole. On the other hand, the marsupial predators do not have a symbiotic relationship with humans thus do not have an urban oasis to retreat to in times of difficulty or gain access to fresh genetics.

 

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1) The Geelong AFL team is known as the Cats.

2) A Perth basketball team is known as the Wild Cats.

Industry

1) Scientific research - Researching the damage caused by cats is a very lucrative profession. Thus far, the research has been effective in ascertaining where the cats have come from, what they eat, how they behave, how they breed, how they hunt and places where they live.

In theory, the research is intended to find a way to eradicate them. In practice, the research is used to justify the need for more research funding. Such is academia.

2) Poisons- Some companies manufacture cat poison and sell it to environmentalists or councils. It is an ineffectual method of control that has undesirable side effects.

3) Enclosures - Private and public funding is sometimes made available to build wildlife enclosures that have big fences to keep the cat out.

4) Pets - Cats are popular pets in Australia. Unwanted litters are often dropped off at the RSPCA or taken out bush and set free.

5) Work for public servants - Rather than implement solutions, the federal government likes to spend money on studies, writing policy, implementing awareness campaigns and then monitoring the success of the awareness campaigns.

As part of this approach, the federal government has created the Threat Abatement Plan for Predation by Feral Cats. In typical public service jargon, the plan uses lots of words to avoid recommending a concrete solution. The jargon includes:

• implementing feral cat control programs in identified regions of high conservation priority
• encouraging the development and application of innovative humane feral cat control methods
• collecting and disseminating information to improve our understanding of the ecology of feral cats in Australia, their impacts and humane methods of control

Feral cats in Tasmania