Feral cats are a non-native species in Australia but will they become native?

The great debate about feral cats in Australia rages on. They are non-native to that country and therefore they are considered to be pests because they prey on native species, often small mammals which are endangered in any case because of human activity. The feral cat gets the blame. But, the question here is whether feral cats will remain non-native to Australia in perpetuity. Will there be a time when we can say that feral cats are no longer non-native in Australia? And I think there is. 

Australian feral cat. Photo: Pixabay.

Peter Banks

I like an article written by Peter Banks, Professor of Conservation Biology, School of Life and Environmental Sciences, University of Sydney, Australia. He makes the point that there can be a time when a non-native species becomes native. He even sets out criteria for classifying whether a species can be considered to be native when at one time they weren't.

He applied his criteria to dingoes and concluded that they are now native to Australia. This is despite the fact that dingoes were brought to Australia from Southeast Asia about 4,000 years ago. Technically they are non-native or alien to Australia. But he says, interestingly, that most legal definitions consider dingoes native because they were brought to Australia before the Europeans arrived.

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Deciding if a species is non-native

So here is his "ecological definition of nativeness". To put that another way, these are the three criterion that should be applied when deciding whether a non-native species has become native.

The first is whether the introduced species has evolved sufficiently into its new environment. The second criterion is whether native species recognise and respond to non-native species as they do to other species. And the third is whether the interactions between established native species and non-native species are the same as if they were interacting with native species. This last point is asking whether the impact of the non-native species is exaggerated because native species don't know how to relate to them.

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Vulnerability of native species to alien species

The last point is important because in Australia some native species haven't learned how to defend themselves against feral cats. It takes a long time in evolution for a species to build up defences against a predator. Therefore, when you introduce a strange and alien creatures into the landscape the resident species are nonplussed and are therefore very vulnerable to predation by that animal.

How long has the non-native species been in an area?

Applying the criteria mentioned, he decided that dingoes are native. And clearly, a major factor as to whether a non-native species become native is the amount of time it has been in that environment. With respect to dingoes it's 4,000 years. That provides enough time for this species of dog to fully integrate to the point where you can't tell the difference between them and native species in terms of interactions.

On this basis, there will be a time when the feral cat in Australia becomes native to that continent. Peter Banks says that cats have not been on the continent long enough to qualify as native. He said that they have not had enough time "to get past the exaggerated impacts on local species".

Non-native animals need not be non-native for ever

What I like about the article by Peter Banks is that he is saying that non-native species need not be non-native forever. There is a cut-off point which is directly linked to the amount of time that they have been alien to a particular country or place. I have always believed that.

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Feral and domestic cat in North America

You could apply that rule to the domestic cat in America. It is believed that the domestic cat was brought to America by European settlers which means they've been in America for about 400 years. But they are non-native to America. Americans unlike Australians don't want to exterminate all feral cats. Americans have a more sophisticated attitude towards feral cat predation on wildlife. And I don't think Americans consider feral and domestic cats to be non-native or if they do it is a very weak point which is rarely if ever raised.