Feral Cats – Australia’s non-native wildcat
On January 16, 2016 “Felicitous felicide” an article about culling feral cats in Australia published in The Economist summarized, quite unconvincingly, Australia’s justification for their practice of culling feral cats.
While I found no biological or scientific assessment in the article about methods, measuring outcomes, and maintaining a balanced ecosystem and biodiversity to implement the practice of culling feral cats as the only means available to protect Australia’s small mammals from extinction, what I did find is a number of idiosyncrasies and an ill placed sense of humor.
The most obvious idiosyncrasy is the lack of any real scientific data. The author “reckons” that feral cats are the “culprits” of causing extinction of 27 out of 29 “disappearances” of small mammals over more than 200 years. In that span of time I wonder how many fauna and flora extinctions have occurred due to human culpability.
Next, the author claims that there is an “estimated” 4 million to 20 million feral cats. Really? A plus/minus range of 16 million is not a sound population estimate. What agency, organization or field researchers is supplying population statistics and by what means are counts being taken?
The author claims that feral cats eat “perhaps” 75 million Australian animals a day. Again really? For argument sake let’s do some math. If there are 4 million feral cats and each take 3 animals a day that equals 12 million animals per day. If there are 20 million feral cats and they each take 3 animals a day that equals 60 million. Based on the author’s range of population numbers and taking a stab at averages 4 plus 20 equals 24 divided by 2 equals 12 million feral cats on average. So 75 million animals divided by 12 million equals 6.25.
In this equation 12 million feral cats would have to take 6.25 animals every day. At that rate of consumption, there should be no animals left for the feral cats to prey on. The numbers are questionable and “perhaps” a bit ridiculous.
Most troubling though is the comparison to human convicts. The author states the “Cats probably arrived in Australia on British ships carrying convicts. Unlike convicts, their descendants have grown wilder and more menacing.” Is this meant to be humorous? At the very least we have indeed found our culprit for causing the extinction of animals and plants—Humans. Funny that in the entire article there is no human responsibility whatsoever in the equation—only the feral cats—cats that were brought to Australia by humans. If feral cats have been growing wilder and more menacing for over 200 years why was nothing done before? And why is the only human solution to death and extinction more death and extinction?
It is too bad that the author of this not so humorous spin and scientifically devoid article on the wildlife issues in Australia didn’t take a bit more time and look up some recent research done on culling cats in Australia by Billie T. Lazenby et. al. School of Biological Science’s, University of Sydney. In “Effects of low-level culling of feral cats in open populations: a case study from the forests of southern Tasmania,” Lazenby found some unexpected results:
“Contrary to expectation, the relative abundance and activity of feral cats increased in the cull-sites, even though the numbers of cats captured per unit effort during the culling period declined. Increase in minimum numbers of cats known to be alive ranged from 75% to 211% during the culling period, compared with pre-and post-cull estimates, and probably occurred to due influxes of new individuals after dominate resident cats were removed. Our results showed that low-level ad hoc culling of feral cats can have unwanted and unexpected outcomes, and confirmed the importance of monitoring if such management actions are implemented. If culling is used to reduce cat impacts in open populations, it should be part of a multi-faceted approach and may need to be strategic, systematic and ongoing if it is to be effective.”
In an interview for ABC News, Lazenby stated the “the reason culling has been so widely used in Australia is that studies have shown how effective it can be. But the problem is these studies have really only been done on islands, rather than mainland Australia. What we should really be focusing on when we talk about managing introduced species like feral cats is reducing their impact, it is really important that we keep in mind you don’t always reduce impact by reducing numbers.”
I do appreciate the issues Australia is facing with their disproportionate population of feral cats and their need to address all the issues involved with maintaining a balanced and healthy ecosystem and biodiversity, however, the methods implemented to achieve this end ought to be based on the best available scientific data, research and effective long-term management strategies versus shock-value, sensational media bites.
Lazenby, Billie T., Mooney, Nicholas J., and Dickman, Christopher R. (2015) Effects of low-level culling of feral cats in open populations: a case study from the forests of southern Tasmania. Wildlife Research 41, 407–420.
Lisa A. Salamat, Esq., Chief Executive Officer, WildCat Conservation Legal Aid Society