You have heard the message of Cat Wars, a new book by the ornithologist Peter Marra writing in conjunction with Chris Santella. Dr Marra is the director of the Smithsonian Migratory Bird Centre in Washington. He said:
“There has never been a book like this that really brought together this science in a way that is accessible for most people. Even as I was pulling the scientific studies together, it was just jaw-dropping to me, how clear this is and how long we have known this. Paper after paper, study after study, showed not only cats’ effect on biodiversity but also the effects on human health.”
Dr Marra concludes that cats kill 1.3 to 4 million birds annually in the USA and up to 22 billion mammals including hundreds of millions of reptiles and amphibians.
His suggestion is that cat owners should follow dog owners: cats should be on a leash when outside.
The trouble is this: you can argue against Dr Marra’s findings and conclusions. It is always possible to argue against this because the studies are inconclusive when extrapolated to a national level and the information is muddied. The picture is not as black-and-white as Marra suggests. The effect of predation on wildlife by feral and outside cats is a hot topic. On the one side, the ornithologists present their argument that feral cats should be killed and outside domestic cats should be on a leash or kept inside permanently. On the other side, in arguments presented by cat lovers, the suggestion is that the solutions presented are inhumane and the arguments about predation are inconclusive.
The discussion about cats and wildlife is very polarised. The arguments are pro-cat versus anti-cat, or pro-cat versus pro-wildlife. It is time to get rid of this polarisation and for the parties to get together and come to some hard conclusions about the effects of predation on wildlife by outside cats and, depending upon the findings, the best way to deal with it humanely.
Margaret Slater Of the Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine, Texas A & M University makes some very good points on this subject.
She says that the divide between pro-cat and pro-wildlife is inaccurate and unhelpful as there are points in common. There is an overlap between the cat groups and wildlife groups.
For example, one often used argument is that cats are an invasive species. They are a non-native species and native species should be protected from them. However, cattle and sheep are routinely protected from coyotes, foxes and wolves. These are native species in America. They are preying on domestic species.
Another argument by anti-cat groups is that, in removing cats from the environment, ecosystem will return to the pre-cat situation. Margaret Slater makes the point that ecosystems are complex. They have been influenced by the effects of human habitation including pollution and the introduction of livestock and construction.
In addition there are often other introduced plant and animal species. These affect the balance of the ecosystem. Removing cats in certain locations may cause serious problems from an increase in rodent populations.
In addition, the interaction between cats and wildlife varies from location to location. It is influenced heavily by other environmental factors such as a variety of prey species and the reliance of cats being fed.
Further, predation studies are often based upon examining the diet of cats in different locations by examining intestinal samples and their faeces. The results of these ‘diet studies’ do not provide evidence of the impact on a species unless abundance is also monitored. In addition the victim species’ reproductive capacity and other sources of predation and mortality need to be monitored.
The point is that the studies upon which Dr Marra has based his findings are, I would suggest, inconclusive when extrapolated and therefore it is unhelpful to make conclusive findings on a national level from them.
Studies about cat predation can lead to headlines in newspapers which are simply incorrect. For example, a questionnaire study involving 1,300 residents living in rural Wisconsin concluded that mammals made up 60% of prey and birds 23% of prey. The study reported 279 prey captures on 2,030 farms and homes in the study area. The headline that followed was “Cats kill millions of small mammals and birds every year”. Fair and helpful?
Today in the Times newspaper there is a headline on page 3 entitled: “Apocalypse meow: Lock up your cats”.
The headline catches the eye but it is misleading. An accurate headline would be boring and difficult to comprehend because this is a very tricky and scientific subject. The data is unclear in my opinion and there is a pressing need for a coming together of both pro-cat and pro-wildlife groups including ornithologists with the objective of arriving at a common agreement on the true effect, nationwide in the USA, of cat predation on native species and a common strategy on how to deal with it humanely.
My bet is that the cat will be exonerated. Humans will be seen as the true perpetrators of any declines in population numbers of native species which are currently assigned to the cat.
My thanks to Margaret Slater writing in ‘The Welfare of Cats’ edited by Irene Rochlitz.