Making the case that domestic cats are not an invasive species in America

It is automatically assumed that domestic cats wherever they live are invasive species. For example, an article written by Catherine D. Mizerany on the St. Louis Post-Dispatch says that domestic cats are the ‘very definition of an invasive species’. But let’s analyse it and see if they really are.

We argue that the logical criterion for determining native status of a long-term alien species must be once its native enemies are no longer naïve.

National Library of Medicine published study entitled: When does an alien become a native species? A vulnerable native mammal recognizes and responds to its long-term alien predator

Defining ‘invasive species’

How do you define “invasive species”. There’s a nice definition on the USDA National Invasive Species Information Center website. It’s a two-part definition (test) which is important. Both parts need to be met before the domestic cat can be considered to be an invasive species.

Definition of invasive species

As per Executive Order 13112 (Section 1. Definitions) an “invasive species” is a species that is:

1) non-native (or alien) to the ecosystem under consideration and,

2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.

Does the domestic cat meet the definition?

By “alien” the definition means that the animal did not evolve naturally over many thousands – even millions – of years in the area where they reside. The domestic cat evolved naturally from the North African wildcat in the area around the country now called Syria (Fertile Crescent). On that basis, it is arguable that the domestic cat is not an invasive species in Syria, Egypt, Iraq, Israel, Jordan, Lebanon, Palestine, Turkey and Iran (western portion).

But in places like America, where the domestic cat is regarded as the very epitome of an invasive species because they were imported by the European settlers in the late 1600s and moving forward, you have to bring in the second part of the above definition to see whether the term applies in America.

And clearly, the domestic cat harms the environment as they kill native species. They kill birds, reptiles, small mammals, marsupials and insects. Therefore, even after 400 years of being in America, on the face of it, the domestic cat is an invasive species

But there are two extra points to make here. Firstly, there will come a time, eventually, when the domestic cat loses its desire to hunt as they all become full-time indoor cats. Also, in conjunction with that gradual development any cat allowed outside will be facing prey species who’ve become adapted to evading the domestic cat. And if domestic cat prey animals are fully successful in avoiding the domestic cat’s predation, there can be no harm to the environment and therefore the second part of the test is not met. We are looking at thousands of years into the future.

Pluses and minuses

Also, we must factor in the benefit that the domestic cat brings to the environment and to the economy. There are three factors in the second part of the definition: “to cause economic or environmental harm or harm to human health”.

Benefits to the human

Most people would argue that the domestic cat benefits the health of many millions of cat owners often substantially. The domestic cat as a companion improves the lives of millions of people in America. In achieving that they improve the environment in which the human lives simply by their presence and companionship.

Many would agree that when you walk into a home with a domestic cat it is much warmer emotionally than one without a domestic cat. One well-known writer said that the domestic cat gives a home a soul. That’s an improvement to the environment inside the home.

I love my cats because I love my home, and little by little they become its visible soul.

Jean Cocteau (1889–1963)

The point I’m making is that the damage that the domestic cat does to the environment in terms of preying on animals might reasonably be nullified by the benefit that the domestic cat brings to the environment as described.

As to human health, overall, the domestic cat brings a benefit because of their calming companionship. Yes, of course there are some downsides such as scratches and bites but on balance the domestic cat must be beneficial to human health and the home environment in which they spend most of their time otherwise they wouldn’t be so massively successful as a companion animal. That’s a simple and conclusive argument.

If that argument is sound, then the second part of the definition is not met and the domestic can no longer be described as an invasive species.

Bodega stores

Bodega cats improve Bodega stores! They bring in business. A small boost to the economy. This needs to be put into the equation on damage to the economy and environment. A small point but the principle is that we should bring these small beneifts into the equation.

Rodent catchers – barn cats

We still have rodent-catching cats as working cats in the human working environment. One of the most high-profile mouser is Larry who works at No. 10 Downing Street, the office and home of the Prime Minister of the UK. There are thousands of other examples. They all help to counteract the negative: preying on native species.

Can you think of other economic and environmental benefits? What about the multi-billion-dollar pet products market? That keeps hundreds of thousands of people in jobs in the USA.

Places other than America

I chose America as it is the biggest domestic cat ‘marketplace’ and the argument that domestic cats are invasive in that country is a balanced one. But in countries where 80% of the domestic cats don’t have homes such as India, the domestic cat’s benefit to society is much more tenuous. In India the domestic cat is an invasive species. The same would apply to many other less well-developed countries where there is a careless attitude to domestic cat caregiving in general.