Is the domestic cat an invasive species?

by Michael

The domestic cat as an invasive species? Balderdash - Photo by Eran Finkle (Flickr)

The domestic cat as an invasive species? Balderdash - Photo by Eran Finkle (Flickr)

I challenge the assessment that the domestic cat is an invasive species. The respected IUCN (International Union for Conservation of Nature) says it is. They work in association with the Species Survival Commission to assess and advise on the Invasive Species Specialist Group ( In short a large number of specialists (7,500 volunteer experts) have decided that the domestic and feral cat is an invasive species - one of the worst.

They define "invasive species" as “animals, plants or other organisms introduced by man into places out of their natural range of distribution, where they become established and disperse, generating a negative impact on the local ecosystem and species.”

This article is a critique of the assessment. They make a number of errors on their page listing the cat as an invasive species, which indicates that so called experts are often not expert at all. I guess we know that.

First on the website they bundle together domestic and feral cats. I think that is a bad idea as many millions of domestic cats in the USA live indoors permanently and these cats cannot fall within the above definition as they cannot have a negative impact or indeed any impact on the local ecosystem.

Secondly they say that "Felis catus was domesticated in the eastern Mediterranean c. 3000 years ago". Felis cats was not domesticated. Felis silvestris catus is the scientific name of the domestic cat. The wild cat Felis silvestris was domesticated. And current information points to the fact that it happened first 9,500 years ago.

Thirdly, ISSG says "Felis catus is a small animal in the wild (up to 5kg, but more commonly 1.5 -3.0kg) but may be considerably heavier when domesticated." I presume by this that they mean that the feral cat is smaller than the domestic cat. They say therefore that the feral cat commonly weighs 3.3 to 6.6 pounds or in-between those figures at less than 5 pounds. This is incorrect in my view. Feral cats have similar weights to domestic cats unless the domestic cat is obese.

ISSG admit that they do not have hard data on the impact of domestic or feral cats in respect of their impact on native species. They say "However, unambiguous evidence of cats causing a decline in a prey species is difficult to find as other factors, such as other predator species, may also be involved in the decline (Dickman 1996)." In other words the feral cat might not have a negative impact on local species. In fact it is conceivable that the cat may have a beneficial impact by reducing other so called invasive species that are clearly detrimental to the environment such as rats. This precludes the cat from being an invasive species.

Also it is by pure chance that the wild cat was domesticated in the Mediterranean. Indeed there may be undiscovered evidence to suggest that the wildcat was domesticated in other areas. That would make it native to those areas and not introduced "by man".

The act of domestication of the wildcat is not an act that falls within the phrase "introduced by man".

I also question the whole concept of invasive species. We devised the concept. And we do the introducing. If we willingly introduce animals to areas where they have not evolved naturally we have no right to blame the species and then to try and destroy the species. The ISSG should be suggesting ways to stop the introductions.

In respect of the cat, it has provided so much in the way of benefit to countless millions of people. To brand the domestic cat an invasive species that needs to be eradicated is ridiculous.

I therefore challenge the assessment that the domestic cat is an invasive species. In general, there is no hard evidence to suggest that it meets the definition.

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Is the domestic cat an invasive species?

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Sep 21, 2011
No they are not !
by: Ruth

I agree, domestic cats are no more an invasive species than any other living creatures, including us humans.
What is wrong with cat haters that they try to find any reason at all to spread their hatred and try to convince others they are right to !
No one hates domestic dogs with such passion, but of course dogs are yes men, cats are much more intelligent and discerning and maybe that frightens cat haters because it makes them feel inferior.
Cats can't say 'Oh how I hate being a cat, I wish I was a different sort of creature'
They are like us and like all other species too, they have no choice what they are born as.

Why oh why can't everyone on this planet just live and let live !!!!

Kattaddorra signature Ruth

Sep 21, 2011
by: Barbara

Of course such "studies" as these fall nicely into the hands of cat haters who would blame cats for every bird that falls from the sky and use it as an excuse to incite hatred of cats. In my opinion cats are no more or less flawed than humans, they take what they want, sometimes for food and sometimes just for the pleasure of it. I think cats have as much right to the world as humans do. And I also think some of these experts need to get a proper job and keep their daft ideas to themselves.

Sep 21, 2011
Love those cats feral and domestic
by: Diane

I think mankind holds the distinction of being the most destructive, wasteful, cruel, greedy species. I will spend my time with a cat any day and trust the cat in a way I would never trust a human.


Is the domestic cat an invasive species? — 24 Comments

  1. You cat lovers are ignorant and irresponsible. Of course Domestic Cats are invasive species. According to the U.S. government, an invasive species is “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” Ecologists would add that an invasive species is a non-native introduced species that spreads rapidly on its own and displaces native species.

    Housecats easily meet all of these criteria. Not to mention the huge toll they take on native wildlife.

    Furthermore, don’t start your gibberish about how humans are invasive species. Well, in that case, why don’t we all jump off a bridge together. And don’t expect me to have any sympathy when your cat gets run over or shot because they roam free in the neighborhood, poop in the kids sandbox and eat newborn bunnies and birds for fun. We are tired of having to deal with the end result of ignorant, irresponsible people like you. All domestic cats need to be kept indoors, all feral cat colonies should be eliminated. End of story.

    • Well, in that case, why don’t we all jump off a bridge together….

      No, why don’t you do it instead? That would solve so many problems with the planet that are caused by gross human ignorance. Why aren’t humans an invasive species? Just answer that. At one time North America had no humans. Where did the first humans to North America come from? You are an animal, or do think you are some superior species?

      In Asia and the Middle east, say Afghanistan, people poop in side streets. It smells. Is that more acceptable than the occasional cat pooping in some outside area? If a cat is a predator (most are indoors and are not real predators) he or she preys on rodents not birds. Look it up and get educated.

      It is you who is ignorant and uneducated. Sorry but there is no doubt that that is true and history will bear me out.

      Why are animals other than cats more valuable than cats? Why are you more valuable than a cat?

      I note that your email address is “agent nut sack”. It sounds suitable to me. An agent of nutty ideas and a sack full of sh*t.

      • Sorry Michael but ibrakeforbirds is right even if he is rude about it, I myself own a cat. also humans are not an invasive species to north America for we got here by migration from Asia originally which makes humans by definition native to the Americas. PS: Ruth you don’t have to bee a d**ch just because he is.

  2. ‘We are tired of having to deal with the end result of ignorant, irresponsible people like you’

    And we are tired of ignorant people like YOU distorting the facts and trying to convince others how bad cats are just because YOU hate them.
    I suggest YOU go and jump off the nearest bridge and put yourself out of your misery because the value of your bitter life full of hatred is ZERO!

  3. I love cats …but not in the wild….
    if they are domesticated keep them inside…
    there no reason for them to be outside.
    I’ve seen the damage they have done.
    from three of them caging a mother rabbit and killing
    her young…my backyard.
    to the little gifts that were left daily on the back steps.
    anything is game . from insects to rodents , chipmunks….don’t see them around the rock fencerow anymore snakes,peepers to birds…ruining greenhouse and garden flower beds.
    or just out to reproduce…oh please birth control is a must.

    these are inside family pets and should be kept as such.
    these cats have homes let them say there.
    love you cat

      • How I agree with you Dee!
        Emily, in England cats are valued as part of the family and treated as a family member but with the consideration that they are feline family members. They are not possessions to be kept prisoners and denied their freedom, they have as much right to their freedom as you have, to breath fresh air and to feel the sun on their backs as Nature intended them to. We took them from the wild, they didn’t ask us to do that, we have taken enough from them already, if it’s safe for them to be free then why deny them?
        So sometimes they kill smaller animals, that’s their Nature, they were programmed into the food chain. Would you keep human beings prisoners because they cause the death of many many animals, all sorts of species of animals and birds, directly by pollution, hunting them for sport etc etc or indirectly by having someone else kill them for them for food?
        People who call cats killers are such hypocrites.
        You either love cats as they are and respect their right to live as a cat likes to live, or you don’t love cats at all.

  4. hi again,
    sorry I upset you all.
    but did you ever hear the cry of a baby rabbit being toyed to death????
    I’m only call “em as I see “em.
    no matter where I’m from.
    hey why do they call barn cats… mousers???
    many a time I’ve heard “that cat there is a good mouser”
    boy and I see some toms…(tomcats) wow some are a hefty size.

    • Hi Emily, we always respect other people’s views. We are not upset. Cats do kill but they do it to survive. They are programmed to do it. People often kill for pleasure (murder of humans and sport hunting of animals). We need to look at ourselves more critically before criticising other animals.

  5. I have to disagree on the cat to survive point.
    and the kill thing…I live in a suburban area there is no hunting here just little creatures on the doorstep.
    my neighbor took down their bird feeder because of the problem.


    • There’s nothing perfect in this animal world.
      Complete harmony would be great, but it’s not possible considering all of the various inate traits.
      And, yes, I have heard the screams of small creatures, ie. a dog shredding a kitten, a snake cornering a rat…and more.
      The only action that I would say isn’t a survival skill is the vicious dog. That was senseless.
      I, and a lot of people, have a “live and let live” attitude.
      I don’t demand that my neighbors keep their children inside because they are throwing rocks at my cats; I don’t demand that bird feeders come down because attracted birds poo on my car and deck.
      There need to be some level of tolerance so we can all peacefully coexist.
      I do respect your opinions, Emily, but I don’t have to agree.

    • Emily would you rather be over run with rodents than cats doing what they were born to do? Would you rather have another plague? Cats have a purpose in life, which is more than some people do (not saying you personally) just the trolls who come here to try to upset cat lovers!

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