The killing machine in (and outside) many homes

Font Size:

CC BY Jaana Dielenberg, The University of Queensland; Brett Murphy, Charles Darwin University; Chris Dickman, University of Sydney; John Woinarski, Charles Darwin University; Leigh-Ann Woolley, Charles Darwin University; Mike Calver, Murdoch University, and Sarah Legge, Australian National University

We know feral cats are an enormous problem for wildlife – across Australia, feral cats collectively kill more than three billion animals per year.

Cats have played a leading role in most of Australia’s 34 mammal extinctions since 1788, and are a big reason populations of at least 123 other threatened native species are dropping.

Read more: Feral cat cull: why the 2 million target is on scientifically shaky ground

But pet cats are wreaking havoc too. Our new analysis compiles the results of 66 different studies on pet cats to gauge the impact of Australia’s pet cat population on the country’s wildlife.

The results are staggering. On average, each roaming pet cat kills 186 reptiles, birds and mammals per year, most of them native to Australia. Collectively, that’s 4440 to 8100 animals per square kilometre per year for the area inhabited by pet cats.

More than one-quarter of Aussie households have pet cats. Jaana Dielenberg, Author provided

If you own a cat and want to protect wildlife, you should keep it inside. In Australia, 1.1 million pet cats are contained 24 hours a day by responsible pet owners. The remaining 2.7 million pet cats – 71 per cent of all pet cats – are able to roam and hunt.

What’s more, your pet cat could be getting out without you knowing. A radio tracking study in Adelaide found that of the 177 cats whom owners believed were inside at night, 69 cats (39 per cent) were sneaking out for nocturnal adventures.

Surely not my cat
Just over one-quarter of Australian households (27 per cent) have pet cats, and about half of cat-owning households have two or more cats.

Many owners believe their animals don’t hunt because they never come across evidence of killed animals.

But studies that used cat video tracking collars or scat analysis (checking what’s in the cat’s poo) have established many pet cats kill animals without bringing them home. On average, pet cats bring home only 15 per cent of their prey.

Wes Mountain/The Conversation, CC BY-ND

Collectively, roaming pet cats kill 390 million animals per year in Australia.

This huge number may lead some pet owners to think the contribution of their own cat wouldn’t make much difference. However, we found even single pet cats have driven declines and complete losses of populations of some native animal species in their area.

Documented cases have included: a feather-tailed glider population in south eastern NSW; a skink population in a Perth suburb; and an olive legless lizard population in Canberra.

Urban cats
On average, an individual feral cat in the bush kills 748 reptiles, birds and mammals a year – four times the toll of a hunting pet cat. But feral cats and pet cats roam over very different areas.

Pet cats are confined to cities and towns, where you’ll find 40 to 70 roaming cats per square kilometre. In the bush there’s only one feral cat for every three to four square kilometres.

So while each pet cat kills fewer animals than a feral cat, their high urban density means the toll is still very high. Per square kilometre per year, pet cats kill 30–50 times more animals than feral cats in the bush.

The impact of roaming pet cats on Australian wildlife.

Most of us want to see native wildlife around towns and cities, but such a vision is being compromised by this extraordinary level of predation, especially as the human population grows and our cities expand.

Many native animals don’t have high reproductive rates so they cannot survive this level of predation. The stakes are especially high for threatened wildlife in urban areas.

Pet cats living near areas with nature also hunt more, reducing the value of places that should be havens for wildlife.

Read more: A hidden toll: Australia’s cats kill almost 650 million reptiles a year

The 186 animals each pet cat kills per year on average is made up of 110 native animals (40 reptiles, 38 birds and 32 mammals).

For example, the critically endangered western ringtail possum is found in suburban areas of Mandurah, Bunbury, Busselton and Albany. The possum did not move into these areas – rather, we moved into their habitat.

What can pet owners do?
Keeping your cat securely contained 24 hours a day is the only way to prevent it from killing wildlife.

It’s a myth that a good diet or feeding a cat more meat will prevent hunting: even cats that aren’t hungry will hunt.

Various devices, such as bells on collars, are commercially marketed with the promise of preventing hunting. While some of these items may reduce the rate of successful kills, they don’t prevent hunting altogether.

And they don’t prevent cats from disturbing wildlife. When cats prowl and hunt in an area, wildlife have to spend more time hiding or escaping. This reduces the time spent feeding themselves or their young, or resting.

In Mandurah, WA, the disturbance and hunting of just one pet cat and one stray cat caused the total breeding failure of a colony of more than 100 pairs of fairy terns.

Benefits of a life indoors
Keeping pet cats indoors protects them from injury, avoids nuisance behaviour and prevents unwanted breeding.

Cats allowed outside often get into fights with other cats, even when they’re not the fighting type (they can be attacked by other cats when running away).

Two cats in Western Australia stopped fairy terns from breeding. Shutterstock

Roaming cats are also very prone to getting hit by a vehicle. According to the Humane Society of the United States, indoor cats live up to four times longer than those allowed to roam freely.

Indoor cats have lower rates of cat-borne diseases, some of which can infect humans. For example, in humans the cat-borne disease toxoplasmosis can cause illness, miscarriages and birth defects.

Read more: For whom the bell tolls: cats kill more than a million Australian birds every day

But Australia is in a very good position to make change. Compared to many other countries, the Australian public are more aware of how cats threaten native wildlife and more supportive of actions to reduce those impacts.

It won’t be easy. But since more than one million pet cats are already being contained, reducing the impacts from pet cats is clearly possible if we take responsibility for them.The Conversation

Jaana Dielenberg, Science Communication Manager, The University of Queensland; Brett Murphy, Associate Professor / ARC Future Fellow, Charles Darwin University; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; John Woinarski, Professor (conservation biology), Charles Darwin University; Leigh-Ann Woolley, Adjunct Research Associate, Charles Darwin University; Mike Calver, Associate Professor in Biological Sciences, Murdoch University, and Sarah Legge, Professor, Australian National University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.

Do you have a cat? Do you keep it inside?

If you enjoy our content, don’t keep it to yourself. Share our free eNews with your friends and encourage them to sign up.

Join YourLifeChoices today
and get this free eBook!

By joining YourLifeChoices you consent that you have read and agree to our Terms & Conditions and Privacy Policy


Strength training can help protect the brain from degeneration

Brawn can be good for the brain in at-risk older people.

Study finds link between vitamin deficiency and COVID-19 death rate

Study finds correlation between this vitamin deficiency and COVID-19 death rate.

Retire the retirement village

We're living longer and we're healthier - our environment must change to reflect that.

Written by The Conversation


Total Comments: 8
  1. 0

    And nobody cares….
    Same as Climate change, and so many other “imperceptible” disasters that are caused by humans. If it does not impact on people directly, and especially if it does not impact on their bank account, then it doesn’t exist. Which is more important, birds and reptiles that you can’t see, or a cute cuddly feline around the house?

    The sooner us humans wipe ourselves out, the sooner Nature will get back to its normal processes. Might not be too long.

  2. 0

    Never would have a cat again. Until councils bring in laws that all cats must be kept in a cat run or inside or they will be euthanized, people will still keep leaving their cats to roam. Some do keep them in at night but most kills are done in the early morning, I lost count how many birds I have had to bury from the cat up the road, and I know which cat because I have to shoo it away when I happen to see it in my yard. Owners could not care less.

    • 0

      It’s not just domestic cats but the Feral Cats that are a plague. Some time back the Govt. of the day considered releasing a Feline Virus to control the increasing numbers of these pests.
      The consideration was based on responsible owners being required to have their cats registered and vaccinated to safeguard their pets. The outcry from cat lovers was too much to proceed with the plan. Cats should be subject to the same rules as Dogs, i.e. registered, micro-chipped and confined to their owners property with substantial fines for breaches of these rules.

    • 0

      Yes of course it i the feral cats, probably a bigger problem really.

  3. 0

    Cats are the primary host for toxoplasmosis. People with weakened immune systems, or infants whose mothers are infected during pregnancy, can develop severe illness.

    Toxoplasma gondii a common parasite that can survive for decades undetected in humans and possibly change the brain’s behaviour and personality.
    Dr Tonkin said the study also revealed the Toxoplasma “modified” the host cell by sending in proteins to manipulate the host cell’s function so the parasite could reproduce and grow.
    There was evidence that in brain cells these modifications could lead to personality or behavioural changes, he said.


  4. 0

    I have indoor cats (2). They have never stepped outside in their 12 years of life. They are very happy. They have a huge run as well that they can get to any time they wish, but most of the time they are inside. It is easy to contain them when you do it from scratch. However when they are used to roaming during the day (as my previous cats were), it is a nightmare trying to lock them in the house. I did it not only for the sake of native life, but also for my peace of mind that my loved animals are safe.

  5. 0

    Some house cats will still try to get outside if they hear the door being opened. Collars can be dangerous as a cat can get hitched up in bushes or trees. Many have been strangled that way. All of our pets – cats and dogs have been neutered. They never bred at all. All but one of them was a rescue pet. That one we were given as a present. I know a family who have a large cat enclosure they can go into for sunshine fresh air etc. Their owners put them in the inner enclosure area if they are going out and they have a space to go out to the outer enclosure. We have had feral cats in the metro area I live in. They are huge cats and will also attack humans who don’t even know the cats are there. They have killed pet cats that have managed to escape outside



continue reading

Health Insurance

Your health insurance is about to go up. Again.

Do you feel like the cost of your health insurance is always going up? You’re not wrong. Premiums are about...


Private health rebate levels are dropping, what does that mean?

We are all used to private health insurance rebates on 1 April every year, but this year the rebates will...

Health news

Doctors call for convicted child killer Kathleen Folbigg's release

A group of 90 expert scientists and doctors is calling for convicted child killer Kathleen Folbigg to be pardoned in...


Adorable celebrity pets

Just like the rest of us, Hollywood's A-listers are pretty obsessed with their pets, especially when it comes to sharing...

Health news

Who needs a colonoscopy most? Ensuring those at risk head the queue

Professor Jon Emery Mary was 55 when she started having on and off tummy pains, and noticed she needed to...

Health & Ageing

What stress does to your skin, hair and nails

Stress can be an all-consuming beast. Not only does it overwhelm your brain, but it can have a physical impact,...


Multi-generational family living grows, forcing design changes

The trend towards multi-generational living, accelerated by the COVID-19 pandemic, is producing fresh approaches to Australian housing. Urban designer Craig...

Seniors Finance

Your retirement 'pay cheque'

Nothing beats the reassurance of knowing there's money coming in each month. Then retirement happens and, suddenly, it's up to...