Breeding out the feral cat problem

By Sophie SchmidtJune 30th, 2022

A new report explores how Australians might feel about the use of gene technology to control invasive feral cats in their local area.
A feral cat staring at the camera with its green eye in focus.

New research by CSIRO shows almost 90 per cent of Australians support the development of genetic technologies to protect our native biodiversity against the growing threat of invasive feral cats. Credit: Unsplash

While feral cats have only existed in Australia for the last 200 or so years, they’ve left a destructive mark on our landscape, contributing to a growing list of Australian native animals that have become threatened or extinct in that time.

Today, feral cats (Felis catus) are rampant in all parts of Australia, covering 99% of Australia’s total land area. That includes ecosystems from deserts to forests and grasslands, and even many of our offshore islands.

Though they might share their species name and genome with their domestic counterparts, that’s where their similarity ends, explains Biosecurity Research Director at CSIRO, Dr Raghu Sathyamurthy.

“Feral cats are opportunistic predators. They’re one of the most significant threats to our native species including small mammals, birds and reptiles,” says Dr Sathyamurthy.

He adds, “We can be fairly certain that they’ve contributed to the extinction of at least 20 Australian mammal species since colonisation.”

Take the Desert bandicoot (Perameles eremiana). Once abundant in the arid country of central Australia, now considered extinct. Or the Mountain pygmy possum (Burramys parvus), currently listed as critically endangered, with fewer than 2,000 of their kind left in the wild.

1.8 billion animals a year

Current estimates are that feral cats kill an average 1.8 billion Australian animals (reptiles, frogs, birds and mammals) every year, or two thousand native animals every minute.

A new type of genetic technology using CRISPR–Cas9, called ‘gene drive’, offers some hope.

It could theoretically be used to suppress populations of invasive pests in parts of Australia. However its potential use in vertebrates, like feral cats, is some way off in most cases (at least ten years).

Gene drive is one of several potential applications of synthetic biology, an area of research that CSIRO has invested in, to build greater scientific capability within Australia over the past five years. Dr Aditi Mankad, Senior Research Scientist at CSIRO, leads a team of social and behavioural scientists exploring the social and economic research aspects of this program.

How gene drive works to control invasive species

Gene drive works by influencing the likelihood of offspring to inherit a certain genetic trait. An enzyme called Cas9, which can cut DNA, could, for example, deliver instructions to shed the X chromosome. This would virtually guarantee the cat’s offspring would be only male. With each generation, the sex imbalance would tip in favour of males, with fewer females left to reproduce. A common misconception is that gene drive might affect other species upon release, which scientists can conclusively rule out.

A single gene drive released into the environment could provide some reprieve for our native birds, reptiles and mammals, sustaining a population decline for at least a couple of decades.

The benefits are significant, and Australia is playing a leading role in the development of vertebrate genetic technologies, according to Dr Owain Edwards, a colleague of Dr Mankad, who leads the Environment and Biocontrol Domain of CSIRO’s Synthetic Biology Future Science Platform investigating the technology. But as with any new area of technology, it’s fair to say that the public would feel cautious about its deployment.

Social acceptability as key

a pair of hands wearing gloves holding a petrie dish .It contains some pink material.
Early social research can help inform technology development, via building a shared understanding of societal expectations for technology development, risk perceptions and the public’s view of the importance of this work. Credit: Unsplash

No gene drives have been released into the environment yet, with experts estimating the technology is at least a decade away from development in most cases. Credit: Unsplash

Dr Edwards has worked in the gene technology space for over two decades.

“It’s not like these kinds of technologies can be released overnight,” he says. “Over the last several decades, scientists have recognised that understanding how the public might feel about a certain technology – and gaining ‘social licence’, is a critical factor to successful deployment.”

“All of this research needs to take place before a trialled release, and way before genetic technologies could feasibly be integrated with current pest management practices,” says Dr Edwards.

Dr Mankad explains that in some cases, early social research can help inform technology development, via building a shared understanding of societal expectations for technology development, risk perceptions and the public’s view of the importance of this work.

That’s why her team set out to uncover the psychological and contextual factors that might influence public attitudes and concerns toward gene drive.

“We knew from previous research that there was lower overall public support for gene drive technology to solve environmental problems when compared to other synthetic biology applications. For example, genetically engineered heat-resistant coral for the Great Barrier Reef or genetically engineered fibres for industry,” says Dr Mankad.

“This study was all about taking a deeper dive into what might influence support and people’s perceptions of risk and value. We hypothesised that community or place-based factors might influence public acceptance for this technology, so we looked to explore those.”

Majority of Australians willing to support gene drive

The Report, Public perspectives towards using gene drive for invasive species management in Australia polled a total of 3,823 Australians as a representative sample of the Australian public.

The researchers produced a simple animation that was provided to survey participants, describing the feral cat problem, gene drive technology and its intended outcomes. A further “local feral cat scenario” was embedded later in the survey, prompting participants to imagine a scenario where feral cats were a problem in their local area and respond to survey questions with that in mind.

As the survey progressed, the researchers posed various questions to understand what made gene drive technology more or less favourable. This allowed them to test several hypotheses, including that cat owners may be more concerned about the consequences of gene drive, or that people who had a feral cat problem in their local area may be more supportive of feral cat management, either using gene drive technology or traditional methods of pest control.

Overall, Dr Mankad’s team found the majority of participants were in favour of gene drive technology.

Almost 68% of respondents were supportive or strongly supportive of the development of gene drive technology for pest control in Australia. A smaller fraction of participants (10%) indicated little or no support for its development.

Participants were more likely to throw support behind the future-oriented technology if they personally felt that feral cats were a problem in their local area.

When it came to when and where to implement the technology, 64% of respondents were comfortable living within 5km of the gene drive release, and another 13% within a broad 20km range. A far narrower margin of participants felt comfortable living upwards of 100km of release (8%).

What do cat lovers think?

Domestic cats (as opposed to feral cats) are often on the receiving end of criticism for the damage cats wreak on the environment. But the survey found that most cat owners would support the technology, although researchers noted that these participants indicated slightly less support than people who did not own or care for a cat.

“We also found that 82% of cat owners would desex any cats they own to prevent cross-breeding with the gene drive cats, which suggests people would be willing to engage in responsible pet ownership practices to facilitate the implementation of this type of technology”.

Was it a case of cognitive dissonance? Pet owners may witness the impact of domestic cats roaming first-hand, and Dr Mankad noted that these results may reflect increased efforts at a local level to educate cat owners on the importance of keeping pets contained.

Social science to inform synthetic biology

From here, the survey results will be used to inform scientists, policy makers, and the wider community about public views on the development and application of possible new biotechnologies in Australia.

“This research has opened an important dialogue for understanding public opinions around invasive species management, and other synthetic biology applications more generally,” says Dr Edwards.

“Gene drive technology is an example synthetic biology application that affects society more broadly, even if it was to be released in a specific geographic area.”

One of the obvious benefits of gene drive is that it offers a more humane approach to invasive species management.

Current strategies available for feral cat management vary across different states and territories including fencing, trapping, baiting and in some cases, shooting.

Generally, experts agree that none of these methods, even when combined, are keeping pace with the catastrophic impact that feral cats wreak on native wildlife.

Levels of support for the local implementation of gene drive technology and conventional cat control methods, as a percentage (%) of total responses. One of the obvious benefits of gene drive is that it offers a more humane approach to conventional invasive species management.

More information on gene drive for invasive species management

Read the report on the CSIRO website.

37 comments

  1. The sooner the better where we are on Magnetic Island.

  2. May I ask why females are not being targeted.

    1. Hi Leigh,
      Great question.
      In the scenario presented to survey participants, the example gene drive would bias offspring to be only male. However, there are also studies into gene drives in which males carry a mutation that suppresses female fertility in their daughters. So, some gene drives can affect females. The reason why we proposed biasing male offspring in this scenario was because it is more efficient for males to spread gene drives through a population rather than females. This is since males can mate many times. This is also why biasing a population towards males is more effective than females in terms of suppressing the numbers quickly.

      Thanks,
      ECOS

  3. Can this be used on feral pigs? They are a huge problem

    1. Hi Ailsa,
      It is theoretically possible that gene drive technology could be used for other feral animals, such as cane toads, feral pigs, or rabbits. However, this report was specific to cats as a target species, and many of its findings around public attitudes are specific to the scenario of gene drive for feral cats. This important research could inform other similar studies into the use of gene drive to control other target species, or public perceptions toward synthetic biology technology more generally.
      We hope that helps.
      ECOS

      1. Please don’t stop at cats

  4. Excellent! Working across the Nullabor Plain in the 70s I was astounded at the number of feral cats across the landscape. For farmers and environmentalist feral cats represent a continuing and never ending problem. It is long past a time when we can afford the luxury of waiting for “nature” to reassert balance. In the age of the techno-natural this technology represents an obvious solution.

    1. Yes please implement it quicker and can we please fund the CSIRO better.

      1. Absolutely right. The CSIRO was a well funded organisation stripped of its assets and functionality by short sighted governments. The Wildlife Division was a fantastic part of the organisation run by dedicated scientists with a passion for learning. Dr Stephen Davies is the point in fact. Resources were stripped away and managerialism imposed. More funding is needed, but more aimed at the researchers and the coal face, not the managers and their advisors. The CSIRO has been treated appallingly, in line with the research efforts of our universities. The consequences are less basic research and more “directed” research tied to corporate outcomes. Can we have our old CSIRO back?

  5. Fantastic.

  6. The sooner the better to get rid of ALL Feral animals !!!!!!!!

    1. Yes and all over Australia .

  7. Agreed . Sooner the better
    Cats , foxes , deer , rats , pigs , mice , cane toads
    There is a lot of research work to do
    Fund it handsomely and fund it now

  8. I’m a cat owner and I love domestic cats. I fully support the use of a gene drive as described here.

  9. I have 3 (wasn’t meant to be 3, I’ve had a succession planing fail, the 16yrs with multiple health issues is still going strong) indoor only cats. We live in rural Vic and I absolutely support any humane measures to control feral cats. Agree with other comments on the possibility of controlling other introduced species. Our environment is so special, so unique, you are not a responsible pet owner if you don’t want to see action. And for the record, I have horses and I believe the same should apply to feral horses especially in our high country

  10. Good work CSIRO !!!
    What can I (joe public )
    do to help ,ten yrs is too long to wait!!

  11. An excellent way to apply CRSPR technology

  12. What consideration has been given to how this technology might be weaponised in the future and used on human populations?

    1. This is not an irrelevant question in terms of public sentiment. The survey topic does beg the question. I’m sure it is technically possible to apply to humans and someone is probably researching it already somewhere. The crisper technology already exists. It’s just a matter of ethics.

      But this question is about putting it to work an feral animal species, particularly cats. Slippery Slope arguments may (ironically!) get traction in public discourse.. but they shouldn’t stop targetted use to save ecosystems and their occupants.

  13. Excellent CSIRO. I strongly support this. More funding for the CSIRO?

  14. What a great piece of work! Congratulations on yet another excellent scientific initiative. Hope it leads to a elimination of all sorts of feral animals in addition to cats.

  15. I fully support this and look forward to the day when it will be available for all feral animals in Oz. Good work CSIRO.

  16. Please please please do what ever you can to get rid of the Feral cats don’t stop there Fox pig camel horse donkey goat etc etc have to be eliminated

    1. I agree and can we please fund the CSIRO better.

  17. Totally agree – get rid of cats, foxes, pigs, goats, etc etc. BUT, how to stop a sort of reverse invasive species thing – can we ensure that the cats, foxes, pigs, goats etc won’t get overseas?

  18. My support also

  19. This is a fantastic idea, it should be developed and used across the board on all introduced pests to Australia, but one question is, should it be used on dogs? Dingoes were introduced to Australia around 3000 years ago and the extinction rate of Australian native animals has been incredibly high since the arrival of the Dingo.

  20. I agree with “Fox pig camel horse donkey goat etc etc have to be eliminated” IN AUSTRALIA.
    But extreme care has to be exercised so that these gene drives don’t go overseas, to where these animals are a natural part of the environment. Just because our place is broken doesn’t give us permission to break other paces in revenge.

    1. Good point and it needs to be addressed. How do we protect non target ecosystems from accidental or malicious export?
      I can imagine even a well meaning altruistic or commercially driven export of an animal to prevent it being subjected to the drive (eg a sentimental pet or fancy variety). If such an export was done without testing to ensure it was not already “edited”, it could be an issue. Even a liability.
      Could CSIRO or Australia be sued for such an event causing a population collapse in an overseas population?

  21. I’m not a fan of GMO’s, but I AM a fan of using this technology to control invasive species.

  22. Never thought I’d see the day! I’m smiling.

  23. We love our domestic cats but never let them loose on the environment: they have a large dedicated secure area to give them some respite from being inside. They are fully accepted of it (you can’t miss what you’ve never had!). Lock up your domestic cats and spend whatever it takes to destroy these environmental destructers.

  24. Can we make it retrospective please?

    Love the concept and fully support feral cat eradication.

    Perhaps the RSPCA could come on board and suppirt the ‘harvesting’ of feral cat hydes in the interim.

  25. Sounds exciting. Interesting to see that gene drive technology has greater community acceptance than conventional feral cat control methods. Let’s up the funding and the pace of research!

  26. Do y’all not have TNR in AU?

    1. Hi Amanda

      I’ve just googled TNR and found websites similar to https://www.neighborhoodcats.org/how-to-tnr/getting-started/what-is-tnr (very pro TNR), as well as others that are more critical. Trap-Neuter-Return may or may not be a reasonable strategy for cats that live in urban areas with easy access, little remaining wildlife, and people prepared to pay the feeding cost and effort for perhaps the next 10 years.

      It seems to me that this approach is favoured by, specifically, cat lovers, who have time and money to spare.

      I am an ecologist. An ecologist is quite different from a lover of a specific animal. I deal with the survival and welfare of not just one preferred species, but hundreds, at a landscape scale.

      If you look at a map of Australia, you will see it is almost the same size as USA, but it has less than 1/10 the population, and has vast areas that are practically inaccessible. One of the areas that I deal with is 520 square miles of rugged mountains. The few vehicle tracks there tend to break gearboxes, axles, chassis, and get about 1500 miles per set of tyres. That country takes two days for fit and experienced hikers to travel 10 miles, the average distance between tracks. The area, despite intense culling efforts, contains around 450 cats. A recent attempt at re-introducing a small native mammal has failed, with cat DNA on the remains showing why.

      As you might imagine, the notion of even catching the cats, let alone humanely delivering them to a vet and then returning them and then feeding them, is quite impractical.

      In order to gain some understanding of the problems that we face, and how different they are to those of urban areas, you might like to peruse the following or similar.
      https://en.wikipedia.org/wiki/Trap%E2%80%93neuter%E2%80%93return
      https://en.wikipedia.org/wiki/Cat_predation_on_wildlife
      https://en.wikipedia.org/wiki/Cats_in_Australia
      https://www.nespthreatenedspecies.edu.au/news-and-media/latest-news/the-mathematics-of-cats

  27. This is a game-changing initiative. I recommend that everyone who reads this writes to their local Federal MP and INSISTS that gene-drive be released to tackle the feral cat crisis. Maybe target Tanya Plibersek, as she is the key person who can make this happen. Send them a copy of this article so they can understand the public IS supportive. Thanks.

Leave a Reply