This Chapter considers matters pertaining to feral cat control raised in evidence to the inquiry, particularly relevant considerations for different methods of control, including animal welfare.
Feral cat control methods
Submitters to the inquiry suggested that no single method for controlling feral cats is effective. One estimate provided to the Committee was that current feral cat control methods result in the decline of less than ten per cent of the population annually.
The Society for Conservation Biology Oceania Section submitted that:
There is no silver bullet for reducing the impacts of cats and the best approach, or combination of approaches requires a broad suite of techniques that include both lethal and non-lethal approaches …
Dr Andy Sheppard of the CSIRO told the Committee that:
Control strategies require robust impact assessments and monitoring programs based on pre-defined objectives associated with the reduction in cat populations and changes in the numbers of relevant listed species. Attempts at widespread culling are rarely sustainable but can be effective where effectively coordinated and targeted at key times—for example, under drought. Eradication has little relevance except in a very limited number of situations.
In its submission to the inquiry, the Department of Agriculture, Water and the Environment (DAWE) included a table of the feral cat control tools available in each state and territory. This is included at Figure 4.1.
Figure 4.1: Snapshot of tools available in each state/territory
Department of Agriculture, Water and the Environment, Submission 58, p. 22.
The most common method for feral cat control in Australia is poison baiting. Essentially, poison baiting is the technique of embedding a toxin in an edible protein that is dispersed in areas of feral cat prevalence. The bait is then ingested by the animal and leads to its likely death.
DAWE told the Committee that:
Baiting can be the cheapest and most effective broadscale technique for controlling the numbers of animals.
Regulation by APVMA
Toxins used for feral cat management are regulated by the Australian Pesticides and Veterinary Medicines Authority (APVMA), under the Agricultural and Veterinary Chemicals Act 1994 and Agricultural and Veterinary Chemicals Code Act 1994.
Ms Lisa Croft of the APVMA described the regulator’s processes in approving products:
The APVMA is the independent statutory authority responsible for the assessment, registration and regulation of agricultural and veterinary chemicals in Australia. Agvet chemical products must be evaluated and registered by the APVMA before they can be legally sold, supplied or used in Australia. The APVMA takes a systematic scientific and evidence based approach to decision-making and operations. We evaluate the safety and performance of chemicals intended for use and sale in Australia to protect the health and safety of people, animals, crops and the environment and to ensure that registered products do not jeopardise Australia's trade.
DAWE advised the Committee that to obtain registration for a product to manage feral cats:
… a comprehensive evaluation of the efficacy and risks of the toxin and product to people, the environment and to specific native animals that could encounter the product is undertaken.
Some submitters were of the view that the APVMA approvals process, while geared towards risk management, was onerous and time consuming. The Invasive Species Council noted for example that it took three and a half years for the APVMA to approve the Curiosity bait (discussed further below).
In discussing the process to approve the Curiosity bait, Ms Croft told the Committee that:
It was a particularly complex application … It was a new novel toxin delivery mechanism. Often when we are assessing new products in the APVMA, the delivery mechanism by which it might be delivered in the marketplace is something that we may have already assessed for a different product at some other point in time, but this was a completely new novel toxin delivery mechanism. In particular, that hard shell delivery vehicle for Curiosity was new technology and therefore it did require an additional amount of consideration beyond what we might expect for other normal new products in the marketplace.
According to Ms Croft, the factors that required the product to have an extended approval time included the requirement for DAWE to provide additional data and mitigation strategies for the product’s intended use. Ms Croft further advised that:
… it is a restricted chemical product and, under the Agvet Code, that requires additional consultations and authorisations by state and territory governments. Also, as part of the application, we were keen to ensure the broadest applicability of the product once it was registered.
The Invasive Species Council said that while it understood the reasoning behind the lengthy approvals process:
Proving the efficacy and safety of new methods across large areas of Australia is complex and expensive. The development of new products for controlling feral cats and other harmful invasive animals is very much in the public interest, so should be facilitated rather than impeded by the processes developed for agricultural products that are applied over very large areas and affect the safety of food for humans.
UNSW’s Centre for Ecosystem Science submitted to the Committee that the current approach to approvals via the APVMA is:
… a state by state approach to regulation. This is an area where there could be considerable harmonisation in approaches whereby one state could adopt legislative and regulatory approaches from another jurisdiction once there has been sufficient review of the potential impacts on non-target fauna.
UNSW’s Centre for Ecosystem Science was of the view that a more risk-managed approach should be adopted to hasten the approval of products. In particular, the risk to wildlife of not conducting feral cat control should be considered.
Approved baits: Eradicat and Curiosity
There are two bait products registered for use in parts of Australia, the Eradicat bait which is registered for use in Western Australia, and the Curiosity cat bait which is registered nationally. The Centre for Invasive Species Solutions (CISS) has developed a collaborative project, led by the Government of South Australia, to facilitate the national registration of the Eradicat bait through the APVMA.
The CISS described the Eradicat bait that ‘consists of a chipolata sausage style bait matrix into which the toxin 1080 is directly injected’.
DAWE told the Committee that the Curiosity bait is also a small meat-based sausage, but it contains a small hard plastic pellet, delivering ‘a new humane toxin called para-aminopropiophenone, or PAPP, which is considered best-practice world-wide’.
Effectiveness of baits
Some inquiry participants commented on the effectiveness of baits. Broadly, DAWE advised that:
Baiting techniques for feral cats tend to be much less effective than techniques for baiting wild dogs and European red foxes because feral cats prefer live prey.
Dr Tony Buckmaster from the CISS advised the Committee that:
… national registration of an effective bait such as Eradicat is quite likely going to assist in turning the tide. … The majority of the tools that we have are limited area use—exclusion fencing, trapping, shooting. They're very good in small areas, but only baiting, in reality, is good for a larger area.
Professor Sarah Legge from the Threatened Species Recovery Hub (TSRH) told the Committee that:
Poison baiting with Eradicat has made a really positive contribution to conserving animals in south-west WA, where native fauna have high tolerance to that toxin.
Dr Buckmaster told the Committee that the PAPP toxin contained in Curiosity is not a replacement for Eradicat’s 1080 toxin:
It's a supplement. It's an additional item in our toolbox. We're loath to use PAPP in areas where there's high goanna activity, because reptiles are generally more susceptible.
Emerging bait technologies
The Committee was advised that there are other emerging bait technologies that may be more effective in targeting feral cats while being less harmful for other species.
DAWE submitted that the APVMA:
… also issues research and minor use permits for … other 1080-based baits such as Hisstory. These are typically issued where a product is in a research and development phase prior to applying for registration or are intended to be applied in [a] small area for a restricted time with minimal risks.
CISS advised that the ‘Hisstory® bait is similar to the Curiosity bait however uses encapsulated 1080 rather than PAPP as the toxin. This bait is not currently registered for use in Australia.’
Risks and concerns about feral cat baits
A number of inquiry participants drew the Committee’s attention to the risks and concerns associated with feral cat baits.
DAWE told the Committee that generally:
Baiting can pose risks to other species that may eat a bait. Baits are designed to contain the least amount of toxin required, which reduces the risk to species that have some tolerance (e.g. goanna species that are tolerant to a cat-sized dose of 1080 toxin).
The Department noted that the placement and timing of baiting can also reduce risks, such as using them when and where reptiles are less active.
With respect to Curiosity, DAWE also explained that its design improved target specificity:
The use of the pellet has been found to minimise exposure to many native species to the toxin. … [In addition,] Felids and canids (cats, dogs and foxes) are particularly susceptible to this toxin meaning only low doses are required, less than what is necessary to harm many native species if they managed to consume the pellet.
A number of submitters nevertheless raised ethical concerns about both the 1080 and PAPP toxins. Concerns included that:
animal welfare concerns once the toxin is ingested by a feral cat are poorly understood, and it may take several hours or days for the animal to pass away; and
wildlife including dingoes; and pets, can be inadvertently impacted or killed by baits containing the toxin.
The use of cat traps is one of the more common cat control methodologies. As discussed in Chapter 3, traps are often used in cat control schemes managed in urban and regional areas by local governments. The Committee was told that there are two types of traps in use – cage traps and padded-jaw traps.
DAWE told the Committee that:
Cage trapping is considered to be an ineffective tool for large areas, but it may be useful in urban/residential areas where domestic cats are present, or where populations have already been reduced and individual cats need to be targeted. Padded-jaw traps are useful for sites where the feral cat can be destroyed by shooting while still held in the trap. They may also be more effective than cage traps for hard-to-catch feral cats that have had minimal exposure to humans.
DAWE explained that:
With both techniques of trapping, skilled operators are required to set the traps and lures to attract the feral cats. Trapping is expensive, labour intensive and time consuming; and is only recommended on a small scale or where eradication is the objective.
Other types of traps also exist but are either banned, such as the steel-jaw trap or are currently being developed under a research permit, such as the Felixer grooming trap.
Felixer grooming trap
The Felixer grooming trap is a technological advance under development. DAWE told the Committee that:
Felixer grooming traps are under assessment for registration as a product with the Australian Pesticides and Veterinary Medicines Authority. Limited use is permitted under research permits while the registration is being assessed.
DAWE told the Committee that the benefits of the Felixer grooming trap include provision of:
… a novel technique for controlling feral cats by ejecting a dose of poison onto the fur of a target animal, which is subsequently ingested through grooming. A series of infrared laser-based range-finding sensors detect object[s] moving in front of the Felixer. The sensors’ positions allow for feral cats to be distinguished from other non-target animals.
Dr John Read submitted to the Committee that the Felixer grooming trap has:
… proven to be highly targeted and efficient at controlling feral cats with particular value in areas where baiting is not permitted or for cats that are reluctant to take baits or enter traps. Felixers have also proven useful in eradicating cats from fenced reserves and for minimising cat incursions and reducing cat predation outside fenced reserves (where cats congregate to prey on emigrating wildlife). Greater attention to deploying Felixers around reserves and along feral cat reinvasion pathways and native wildlife corridors should assist threatened wildlife to colonise areas outside reserves. Other fences and barriers (e.g. along highways or around rubbish dumps) are also prime locations for Felixers to be deployed to reduce feral cat and fox predation without exposing wildlife or pets.
The Society for Conservation Biology Oceania Section commented that the Felixer:
… can be loaded with 20 dischargeable doses of 1080 and are powered by batteries with solar rechargers ... Therefore, they can be left in situ for months, making them a less labour-intensive management option compared to trapping, shooting and poison baiting.
On the future potential and success rates for the traps, DAWE told the Committee that:
Felixer grooming traps have the potential to provide feral cat, and European red fox, control at conservation sites where the feral cats can be directed to walk in front of the site, such as along a management track or stream bed.
The Society for Conservation Biology Oceania Section submitted that:
Felixers record data on detections of both target and non-target species, and two recent trials suggest they have a low rate of false-positives (i.e. non-target species squirted; 8.53% and 0.00%, respectively), and a high rate of correctly identifying as cats as targets (82% and 77%, respectively ...
Feral cat-free areas
According to evidence presented to the Committee, feral cat-free areas are very effective in the management of feral cats and importantly, in the recovery and reintroduction of native wildlife. Two types of feral cat-free areas exist in Australia: predator-free fences and islands.
Predator-free fencing is considered an effective technique against feral animals and provides native animal populations with a safe and secure environment within which to be reintroduced without the threat of predation. DAWE submitted to the Committee that:
Exclusion fencing to protect against invasive species is an effective technique for native fauna vulnerable to feral cats. There are at least 24-30 functional fenced areas maintaining wild, self sustaining populations of threatened species across Australia.
One of Australia’s key developers of predator-free fencing is Australian Wildlife Conservancy (AWC). AWC told the Committee that:
Well-designed and maintained conservation fences are highly effective in protecting and recovering small- to medium-sized mammals vulnerable to feral cats. Conservation fences are substantial pieces of infrastructure requiring careful planning and competent, long-term management, as well as scientific capacity for planning and managing populations/genetic integrity over the long-term. Fences have relatively high capital costs and up-front feral predator eradication costs, but modest running costs.
One of the key benefits of predator-free fencing is the ability for the recovery and reintroduction of native wildlife. AWC submitted to the Committee that its fences currently support a total of 15 nationally threatened mammal species: Kangaroo Island Echidna, Northern Quoll, Western Quoll, Red-tailed Phascogale, Kangaroo Island Dunnart, Numbat, Golden Bandicoot , Western Barred Bandicoot, Greater Bilby, Western Ringtail Possum, Burrowing Bettong, Woylie, Northern Bettong, Mala, Banded Hare-wallaby, Bridled Nailtail Wallaby, Black-footed Rock-wallaby, Greater Stick-nest Rat, Plains Mouse, Shark Bay Mouse, and Central Rock-rat.
AWC submitted that there were a range of advantages to predator-free fencing:
Efficacy - at present, conservation fences are the only proven method for conserving and reintroducing species highly vulnerable to predation by feral cats on the mainland and large islands.
Security - fences secure populations of threatened species, allowing more risky control measures to be attempted in adjacent areas ‘outside the fence’.
Ecological understanding - conservation programs associated with fences enable research on otherwise locally-extinct species and their ecological interactions; and allow for ready comparison of animal communities and environments with and without the distortion due to introduced predators.
Cost-effectiveness - long-term cost savings, compared with on-going direct control.
No requirement for long-term poison baiting, with its accompanying risks of non-target impacts.
Exclusion of other feral pests (e.g., goats, donkeys), with benefits to ecosystems.
Community engagement – reintroduction programs in fenced exclosures allow the public to realise that Australian mammals can and should be abundant, and offer hope and a basis for a restored future.
Predator-free fences do have some limitations. DAWE told the Committee that:
Their use is increasing but tends to be limited to the management of highly valued threatened species that can live in relatively small areas from which feral cats can be eradicated. Fencing also affects the movement of other wildlife and may prevent their dispersal and interbreeding with other populations.
AWC summarised the disadvantages of predator-free fencing:
Scale - the largest completely feral predator-free fenced areas on the Australian mainland are 95 km². While large enough to support viable populations of many threatened species, and larger than many protected areas, nevertheless this is a tiny proportion of the Australian continent.
Landscape suitability - limitations on fence construction in steep, high rainfall and/or flood-prone landscapes.
Connectivity - fences may constrain the movement of terrestrial species.
Collision/entanglement - potential impacts on some birds and reptiles.
Predator naiveté - removes opportunity for populations to adapt to introduced predators, although evidence that such adaptation may occur in vulnerable Australian species is extremely limited, and some animals in fenced areas can be exposed to feral cats to develop predator awareness.
‘Overabundance’ – in the absence of feral predators, native mammals may reach relatively high densities, with knock-on effects for vegetation/habitat. These issues appear mostly to be associated with small enclosures and arid environments. Densities in AWC large fenced areas generally appear similar to remnant ‘wild’ populations, and respond to resource availability (increase/decrease with rainfall, etc).
Society for Conservation Biology Oceania Section noted the costs of predator-free fencing:
Exclosure fencing also requires a considerable upfront cost, including feral eradication, fence construction, and ongoing maintenance and repairs, resulting in an estimated cost of $120,000 for 1km² and $400,000 for 10 km.
Despite these concerns, some inquiry participants were of the view that there should be more predator-free fencing erected around Australia to ensure the survival of more threatened species.
During the inquiry, Committee members learned about the AWC’s proposal to use ‘social bonds’ as a tool for the funding of predator-free exclosures. AWC submitted to the Committee that:
AWC has been engaging in ongoing discussions with government in relation to this Proposal. The Proposal…is an innovative 10 year $50 million Biodiversity Impact Bond (BIB) which will be invested in by Australian superannuation funds (First State Superannuation) and be matched dollar for dollar by philanthropic contributions to AWC, resulting in projects with a total value of circa $100 million. Importantly, the Proposal will deliver circa $100 million of projects but will have no impact on the Federal Budget over the forward estimates.
Professor Legge discussed the advantages of this type of innovation, advising the Committee that:
… One of the advantages of an NGO is that they can have quite a focused objective and they can push all of their energies towards achieving that objective and demonstrate that it works. Sometimes in government things are more complicated, so having private innovation mixed with the scale of government and the responsibility and obligations that governments have can be very productive.
As part of the inquiry, the Committee had the opportunity to visit Mulligans Flat Woodland Sanctuary, which includes a predator-free fence and is home to a number of reintroduced native species. The Committee also explored the work of AWC, and in particular, a project that it is undertaking in northern NSW. Unfortunately, travel restrictions imposed during the
Covid-19 pandemic prevented the Committee from undertaking a proposed visit to the AWC site. Boxes 4.1 and 4.2 provide further information about these projects.
Box 4.1: Mulligans Flat Woodland Sanctuary
Mulligans Flat Woodland Sanctuary is situated within the Mulligans Flat Nature Reserve. The Sanctuary is owned by the ACT Government, is part of the ACT’s nature reserve system, and is managed by the ACT Parks and Conservation Service as one of the many areas that are known collectively as Canberra Nature Park. The Sanctuary includes a predator-free conservation fence.
The Sanctuary fence encloses approximately 485 hectares of Mulligans Flat Nature Reserve and has a perimeter of 11.5 km. The fence design is largely based on the cat, fox and rabbit-proof fence surrounding the Arid Recovery Reserve near Roxby Downs, South Australia. The design was adapted by the ACT Parks and Conservation Service using local expertise in ACT reserves, and in consultation with fencing contractors to cater for the grassy-woodland habitat at the site.
The fence is 1.8m high, with 7 plain wires supporting rabbit-proof mesh (30 mm), two electric wires, a 60cm ‘floppy overhang’, and with trenched/buried netting for a width of 45cm on either side of the centre of the fence.
Nineteen gates are located on the main management tracks along the entire length of the fence to facilitate public access in the Sanctuary and to allow for routine and emergency vehicle access. Each gate has a self-closing mechanism designed to maintain the integrity of the barrier to predators, and remote sensing of the gates alerts ranger staff to any malfunction to gate closures.
Some specially designed internal fences have been erected within the Sanctuary as part of an experimental research program being conducted by the Australian National University. These fences are designed to exclude kangaroos or bettongs from several groups of experimental sites.
Box 4.2: AWC Pilliga
Australian Wildlife Conservancy’s project in NSW’s Pilliga National Park is managed under a partnership between the NSW National Parks and Wildlife Service and AWC. The agreement provides a new model for collaboration between the public sector and the private (not-for-profit) sector. As part of the NSW Government’s Saving Our Species program, a feature of the partnership is the construction of a large predator-free area, and the reintroduction of several regionally extinct mammals.
The Pilliga project is part of the traditional area of the Gamilaraay (also known as Gamilaroi or Gomeroi) people. Extending over half a million hectares, the Pilliga forests are the largest consolidated block of forest and woodlands in western New South Wales, giving them extraordinary conservation value.
Across the 35,632 hectare Pilliga project area, AWC is implementing a landscape-scale feral animal control program, combined with intensive weed control. The research effort by AWC informs ecological fire management practices.
The focus of AWC’s science and land management at the Pilliga project area has been the establishment of a large (5,800 hectare) fenced fox and cat-free area. This will be one of the first large feral predator-free area in the NSW national parks estate, and allows for the reintroduction of species that have been extinct in the area for more than 100 years:
Western Barred Bandicoot;
Bridled Nailtail Wallaby; and
TSRH considered the prevalence of cats on Australian islands, concluding that:
… feral cats are now present on about 100 Australian islands, representing about 2% of the number of Australian islands larger than one hectare (ca. 5500 islands); however, cats are present on most larger islands, so their island occurrence represents about 80% of the total area of Australian islands (ca. 33,000 km²). The total area of islands known, or likely, to be unoccupied by cats is between 5,539 km² to 8,074 km² (about 0.1% of the Australian land mass).
In relation to islands, TSRH said:
Australian islands are critical for the conservation of many Australian animal species that are susceptible to introduced predators (cats and foxes); and many also have significant breeding colonies for seabirds and marine turtles that are also readily depleted or destroyed by introduced predators.
DAWE submitted to the Committee that eradication of feral cats is ‘an attractive option because, once achieved, it requires no further commitment of resources other than for monitoring and maintaining biosecurity’. DAWE advised that:
There are a number of conditions necessary to achieve eradication from a site:
The rate of removal exceeds the rate of increase at all population densities
There is no immigration
All reproductive animals are at risk (e.g. all females in the population can be eliminated).
All animals can be detected at low densities
Discounted cost-benefit analysis favours eradication
There is a suitable socio-political environment.
In terms of island eradications, DAWE told the Committee that it has:
… an expensive up-front cost. For all islands there will be planning and implementation costs, and highly variable costs for the remoteness of the island and managing non target native species risks. Any inhabited island or an island with cultural significance to Traditional Owners or interested people will require significant community engagement.
The Ecological Society of Australia told the Committee that:
There are many opportunities to increase the use of cat-free islands to recover native wildlife populations that have declined due to cat impacts on the mainland …Of the 592 Australian islands known to be cat free, only 101 are known to currently support populations of mammal species vulnerable to predation by cats … Many of the remaining islands are suitable for translocation of cat-sensitive species. A more coordinated, centralised approach to designating cat-free exclusion areas at a national scale is necessary.
Many inquiry participants were supportive of the use of islands as a basis for feral cat eradication projects. As part of the Action Plan within the Threat Abatement Plan, the Australian Government has targeted the eradication of cats from five Australian islands. The Department highlighted some of this ongoing work:
An ambitious program on Christmas Island that aims to eradicate all feral and stray cats. The program employs roadside baiting, cage trapping, soft-jaw leg-hold trapping and shooting. Since 2010, over 1,200 cats have been removed from the island. The program has a strong focus on evaluation and improvement … The program is underpinned by community engagement. Eradication is only possible because of support from the Christmas Island community. Christmas Island requires pet owners to register and de-sex all domestic cats on the island, and no new cats may be brought in.
DAWE also told the Committee of another project that is underway:
A feral cat management program that commenced on Norfolk Island in 2018 to reduce impacts on the island’s threatened bird species, particularly the Norfolk Island green parrot. The program has seen an increase in trapping effort across the island, accompanied by monitoring to record changes in patterns of cat occurrence and evaluate effectiveness of management, as well as community engagement to strengthen management of domestic cats.
Submitters told the Committee of work on other islands to eradicate feral cats including:
A project underway on South Australia’s Kangaroo Island which has included the trial of some emerging technologies, and the creation of a ‘safe haven’ for the Kangaroo Island dunnart and other priority threatened species.
Successful feral cat eradications on six Tasmanian islands (Little Green, Great Dog, Macquarie, Tasman, Wedge and historically Betsey Island). Cats have likely died out from seven islands (Deal, Outer Sister, Courts, Fulham, Swan, Schouten and St. Helens Island).
Some inquiry contributors discussed the potential use of biological agents, such as the release of a virus, to assist in managing the feral cat problem. The Committee was told that such a strategy had been shown to be effective for rabbits. According to the evidence before the inquiry however, it is clear that such a proposition for feral cats has yet to be proven effective.
DAWE told the Committee that:
The use of a biological control, such as a cat-specific virus, has appeal as a broadscale control tool for feral cats. For Australia, a study … found it unlikely that any felid-specific pathogen may be suitable as a sufficiently virulent and humane biological control agent from which domestic cats can be protected. Research has been underway for a number of years to identify other potential viruses and pathogens however no new suitable pathogens have been identified since 1995. None are available or acceptable for immediate application as a lethal biocontrol agent for cats.
The Western Australian Biodiversity Science Institute (WABSI) told the Committee that:
Feline leukaemia virus, feline immunodeficiency virus and feline panleucopaenia virus are all present in Australia, but have low transmission rates where cat density is low. However, feline panleucopaenia virus was successfully used as part of an integrated control program against feral cats on one small subAntarctic island … and, if social acceptability changes, may be effective as a control solution where cats occur at higher densities. If this approach was given further consideration, effective vaccinations are available for all three viruses to protect the pet cat population. As with any disease-causing biological control agent, humane aspects will also need to be considered to meet community expectations regarding animal welfare.
Asked about whether the potential for a cat calicivirus or similar virus or a cat myxomatosis that could be selective for feral cats, Dr Tanja Strive of the CSIRO advised:
There was a really extensive systematic review conducted in 1995 by Elizabeth Moody and funded by the Australian Nature Conservation Agency. This report systematically assessed over 150 known pathogens of cats, including seven viral diseases. But the recommendations of that report were that none of the pathogens was considered a suitable—or available, at least—biocontrol for cats in Australia, and to my knowledge no new cat pathogen has emerged since then that would meet the requirement for an ideal viral biocontrol agent and warrant a second look.
Gene drive technology
Many submitters to the inquiry suggested that gene drive technology held promise as a method to control feral cats. However, development of the technology was in its infancy. Other submitters also noted ethical concerns.
Novel gene drive technology is an emerging technology that has potential for use in feral animal control programs by genetically altering entire populations … Novel revolutionary genetic technologies have recently been developed that can force modified genetic traits into an animal population, defying the constraints of normal Mendelian inheritance.
DAWE provided some examples of the potential application of gene drive technology, advising the Committee that it could be used ‘to alter the sex bias of new animals that will eventually lead to a population crash or sensitising specific species to a particular toxin and thereby rendering them susceptible to it.’ DAWE added that:
Delivered and spread through sexual reproduction, the potential of this powerful new technology is unprecedented, making species specific and more humane pest control or even eradication theoretically feasible.
WABSI was of the view that:
Synthetic gene drives could be used to force deleterious traits (many are being considered) through target populations or lead to male-only progeny. Alternatively, gene shears could be carried within germ cells that shred a sex chromosome to achieve the same result. Other potential approaches are still under development, including safety mechanisms to prevent uncontrolled spread to other species and the theory and understanding of their likelihood of success.
Dr Owain Edwards from the CSIRO advised the Committee that the development of gene drive technology is in its early stages, is presently focussed only on laboratory work in mice and could take some 10 to 13 years before it is fully developed for use in species such as cats. Dr Edwards noted that following development, ‘we then have to meet regulatory requirements and ensure that the public is accepting of the use of the technology. So it would probably be a 15- to 20-year time frame at least before it would actually be available for use.’
Dr Edwards also considered the research that is still required for gene drive technology’s use on cats:
… considerable research is required on feral cat reproductive biology, ecology and population genetics, which is necessary before we can assess whether feral cats are a feasible target for this technology. This research can be done while we wait for the technology to be fully evaluated in mice and will tell us whether it's worth making the investments with that technology for feral cats. It's good that this same research would also be relevant to other landscape focused management strategies.
Given the relatively recent emergence of gene drive technology, the Committee was made aware of several projects that are underway to understand more about how it could be applied.
The Committee was advised that the CSIRO had begun to investigate the issue of gene drive technology but it was not yet considering such methods for cats:
CSIRO is currently working as part of an international consortium called GBIRd or Genetic Biocontrol of Invasive Rodents, which is aiming to develop a gene drive type genetic control for mice on islands. But CSIRO will not start developing this technology in any other invasive vertebrate, including feral cats, until it has been proven safe and effective in mice. This is because mice, in addition to being environmental and agricultural pests, also have the benefit of being excellent laboratory animals for genetic research.
Risks of gene drive technology
While some submitters were supportive of the development of gene drive technology, others warned of the possible risks.
DAWE told the Committee that:
With the use of any form of genetic technology consideration will need to be given to the risk of movement (legal or illegal) of the gene-drive modified populations internationally to countries where Felis catus is a native or desired species. In addition, there will need to be public acceptance in Australia of both the technology and the specific application to feral cats prior to any release.
WABSI told the Committee that:
The social licence aspects of such a control solution are arguably just as important as the technology itself, which is why this is a high early research priority.
Friends of the Earth Australia and GeneEthics submitted to the Committee that there ‘is a concern that gene drives could potentially spread to populations that they are not intended to– or … related species.’
Shooting and hunting
Traditional methods of lethal animal control, such as the hunting and shooting of feral cats, are a known quantity. These methods were a significant feature of the Victorian parliamentary inquiry that was discussed in Chapter 3. Broadly, that report found:
… that recreational hunting cannot remove enough animals by itself to manage the invasive animal problems in Victoria. Nonetheless, the evidence received by the Committee suggests that recreational hunting can be an effective part of programs involving multiple control methods for certain species in some circumstances, if the hunting effort can be focussed at particular times and places.
Submitters to this committee’s inquiry offered mixed views on the efficacy of these techniques. A number of submitters were supportive of hunting and shooting. In contrast, other submitters offered a different view, highlighting the limited scope of the techniques and the circumstances in which these could be used.
DAWE submitted to the Committee that:
As a control technique, shooting is most appropriate if applied for an extended period or timed for critical periods. Ongoing shooting is appropriate in areas where there is a continual immigration of feral cats from surrounding areas and the species being protected from predation is vulnerable all of the time. Critical periods of shooting can be undertaken in locations where either there is a rapid increase in feral cat numbers, such as in response to a prey irruption, or at a time in the threatened species life cycle, such as during breeding, when the population of the threatened species is at a higher risk.
DAWE also told the Committee that:
Shooting is usually done at night from a vehicle with the aid of a spotlight but can also be conducted during the day. Shooting is expensive, labour intensive, time consuming and can only be done on a relatively small scale because of the resource requirements and high cost.
The CISS advised that shooting:
… is both labour and time expensive and is not able to be used at a landscape level, nor …an option for management of feral or stray cats in urbanised areas.
Some submissions advocated that scope for existed for recreational shooters to contribute to feral cat control efforts. Some proposed the payment of a bounty. Others advocated against the use of shooting on the basis that it was an inhumane practice.
Feral and stray cat control in urban environments
Dr Sally Box told the Committee that:
The control tools that you can use in an urban area for stray and feral cats are going to be limited because of roaming domestic cats. But there are certainly things that can be done, like fencing off rubbish dumps and things like that where you can get a concentration of stray and feral cats around those food sources. So, there's the work that you can do with domestic cats and responsible pet ownership and there's the work you can do to try to cut off the food sources for stray cats in cities. Then, obviously, there's the trapping that you can do to try to capture those stray and feral cats in the cities, but you're going to be limited with your shooting and baiting tools.
Trap Neuter Release
One technique that was proposed by submitters to the inquiry was that of trap, neuter, release (TNR) – where urban stray cats are caught, desexed and then released. A number of inquiry submitters were supportive of this method of feral cat control which has been successful in the United States, however the vast majority of submitters were not.
Dr Jacquie Rand of the Australian Pet Welfare Foundation said that the TNR technique is often a used within community-based cat programs where residents take it upon themselves to care for a cat which they may not necessarily own. Dr Rand elaborated on this notion:
We're seeing that about 70 per cent of the cats that we're discussing are semi-owned cats. People are saying that, before they heard about the program, they didn't consider themselves the owner of the cat and that the cat was their property; they considered themselves the carer or the guardian, but they are happy to take ownership and have their name listed on the microchip database.
Dr Rand provided an example to the Committee of how such programs operate:
We were dealing with a farm. This lady lives right on the edge of the suburbs and she has about a dozen cats. There are adult females that keep having kittens. … She is happy to have them desexed. She wants to own three of them … [TNR is] only a small component but it's an important component, because you don't want those other nine cats continuing to produce kittens. It's been shown overseas to work. These people who are against it have no other solution but to increase the killing of cats …
DAWE submitted to the Committee that it does not support TNR as a management tool for stray cats:
… as effective programs require a well-defined and contained area with no immigration of other cats, where there is limited impact on wildlife and the wellbeing of the animals is able to be maintained. These requirements cannot be met in Australia.
The TSRH submitted that:
The evidence from numerous trials carried out in a range of countries show that TNR does not reduce the overall population size of urban ferals (owned, stray) cats because of continual immigration from outside the colony. Desexed cats that are returned to the area where they were caught continue to hunt, so their impacts on wildlife are unabated.
Dr Tony Buckmaster from the CISS told the Committee that:
It's undoubtable that the inquiry will have received submissions indicating that trap, neuter and release programs should be used to manage feral cats. There is, however, extensive evidence that these TNR programs are not capable of effectively reducing feral cat or stray cat populations even at a very small or localised scale. And, even if these programs could reduce feral and stray cat populations, it would take many years and the cats would still be capturing and consuming prey items during this time.
Animal welfare issues in feral cat control
Many submitters were very concerned about the welfare of all cats and implored the Committee to ensure that feral cat control methodologies were conducted humanely.
RSPCA Australia submitted that:
There has been some work towards national consistency including the draft Australian Code of Practice for the Welfare of Cats which was initiated under the Australian Animal Welfare Strategy and the Australian Cat Action Plan but further work is needed.
In particular, the RSPCA’s strategy notes that:
Best practice feral cat management requires an understanding of the animal welfare impacts (humaneness) of control techniques and how to carry them out in the best possible way. All existing control methods for feral cats cause some pain, suffering or distress: more humane methods need to be developed and adopted as a matter of urgency.
Best practice considerations in relation to domestic cats will be addressed in Chapter 5.