Aliens Among Us - The Q&A Sessions

ALIENS AMONG US - THE Q&a SESSIONS

Our online forums with special guest speakers explore the complex world of invasive species in Australia.

All Things Harmless, Useful, and Ornamental

Look around your garden or neighbourhood right now. What do you see? Can you pick the native species from the non-native?

What about in the trees and sky? Do sparrows, starlings and Indian mynas outnumber the pardalotes, parrots and rosellas?

Our new online Q&A Sessions: Aliens Among Us, are aimed at exploring the complex and chaotic world of invasive species in Australia. How did they get here? Are they harming our native ecosystems, plants and wildlife? And what’s being done to repair the damage they have caused up.

Our twelvth episode is about a devastating new plant disease called myrtle rust

In this 11th episode of our Aliens Among Us Q&A webinar we were lucky to have Dr Brett Summerell, plant pathologist and the Chief Scientist & Director of Science, Education and Conservation at the Botanic Gardens of Sydney. He has professor roles with 3 universities and is an international authority on plant diseases and their impact on plant conservation.

We also have Tim Low AM, author and ecologist, co-founder of the Invasive Species Council and Dr Carol Booth, Invasive Species Council Principal Policy Analyst.

Q&A: Questions from the Audience Answered by our Panel

Question from Anon:

Thankyou for this opportunity to discuss.. My question is about what can be done in regards to protection, or treatment of botanic gardens/collections in areas prone to both myrtle rust and phytopthera? In my case close to Toowoomba & the Bunya Mountains?

The key thing to do would be to ensure that there are appropriate hygiene procedures in place before entering the botanic garden – either foot wash stations or some other form of boot cleaning strategy to make sure visitors are not bringing in Phytophthora with them. This can either be at the entry to the garden if that is feasible or in entry to critical areas such as a nursery. Keeping people on the paths is also important so they are not walking over the garden beds. It is difficult to keep Myrtle Rust out as the spores are airborne and can blow around.

Question from Andrew:

Brazil has invested millions in Eucalyptus plantations and obviously are concerned about the potential impacts of MR on these investments. Are we, in Australia, in discussion and sharing MR data/research with Brazil and vice versa?

Yes there are lots of global collaborations – particularly with researchers in Brazil and in those localities where the disease is problematic, especially in New Zealand and South Africa.

Question from Lee-Anne V:

Could there be any relationship between myrtle rust and the paralysis event impacting flying-foxes and lorikeets?

There is no indication that there is any association.

Question from Sharyn D:

How will myrtle rust affect the honey industry, especially for those apiarists that follow the flowers?

Potentially it can have an effect, depending on the plant species that the bees are visiting. If the plant species are affected then the flowering is reduced (or non-existent) and consequently less resources for the bees. This is a big concern in New Zealand with manuka honey.

Question from Vanda:

Can the virus die off naturally over time?

The pathogen is a fungus and there are no indications that it will die out. As long as there is a host it will keep reproducing. Of course if the host plants dies out the fungus will die out but we are a long way from that scenario.

Question from Sue C:

How quickly do trees take to die once infected?

It does depend on the species of tree – some are very susceptible and can die quite quickly (over a season) but others that are less susceptible will have a slow gradual demise – perhaps over a number of years.

Question from Anon:

Is any work being undertaken anywhere around the country to regrow endangered Australian native myrtaceae from seedbanks in protected environments?

There is some work happening in NSW and Qld to grow the most affected species. Unfortunately most of these species are difficult to store in seed banks as the seed of many rainforest Myrtaceae do not respond well to storage at low temperatures and many have not been able to produce seed because of the disease. Consequently it is necessary to collect cuttings and propagate in the nursery and grow the plants in pots; some grow well in tissue culture and research on cryopreservation is under way. Good collections of a number of severely affected species are now in botanic gardens and these are kept healthy via a rotation of different fungicides. All of this is very labour intensive, takes time and space.

Question from Brad:

How about Alpine or Cool Temperate Rainforest environments?

The Myrtle rust pathogen prefers warmer temperatures – it has evolved in Brazil – and so is not a significant issue in Alpine regions. This of course may change with climate change.

Question from Anon:

What procedures we should follow when Myrtle Rust is detected in our not for profit nursery?

It would be appropriate to consider application of fungicides if the plants are critical for conservation purposes. If they aren’t for that purpose it might be best to dispose of them as you will be continuously trying to keep the pathogen at bay.

Question from Michelle:

Should we be applying pre-emptive fungicide treatments?

Not likely to be effective – it is better to carefully monitor plants and consider use of fungicides at the first sign of the disease.

Question from Lee-Anne L:

What can individuals or on ground organisations do, if anything, to slow/stop Myrtle Rust?

At this point information is key – so monitoring for the presence of the disease and the species that are being affected. At the Atlas of Living Australia there is a citizen science program to help assist this.

Question from Lisa P:

Is there an interactive map showing where myrtle rust is present?

There are some resources on the ANPC website here and also on iNaturalist Gum Tree Guardians project page.

Question from Craig A:

How many species have been made functionally extinct as result of myrtle rust?

We have significant concerns about 16 species and there are another 27 species that need action. Over 380 species are known to be infected. Not all are functionally extinct – perhaps only 6 are heading that way immediately.

Question from Claire B:

Is there ANY hope at all? This seems very dire.

Yes there is – there is very promising research highlighting some ways in which this disease can be overcome but it will take resources and time.

Question from Janelle S:

How can the education around Myrtle rust and other diseases become ‘general knowledge’ so people are aware. Most people would not understand the impacts or even be aware of what Myrtle rust is doing so how do we move forward?

There are many efforts to raise awareness but we do suffer from a tendency to not care too much about plants and their role in ecosystem (just the green background). This is despite the fact that healthy plants are key to maintaining a healthy ecosystem and for fauna to survive.

Question from Belinda C:

I’m in Broome in the West Kimberley. Do we know how MR may react to many months of dry weather after a wet season? And from that, is MR destroyed by fire?

The spores can survive longish periods (3 months) and persist in the leaves. Fire will kill the pathogen in leaves if they burn but perversely the new growth post fires is much more susceptible to infection so you will expect there to be more myrtle rust after fire.

Question from Neil P:

What is happening about the Biological treatments? Timeframe to it being commercial? Information on getting involved in experimenting with this?

There has been some research on antagonistic microbes to the rust fungus but not with great effectiveness. Some RNA treatments show some promise.

Our eleventh session is about the danger of living with fire ants

In this 10th episode of our Aliens Among Us Q&A webinar we were lucky to have Dr Robert Puckett, associate professor and extension entomologist at Texas A&M University whose work on fire ants have significantly advanced our understanding of these tiny killers in Australia.

We also have Dr Rachel Chay, Queensland Chief Biosecurity Officer, overseeing Australia’s national fire ant eradication program and Reece Pianta, Invasive Species Council advocacy manager and fire ant specialist.

Our tenth session is about the ecological exchange between Europe and Tahiti

In this 10th episode of our Aliens Among Us Q&A webinar we were lucky to have Dr Jenny Newell as our special guest. Jenny is the author of Trading Nature: Tahitians, Europeans, and Ecological Exchange. She is also the visionary curator of Climate Change at the Australian Museum’s Climate Solutions Centre in Sydney.

We discuss the introduction of species to Tahiti, their environmental and cultural impact (and more!) which you can watch in the video below.

Our ninth session is about the history invasive species in Australia with best selling author Guy Hull

In this 9th episode of our Aliens Among Us Q&A webinar we are glad to have had Guy Hull as our special guest. Guy Hull is a best selling author, qualified dog behaviouralist and former recreational hunter. His most book from 2022 The Ferals that Ate Australia discusses the history of feral animals in Australia and the damage they’ve caused.

We discuss all of this and more which you can watch in the video below.

Additional Q&A

There were so many good questions we ran out of time to answer them all live! Our panel have taken the time to answer them below:

Leeanne: Hello Richard, What do you think can help to expand this awareness and encourage people to care for, or even about, our natural environment? Thank you.

What is needed to create the cultural shift required for Australians to accept the responsibility of custodianship is everyone who has the ability to influence culture needs to do their part. Historians, authors, sports people, the arts, advertising etc.

– Richard Swain

James: Can we expand the feral horse reduction program in the KNP to include other/all feral animals?

As of March 2024, the total number of horses removed since November 2021 is 4,152, by a range of methods including aerial and ground shooting and some rehoming.

As a point of comparison for those numbers, over this same time period (since November 2021) more than 13,000 feral animals, including more than 8,000 feral deer, have also been shot in Kosciuszko National Park.

– Richard Swain

Emma: Invasive animals are mostly here to stay and it feels a bit hopeless sometimes. Is there a positive story about managing an invasive species that might give us hope? For example rabbits were mostly brought under control with viruses, what else is in the works?

The removal of rodents from Lord Howe Island is a huge good news story. The native species are multiplying dramatically in response. Invasive mammals have also been removed from Macquarie Island and cats from a few islands, all with inspiring results. There are new biocontrol agents for weeds such as wandering trad (Tradescantia fluminensis) and sea spurge (Euphorbia paralias). A new fungicide will become available soon for myrtle rust control.

– Tim Low

Annonymous: Did the dingoes outcompete the Tassie Devils, Tassie Tigers and Thylacoleo? If not, why did they die out on the mainland?

It is widely believed that dingoes outcompeted tigers and preyed on devils, causing their extinction from the mainland (and also the mainland extinction of the Tasmanian native hen), although an alternative view is that increasing intense Aboriginal resource use played a larger role than dingoes. The marsupial lion (Thylacoleo) went extinct tens of thousands of years before dingoes arrived

– Tim Low

Jill: Getting rid of destructive invasives is top priority - absolutely. But is there much progress in developing more humane and target-specific methods of eradication? It doesn't seem to be a priority for funding or research.

We agree it should be a high priority. For example, the Invasive Species Council has been advocating research on alternatives to 1080 baiting (currently essential for saving rare species). The recently developed Felixer is one example of a more targeted technology for cat and fox control.

– Dr Carol Booth

James: Is the use of drones and other technology providing hope for more effective programs (including weeds etc) moving forward?

One example of drone use is for deploying baits near urban areas for the control of Fire Ants.

– Richard Swain

Yes, recent improvements in technology offer hope – new methods for detection (such as eDNA detectors and thermal imaging) and new methods for trapping and controlling species (such as the Felixer for cat control and the pheromone trap being developed for northern Pacific seastars).

– Dr Carol Booth

David: How can we manage and/or control feral cats and foxes and their undoubted predation impact on birds (and of course other animals)?

The most effective method for large-scale control of these predators is aerial baiting. Unfortunately, because cats prefer to take live prey, baiting is often ineffective for them. Developing effective large-scale methods for cat control is one of Australia’s most important conservation challenges.

– Dr Carol Booth

Michele: Could the panel comment on the potential of harvesting (using) invasive species, like deer and pigs and others, even kangaroos?

The harvesting of invasive species can be counterproductive. You can read more about that in our article here.

– Tim Low

David: I have found that people are very quick to complain or be concerned about ferals, but do not act, even when they have suitable methods and are trying to control the pests. How do we make people comfortable about the pest animal being killed?

We focus attention on the harm being done if pest animals are not killed, such as native animals killed by foxes and cats, and wildlife with no habitat because rabbits have prevented regeneration of mulga and myall woodlands.

– Tim Low

David: Could a bounty of sorts could work to help reduce invasive species?

Every study of bounties finds that they do not work as expected. The money is worthwhile when the pest is plentiful but as soon as its numbers go down the rate of return decreases and people reduce their effort without the bounty having achieved a lasting benefit. ISC does not support bounties and nor do government pest experts.

– Tim Low

Our eighth session is about horses from the perspective of a cultural historian

Feral horses through trashing and trampling cause enormous amounts of damage to our national parks and native wildlife, yet there are fringe groups of feral horse advocates who want them protected.

In this 8th episode of our Aliens Among Us webinar we have Dr Isa Menzies as our special guest. She is a cultural historian with a PhD in cultural studies from ANU and has published many scholarly articles on this topic. We dive in to find out they become bound up in the identity of a small but vocal minority? Why did the NSW government change laws to protect feral horses in a national park? Is there a connection between this and the voice referendum and more.

Additional Q&A

Our panel was kind enough to write some quick answers to some of the questions asked during the session that we didn’t have time to get to.

Linda: Any comments on the reluctance of some people to look at feral horse carcasses, compared to the lack of concern when they see the carcasses of feral deer or pigs?

Our culture treats pigs as farm animals that end up as meat. Our culture treats horses as something we don’t normally kill. We don’t have strong cultural associations with deer.

– Tim

Lynlee: So much pushback from the pro-brumby community includes their justification for keeping horses in the Alps as “Horses don’t do damage, it’s deer and pigs creating wallows and destroying creek banks.” Are there any stats to show horse specific damage?

Yes there have been studies of damage that found it strongly associated with presence of horse dung, not deer or pig dung, eg. An assessment of feral horse impacts on treeless drainage lines in the Australian Alps, and Horse activity is associated with degraded subalpine grasslands structure and reduced habitat for a threatened

– Tim

Daniel: Would it be right to assume that the glorification of brumbies is a relatively recent phenomenon?

In short, yes. Up until a generation or two ago the horses in the high country were viewed as competition for cattle. Nineteenth and early twentieth century newspaper reports document thousands of them being slaughtered by graziers. They are still shot pretty routinely on private land elsewhere in Australia. Outside the animal rights advocates, the debates about brumbies representing settler heritage are about identity and belonging – Isa

David: Do the supporters of feral horses agree or acknowledge that the horse numbers in parks are increasing and will continue to, to the degradation of the land?

The current aerial shooting is not provoking the public outcry that happened when there was shooting in the past, and that suggests that the degradation from horses has become too obvious to deny – Tim

Jody: If the damage a horse can do on pretty sturdy lands is recognised, why is it so hard to recognise the damage they do to fragile areas?

Because it’s not an argument based on logic, but on emotion – Isa

Marita: Hunting deer is a sport in New Zealand. How does the hunting community respond to predator free New Zealand?

Some of the hunting community are also keen trappers, the challenge is having a conversation about whether there are too many deer (there are in many places) … I’m a hunter too, and I can assure you I’m not contributing much to the reduction of deer! – Nicola

Jo: I also recently witnessed the terrible state of the Barrington Tops NP. Is Tim aware of any control measures happening there?

There is currently no control of horses happening in Barrington. – Tim

Don: How much do feral horses in Kosciusko National Park suffer during drought, especially during winter?

They suffer greatly. Horse starvation is addressed here: https://theconversation.com/the-grim-story-of-the-snowy-mountains-cannibal-horses-31691

Register for our next session with Nicola Toki on how New Zealand launched one of the world’s most ambitious invasive species projects – Predator Free 2050

Rats that attack adult albatross and dive into water to prey on crabs. Possums that forgo their plant-based diet for native birds eggs. Welcome to the world of invasive species across the Tasman where masses of stoats, ferrets, possums, cats and weasels are playing havoc with nature. Like Australia, Aotearoa/New Zealand has experienced many extinctions and many more of their native species are in big trouble due to introduced species.

But New Zealanders agreed they were worth saving.

So, in 2016, they started Predator Free 2050 – an ambitious nationwide program to protect biodiversity by eliminating the country’s most damaging introduced predators.

But how did they rally Aotearoa/New Zealanders in a collective effort in the pursuit of this ‘crazy and ambitious’ goal to bring back their dawn chorus? Bringing government, community groups, Maori, charity groups and the community together to agree on anything is no easy feat, let alone for such a mammoth challenge.

Joining us will be:

Nicola Toki, chief executive of Forest & Bird NZ,
Rebecca Spindler, executive manager for science and conservation at Bush Heritage Australia,
Richard Swain, Invasive Species Council Indigenous ambassador,
author and biologist Tim Low, and
Andrew Cox, Invasive Species Council CEO, as moderator.

Nicola has an impressive history of conservation leadership and advocacy for New Zealand’s wildlife and wild places. Having worked in a range of roles across the private and public sector, Nicola is a well-known champion for New Zealand’s natural world and has a deep understanding of the environmental management challenges and opportunities.

She has worked in conservation leadership roles in the agribusiness industry, the Predator Free New Zealand movement, in the Department of Conservation as the Operations Director for the Eastern South Island, as the Department of Conservation’s Threatened Species Ambassador.

All welcome to come along to this free webinar! Just note that registrations are essential and numbers are limited.

Our seventh session tells the story of how New Zealand started Predator Free 2050

In 2016, Aotearoa/New Zealand started Predator Free 2050 – an ambitious nationwide program to protect biodiversity by eliminating the country’s most damaging introduced predators.

But how did they rally in a collective effort in the pursuit of this ‘crazy and ambitious’ goal to bring back their dawn chorus? Bringing government, community groups, Maori, charity groups and the community together to agree on anything is no easy feat, let alone for such a mammoth challenge.

Additional Q&A

Our panel was kind enough to write some quick answers to some of the questions asked during the session that we didn’t have time to get to.

Julie: How do we avoid 'demonising' natural predators and predation? Predation is integral to Australian and New Zealand ecosystems, how do you distinguish between unnatural predation (e.g. foxes, cats, etc.) and natural predation (dingoes, wedge-tails, quolls, etc.)?

Hi Julie, this is a good question. I suspect that when one says ‘predator’ people think of a fox but not of a quoll because when quolls are featured in the media it is usually in the context of them as special and disadvantaged. A hundred years ago eagles were shot as lamb-killers but that persecution passed away and when someone sees an eagle today it is more likely to be thought of as majestic. Yes it is a predator but that word doesn’t come to mind when I see an eagle, or see small birds preying on insects. I suspect that in an anti predator campaign there is an accepted assumption that introduced predators are the topic. – Tim
This is a key consideration for us. Bush Heritage recognises that native predators play and essential role in the ecosystem and we protect them as we do all species in the landscapes where we work. This is a key consideration in undertaking any control mechanism. We consider the humaneness and the potential by-catch of any native species in the area – how are they likely to be impacted. The most broadscale is of course poison and disease mechanisms – these need to be disseminated with a strong understanding of the biology and behaviour of the surrounding species – when are they active (season and time of day), do they dig? Are they arboreal etc…. all of this is taken into account when we design integrated pest management systems. – Rebecca

Doug: Are we missing a 'circular economy' trick in how feral animals are killed? Would a market for products help?

Yes, would be really keen to learn more about what would be possible and required to make this happen. – Rebecca

Rosemary: Would you kindly advise the invasive species of New Zealand?

Feral cats, stoats, rats, ferrets, weasels, mice, hedgehogs, goats, deer, pigs… the list goes on! – Nicola

James: Is New Zealand planning to ban domestic cats?

Nope not at all! But we want our domestic cats to be safe and not lost and beaten up by feral cats. We also want our wildlife in those landscapes to be safe from cats. – Nicola

Michele: Does New Zealand have cane toads?

No fortunately we do not have cane toads – and I don’t know how our wildlife cope with yet another invasive species such as that one! – Nicola

Marita: Hunting deer is a sport in New Zealand. How does the hunting community respond to predator free New Zealand?

Some of the hunting community are also keen trappers, the challenge is having a conversation about whether there are too many deer (there are in many places) … I’m a hunter too, and I can assure you I’m not contributing much to the reduction of deer! – Nicola

Jill: Can you continue and improve the harvest of possum fur for clothes?

You can collect possum fur and many people do, and the money is pretty good. The challenge is not incentivising accidental ‘farming’ of possums to create a market for them. – Nicola

Our sixth session on stopping red fire ants before it’s too late with Sarah Corcoran

Earlier this year, red fire ants were detected in the precious environments of Minjerribah (North Stradbroke Island) for the very first time. These highly invasive and dangerous ants were first found in Australia in 2001. A large outbreak in southeast Queensland remains active and is still subject to a major eradication effort. But if we fail to get on top of red fire ants, modelling shows they will spread to every corner of Australia. Our way of life will be changed forever.

Our expert panel, joined by Eli Perry from QYAC, talks with Sarah Corcoran who has been up close and personal with red fire ants and knows what’s at stake if fire ants swarm Australia.

Our fifth session with Anthony Sharwood, author of The Brumby Wars

On September 16, in response to allegations aired on shock-jock Sydney radio, the NSW Environment Minister announced a ban on all shooting operations in Kosciuszko National Park. The ban was supposed to only last two weeks. Five weeks later, not only was it still in place, but we learnt the ban had been applied to every national park across the entirety of NSW. The surge in feral animals being reported state-wide thanks to recent wet weather meant that the lack of feral animal control across NSW was jeopardising nature and livelihoods.

The issue of protecting Kosciuszko from feral horses is once again coming to a head.

Come behind the scenes with us in this Aliens Among Us session as we lift the lid on how we discovered feral animal control had been banned across the state of NSW, and how we worked with our tireless supporters to have the ban reversed.

Our fourth session with State of the Environment Report 2021 co-author Barry Hunter

Australia’s State of the Environment Report 2021, finally released earlier this year, makes for grim reading. But how central are invasive species to Australia’s extinction crisis? What can we take from the record level of Indigenous authorship in this edition of the report? What do cut flowers have to do with the state of Australia’s environment?

Our fourth Aliens Among Us session welcomes Barry Hunter, one of the co-authors of Australia’s latest State of the Environment Report. Alongside Barry is author and biologist Tim Low, Invasive Species Council Indigenous Ambassador Richard Swain, and Invasive Species Council CEO Andrew Cox as host.

Additional Q&A

Our panel was kind enough to write some quick answers to some of the questions asked during the session that we didn’t have time to get to.

Euan: How do we reverse the trend for much of the public to see invasive species as part of our natural landscape? The word 'Naturalised' is being used to describe invasive species in the environment which for many implies it is a natural part of the landscape. Deer, horses, camels and donkeys are starting to be seen as 'natural' in our national parks.

It is not easy to do this. I am writing a book on invasive species to address this issue, to explain why we should not embrace deer, etc. as belonging. It will be the topic of one chapter. – Tim

Anonymous: Are we suggesting that quarantining is dropping the ball?

The flow of people and goods into Australia has become such a torrent that quarantine, usually called biosecurity these days, has become very difficult to do properly The Inspector-General of Biosecurity keeps issuing critical (and sometimes scathing) reports saying the department is operating poorly and lacks an adequate budget. See: https://www.igb.gov.au/current-and-completed-reviews – Tim

Eva: In 2016 our neighbours in Aotearoa/New Zealand pledged to make New Zealand predator free by 2050. In the opinion of the panel, what would it take for Australia to make a similar commitment - at a government and community level?

The technology does not currently exist to allow NZ to achieve that goal. The Australian Government would need to see better methods of controlling cats than currently exist. – Tim

Marg: It's really distressing seeing the spread of Indian Mynas out to Dubbo and beyond. We have no help from local or state government to help and our Dubbo IM control group has to apply for grants and lend out traps completely voluntarily. In Sydney, a recent visit showed that the IMs have taken over the southern NP area of Bradley Heads, yet Sydney has no control program. What can be done to address this problem?

It is my view that Indian mynas are a classic case of the horse that has bolted, meaning they have become unstoppable. Traps can be used to limit breeding, but not to stop breeding altogether because they sometimes choose high dead trees. The proper response to the Indian myna is to say lets not let more introduced birds spread in Australia. That means a strong response when a few foreign birds appear, eg. the Canada geese culled in NSW some years ago, and house crows arriving in Fremantle on ships. – Tim

Simon: How do we achieve any progress while government decision makers seem unable to differentiate between long-term scientific evidence, and emotionally based cultural opinion/pride (eg. feral horses).

I don’t know, but it is interesting to read Sharwood’s book The Brumby Wars. He says the NSW Government knew it should not have banned the shooting of horses but the public pressure was so relentless it submitted to that. Ray Hadley on 2GB is currently telling listeners that a recent cull of horses in Kosciuscko National Park was immoral and that he will be talking about it at the next election if he doesn’t get answers. Governments want to get re-elected so they may understand scientific advice but not heed it for that reason. The Invasive Species Council does its best to argue for sensible policy. – Tim

Angus: Any tips for me on how I could start my invasive species journey?

Books you could obtain from a library include my Feral Future and A Plague of Rats and Rubbervines. – Tim

Richard: Do you think many Australians appreciate that most of what we have to protect from invasive species - our unique endemic fauna and flora - is found nowhere else in the world?

Insufficient awareness is a big concern to us. A recent survey found 18% of Australians think horses and foxes are native. There are academics in Australian universities who want the native-introduced dualism to be forgotten about. I am criticising their thinking in my next book. – Tim

Joan: Is there any chance of eradicating bridal creeper from South East Australia?

No. Bridal creeper is very well-established over a large area. Efforts to eradicate weeds have only succeeded where the weed was very limited in occurrence. In other words, action has to be taken very early on the invasion curve. Biocontrol agents can be a good way to reduce weed success and two agents – a leafhopper and rust fungus – are helping curb bridal creeper. The Invasive Species Council puts pressure on governments to limit the possibilities of more garden plants becoming weeds. – Tim

Janine: Why are our kangaroos considered a 'pest'? Is it just because a commercial industry has grown up around their slaughter? Or because they are considered competition for invasive grazing animals?

They are considered a pest by the grazing industry because they can reach very high numbers and they eat pasture wanted for cattle and sheep. They are considered a problem in some national parks and nature reserves in temperate Australia where, with no dingoes as predators, they achieve such high numbers they threaten survival of some ground orchids and other rare plants. As a native animal, they are not a species that the Invasive Species Council has anything to do with. – Tim

Amy: I'd be interested to hear opinions on varroa mites. It's an invasive species that directly affects an introduced species (European honeybees), but may have indirect impacts on our native bees. Do you think the control measures are sensible and likely to work?

Varroa mites are an interesting issue because they will reduce feral bees if they establish, and feral bees nest in tree hollows wanted by mammals and birds, and take nectar and pollen wanted by native pollinators. In other words, varroa mites could benefit native bees and other wildlife by reducing honeybee numbers. The control measures may work, but attempts to eradicate varroa mites elsewhere in the world haven’t worked. – Tim

Angus: Is getting rid of all the foregin plants (apart from produce) in my garden and replacing them with native plants a good way to deal with the problem?

Not necessarily. Some Australian plants taken from one part of the country and grown in another become weedy and undesirable, for example sweet pittosporum and Cootamundra wattle. Most local governments in Australia produce lists of undesirable weedy garden plants (foreign and Australian) to guide gardeners and these should be consulted. Many foreign plants, for example roses, pansies, snapdragons, do not spread from gardens so they are safe to grow. – Tim

Anonymous: There was very little focus on invasive aquatic species like fish in the State of the Environment Report. Terrestrial invasives seem to always be a priority. Is this reflective of our top invasive species overall, or more so because we overlook what we can't see (i.e. underwater)?

It partly reflects our visual biases and also our orientation as a land-dwelling mammal. Invasive fish are difficult to detect and also difficult to eradicate. If a new weed appears at the side of the road it may be noticed very quickly, but if someone dumps aquarium fish in a stream they might not noticed for several years, by which time it is not feasible to remove them. The Siamese fighting fish established near Darwin are an example of that. Brown trout can be counted as one of our worst invasive species, having caused the near-extinction of some native fish, but the fishing lobby is so powerful they mostly get their way on trout. Aquatic weeds are a high priority for governments because they tend to be visible and have very serious impacts including clogging water supply dams and irrigation channels. Kakadu National Park is very serious about limiting semi-aquatic hymenachne and para grass. – Tim

Our third session with ecologist and author John Read

Our third Aliens Among Us session welcomed John Read, ecologist and author of Among the Pigeons; Why our cats belong indoors. John is considered by some to be Australia’s leading expert on the impacts of feral and roaming cats, and this is a special opportunity to see the world of cats through his eyes.

Alongside John was our expert panel consisting of former Tasmanian Senator Christine Milne, author Tim Low and Invasive Species Council CEO Andrew Cox.

Additional Q&A

Our panel was kind enough to write some quick answers to the many questions that were asked during this session. It was fantastic to see so much interest in what is such a tricky issue to talk about!

Who is the best organisation to report cat sightings to within National Parks?

The Invasive Species Council would favour using iNaturalist as the best smartphone app for recording sightings since all data is publicy available and is imported into the Atlas of Living Australia. Feral Scan has a specific app for feral cats – FeralCatScan – and in addition to records of sightings, also allows the recording of cat damage or attacks and control activities. – Andrew

Based on current control methods and levels of control, what is the projected growth of feral cat numbers nationally and what are the estimates of native species extinctions due to feral cat predation based on current modelling?

Cats already now cover over 99% of the Australian continent, numbering between 5.9 – 10.1 million cats depending on rainfall conditions. There is evidence cats have contributed to the extinctions of 27 native animals in Australia since colonisation. Recent expert assessments of extinction risks have found that 25 species are at 20% or higher risk of extinction within 20 years due largely or substantially to cats. Many more mammals at extreme risk from cats are now safe from extinction because they have been translocated to islands or fenced reserves. – Andrew

Have there been examples of unintended consequences when eradicating feral cats e.g. explosions of other invasive species like rats/mice?

Good question. Often it is better to target invasive prey first and the invasive predators. Rabbits increased on Macquarie island after cat eradication, before the rabbits too were eradicated. – John

What can local councils do to address the problem of roaming domestic cats?

Legislate that cats are registered and contained exactly like dogs, same encouragement, same fees and same fines. But even though several proactive councils have introduced such bylaws they are very difficult to monitor or enforce. Therefore councils should look to trial ADIMA Safepet Bluetooth tracking technology developed by Thylation to help reunite wandering pets with owners and allow councils to enforce ‘cat free zones’. – John

What is the best way to encourage our local councils to follow the ACT in changing the law for keeping cats contained?

Lobby councils about the health risks to humans of free-ranging cats and the welfare risks to the cats themselves – introduce them to the Safe Cat program run by Zoos etc. – John

Which level of government can enforce cat containment and how will they do that?

Typically the remit of Local Government although State and Federal Government could potentially enforce cat-free zones in high value parks etc and hence indirectly encourage/enforce cat containment. – John

Am I correct in saying that any animal that eats any infected prey will subsequently become infected, so toxoplasmosis will still spread for a while without cats?

es, any animal (including sheep, mice, humans, bandicoots and even seals etc) can become infected, but the Toxoplasmosis life cycle (production of oocysts) requires a Feline host, so Toxo will rapidly diminish without free-ranging cats. – John

Could you please discuss what new technologies are being used to control feral cats and where are the highest numbers of feral cats in Australia?

Feral cat numbers are primarily driven by kitten survivorship which is primarily driven by food availability. Where mice or rats (native or exotic) or rabbits are abundant, feral cat numbers can increase dramatically, likewise dumps and other resource-rich locations often support high densities of feral/stray cats. Effective strategies to control cats include reducing food availability and absolutely banning feeding of any stray cats. Technologies include traps (some monitored remotely), Felixers and specialised cat baits (Eradicat/Curiosity), each with their own advantages and limitations. – John

What would you recommend is an effective approach to encouraging cat enthusiasts to keep their domestic cats indoors?

Introduce them to safe cat literature that shows indoor cats are safer and make healthier, longer-lived pets. – John

Poor cat owner behaviour seems to be at the core of the issue for feral cats. It seems a broad and ongoing ad/marketing campaign is needed to educate owners of the dire consequences. Is there funding for such a campaign?

The Invasive Species Council is currently launching a national cat campaign to advocate for feral cats to be controlled and pet cats contained at all times. We will look at how to support existing education efforts and to ensure that there are also clear rules (increasing over time) so there are consequences for those that choose to ignore the impacts. The NSW Government has recently announced $2.5 million for RSPCA NSW to deliver a Keeping Cats Safe at Home project. There is also a Safe Cat Safe Wildlife project in Victoria run by Zoos Victoria and RSPCA Victoria. – Andrew

Domesticated cats are deemed to be companion animals along with dogs/canines. It seems that dog management and control has been accepted for many years while the legislated controls and options for cats has lagged (at least in NSW). In terms of impacts on local wildlife, is there research data to determine how much impact the average domestic cat has (let alone a feral cat) compared to dogs?

The ‘average’ Australian domestic cat kills approximately 186 animals a year, although only 28 (on average) of these victims are visible to their owners. Not sure on the data on dogs but dogs are largely restricted to yards whereas most cats are not. – John

While CSIRO may be investigating gene-drive technology for short-lived species like insects and mice, this CSIRO survey shows many people would support its use on cats. What are your views on the technology and how far do you think this technology is from practical use? This technology is a long-way before it will be used practically.

There needs to be trials on gene-editing for species like mice to test the practicality and the level of public support before other species are considered. The trials will take a number of years. – Andrew

Are cat runs satisfactory? Such as netting from the house eaves to a side fence and to the ground at the ends. A cat door to allow the cat access.

Outdoor cat enclosures are a fantastic way of ensuring cats can get some fresh air while not endangering native wildlife providing all cats are fully contained at all times. – Andrew

Most people don't like cleaning out litter boxes - is this likely a strong 'cultural' factor in allowing domestic cats to roam? Is the transmission of toxo and other diseases from cat poo an approach to better regulation for indoor cats?

Good point and good idea. – John

What is the evidence for toxoplasmosis in cat faeces or urine being an attractant for prey?

Several scientific studies referenced in Among The Pigeons. – John

To what extent is the availability of surface water a factor in cat distribution?

Unlike dingoes that require surface water, at least in summer, feral cats derive all the moisture they need from their prey. They are awesomely adapted to deserts. – John

Is it possible to build an exclusion fence that will allow small mammals to cross? We will soon be building exclosure fences for revegetation, keeping out macropods.

Absolutely, and this is an important consideration. Macropod-proof fencing should allow small mammals to walk through or climb over. In addition, you call install one way gates. – John

Would protecting dingoes as top-order predators here in northern NSW help?

Dingoes are better at reducing the numbers and hinting ability of foxes than cats, although in some (open) environments they do limit cats to some extent. In areas with many trees, caves or warrens, cats are pretty good at evading dingoes. – John

Regarding cat trapping, what options are there for the 'low tech' (cheaper) traps for use. The Felexer is great, but very expensive and calling the old wire cage possum trap a cat trap doesn't seem to work! Any new developments? Can foot hold be used in Victoria. Why/Why not?

There is a need to provide more cost-effective and low-tech traps for cat control. In some circumstances, soft-jawed foothold traps can be used in Victoria with ministerial approval. – Andrew

Our second session with author Leslie Anthony

For our first Aliens Among Us of 2022, we welcome Leslie Anthony – author of the book that we named this series after!

Join Leslie, former Tasmanian Senator Christine Milne, author Tim Low and Invasive Species Council CEO Andrew Cox as they explore the complex and chaotic world of invasive species.

Based in Whistler, Leslie is a writer, editor, biologist and occasional filmmaker. His former life as an editor for a number of acclaimed mountain and ski publications has left his name printed into the masthead of a swathe of magazines.

His zoology PhD from the University of Toronto and postdoctoral fellowship at McGill University’s Redpath Museum have left him well-equipped as he has turned his attention towards writing about travel, adventure and science.

Aside from being the inspiration (with permission!) for the name of this seminar series, his book ‘The Aliens Among Us: How Invasive Species are Transforming the Planet—and Ourselves’ is a thoughtful, accessible look at the rapidly growing issue of invasive plants, animals, and microbes around the globe. He draws on science, travel, history and humor to understand the ecological, social, and economic aspects to the burgeoning problem of invasive species.

Our first Q&A with author Pete Minard

Our first session stars Australian author Pete Minard, who wrote All Things Harmless, Useful and Ornamental.

Pete grew up in regional Australia surrounded by a landscape infested with rabbits, sparrows and hares. His fascination with how Australia’s landscape and ecology has changed through the introduction of non-native plants and animals reveals an intriguing history shaped and formed by the men behind early acclimatisation societies.

In his book he tells the story of this movement, arguing that far from attempting to re-create London or Paris, settlers sought to combine plants and animals to correct earlier environmental damage and to populate forests, farms, and streams to make them healthier and more productive.

By focusing particularly on the Australian colony of Victoria, Minard reveals a global network of would-be acclimatisers, from Britain and France to Russia and the United States.

Although the movement was short-lived, the long reach of nineteenth-century acclimatisation societies continues to be felt today, from choked waterways to the uncontrollable expansion of European pests in former colonies, including Australia.

Our Work

Striving for a future where invasive species are no longer a major cause of environmental decline and extinctions.

Join our campaign to protect Kosciuszko from feral horses.

The Invasive Species Council publishes a range of information resources including fact sheets, submissions and reports.