Case studies

Our Work  |  Biosecurity

Our case studies of dangerous invasive species that have made it into Australia or are likely to arrive illustrate the need for changes in how Australia prevents the establishment of new invasive species.

The case studies are made up of our ‘dirty dozen’, 12 dangerous invasive species that have made it past Australia’s border controls since 2000. Our invasion timeline shows when these and other invaders were first found in Australia. The case studies also include two more invaders while they have not yet made it into Australia, are of great concern – the green iguana and pathogens of eucalypts and wattles.

They were compiled using publicly available information at the time of the last update in December 2017. We would welcome new information or updates to biosecurity response for inclusion in future updates.


The 'dirty dozen'

Species: Asian black-spined toad (Duttaphrynus melanostictus).

Environmental impacts: The Asian black-spined toad may cause serious ecological problems, comparable to the impact of the cane toad due to competition with native species, its potential to spread exotic parasites and pathogens and its toxicity. Like the cane toad, the black-spined toad secretes poison from a gland on its back to ward off predators.

Species: Argentine ant (Linepithema humile).

Impacts: Argentine ants farm aphids for honeydew, and more abundant aphids can destroy or reduce the yield of horticultural crops. The permanent establishment of these ants on Norfolk Island would ‘seriously threaten the island’s self-sufficiency
in horticultural production’.

Species: Asian honey bee (Apis cerana javana).

Environmental impacts: Poorly known due to limited research. Asian honey bees have a broad floral appetite and will compete for pollen and nectar with native birds, mammals and insects, and for nesting sites in tree crevices. There is a risk native pollinator systems will collapse ‘under the pressure of these super-consumers of floral resources that perform poorly as pollinators and exclude native pollinators through resource depletion’.

Species: Avian bornaviruses that cause proventricular dilatation disease . Two genotypes have been introduced into Australia (through the importation of parrots) and are present in avicultural collections. Other genotypes could also be present, either as introduced pathogens or naturally occurring viruses in native birds.

Environmental impacts: The impacts of bornoviruses on captive-raised parrots are sometimes ‘catastrophic’. According to Wildlife Health Australia, these viruses threaten captive breeding and reintroduction programs for threatened parrots, and their escape from captive birds into wild populations would pose ‘a significant risk to native parrot and passerine species’.

Species: Emerald furrow bee (Seladonia hotoni).

Environmental impacts: This bee could have serious impacts due to its high relative abundance, long seasonal activity, and an apparent preference for introduced plants and declared noxious weeds in New South Wales. Impacts could include competition with native fauna, transmission of parasites and pathogens, disruption of native plant pollination networks and exacerbation of weed problems.  NB: The species was previously thought to be Halictus (Seladonia) smaragdulus. but further taxonomic work has confirmed it to be Seladonia hotoni.

Species: Red imported fire ant (Solenopsis invicta).

Environmental impacts: The red imported fire ant is one of the worst invasive species in the world. In Australia there are concerns for many native species that are declining already from other impacts, including threatened turtles, crocodiles, lizards, frogs, and ground-dwelling birds such as the malleefowl, black-breasted button-quail and plains wanderer, among many others.

Species: Jack Dempsey cichlid (Cichlasoma octofasciatum).

Environmental impacts: The features that make cichlids popular pets are also those that contribute to their invasive potential: ‘they are hardy, adaptable and breed prolifically’. They eat almost anything smaller than themselves, including fish, invertebrates and frogs.

Species: Mexican feather grass (Nassella tenuissima).

Environmental impacts: Mexican feather grass has been described by weed experts as ‘a potential disaster for the Australian environment’. It is a high-fibre, low-protein grass of no grazing value to livestock, which presumably also has no value for kangaroos and other native grazers.

Species: Myrtle rust / Eucalyptus rust (Puccinnia psidii)

Environmental impacts: Australia is in the early stages of invasion by myrtle rust, a fungus that causes disease in Australia’s dominant plant family, Myrtaceae. The impacts so far indicate it will have very serious ecological impacts.

Species: Pigeon paramyxovirus (an avian paramyxovirus serotype, closely related to Newcastle disease; both are serotype 1).

Environmental impacts: The pigeon paramyxovirus causes an often fatal disease in many bird species worldwide, not just pigeons. Overseas it has infected raptors, pheasants, swans, cockatoos and budgerigars. So far in Australia the virus has infected racing, show and feral pigeons (rock pigeons and one spotted turtle dove).

Species: Red-eared slider turtle (Trachemys scripta elegans, subspecies elegans).

Environmental impacts: Red-eared slider turtles are rated one of the world’s worst invasive species. They could cause declines in rare frogs and other aquatic animals they prey on and show all the hallmarks of being the reptile equivalent to the carp’.

Species: Smooth newt (Lissotriton vulgaris).

Environmental impacts: The smooth newt is a generalist carnivore, eating invertebrates, crustaceans, and frog and fish eggs and larvae. It may compete with or prey on a wide range of native land and freshwater species. Potential impacts could arise from predation, competition, toxicity and disease spread.

Species: Yellow crazy ant (Anoplolepis gracilipes)

Environmental impacts: Yellow crazy ants can form large-scale super-colonies, extending over more than 100 hectares. On Christmas Island, they have killed tens of millions of ecologically important red crabs and robber crabs. Prior to a multi-million dollar baiting program, they had invaded more than a quarter of the island’s rainforest, reaching densities of more than 2000 foraging ants per square metre and transforming the ecosystem.

Potential new invaders

Species: Green iguana (Iguana iguana).

Environmental impacts: Green iguanas can grow up to 2 metres long. They are agile climbers and live in trees. A habit of diving into water (and staying submerged while swimming) makes them difficult to capture. Large areas in Australia, particularly across the north and down the east coast are considered climatically suitable for green iguanas

Species: Several pathogens not in Australia that infect Acacia and Eucalyptus species in overseas plantations.

Environmental impacts: As exemplified by the impacts of myrtle rust plant species exposed to new pathogens can be devastated by disease. By exporting eucalypts and wattles for large-scale cultivation in plantations, Australia has created conditions for overseas pathogens to shift host species and adapt to infecting Australian natives.

Dear National Deer Management Coordinator,

Please accept this as a submission to the National Feral Deer Action Plan.

[Your personalised message will appear here] 

I am very concerned about the spread of deer and am pleased that a national plan has finally been developed. Without urgent action, funding and commitment from all levels of government it is clear that feral deer will continue to spread and damage our environment.

The feral deer population in Australia is growing rapidly and spreading across the country, damaging our natural environment, causing havoc for farmers and foresters and threatening public safety. Unlike much of the world where deer are native, our plants and wildlife haven’t evolved to deal with these heavy hard hooved animals with a voracious appetite.
With no natural predators and an ability to adapt to almost all environments, they could occupy almost all of Australia unless stopped. Despite this, state and territory governments have been slow to respond and in Victoria and Tasmania they are still protected by law for the enjoyment of hunters.

This plan should be adopted by all governments but must also be underpinned by dedicated funding and clear responsibilities. A plan without funding or accountability is a plan that will fail and Australia cannot afford for this to fail.

In order to prevent the spread of feral deer and reduce their impact on our native wildlife, ecosystems and agriculture, I ask that the following recommendations be adopted for the final National Feral Deer Action Plan:

1. All federal, state and territory governments should adopt the National Feral Deer Action Plan and declare feral deer to be a priority pest animal species.

2. All federal, state and territory governments should commit to:

  • Contain deer to the existing large population areas.
  • Reduce and eradicate smaller and isolated populations.
  • Protect important environmental assets such as world and national heritage areas.
  • Develop and fund regional plans and strategies to manage deer populations which involve land managers across all tenures.

3. In order to drive action and the success of this plan, there should be dedicated Commonwealth funding and support for:

  • A permanent national feral deer coordinator position.
  • A permanent federal feral deer action committee with representatives from the commonwealth and state and territory governments and the environmental and agricultural sectors.
  • An ongoing public education campaign on feral deer.
  • A network of regional feral deer coordinators to drive local action across tenures.

4. The expected outcomes for the plan need to be more ambitious, with clear interim targets including:

  • Within one year, all States and Territories should have in place arrangements to implement the National Feral Deer Action Plan, including allocating dedicated funding for implementation.
  • Within one year, feral deer management plans should be developed for key environmental assets of national significance, including the Tasmanian Wilderness World Heritage Area, the Greater Blue Mountains, the Australian Alps, the Gondwana Rainforests and the Wet Tropics of Queensland.
  • Within five years coordinated landscape scale management should be in place where land owners, land managers, government and community are demonstrably working together.

5. A national feral deer containment map with three zones should be adopted. It should be more ambitious than the zone map in the current draft plan and there should be greater clarity in the naming of the zones. Improvements that should be adopted include:

  • Renaming the zones to better reflect the management intention to ‘Containment Zone 1’ (the current large population zone), ‘Containment Buffer Zone 2’ (the current buffer zone) and ‘Eradication and prevention Zone 3’ (the current small isolated population zone).
  • The NSW northern rivers area should be in the eradication and prevention zone as there are few feral deer currently in this region and eradicating isolated populations and preventing spread into this area is still possible.
  • The whole of South Australia should be in the eradication and prevention zone as eradication is the goal of the SA Government.
  • The Tasmanian region in the containment zone should be smaller to reflect greater ambition and potential for eradication of deer populations.
  • In eastern Victoria areas such as Wilson’s Promontory, Westernport islands and the Mornington Peninsula should be in the eradication and prevention zone.

6. There should be consistent laws and regulations across all states and territories that:

  • Recognise feral deer as a pest animal and treat them as such.
  • Establish a clear responsibility for all landholders and managers to be involved in feral deer control programs.
  • Set clear penalties to stop the wilful or negligent release of feral deer.
  • Prevent new deer farms in areas where no feral deer are present and phase out all deer farms in the eradication and prevention zone.
  • Enable enforcement of compliance, including on government land.

I support the follow principles being adopted in the final National Feral Deer Action Plan:

  • Feral deer are a pest and should be treated as such on all tenures, except on approved deer farms.
  • Federal, state and territory governments have a responsibility to fund the outcomes under this plan.
  • All land managers in areas where feral deer are present have a responsibility to be involved in feral deer control programs.
  • The focus of management efforts should be on eradication of isolated, satellite populations, protection of key environmental assets currently impacted and stopping the spread to new regions.
  • Feral deer control should be undertaken humanely, safely and professionally according to agreed protocols and all tools which meet this criteria should be adopted, including aerial control.
  • Funding for coordination, regional planning and community engagement is necessary for effective feral deer management.
  • Ongoing management and follow up control efforts are required to achieve long lasting results.
  • Rules and regulations should be consistent across jurisdictions and land tenures.
  • Recreational hunting is not an effective strategy for feral deer control and should not be relied upon.
[Your name]
[Your email address]
[Your suburb], [Your state]