Conservation and Environment

Invasive Species - past projects

A wide range of introduced species live in Australia's land and water environments. Many of these - including European rabbits, feral pigs, red foxes, wild dogs, feral cats, deer and carp - are believed to have contributed to the extinction or decline of a wide range of native species, and for harming ecological communities. Preying on native species, changing habitat and competing for food and shelter are some of the ways these 'invasive' species affect our fauna and flora.

Key past projects

Cat and Fox Exclusion Fencing Trial Williams' Carp Separation Cage Point-Source Management of Carp Review of Feral Mammal Control Feral Animal Exclusion Fencing Review Fox Adaptive Experimental Management Aerial Baiting: Effectiveness in Reducing Wild Dog Populations

Details of these projects are given below.

For more recent and current projects within this theme see the Invasive Species page.

Cat and Fox Exclusion Fencing Trial A series of trials have been completed testing the effectiveness of a purpose-designed fence in keeping out feral cats and foxes. A fence identified as one of the ‘best possible’ during an Australia-wide review of exclusion fencing was used as the base design. Certain components of this design were then modified with six fences constructed. All fences had horizontal mesh overhangs and were either non-electrical or combined with various arrangements of offset electrical wires. Two heights were used. The fences were integrated into animal enclosures into which a single fox or feral cat was released. Each fence was tested with three individuals of each species. Remotely activated infra-red video cameras monitored the responses of each animal to the fence. Footage was viewed to record the number of times individuals approached the fence, attempted to scale it and the degree of success in doing so. It is recommended that to keep out feral cats and foxes an exclusion fence should be at least 1800 mm high and have an overhang extending 600 mm to prevent animals climbing over. Good quality mesh should be used to prevent animals chewing through. The trial reinforced the importance of the presence of an apron (horizontal continuation of the fence mesh buried just under the ground and a generally accepted feature for exclusion fences) to stop animals digging under the fence. If these features are included it appears that electric wires are unnecessary, which reduces the potential construction and maintenance costs markedly. For further information contact Alan.Robley@dse.vic.gov.au or Daniel.Purdey@dse.vic.gov.au The final report is available from the Department of the Environment, Water, Heritage and the Arts website and the following journal article is available: Robley, A., Purdey, D., Johnston, M., Lindeman, M., Busana, F., and Long, K. (2007) Experimental trials to determine effective fence designs for feral cat and fox exclusion. Ecological Management and Restoration 8(3): 193-199 Page Top

Williams' Carp Separation Cage Common carp, Cyprinus carpio, are present on every continent except Antarctica, and are classified among the world’s worst invasive species, causing ecological, economic, and social impacts. ARI, in cooperation with Goulburn Murray Water and with funding from the Murray-Darling Basin Commission, have developed a major new technology to control the dispersal and abundance of this fish. The Williams’ cage automatically separates jumping carp from non-jumping native fish and was tested between November 2002 and April 2005 at Torrumbarry Weir fishway on the Murray River. During testing 88% of 421 adult carp passing through the fishway were separated into a confinement area. In contrast, of 8,031 native fish, more than 99.9% passed through the cage and exited the fishway. The cage is in the process of being adopted at six new fishways along the Murray River, effectively providing carp control over 926 km of river. This device provides a practical and low cost option for carp management, although further work is needed to assess any population-level effects. It may also be used as an education tool to encourage community-based pest management, and has potential to be applied to other pest fish species. The team behind the development of the cage won the 2004 Land and Water Eureka Prize for Water Research. See the About ARI page for news on awards won by the carp project team. See the following article and report for design, testing and application details: Stuart, I.G., Williams, A., McKenzie, J. and Holt, T. (2006) Managing a migratory pest species: a selective trap for common carp. North American Journal of Fisheries Management 26(4): 888-893 The Williams Cage A Key Tool for Carp Management 2006 Part I (PDF - 1.4 Mb) The Williams Cage A Key Tool for Carp Management 2006 Part II (PDF - 802 Kb) The Williams Cage A Key Tool for Carp Management 2006 Part III (PDF - 912 Kb) Page Top
Point-Source Management of Carp Common carp have been implicated in causing damage to riverbanks, aquatic macrophytes and competing with native fish for food and habitat. The life history of carp has been investigated for several years at ARI to fill gaps in knowledge about their movement and spawning patterns. This information will be used to assist in the management of carp populations in the Murray-Darling Basin. The floodplain system in the Barmah-Millewa forest (220km north of Melbourne) was the focus of the study, which included the radio tracking of adult and sub-adult carp. Most carp were found to migrate short distances between the Murray River and the floodplain to spawn, however some migrated 100’s of kilometers. It was previously unknown that carp migrate to spawning areas. The mouths of the Barmah and Moira lakes were found to be critical floodplain entry and exit points. Trials of carp trapping methods at these points resulted in the removal of large numbers of fish. Targeting control efforts at access points to spawning habitats may limit recruitment and is likely to be a key management option. During the project a cage that automatically separates carp from native fish was developed: the Williams’ cage. The following report is available for download: Ecology and Mgt of Carp in the Barmah-Millewa Forest Part I 2002 (PDF - 1.7 Mb) Ecology and Mgt of Carp in the Barmah-Millewa Forest Part II 2002 (PDF - 1.2 Mb) See also the About ARI page page for news on awards won by the carp project team. Page Top
Review of Feral Mammal Control in Australia Many organisations commit significant resources to managing pest species. However, there is limited evidence of the benefits of feral animal control on mitigating the threats they pose to native species and ecological communities. The former federal Department of the Environment and Heritage (now Department of the Environment, Water, Heritage and the Arts, DEWHA) has funded an audit of existing feral animal control activities in Australia. Information on 1308 feral animal control operations was collected via surveys from 27 organisations that have undertaken control on ‘public’ land. This included questions on the objectives, period and area of control, techniques used, presence of threatened species in the control area and whether any monitoring was undertaken. Surveys found that foxes and rabbits were the most frequently targeted species. The primary objective of control operations targeting foxes, feral cats and wild dogs was the protection of threatened fauna. In contrast those control operations targeting feral goats, feral pigs and rabbits listed habitat conservation as the primary objective. More than 75% of all control programs did not monitor changes in pest abundance or native species/ecological community. Until such programs use study designs that include replicated treatment and non-treatment areas, and adequate monitoring of changes in the abundance of both pests and resources being protected, our knowledge of the costs and benefits of feral animal control for native fauna and flora will remain unreliable. For more details see the final report, available via the DEWHA website. An additional report, also on the DEWHA website, identifies gaps in knowledge on control activities and recommends priorities for filling those gaps. This information has also been published as journal articles: Reddiex, B, Forsyth, D.M., McDonald-Madden, E., Einoder, L.D., Griffioen, P.A., Chick, R.R., and Robley, A.J. (2006) Control of pest mammals for biodiversity protection in Australia. I. Patterns of control and monitoring. Wildlife Research 33: 691–709 Reddiex, B., and Forsyth, D.M. (2006) Control of pest mammals for biodiversity protection in Australia. II. Reliability of knowledge. Wildlife Research 33: 711–717 Page Top

Feral Animal Exclusion Fencing Review Exclusion fencing is increasingly being used to protect areas of high conservation value from the threats posed by vertebrate pests. Are these fences excluding pests and are they cost-effective? ARI, supported by the National Heritage Trust, through the former federal Department of the Environment and Heritage (now Department of the Environment, Water, Heritage and the Arts, DEWHA), carried out an Australia-wide audit assessing fences designed to exclude feral animals (particularly foxes, cats, rabbits, dogs, pigs and goats) to assist land-managers in choosing appropriate fence designs. 22 fences were assessed via surveys and field visits. Information was gathered on the fence design, fencing materials used, frequency of fence maintenance required, effectiveness of the fence in excluding feral animals and any impacts the fence has had on non-target species. 70% of 20 fence managers surveyed felt that their fence was sufficiently effective despite most being breached occasionally by feral animals (only three fences reported no known breaches). To maximise the effectiveness of a fence, lethal feral animal control programs are often conducted in the surrounding area. Of the fence designs reviewed, few have been formally tested. Floppy-top and capped fence designs aimed to keep out cats and foxes are recommended. Evaluation and diagrams of fence designs have been collated into a catalogue. Minimum fence specifications required for particular pest species are based on the measured effectiveness of those designs, the effectiveness of fences in situ, as observed by field personnel, combined with knowledge of the relevant physical capabilities and behavioural responses of feral species. The report and catalogue are available for downloading: Exclusion fencing review 2004 part I report (PDF - 2.0 Mb) Exclusion fencing review 2004 part II fence catalogue (PDF - 1.7 Mb) this report is also available from the DEWHA website. Page Top

Fox Adaptive Experimental Management Program Initiated in 2001 in partnership with Parks Victoria to measure the costs and benefits of a range of fox control strategies, this project involves five parks; Coopracambra National Park, Grampians National Park, Hattah-Kulkyne National Park, Little Desert National Park and Wilsons Promontory National Park. A unique combination of fox control timing (the period of baiting) and intensity (the number of baits per kilometre) is being applied at each park. There are also several non-treatment (experimental control) sites. Current results indicate that continuous control operations over large areas are more likely to suppress fox numbers (as measured by bait take and fox activity indices) than seasonal or short-term operations over small areas. It is thought that monitoring of medium-sized native fauna at risk from fox predation will need to continue for at least 3-5 years before a response to fox control is evident. Initial monitoring has established for the first time the presence of the Southern Brown Bandicoot, Long-nosed Potoroo and Long-footed Potoroo at Coopracambra National Park. Little Pygmy Possums were found at the Little Desert National Park, which is an extension of the known range for the species. For more information contact Alan.Robley@dse.vic.gov.au See the following report for extra details: Adaptive Experimental Management of Foxes 2003 (PDF - 899 Kb)

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Aerial Baiting: Effectiveness in Reducing Wild Dog Populations It is estimated that wild dog attacks on livestock cost the rural community $200,000 annually. These attacks also cause emotional distress to individual landholders and have a broad effect on rural communities. The Victorian Government invests around $3.5 million per year to manage wild dogs, and uses a variety of control methods. Aerial-based distribution of baits is not currently permitted in Victoria, and a recent trial investigated various aspects of the safe and effective use of this method to reduce the impact of wild dog attacks on livestock. Seven wild dogs known to reside within a 400 km2 area in Gippsland were tracked via collars fitted with GPS and VHF radio-transmitters. Predator meat baits (containing 4.5 mg of 1080) were dropped within this area and the collared dogs were monitored for several weeks post-baiting. Although one wild dog died soon after the baits were laid, there was no conclusive evidence that any of the tracked dogs were affected by the aerially laid baits. However, the trial provided valuable information regarding wild dog ecology and movements. The tracked dogs generally stayed in defined home ranges within forested areas away from livestock, even during the middle of winter when food is likely to be scarce. These results support the current policy of limiting wild dog control activities to the interface between public and private land. Currently, aerial baiting has been deferred in Victoria while other investigations are carried out, including a proposed extensive study in NSW to establish the rate of laying baits needed for effective wild dog control. The Ministerial advisory group; the Aerial Baiting Stakeholder Consultative Committee, in consultation with wild dog management groups has recommended that future research should focus on the efficacy of 1080 baiting in general, bait size and position, and dosage levels and density, and that in Victoria there should be increased emphasis on ground-based baiting effort. For further information contact Alan.Robley@dse.vic.gov.au Page Top