Conservation and Environment

Invasive Species

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 have harmed 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 projects

Identifying Sources of Carp in the mid-Murray River Using Otoliths Feral Cat Toxicant and Bait Delivery System Tracking Wild Dogs using GPS Technology

Details of these projects are given below.

For information on previous projects, such as the Williams' carp separation cage, management of carp, aerial baiting for wild dogs, fox predation and Australia-wide reviews of feral mammal control and exclusion fencing, see our Invasive Species - past projects page.

Identifying Sources of Carp in the mid-Murray River Using Otoliths The Barmah-Millewa Forest floodplain is recognised as an Icon Site under the Murray-Darling Basin Commission’s Living Murray program. Although the significance of the site to native flora and fauna is well recognised, the floodplain lakes have also been suggested as a major spawning and recruitment source for the introduced common carp Cyprinus carpio in the mid-Murray River. Carp, like all bony fish, have earstones called otoliths. Each day a new ring of calcified material is formed on the otoliths, which can be used to determine the age of a fish. Otoliths can also reveal information about the chemical environment in which a fish has lived. The otolith chemistry of juvenile carp (4-6 month old) was matched to that of larval carp (2-3 weeks old) collected from several potential recruitment areas. Results suggest that during the 2005/06 summer the Barmah-Millewa Forest floodplain lakes acted as the key source area for mid-Murray River carp populations, with the lower Goulburn River acting as the next major contributor of carp recruits. The study shows that otolith chemistry techniques can provide an effective and repeatable monitoring tool for identifying ‘hotspots’ of carp recruitment in the mid-Murray region. Repeating this work on an annual basis will provide valuable insights into the dynamics of carp populations that can contribute to adaptive management of the Barmah-Millewa Forest, the Murray River and its tributaries. For further information contact David.Crook@dse.vic.gov.au or see the following article: Crook, D.A. and Gillanders, B.M. (2006) Use of otolith chemical signatures to estimate carp recruitment sources in the mid-Murray River, Australia. River Research and Applications 22: 871-879 Page Top

Feral Cat Toxicant and Bait Delivery System Feral cats are widely distributed across Australia and many offshore islands where they maintain self-sustaining populations without any intentional assistance from humans. Feral cats are implicated in the decline of populations of native species through direct predation, competition for resources and the spread of disease. There are currently no cost-effective techniques that can be used to manage feral cat populations over large areas in Australia. Existing techniques such as shooting or trapping require significant investment in skilled labour and as such can only achieve population reductions in relatively small areas. Alternatives such as poison baits intended for feral cats need to be surface-laid and this can present a significant hazard to wildlife that must be carefully addressed. A collaborative research group is developing a bait and toxicant delivery system that will offer a humane and highly target-specific technique for managing populations of feral cats over large areas. It is intended to restrict the use of this bait to areas of land managed for conservation such as National Parks. The project has pioneered the development of a new toxicant formulation using para-aminopropiophenone (PAPP). A hard-shelled pellet delivery system achieves improved specificity by exploiting physiological and behavioural differences between feral cats and native wildlife species. The first field trial was conducted in French Island National Park, Victoria. Ten feral cats were trapped within a 50km2 study zone and fitted with VHF/GPS radio-collars two months prior to baiting. Baits were surface-laid at a density of 69 baits/km2. Two feral cats died prior to the application of baits, six feral cats died following consumption of bait and two feral cats survived. It is not known whether the surviving cats consumed any bait. This result is very promising in terms of providing land managers with a new tool for management of feral cat populations on conservation estate. Further field efficacy trials will be undertaken in the tropical and arid zones prior to seeking an agricultural chemical registration for the product in Australia. Project collaborators include Commonwealth, Western Australian and Victorian government conservation agencies along with Scientec Research Pty Ltd. For further information contact Michael.Johnston@dse.vic.gov.au The following journal articles detail preliminary studies on bait development: Johnston, M.J., Shaw, M.J., Robley, A and Schedvin, N.K. (2007) Bait uptake by feral cats on French Island, Victoria. Australian Mammalogy 29(1):77-84 Marks, C.A., Johnston, M.J., Fisher, P.M., Pontin, K. and Shaw, M.J. (2006) Differential particle size ingestion: Promoting target-specific baiting of feral cats. Journal of Wildlife Management 70(4): 1119-1124 Page Top
Tracking Wild Dogs using GPS Technology Wild dogs (which include Dingoes, feral dogs and their hybrids) are declared pests in most states of Australia. Global Positioning System (GPS) technology has been used to track the movement patterns and interactions of wild dogs in forests in south-east New South Wales, north-east Victoria and Gippsland. This study is being run in partnership with State Forests NSW, the Australian Hydatid Control and Epidemiology Program, the Victorian Department of Primary Industries and DSE. Thirty-five wild dogs have been fitted with collars containing a GPS unit and conventional VHF transmitter programmed to collect data at regular intervals throughout the night and day. This information is sent to researchers via the Argos satellite network. Transmitter data indicates that wild dogs stay within their territories, and in general don’t make a special effort to travel long distances to reach agricultural enterprises such as sheep grazing. This dispels the assumption that wild dogs target these areas It appears that wild dogs have at least two distinct behavioural modes, 1) encamped; where they move over relatively short distances and make many sharp turns, and 2) exploratory; where movements are longer in distance and more direct. Territories of the wild dogs tracked ranged from 10 km2 to over 150 km2. A small number of individuals have been tracked moving hundreds of kilometres, most likely in search of a new territory. Mathematical models are currently being used to try to identify how certain landscape features influence habitat use and movement by wild dogs. This will improve the capacity of land managers to limit the impact of wild dogs on agricultural communities, and increase our understanding of their role in the ecosystem. The GPS method of tracking has the potential to provide information on a range of aspects of wild dog ecology in a short period of time and is relatively cost-effective compared to the alternative method of ground based radio-tracking. For further information contact Alan.Robley@dse.vic.gov.au The following article outlines some of the issues related to wild dog and fox populations in Australia: Fleming, P., Allen, L., Lapidge, S., Robley, A., Saunders, G., and Thomson, P. (2006) A strategic approach to mitigating the impacts of wild canids: proposed activities of the Invasive Animals Cooperative Research Centre. Australian Journal of Experimental Agriculture 46: 753-776. Page Top