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Investigating the role of disease in the decline of small mammal species in the Top End of the Northern Territory

Investigating the role of disease in the decline of small mammal species in the Top End of the Northern Territory

Dr Kris Warren, Dr Andrea Reiss, Dr Bethany Jackson – Murdoch University; Dr Graeme Gillespie and Danielle Stokeld Northern Territory Department of Land Resource Management

Final Report June 2015: Investigation of Potential Diseases Associated with Northern Territory Mammal Declines

This two year study is being conducted by Murdoch University as a collaborative project with the Northern Territory Department of Land Resource Management (NT DLRM), James Cook University and Charles Darwin University. This project is funded by the National Environmental Research Program (NERP) Northern Australia hub, Theme 4 Terrestrial Biodiversity Conservation and sits within Project 4.1: Research and management to reverse decline of native mammal fauna.

Research objectives

This project will investigate the potential role of disease in the declines of mammal species in northern Australia using:

  • Epidemiological assessment of existing and newly gathered health, disease and ecological data.
  • A hazard identification and prioritisation process to determine and rank potential pathogens (disease-causing infectious agents) affecting small to medium sized mammals.
  • Collection and analysis of data on health and disease in fauna focussing on, but not limited to, four target species of native mammal and two introduced species.

The project will also:

  • Establish baseline information on health and disease in selected target mammal species and populations.
  • Establish baseline information on presence of potential pathogens in common introduced and native by-catch species.
  • Develop protocols and expertise to facilitate incorporation of health assessment and disease surveillance into existing and new field studies.
  • Collect, process and archive biological samples (from target and additional species) to facilitate future studies. 
  • Guide priorities for ongoing research into mammal health and disease in northern Australia.
  • Develop recommendations for management of health and disease in northern Australian mammal populations.

Significance and general description of research

Many small to medium sized native mammal species are in rapid and broad-scale decline across northern Australia, even in relatively well-resourced conservation reserves such as Kakadu National Park. Although impacts from feral cats and changed fire regimes are thought to be major contributors to these declines, there is little evidence to determine the relative impact of each of these factors. Disease may be an unrecognised factor in mammal declines in northern Australia (Fitzsimons et al 2010, Jackson et al 2010, Woinarski et al 2010). There is limited information on health and disease in northern Australian mammal species. For the future of these species and these ecosystems, it is vital to understand not only the role that disease may be playing at present, but also to gain understanding of the likely impacts of disease into the future. If animal numbers continue to fall and populations become more isolated, genetic diversity will diminish and disease threat will grow (Pedersen et al 2007, Jackson et al 2010).

The Conservation Medicine staff from Murdoch University will collaborate with NT DLRM during routine fauna surveys, adding health and disease surveillance to existing protocols. The disease investigation will focus initially on one (or two) species from each major taxonomic group undergoing decline: 

  • Common brushtail possum (Trichosurus vulpecula)
  • Bandicoots, northern brown (Isoodon macrourus) and golden (Isoodon auratus)
  • Northern quoll (Dasyurus hallucatus )
  • Brush-tailed rabbit-rat (Conilurus penicillatus)

And on two key feral mammals:

  • Black rats (Rattus rattus)
  • Feral cats (Felis catus)

Research will be conducted at a range of sites over the Top End, including Kakadu National Park, Bathurst Island, Garig Gunak Barlu National Park on the Cobourg Peninsula and peri-urban areas around Darwin. Other potential study sites include remote islands, West Arnhem Land and collaborative northern quoll study sites in Kakadu.

It should be noted that all aspects of the field work are covered by NT (Charles Darwin University) and Murdoch University Animal Ethics Permits.

Additional collaboration and support

We acknowledge the support of landholders, community groups and other supporters who all contribute to the outcomes of this research.

Many researchers are collaborating to assist with the research and diagnostics, including Dr Cathy Shilton from Berrimah Veterinary Laboratory NT, Dr Carly Holyoake, Dr Lian Yeap, Prof Peter Irwin and Prof Una Ryan of Murdoch University, Dr Joanne Devlin of University of Melbourne and Dr Deborah Holt, Menzies School of Health Research NT.

Sponsors and supporters include the NT Department of Land Resource Management, NT Berrimah Veterinary Laboratories, Charles Darwin University, James Cook University, Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Elizabeth MacArthur Agriculture Institute NSW, Vetpath Laboratory Services WA and the NT Centre for Disease Control.

References

  • Jackson B et al (2010) Research on small mammal decline and disease: Rattus rattus as a potential disease vector. Final Report to Kakadu National Park Ref no: K2010/0030
  • Fitzsimons J et al (2010) Into Oblivion? The disappearing native mammals of northern Australia The Nature Conservancy, Melbourne
  • Pedersen AB et al (2007) Infectious Diseases and Extinction Risk in Wild Mammals. Conservation Biology 21(5), 1269-1279.
  • Woinarski JCZ et al (2010) Monitoring indicates rapid and severe decline of native small mammals in Kakadu National Park, northern Australia Wildlife Research 37(2) 116–126

Charles Darwin UniversityNational Environment Research ProgramNorthern Territory GovernmentJames Cook University