Over the past 20 years, there has been an alarming decline in a wide range of small native mammal species in northern Australia. The declines have occurred in remote areas that were previously considered ecologically sound. The causes of the declines are under investigation; changed fire regimes, grazing and introduced predators (including feral cats) are implicated. There is still much to learn about health and disease of small mammalian wildlife species in Australia and the paucity of knowledge has made assessment of the impact of disease in these declines challenging.
Over a two year period, research was undertaken by the Conservation Medicine Program, Murdoch University, in collaboration with Northern Territory (NT) Dept. of Land Resource Management to assess health and disease in native mammals in the tropical savannahs of the NT. Study sites were located in urban (Darwin) and remote regions (Bathurst Island, Cobourg Peninsula, Kakadu National Park and Groote Eylandt), and included both mainland and island sites. Investigation focused on four target species across four different families (brushtail possum, northern brown bandicoot, northern quoll and brush-tailed rabbit rat). Black rats and feral cats, as potential pathogen reservoirs, were also examined and sampled.
Animals were anaesthetised and investigations included assessments of health and specific testing for a range of prioritised pathogens of concern, including toxoplasmosis, herpesvirus and blood borne pathogens. De novo molecular testing was undertaken to investigate the presence and potential impact of novel pathogens. Sampling and testing was undertaken on almost 200 individuals. This is one of the most comprehensive and wide ranging disease investigations undertaken on multi-species declines in Australia.
The implications of our findings will be discussed in the context of wide scale population declines in the Top End of the NT and will include recommendations for ongoing work in this area.