The latest news about mouse populations in Western Australia.
Localised mouse plagues are currently impacting areas around Geraldton, the central wheatbelt around Merredin, and around Esperance in Western Australia. Mouse populations in these areas are extreme, exceeding 8000 mice per hectare.
The town of Morawa, southeast of Geraldton, is being overrun, with mice in beds and driving along roads in the area sounding like “popping bubble wrap”. Not only is there increased risk from rodent diseases, but the smell from the large number of carcasses, which can’t be cleared despite best efforts, means air fresheners are in big demand. Apart from the personal impact, businesses and agriculture are being hit hard – up to $3 billion worth of exports are under threat. The town has had to suffer these conditions for a number of months now, and there has been frustration regarding the time taken for the APVMA to approve the use of double strength rodent baits.
Zinc phosphide baits are the bait of choice for plague outbreaks, being fast acting with apparent low risk of secondary poisoning. However, the standard bait of 25 g/kg zinc phosphide is apparently providing variable results – an observation supported by CSIRO research has confirmed that the 25 g/kg bait does not provide consistent results and that the 50 g/kg bait is more effective. An emergency application was submitted requesting a permit to produce and use these higher concentration baits. Homeowners, business and farmers suffering from the mouse plague were getting frustrated about the time it was taking to get the application assessed and approved. Fortunately, these higher concentration baits have now been approved by the APVMA.
As we move through winter, the plague areas are likely to extend in Western Australia. There are also concerns for areas in the Adelaide Plains and Yorke Peninsula in South Australia, where mouse populations are currently moderate to high. Mouse populations in Queensland, New South Wales and Victoria are currently low.
