A mouse plague is devastating farms and homes in southern and Western Australia, with scientists estimating up to 8,000 mice per hectare in the worst-hit areas. The national science agency, the CSIRO, defines a plague as more than 800 mice per hectare, but some farming communities in Western Australia are experiencing numbers ten times that.
To visualize the scale, researchers count mouse burrows, finding areas with 40 burrows per 100 square metres, equating to 4,000 burrows per hectare. With at least two mice per burrow, the estimate reaches 8,000 mice per hectare. For context, a typical suburban block of 400 square metres could host hundreds of mice, and a 3m x 4m bedroom might be shared with about 10 mice.
The psychological impact is severe, according to CSIRO mouse plague expert Steve Henry. “You simply can’t get away from them,” he says. In Morawa, 370 kilometres north of Perth, shire president Karen Chappel reports mice are everywhere: in homes, cars, sheds, paddocks, and schools. People have been bitten on the toes and found mice nesting in their beds after returning from holiday.
A CSIRO report from March forecasts high mouse numbers will affect parts of Western Australia’s west coast around Geraldton, near Merredin, and the Esperance region, as well as the Adelaide Plains and Yorke Peninsula in South Australia. Mice are spreading from farmland into towns, inundating businesses and forcing some to discard thousands of dollars of stock.
Mr Henry says the current plague in Western Australia is similar to the out-of-control numbers seen in New South Wales and Queensland in 2021, which caused millions of dollars in damage and mental distress. Mice have plagued Australian grain farms since the 1880s, with plagues typically breaking out every four to five years after plentiful rain. The worst recorded plague was in 1993 across South Australia and Victoria, causing an estimated $96 million damage.
