The threat of a mouse plague is intensifying across Australian grain-growing regions, with visible damage already reported. Growers near Geraldton and Ravensthorpe in Western Australia have shared footage of mice moving through paddocks, and residents in Morawa described mice overrunning their pantries. Pest controller Peter Cekanauskas put out 7.5kg of bait, which was consumed in less than three days. Mice dig along seed furrows and consume grain before germination, causing visible damage described as UFO rings. A mouse plague is officially defined as 800 mice per hectare.
Farmers are already under compounding pressures from fuel shortages and spiralling fertiliser prices due to disruption to global trade from the US-Israeli war on Iran. Roughly 20-30% of global fertiliser supply comes from the Middle East, and the effective closure of the Strait of Hormuz has halted exports of urea, ammonia and phosphate from Saudi Arabia, the UAE and Qatar. Australia imported 3.85 million tonnes of urea in 2024. Andrew Weidemann, research and development spokesperson for Grain Producers Australia, said the mouse threat is the latest blow for growers who already cut paddock movements to conserve fuel.
The last major mouse plague in 2021 caused an estimated $1bn damage across several states, with rural New South Wales alone suffering losses of around $660m. Scientists say the industry is better prepared this time with improved understanding of zinc phosphide bait and earlier warning systems. Steve Henry, research officer at CSIRO, warned that high-value crops like canola are at particular risk given seed shortages this year.
Elevated mouse numbers have been seen from Geraldton to Esperance in Western Australia and into southern Queensland. Western Australia's Kwinana West region has been assessed as high risk. Mouse populations can escalate rapidly, with small numbers turning into large infestations within weeks.