Exploding Mouse Populations Threaten Western Australia’s $1 Billion Grain Sector

Scientists warn of a devastating mouse plague in WA as numbers hit 8,000 per hectare. Farmers seek urgent federal aid to protect billion dollar crops.

By: AXL Media

Published: Apr 3, 2026, 4:00 AM EDT

Source: news.com.au

Critical Infestation Levels Across the Western Cropping Zone

A biological crisis is unfolding across Western Australia’s primary agricultural regions, with scientists documenting a "really serious situation" as mouse numbers reach plague proportions. Research from the CSIRO indicates that in parts of the Mid-West, Wheatbelt, and Goldfields-Esperance, farmers are discovering upwards of 4,000 burrows per hectare. In the most severely impacted paddocks, the density has surged to 8,000 mice per hectare, creating an environment where traditional management strategies are being overwhelmed.

CSIRO research officer Steve Henry warned that the timing of this explosion is particularly catastrophic. As farmers prepare to sow their winter crops, the massive rodent population is poised to follow sowing lines, extracting and consuming seeds directly from the soil. This behavior is especially damaging to canola crops; unlike some cereals that can occasionally recover from early grazing, the removal of a canola seed results in a total loss of that plant, leading to significant yield deficits.

Environmental Drivers and the Impact of Cyclonic Weather

The current outbreak is the result of a "perfect storm" of environmental factors that began during the previous spring. A series of high-yield harvests left an abundance of grain on the ground, providing both high-energy food sources and dense stubble for shelter. These conditions allowed for continuous breeding throughout the warmer months. Local farmers report that the situation has transitioned from a manageable nuisance to a full-scale crisis following recent cyclonic rainfall across the state’s west.

WA Farmers chief executive Trevor Whittington noted that the combination of warm temperatures and high moisture levels is expected to cause population numbers to "explode" again within days. As the first germinations appear following the rains, the emerging sprouts will provide the only green feed available in the landscape, making them prime targets for the hungry rodent masses. The convergence of these weather patterns has accelerated the breeding cycle just as the $1 billion cropping program enters its most vulnerable phase.