A perfect storm of conditions could cause the return of a mouse plague ­similar to that which caused havoc and financial devastation in farming communities in 2020-21, warnings emerging across western NSW suggest.

Despite no official alerts yet, monitoring data and field reports from late last year show mouse numbers are increasing across several key cropping zones, with scientists noting a higher-than-normal number of pregnant females – an early indicator that populations could surge rapidly if favourable conditions continue.

Ongoing freight disruptions, highway closures and sharply rising fuel prices have already stretched farm budgets and supply chains, leaving little ­capacity to absorb further ­losses should mouse numbers surge again.

For Wirrinya farmer Jesse Mundy, there has been a steady rise in mouse activity over the past few months.

“I have seen a few more in the sheds for sure. It’s been going on for a few months now,” he said.

Mouse plagues are a recurring threat in southeastern Australia, typically occurring every four to six years, placing the region within the expected window following the devastating 2020-21 outbreak.

That last plague caused an estimated $600m in damage across rural eastern regions, with mice destroying crops, contaminating grain stores, and damaging machinery and household infrastructure.