Western Australia’s farmers are dealing with a severe mouse outbreak that has spread across large farming regions after a strong harvest season. Farmers say the combination of leftover grain and fresh plant growth has created ideal conditions for the rodents to multiply.
About two hours north of Cosgrove’s farm, agronomist and farmer Belinda Eastough described how quickly the situation has escalated on her property near Nolba, around 80 km northeast of Geraldton. She recalled a past outbreak where mice even entered personal belongings inside the house.
During the earlier outbreak in 2021, she said mice were found in unexpected places, including bags, floors, walls, and kitchen storage areas. This year, however, the situation has shifted outdoors, with most activity concentrated in the fields.
Record Harvest Created Food Boom for Mice
Eastough explained that last year’s record harvest left large amounts of spilled grain in the paddocks. That grain became an easy food source for mice and helped their population grow rapidly.
Summer rainfall followed the harvest, which encouraged new green crop growth. This created a constant food supply across the fields. She described the conditions as giving mice both grain and fresh vegetation, which allowed them to thrive.
She said the result was a population explosion, with mice spreading heavily through crop areas rather than moving back into homes.
Thousands of Mice Per Hectare in Crops
Eastough grows wheat, canola, and lupins across her 5,500 hectare farm. The wheat is exported for products like noodles or used in everyday foods such as bread, biscuits, and pasta.
In her canola fields, she estimates mouse density at around 8,000 to 10,000 per hectare. She compared this level of infestation to a rugby field covered in rodents.
She added that past mouse outbreaks often collapsed once food sources ran out. This time, however, populations have stayed high because food remains available across paddocks.
Farmers Say Conditions Are Not Improving
Despite previous cycles where numbers dropped naturally, farmers report that this outbreak is not following the same pattern. Continuous food supply from crops and regrowth has allowed the mice to survive longer than expected.
Eastough described the situation as overwhelming, saying the scale of infestation has made normal farm work more difficult. She said the paddocks feel fully occupied, with little sign of relief.
