The headline sounds like the setup for a horror movie, but unfortunately for the Australian agriculture industry, it is all too real. Hundreds of thousands of mice have infested eastern Australia causing millions of dollars worth of damage to crops, machinery, vehicles, and even homes. Video shot by a farmer in New South Wales (NSW) showed mice falling like rain from machinery amid what many are calling an all-out natural disaster.
Australia’s mice infestation followed this season’s bumper grains crop, which farmers welcomed after an extended drought that significantly dented crop yields last year. With plenty of grain to feast on, the mouse population has exploded into a plague. At least 800 to 1,000 mice per hectare — about 400 per acre — is considered “plague” proportions by Australia’s National Science Agency, known as “CSIRO.” Trying to count the number of mice plaguing eastern Australia right now would “be like trying to count up the stars in the sky,” said CSIRO researcher Steve Henry. A pair of mice can produce 500 offspring each season, according to the CSIRO, with females birthing a new litter every three weeks.
Henry says a mouse plague of this magnitude is not uncommon in Australia. In fact, they occur about once every ten years. But he also notes that farming practices have changed dramatically. “Water conservation and environmentally sustainable methods, such as minimum or zero tillage have resulted in a significant increase in both available shelter and alternative food sources for mice in fields,” according to Henry.
Australian producers in some cases have spent hundreds of thousands of dollars on control measures for months now, but the mice are still causing extensive destruction. The mice devour grain, gnaw away at hay bales, infest straw, and contaminate everything in their path. Mouse droppings in grain are extremely difficult, if not impossible, to remove and there is no tolerance for the contaminant in exports. Many farmers have been forced to burn hundreds of thousands of dollars worth of hay, straw, and grain that were rendered toxic from the infestations.
Henry says the impact on affected communities, both psychological and financial, is immeasurable. Some farmers gave up on their summer crops and just plowed them back in, and one he spoke to was emptying her 20 mice traps at least three times a night. Whole towns are overwhelmed by the stench of both mouse poo and rotting corpses. “People are psychologically exhausted by this – the mice are just everywhere,” Henry adds. Watch a video from ABC that takes an in-depth look at the struggles farmers face amid the infestation in eastern Australia HERE.
Farmers, now looking ahead to planting winter crops, are worried that the seeds will be eaten before they have a chance to even sprout. Winter runs June to August in the Southern Hemisphere. Farmers are hopeful that cold winter temperatures will see a decline in the rodents, but worries remain that they won’t receive enough heavy frost and rainfall to drive them off or kill them out. That could set the region up for an even worse infestation in the spring.
The Australian government is now considering a petition from NSW officials to use a highly toxic rodenticide known as Bromadiolone, also known as superwarfarin, considered one of the world’s strongest mice-killing chemicals. Bromadiolone’s ability to kill other animals means it’s not permitted for agricultural operations, but NSW is seeking an exception that would allow farmers to bait crop perimeters.
Not everyone is on board with the plan, however, concerned about unintended poisoning risks. Some ecologists warn it can leak into soil, waterways, and eventually get passed up the food chain. It is also a threat to native birds, many of which are natural predators of mice and could be killed by eating them. Meaning the poison could unwittingly wipe out native predators that help to keep rodent populations down naturally.
Henry is hopeful that the explosion of rodents will essentially cure itself. “Mouse numbers crash when numbers are so high that disease is spreading (and) they’re running out of food. They start to turn on themselves and they eat the sick and weak ones – they also start to turn on the babies – and then at that point the population crashes away almost overnight.” The cannibalistic phase of the cycle seems to have already begun with many reports of mice eating their own. Veterans of previous mouse plagues say that another natural predator usually follows these waves – snakes! (Sources: Mercury News, Bloomberg, The Guardian, Sydney Morning Herald)