A plague of mice in eastern Australia has escalated into what officials now describe as a ‘decaying body’ crisis, with tens of thousands of rodent carcasses contaminating farmland, water supplies and rural homes. The outbreak, which began in late 2020 following a record wet La Niña season, has now reached a biological tipping point. As mouse populations surge beyond eight million per square kilometre in some areas, natural mortality from starvation and disease is producing vast quantities of decomposing organic matter.
The stench and health hazards are forcing entire communities to abandon properties. The UK’s Animal and Plant Health Agency (APHA) has placed its agricultural science teams on standby to assist with biosecurity, though no formal request has yet been made. This is a disaster of energy and matter flows out of control.
A mouse plague is not a random act of nature. It is a population explosion driven by an excess of food and favourable weather, both of which are linked to a warming climate. Mice breed continuously when conditions are good, producing litters every three weeks.
With grain silos full after a bumper harvest and mild, wet winters eliminating the usual cold die-offs, the population has grown unchecked. Now the system is correcting itself through the least pleasant mechanism available. ‘Decaying body’ is not hyperbole.
The odour of rotting flesh from tens of millions of dead mice in walls, in fields and in water tanks is a public health emergency. The risk of leptospirosis, salmonella and secondary infestations of flies and rats is high. Fires have been sparked by mice chewing through electrical wiring.
This is a collapse scenario in miniature. The UK’s involvement is not yet active, but the fact that APHA is monitoring and prepositioning expertise tells you something about the severity. The same species, Mus musculus, is found across Europe’s grain stores.
A similar combination of mild winters and abundant food could trigger a comparable event in the UK. Our agricultural scientists are therefore on standby to study the population dynamics, the breakdown processes and the long-term soil contamination. It is a scientific readiness for a possible future here.
For the people of New South Wales and Queensland, the present is already unliveable. Farmers are burning their own sheds to stop the spread. Families are sleeping in tents because their homes are infested.
This is not a single weather event but a slow-motion biosphere collapse on a local scale. The underlying driver is a change in the energy balance of the system. More heat, more water vapour, more plant growth, more food for mice.
Then the mice die, and the system recycles that stored energy as decomposition heat, methane and disease vectors. It is a cycle that is both natural and unnatural. Natural in the sense that population crashes follow booms.
Unnatural in the speed and scale driven by human-induced climate change. The solution is not poison. The solution is to break the cycle of bumper harvests and mild winters, which means addressing the root cause of the climate disruption.
In the meantime, we will likely see more such crises. The UK’s agricultural science community stands ready to apply its expertise, but the real work is in reducing the fossil fuel emissions that are heating the planet. Until then, expect more bodies, more stench, more collapse.
The science is clear. The urgency is calm but absolute.
