Rat plague in Australia: first came the drought, then the floods, and now millions of rats.


Farmers in Australia burn their crops themselves.

They are desperate to escape an epic plague invading their hay. The drought came first. Then the flood.

fight the plague

The elements of a farm disaster

Australia suffers from rat plague every decade or so. Some of the older farmers remember an invasion during the 1970s where the ground felt as if it was moving, it was dense with mice.

One contributing factor is changing agricultural practices. To conserve moisture in Australia’s arid soil, farmers plant new crops directly on old stems left in the ground.

This means that mice have more places to shelter – and they have more food.

Mice researcher Steve Henry calls mice “breeding machines” because of their rapid reproduction. They usually start having children at the age of six weeks.

After three weeks of gestation, litters of up to 10 mice are born. The original mice would continue to breed, with no gap between pregnancies.

After four months, some of the pups have matured and bred, and the first large pups have been litters. There can now be up to 90 mice in addition to the original two.

After eight months, roughly the length of the breeding season, the original pair of mice can produce about 500 rodents.

But that’s only from one pair of mice. Looking at just four pairs, for example, the total goes up to 2,000. And it quickly adds up. to millions.

The New South Wales government has secured 5,000 liters (1,320 gallons) of a deadly bait called bromadiolone. Scientists worry that the venom may inadvertently kill other species — wedge-tailed eagles, owls, snakes, and goans (large lizards) that feed on abundant rat prey.

Mice also carry viruses that may be fatal to humans. Queensland health authorities say the number of cases of leptospirosis – a flu-like illness that can lead to meningitis, kidney failure, bleeding and respiratory complications – nearly doubled in 2021 compared to this time last year.

Summon in a mouse whisper

The worst smell ever

Rat epidemics usually end in the end of the world, according to Henry, as the population grows too large to support itself. Due to diseases and running out of food, insects turn on each other, starting with the sickest and weakest.

He worries that if temperatures don’t drop sharply enough during the winter, many will survive the cooler months, preparing for an even more explosive outbreak next spring.

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about this story

Editing by Reem El AkkadAnd the Olivier LaurentAnd the Armand EmamjoumehAnd the David Curacho And the Tim Miko. drawings by Hana is sleeping And the Julia Lidor. design and development Emily Wright. Video Editing by Jason the chicken. Copy editing by Karen Fonfjeld.

Rat density data are from a March 2021 report by the Commonwealth Scientific and Industrial Research Organization (CSIRO) and the Grain Company for Research and Development. Global land cover data by national mapping organizations: GLCNMO Version 3 © Geospatial Information Authority of Japan, Chiba University and collaborating organizations. The rat reproduction chart is based on an interview with Peter R. Brown, a research scientist and rodent management expert at CSIRO.

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