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Australia is currently dealing with a mouse infestation problem, but Australia is awash with different types of predators that presumably eat lots of mice like animals. Snakes in particular are well suited to kill mice, especially in close quarters. Snakes can fit in places most other predators can't due to their size. Additionally large invertebrates (like huntsman spiders) should also be able to take on some of the mouse load.

And it would be one thing if this was the first time the population ever boomed like this, but mice population booms have apparently have happened since Australia has existed. So why aren't we seeing large spikes in those predators when mice populations boom like this?

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    $\begingroup$ it takes time for the predatory population to respond - mice can breed in as little as 6 weeks (42 days), snakes take 45-70 days from laying to hatching, don't know how long from hatching to breeding... $\endgroup$
    – bob1
    May 13, 2021 at 4:54
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    $\begingroup$ Well for one thing we hunted many of the native predators to extinction. For another why haven't predators wiped out mice on other continents, because predators rarely wipe out their prey. $\endgroup$
    – John
    May 13, 2021 at 5:07
  • $\begingroup$ @bob1 yes but this has happened before, and I've seen no mention of increasing predator populations. $\endgroup$
    – Krupip
    May 13, 2021 at 13:22
  • $\begingroup$ No doubt people have killed most mouse eating snakes in populated areas where mice find food easily. I see the same thing here in east TX; Copperheads ( mice eaters ) were common when I moved here 25 years ago. More people moved in and killed every snake they could . Now these same people are the ones who whine the most about the increase in mice and rats. I have encountered many copperheads , they were about the most docile type snake I know . $\endgroup$
    – blacksmith37
    May 13, 2021 at 23:31
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    $\begingroup$ a) you've got most of Australia's predators in your list: spiders and snakes. Snakes aren't that populous and spiders don't have a huge appetite: 1 mouse per week would be overfeeding. Dingoes don't eat 'em coz that's a cat's job. We have no native cats, no rodent eating mammals like stoats, ferrets etc. Basically it's up to eagles & goannas. and b), Australia has existed for over 65,000 years. Rodent plagues have been around for 200. $\endgroup$
    – mcalex
    May 14, 2021 at 16:04

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The mice aren't invading Australia, they are invading the wheat producing zones, where the tractors are leveling the land and putting on pesticides. The local frog, amphibian and snake populations downstream of the farmer's fields is strongly affected by the farmland, and so are the birds of prey, if they weather the pesticide use, they have to hide in dense trees, hollow logs, caves, and old barns, which are very lacking in Australian farmland.

If the government enforced laws for field edge habitats for local ecology, then there would be less mice.

Have a look at the map of wheat producing areas. wheat producing areasRodent Outbreaks: Ecology and Impacts pages 225-238 PDF Google book

The map of mice infestations: map of mice infestations

From pestsmart.org.au, though no longer available.

and a map of Australian climate: map of Australian climate

wikimedia

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    $\begingroup$ Very nice answer and awesome images! Makes me wonder how a cold desert can be so directly adjacent to a hot desert, but perhaps it's just a matter of definition. $\endgroup$
    – Sixtyfive
    May 14, 2021 at 14:33
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    $\begingroup$ @Sixtyfive: See en.wikipedia.org/wiki/Desert_climate. A few different definitions are in use, but in all cases there's a temperature cutoff directly from "cold desert" to "hot desert". There are no in-between types. (And the names shouldn't be taken too literally. The Gobi Desert is a "cold desert" climate, but at the height of summer, temperatures there regularly rise above 100 °F or 40 °C.) $\endgroup$
    – ruakh
    May 14, 2021 at 22:35
  • $\begingroup$ @sixtyfive The barrier of the warm vs cold desert is defined where the annual temperature average is higher and lower than 18'C, Koppen was a botanist, he devised regions based on vegetation types, the mix of temperature and rain where the same plant-types can grow. The temperature map is very different: researchgate.net/profile/Ferne-Edwards/publication/232319271/… Vs rainfall maps bom.gov.au/climate/how/newproducts/images/annrain2.jpg $\endgroup$
    – bandybabboon
    May 20, 2021 at 7:23
  • $\begingroup$ Central Australia at Uluru and the cold desert regions can both sometimes be freezing on the thermometer for three/four months of the year, averaging 5'C at night. I think it's the summer that is hotter by about 10'C, i.e .30 vs 40'C. $\endgroup$
    – bandybabboon
    May 20, 2021 at 7:28

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