12. Billions of Feral Rabbits
Australia’s rabbit numbers just kept growing, and growing, and growing some more. By 1920, there were an estimated 10 billion feral rabbits hopping around Down Under. They competed with livestock for pasture, ate crops, and stripped the soil of vegetation. The latter is particularly problematic: of all the habitable continents, Australia has the most vulnerable soil and is the one most susceptible to erosion.
For over a century, Australia has struggled to control its rabbit population. Measures have included shooting, poisoning, and infecting the pests with epidemic diseases. The most conspicuous measure, though was and remains fencing, ranging from fences around individual farms and pastures, to massive fences stretching for hundreds of miles, such as Western Australia’s Rabbit-Proof Fence. The latter failed to live up to its name: rabbits burrowed beneath and jumped over it.