You’ve probably heard that Australia is overrun with an invasive species: rabbits. Or at least you’ve heard of the “rabbit proof fence,” which incidentally, turned out to be anything but rabbit proof. How did this invasion start, anyway?
In 1859, Thomas Austin made a very small decorative decision with very large consequences. Austin was a British expat living in Australia, grown newly wealthy through sheep farming, and he had most of the trappings of his new lifestyle in place—the bluestone mansion, the horses, the 29,000-acre estate. All he was missing were some atmospheric reminders of his homeland. So he asked his nephew to bring him some English fauna—a bunch of blackbirds, thrushes, and partridges, and 24 European rabbits. Hunting them would make for a good weekend activity, and besides, he wrote, "the introduction of a few rabbits could do little harm."
Well, of course, they bred like rabbits. From those two dozen bunnies, the population boomed to ten billion by 1920. The rabbits eat vegetation until a formerly-lush area is completely barren. They dig warrens that destabilize soil and encourage erosion. They ruin the habitats of native animals. They destroy agriculture. The Australian government has tried several ways to control the rabbit population, with grim results. Read about how rabbits took over Australia (as well as the rest of the world) at Atlas Obscura.