24 Rabbits to 10 Billion — Australia’s Worst Import

In 1859, English settler Thomas Austin released 24 rabbits in Australia.
"The introduction of a few rabbits could do little harm and might provide a touch of home."
By the 1920s, Australia had around 10 BILLION rabbits.

From 24 to 10 billion in 60 years. The worst case of ‘it seemed like a good idea at the time’ in ecological history.