It was Puerto Rico’s fault. The Caribbean island introduced the Giant Neotropical Toad (officially Bufo marinus) from nearby Central America in the early years of the 20th century, in an attempt to control damaging beetle infestations in sugar cane plantations. The cunning plan worked, establishing this large terrestrial amphibian as the sugar planters’ friend and earning it the popular name ‘cane toad’.
But this is not a nice creature, growing as it does to a maximum length of around 38 cm (15 in), weighing in at up to 2.65 kg (5.8 lb) and protecting itself by excreting deadly toxins. The warty cane toad is a prolific breeder and its tadpoles, too, can prove fatal when ingested by predators. Undeterred by this alarming CV, and encouraged by results in Puerto Rico and Pacific islands like Hawaii, a few hundred cane toads were introduced to Australia in 1935.
A half-hearted study into the newcomers’ feeding habits was conducted – which failed to detect the fact that they would prove ineffectual in controlling the very beetles they were expected to eradicate – before over 60,000 toadlets were released into the Queensland cane fields the following year. It ultimately proved to be a disastrous decision. Not only did the interlopers fail to control pests that were ravaging the sugar cane, but they also had a hugely negative impact on indigenous wildlife.
From relatively small beginnings the population expanded to the point where it is estimated in the hundreds of millions, with an increasing range that now encompasses the whole of Queensland plus large areas in New South Wales and Northern Territory.
Australia’s isolation ensured that it developed a balanced ecological system, but the introduction of feral species like rabbits, domestic cats and foxes after colonization and latterly the cane toad – has seriously disrupted the natural order of things.
When: 1935 and 1936
Where: Queensland, Australia
Death toll: Many millions of native animals, notably cane toad predators like the Northern Native Cat, monitor lizards, land snakes and freshwater crocodiles whose populations have declined significantly as a result of eating the poisonous amphibians.
You should know: One of the chemicals produced by a cane toad in defensive mode is bufotoxin, which induces pleasantly mild hallucinations and is a banned Class 1 drug in Australia. Unfortunately, thrill seekers who lick cane toads in the hope of achieving a ‘high’ ingest a cocktail of powerful toxins that can prove fatal… and has been on several recorded occasions.