|Adult female cane toad with human hand for comparison|
|Northern Quoll (Dasyurus hallucatus) – went from “Least Concern” to Endangered in a decade due to the spread of cane toads|
However, it is almost unknown that at the very time the cane toad was released into Queensland, the CSIR was experimenting with the European Common Toad (then Bufo vulgaris; now Bufo bufo) as a pest control agent for Oncoptera grass grubs that were eating pastures in southern Australia. Proposals to import Bufo vulgaris (as I will call it for the rest of this post) and also the natterjack toad Bufo calamita date back to Western Australia in 1897. They were never executed in the first third of the twentieth century, but with increasing pest problems in the 1930s, the CSIR imported several specimens of Bufo vulgaris for a thorough test as a biological control agent against various Oncoptera. The CSIR found that Bufo vulgaris devoured all stages of Oncoptera (except, perhaps, the eggs) but that it could not dig down to reach them in their burrows. Consequently, the CSIR did not release Bufo vulgaris into southern Australia.
|European common toad (Bufo vulgaris; now Bufo bufo)|
|Eastern Quoll (Dasyurus viverrinus) now extinct on the mainland due to cane toads, and “Endangered” even in toad-free Tasmania due to rapid anthropogenic climate change|
|Spotted-tailed quoll Dasyurus maculatus – the largest Dasyurus. The CSIR’s prudence in not releasing Bufo vulgaris has so far saved this species from either extinction or being “Critically Endangered” and confined to small islands|
Belief in the magical power of toads to control pests was dogma among the globe’s closely-knit sugar growing fraternity in the 1930s. It is highly plausible that this fraternity feared science for the same reason that large landowners in Catholic Europe did – that it would undermine their political power by providing justification for wealth redistribution from them. While the large landowners of Catholic Europe turned to stigmata stories and Marian apparitions as their means of countering class war, sugar planters held firmly onto beliefs about certain predators as effective pest control agents whether they worked or not. Thus, when the release of Bufo marinus in Puerto Rico coincided with reduced grub density and Raquel Dexter’s dissections showed Bufo marinus to eat beetles, it became dogma among the global sugar fraternity that toads would control beetles everywhere they be introduced. However, as demonstrated by Nigel Turvey in his Cane Toads: A Tale of Sugar, Politics and Flawed Science, the actual reason for the (temporary) decline in grubs in Puerto Rico was due to unusually wet rainy seasons pinching breeding by waterlogging soils.
The cost of this false belief to Australia’s unique native wildlife has been qualitatively different from other landmasses without native bufonids. Oceanic island predators – even when living on a landmass without toads – were chiefly predatory raptors that evolved on continents with toads. Thus, unlike quolls or Pseudechis snakes, other landmasses where Bufo marinus was introduced had predators who could effectively regulate its numbers – not to mention merely one-thousandth to one-hundredth the space to expand. Thus even with uniquely bad soils, uniquely low secondary productivity and uniquely unreliable runoff toads in Australia can reach higher densities than anywhere else in the world – further condemning those who introduced the cane toad based purely upon dogma.