But less luck for the toad…
Cane toads have been in the news again lately. Huge specimens have been found and last week one individual, dubbed ‘Toadzilla’, was picked up weighing in at just under two pounds. The toxic toads have become a pest since their introduction in 1935 and, in desperation, Australians are spending lots of time and money trying to find a solution.
Faster westward expansion of the toads has been recorded in a study by Philips et al. (2007) finding that since reaching the wet tropics of the Northern Territory, they’ve progressed an average of approx. 55km/yr with toads often moving more than 200m in one night! Ben Philips and his colleagues suggest that this accelerated rate may mean that either the toads have evolved or are in a more favourable environment for expansion.
Possible reasons for the toads’ success include (from Biocontrol News and Information):
- Digitalis-like toxin which stops the heart, affecting the sodium pump present in all animal cells
- females produce a large number of eggs
- the toads are generalists – making them able to exploit a variety of resources
- a short tadpole stage gives them an advantage over native amphibian species.
Potential solutions for control include farming the toads for their medicinal properties, as used in traditional Chinese medicine, and genetic modification to cause female-to-male sex reversal, eventually reducing numbers. It is also hoped that the toads’ progress can be slowed whilst a biological control method is devised but, in the meantime, the Western Australia government is trying to trap and kill toads before they reach the border.
Australian MP Dave Tollner also added his own control tips when he suggested that people hit cane toads with golf clubs, whereas an RSPCA-recommended method was to rub them with haemorrhoid cream to anaesthetise the toads before placing them in the freezer. In an attempt to ease the passing of the ill-fated toads, a scheme was initiated by the RSPCA, Coopers Brewery and the Cavenagh Hotel, to encourage people to catch the toads but not smash them. Everyone who took a live toad to the RSPCA to be disposed of humanely received a voucher for free Coopers ale.
There’s a fact sheet available to help with identification, especially as native frogs such as the Giant Frog (Cyclorana australis) are frequently mistaken for the aliens. Recognition is further aided by a sample of the cane toad’s call.
Once disposed of, Australians are now finding novel ways to make use of the toads. FrogWatch is using carcasses to make garden fertiliser and at the Australia Gift website you can buy cane toad accessories.
Somewhat ironically, it seems that everyone is waiting for a biological control method to halt the march of the cane toad, which was originally introduced to control cane beetles and didn’t make a very good job of it. Still, I suppose any control method has to be better than being placed in a refrigerator, then being euthanised with a sharp blow to the skull with a heavy blunt object, as recommended by FrogWatch, a group which organises hunts to destroy the toads.
A huge amount of information is available on the web and with access to CAB Abstracts you can find even more by searching with some of the technorati tags below.
Phillips, B. L., G. P. Brown, M. Greenlees, J. K. Webb, and R. Shine. 2007. Rapid expansion of the cane toad (Bufo marinus) invasion front in tropical Australia. Austral Ecology 32(2), 169-176.