THE GUARDIAN (London, UK) 05 August 08 It's not just crickets toads are waving at (Marc Abrahams)
Who waves what at whom, and to what effect, are the central questions in a study called Deceptive Digits: The Functional Significance of Toe Waving by Cannibalistic Cane Toads, Chaunus Marinus. Professor Richard Shine, of the University of Sydney, and his postdoc student Mattias Hagman published this nine-page report in the journal Animal Behaviour.
The cane toad, they muse, "is one of the most intensively studied anuran species worldwide ... It is thus remarkable that the distinctive toe waving behaviour of this species has not been reported in earlier literature." This is the toad Australians have loved to hate ever since the 1930s, when it was imported from Hawaii to prey on certain agriculturally annoying beetles. Because nothing much in Australia is keen to eat cane toads, the warty immigrants have bred themselves into multitudes ever increasing.
Actually, there is one species that's keen to eat the toads. Shine and Hagman once dissected 28 juvenile cane toads, "and found that other cane toads made up 64% of the total of 149 prey items".
For the study, they collected toads in the Adelaide River floodplain, housing them in glass aquaria back in Sydney. Food items were placed into a terrarium next to them. Live crickets. Dead crickets. Live young toads. Dead toads.
For each trial run they filmed what happened immediately after a cane toad got to see whatever was in that other box. The filming made it possible to study "the kinematics of toe-waving behaviour by captive cane toads", and in particular to count the number of times an individual lifted and lowered its toe per second. Typically, the film captured "bursts of rapid toe waving punctuated by periods of slower toe waving".
Small and medium-sized toads often waved at live juvenile toads and at live crickets, but seldom at dead juvenile toads or dead crickets. Large toads waved hardly at all. Does the toe-waving attract prey? To find out, Shine and Hagmen constructed a machine "to simulate the waving toe of a toad. We amputated the longest toe of the rear foot from a 'dummy' toad (a taxidermic mount from a dead animal)." Juvenile toads, the scientists learned, respond often to such stimulation, though crickets seem indifferent.
Intriguingly, a dummy toe painted brown elicits a better response than one painted black, white or blue.
It's not just crickets toads are waving at

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