A hit love song for toads

JCU's Ben Muller placed cane toad 'audio traps' with differing characteristics at various sites in the Townsville, Queensland, region.

"We varied the sound they were playing to have different combinations of volume, frequency and pulse rate," he said.

The team were particularly interested in attracting reproductive female toads (those carrying eggs).

"A female cane toad may lay upwards of 20,000 eggs per clutch so removing a single female with eggs from the population is more effective for control than removing a single male," said Mr Muller.

He said that male cane toads did not appear to care what variation of volume, frequency and pulse rate were used, but female toads were much choosier.

"We found we could manipulate the proportion of females, and reproductive females, that we trapped by changing the calls used as lures."

The scientists found that approximately 91% of the females trapped using a loud, low frequency tone with a high pulse rate were reproductive.

"We think that low frequency calls indicate to female toads that they are hearing a large-bodied male and the high pulse rate means the male making the call has high energy reserves. These things combine to make them believe they have found a good breeding partner," he said.

Mr Muller said the finding may help suppress toad numbers, but it was not a silver bullet.

"Large-scale eradication of cane toads from mainland Australia using traps is probably not possible; however, eradication of island populations could be achievable if the trapping regime was correctly designed and implemented," he said.