Last year Prof Rick Shine of the University of Sydney’s School of Biological Sciences outlined a number of ways in which the sensitivity of the toads to chemicals produced by their own species might be used against them (AS, Jan/Feb 2012, p.9). Now research published in the Proceedings of the Royal Society B has revealed just how effective one of these approaches has been.
Shine’s team pondered the fact that toad tadpoles are attracted to dead toads. After testing a number of possible chemicals, team members discovered that the poison itself is a powerful attractant to cane toad tadpoles while repelling those of most native species. “A few species just ignore it,” Shine says.
Funnel traps baited with secretions from the shoulders of adult toads attracted so many tadpoles that bodies of water in which the traps were placed were clear of toads afterwards. This is a stunning finding given the difficulties of removing toads using other techniques.
Shine notes that a single female toad can lay 30,000 eggs. “This means that even if you catch and kill 99% of the adult toads in an area, the few that are left can produce so many offspring that before you know it you are back to where you started – just as many cane toads as ever.”
Toads have colonised such large areas of Australia that Shine considers eradication impossible. However, by placing traps in...
