Aussies cane cane toads with cat food
Carnivorous ant solution to amphibious assault
Researchers from the University of Sydney have joined the battle to rid the Lucky Country of cane toads by suggesting cat food might be a useful tool in seeing off the invasive amphibian.
They found that just a small amount of the feline chow left next to Northern Territory ponds was enough to attract carnivorous meat ants, which then turned their attentions to baby toads as they emerged from their birthplace.
The team's abstract, from the Journal of Applied Ecology, explains: "In tropical Australia, high desiccation rates restrict newly-transformed (metamorph) cane toads Bufo marinus to the margins of waterbodies, rendering the metamorphs vulnerable to predatory ants (Iridomyrmex reburrus). By adding bait (cat food) to selected areas, we increased ant densities (and thus, toad mortality) more than fourfold."
The scientists elaborate that "50% of attacks by ants in the field were immediately fatal to the metamorph toads, and most 'escapee' toads (88%) died of their injuries within 24 h after the attack".
They note: "When we increased ant densities by artificial baiting, 98% of metamorph toads were encountered, and 84% attacked, within the two-minute observation period."
Rick Shine, the professor of evolutionary biology who oversaw the slaughter, told the Guardian: "A single toad can have 30,000 eggs in a clutch, so there's a heck of a lot of tadpoles turning into toads along the edge of a billabong.
"You can literally have tens of thousands of toads emerging at pretty much the same time. They are vulnerable to meat ants if the colony discovers there is a source of free food."
While the research looks promising, Graeme Sawyer of toad-busting ecogroup Frogwatch didn't reckon the technique would contribute much to the struggle. He said: "The impact of meat ants on cane toads can be significant with a small number of cane toads, but when you get areas where there are large numbers of cane toads it doesn't seem to make any difference at all."
Shine himself admitted: "You'd have to be a desperate optimist to think that we'll ever see the end of cane toads in Australia."
In any case, exponents of the killer cat food plan have to convince Oz's Royal Society for the Prevention of Cruelty to Animals that setting hungry ants on defenceless toads is not inhumane. The society declared: "RSPCA Australia recognises that cane toads must be controlled, but urges researchers to concentrate on identifying effective methods that do not cause unnecessary pain or distress."
Australia has been battling the cane toad since it was introduced into Northern Queensland from Hawaii in the 1935. Since then the population has swelled to 200 million individuals and spread up to 3000km from their hopping-off point.