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Farmer solves decade-long cane toad 'murder mystery'

Poisonous cane toads once had no predators in Australia, but native animals and birds have creatively adapted to target them.

A “murder mystery” involving a notorious super-pest in a tiny Aussie town has been solved.

The dismembered bodies of invasive cane toads had been found scattered around a Queensland seed farm for over a decade.

Pictures supplied to Yahoo News Australia show toad corpses lying at the edge of an aquaculture pond and on the branches of trees. The property's owner has frequently found dried out toads with their “guts picked out” and they are sometimes missing legs.

Leigh, who runs Fair Dinkum Seeds west of Bundaberg, had been pondering since 2013 what had been killing them. He would discover around 30 eviscerated bodies a year, but this summer's relentless rain has escalated the presence of toads and so he's now seeing a dissected toad every day.

Dead cane toads around a floating plant farm in a lake. The dead toads are highlighted in white.
Dozens of cane toads have been discovered around a Queensland pond, sparking an internet "murder mystery". Source: FairDinkumSeeds

The first time Leigh shared an image of an attacked toad in a tree was in 2013, when little was known about native Australian cane toad predators. Some with knowledge of the subject responded to his Facebook post by pointing out crows had adapted to kill them.

Since the 1930s cane toads had spread across Queensland, and into the Northern Territory, NSW and Western Australia. For most of last century they had no known natural predators, because their venom-secreting glands above each shoulder swell and produce poison when they are attacked by native species.

Surge in cane toad 'murders' around pond

A decade after his original Facebook post, Leigh has shared a fresh account after a surge in bodies began appearing around a newly created water plant platform on his pond. “Cane toad murder mystery. Who has moved in and started using my fancy new water plant platform as an abattoir?” he wrote.

Since his first post, research had revealed several species including ibis and rakali water rats have been observed dissecting the troublesome glands and eating the surrounding bodies.

His post attracted dozens of responses and many respondents marvelled how clever ibises are after someone pointed to the research. The response was pleasing to some, because ibis seldom get much love — because of their habit of searching out food discarded by humans, city-folk often use the pejorative term “bin chickens” to describe them.

“Perhaps we have been judging the bin chickens too harshly,” one person quipped. “They are an elegant looking creature,” someone else said of the ibis.

Dead toads highlighted on tree limbs.
Toads were discovered lying dead on tree branches, and photographed in 2013. Source: FairDinkumSeeds

What's been killing the cane toads on Leigh's pond?

Leigh has now set up cameras to monitor the pond. And while he hasn't seen toads being attacked he's seen them being eaten. His observations have led him to believe the main killer is rakali, but ibis are also taking out a few. Then turtles living in the water chew the bodies.

He guesses butcherbirds as well as crows could also be hunting them, as the former are known to spike their prey on tree branches.

Leigh also kills toads himself, so he can feed their bodies to the soldier flies which he then feeds to his ducks and chooks. But despite the destruction they cause around his farm, he doesn't hate them.

“I'm sympathetic to the toad as it isn't their fault they suck. The fact remains they do,” he said, adding “to me they are an incredibly destructive, invasive, but also a useful, sustainable and free resource, that gives me high protein poultry feed and in turn more eggs.”

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