School For Marsupials To Stop Them Eating Toads Delayed

Northern quolls will soon learn an essential life lesson in a schooling program. Jonathan Webb

A school has been established for northern quolls (Dasyurus hallucatus), a carnivorous marsupial, but unfortunately the arrival of the first pupils has been delayed. It is hoped the soon-to-be educated quolls will go forth and repopulate one of Australia's greatest wildernesses, after being almost entirely wiped out by cane toads. To do so, however, they need to learn one life lesson: don't eat the toads.

Cane toads (Bufo marina) were imported to Australia in 1935 in the hope they would control the cane beetle. Instead, they turned into a contender for the continent's most devastating pest. The toads not only out-compete local species, they are poisonous to eat and have devastated populations of local predators not yet savvy enough to avoid them.

Quolls have been particularly affected. A single bite of a cane toad can release enough poison to kill a quoll; only those lucky enough to have their first toad encounter occur with a juvenile live to learn better. Sadly, most quolls tackle something bigger and die.

In 2010, a group of researchers successfully demonstrated the feasibility of teaching quolls to avoid cane toads. They did this by feeding the marsupials small quantities of the toad combined with thiabendazole, a chemical that makes the quolls nauseous. According to lead researcher Dr. Jonathan Webb of University of Technology Sydney, the quolls not only avoided toads thereafter, the mothers passed their aversion on to their offspring as well.

“We found when we put radio transmitters on the young quolls that, even after leaving home, they were meeting up with their mothers at night and foraging with them,” Webb told IFLScience. “If you have kids, you know that the way to get them to eat something is to eat it yourself. If the young see their mothers sniff and reject a toad, they learn the lesson.”

Webb says they even have footage of educated quolls that were released into the wild sniffing toads and moving on.

One path to save the quolls is to make sausages combining non-lethal quantities of toad and thiabendazole, and then drop them from helicopters ahead of the toad invasion. Sadly, however, it is too late to do this for the extraordinary Kakadu National Park. Here, quoll populations have been so devastated by cane toads that Webb says fires such as the one currently spreading from a nearby mine could drive them to local extinction.

Fortunately, the arrival of cane toads in Kakadu was predicted: Before it occurred, 64 quolls were moved to Astell and Pobassoo Islands off the coast of Australia. With litters of six to seven and no predators, their numbers have swollen to an estimated 6,000 in the space of 11 years.

In November, a trip was made to the islands to collect some quolls to spend a week at toad avoidance school, after which the suitably quollified graduates would be released back to their ancestral homeland.

However, the plan hit a snag, Webb said, because “for some reason, the quolls bred late this year,” and the babies were too young to be moved. A new collection trip has been scheduled for February, with release planned for later that month.

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