The quoll’s last stand

A Northern Quoll eating a non-lethal amount of cane toad

The Northern Quoll is kicking the cane toad off the dinner menu (Photo by Jonathan Webb)

In summary: 
  • The endangered Northern Quoll is under attack from the cane toad but a radical solution is at hand
  • It is hoped a research program to teach the small marsupial to be “toad-smart” by feeding it non-lethal amounts of toad will result in quolls teaching their offspring to avoid live cane toads in the wild

Undeniably charismatic, the Northern Quoll’s big black eyes and impossibly long whiskers belie the face of a feisty, nocturnal predator that has – as conservation biologist Dr Jonathan Webb discovered – very sharp teeth.

“I received a nasty bite from a Northern Quoll ... ironically it was a female and they’re normally much calmer and less aggressive than the males,” says Dr Webb, of the School of the Environment at UTS.

What the quoll couldn’t know was that she had just bitten the hand of the very person whose research could save her and the entire critically endangered species.

Like many of Australia’s small marsupial mammals, the Northern Quoll is under serious threat of extinction from habitat destruction, feral cats and changing fire management.

However, it is the newest pest on the block, the lethally poisonous cane toad, which jumped across Kakadu National Park boundaries in 2001, that has decimated quoll numbers.

“Quolls have no physiological resistance to toad toxin and die after [trying to eat] large toads. In many parts of the Top End quolls have disappeared completely since the arrival of cane toads,” says Dr Webb.

However, he and colleagues from the University of Sydney have shown that quolls reared in captivity can be trained to avoid eating the toads – training known as taste aversion therapy.

In a 2010 project, researchers cut up dead toads, skinned the legs and discarded the poisonous parts of the toad. A small, non-lethal amount of toad was mixed with a nausea-inducing chemical and then stuffed into the leg skin creating what can only be described as a cane toad sausage. The sausage was fed to the quolls leaving them feeling mildly sick. Presented with a second helping of sausage the next day, many of the normally rapacious carnivores rejected the bait. Some of the trained quolls also refused to attack live cane toads.

The subsequent release of “toad-smart” quolls into the wild (in a study also involving the Territory Wildlife Park and Kakadu National Park) will hopefully show that the quolls can teach their offspring to exclude cane toads from the dinner menu, and therefore help ensure the quoll’s long-term survival.

Monitoring by PhD student Teigen Cremona shows that some of the females have survived in the wild for more than two years, while genetic paternity analysis by Murdoch University’s Dr Peter Spencer has identified descendants of the original “toad-smart” quolls, says Dr Webb.

This Kakadu project, supported by the Australian Research Council, the Mazda Foundation and National Geographic, so caught the imagination of renowned British naturalist and conservationist Sir David Attenborough that he included the Northern Quoll among 10 animals he has chosen to “save”, in his latest wildlife documentary Attenborough’s Ark (see accompanying story 'Attenborough’s top 10 animals').

Dr Webb is doing further research with the Australian Wildlife Conservancy (AWC) at its Mornington Sanctuary in the Kimberley region of north-western Australia.

The sanctuary is free of cane toads, and quoll numbers there are strong. But the toads are estimated to be living as close as 50 kilometres away, according to AWC senior wildlife ecologist Dr Katherine Tuft.

“We’re gearing up for their arrival, which we think will be either this wet season or the one after,” says Dr Tuft.

“We’ve been paying close attention to Jonathan’s Northern Territory research and we felt this was a good opportunity to test a wild quoll population that has been trained to avoid cane toads ahead of the predicted toad invasion.”

This new program will give Dr Webb and his collaborators a chance to study a relatively large quoll population before and after it comes in contact with the toads.

It’s also a chance to protect a quoll population under threat in one of its last strongholds.

“Training quolls to avoid eating toads is not a 100 per cent solution but it offers some hope that we can keep this small, beautiful marsupial carnivore in the landscape,” says Dr Webb. “If we can keep the mums in the system long enough so they can reproduce and even pass on their knowledge to their daughters we may be able to prevent more local extinctions.”

Dr Jonathan Webb’s research at the Territory Wildlife Park will be featured in an ABC series, Kakadu, to be screened later this year.

Brink, Health and Science

Given the extent of the cane toad problem, couldnt the Government bring in a bounty on the critters? Run a short training course on how to handle them so as to avoid the toxins (even as simple as outlining recommended PPE and perhaps issue a training card to present upon claiming your bounty) and let people go. I remember seeing thousands of toads on the streets of Cairns last time I was up there. If people were to get even 10c or 20c a toad it would go a fair way to disrupting their breeding cycles and at least slow them down. They could be brought into disposal centres alive in sacks and humanely dispatched to appease the greenies and everyone is happy.

My personal view is that a breeding program should be set up to produce a predator which has resistance to the Cane Toad toxin and eats tadpoles. Good candidates would be either the Straw Necked or Sacred Ibis as they eat tadpoles, their distribution overlaps that of the Cane Toads and their size, relative to the Cane Toad Tadpole, would give them some protection from the toxin. If they could eat the eggs too that would be an added bonus.
Regards Bob Pendrey

Bob, Cane Toads were introduced to get rid of another animal (the native Cane Beetle). Introducing yet another animal to get rid of the Cane Toad just perpetuates the root problem. It simply replaces one predator with another.

@ Carl both of the Ibis species which Bob has referred to are both Native Australian birds and already occur with in the regions where cane toads are and are expected to traverse. There are a number of birds that seem to be able to tolerate eating the metamorphs without having population impacts at a species level though individual deaths have occurred (personal Obs from 7 years of living through the cane toad invasion in the NT). I feel funding for this project is misdirected and funds would be better spent looking at what is naturally killing cane toads across the top end (I personally found emaciated adult toads post wet season which seemed to have suffered some kind of internal hemorrhaging and also specimens with odd polyps around their organs) and also breeding from the populations which survived the invasion through natural selection (the animals which just don't seem to eat cane toads and are primarily insectivores and fruit/seed eaters) than wasting funds on novel ideas with no real long term impact. The Northern Quoll is an essentially semelparous breeder and young spend such a short period of time with their mother in the home range before dispersing that there really is no time "teach" food aversion. In addition Cane toads are not the only factor impacting their population numbers, dog attacks, hawks, fire regimes and vehicles also remove individuals from the populations, but the toads certainly push them over the edge as their peak movement/breeding coincide with the quolls juvenile dispersion and breeding times.

The northern quoll seems to be quite abundant around mareeba. I have just relocated four from a shed in which I have been living. I have also seen them on the road at night.