Quolls v Toads

The northern quoll is a really cool marsupial predator.  They’re also in trouble.  Like many Australian predators, they’re quite partial to snacking on the odd frog, and, when toads arrive, they make the mistake of thinking toads might make a good repast.  Bad move.  Toads carry a suite of defensive toxins to which Australian predators are naive, and unwitting predators, quolls included, typically suffer an unpleasant death after they attack a toad.

As cane toads have swept across northern Australia — they now occupy more than 1.5 million square kilometres of it — they have wiped out populations of snakes, goannas, and quolls.  The northern quoll is now federally endangered, and toads are to blame.

Stephanie O'Donnell with a young northern quoll.
Stephanie O’Donnell with a young northern quoll.

It would be all doom and gloom really, except for two interesting points.  First, there are several populations of quolls persisting in areas where toads have been for more than 70 years.  Second, we know (from pioneering work by Jonno Webb and his students Stephanie O’Donnell, and Teigan Cremona) that quolls can, under carefully contrived conditions, learn to avoid toads.

The observation that quolls are doing just fine in areas long-colonised by toads suggests that these quolls are toad-smart.  They know not to eat toads.  How do they know?  Is it something they learn each generation (perhaps taught by their mum), is it an innate (evolved) trait, or is it perhaps a mix of the two?  We don’t currently know, but the answer matters, because it will determine the best way to save quoll populations from toads.

If quolls need to be trained to avoid toads, and then they pass that trait onto their offspring (through cultural means), then we can simply train a whole bunch of quolls in a population before toads arrive, and then let the quolls teach their kids.  Alternatively, if there is a genetic basis to these toad smarts, training alone won’t cut it: we would need to introduce the genes for toad-smarts into toad-naive populations.  Finally, if there is a bit of both going on — perhaps it is teaching, but quolls from long-exposed populations have an innate tendency to learn certain lessons — then we will need to couple genetic translocation with training.

So these questions are interesting — cultural vs genetic transmission — and the answers to them matter.  Jonno Webb and myself have just been lucky enough to be awarded an ARC Linkage grant to explore these exact questions, and, in the process of answering these questions, make some serious attempts to reverse and halt the decline of northern quolls.  It’s an exciting prospect.  The project has some great support, not only from the ARC, but also from Kakadu National Park, The Territory Wildlife Park, The NT Department of Land and Resource Management, and The Australian Wildlife Conservancy.  On the Queensland end, we’ve also been receiving some fantastic support from the Wildlife Conservancy of Tropical Queensland.  Ella Kelly is already off and running on her PhD looking at aspects of this work, and two additional PhD students will be starting in 2016.  The assembled team is going to be doing some exciting science, and some important conservation work over the coming years.  Watch this space!

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