Preventing and reversing population declines of northern quolls
Northern quolls are marsupial predators threatened by the spread of cane toads. This project tested the idea that we might be able to teach quolls to avoid eating toads. It also tested the idea that we might be able to use targeted gene flow to bring toad adapted genes into quoll populations about to be impacted by toads.
Progress
This was a huge project, with daunting logistics. It simply would not have been possible without support from our industry partners. The project supported three big PhD projects, executed by Ella Kelly, Naomi Indigo, and Chris Jolly. Amberlee Hatcher made a brief cameo also.
Ella found compelling evidence that quoll populations in eastern Australia (in QLD, where toads have been for 80 years) had adapted to the presence of toads. Quolls from these populations simply knew not to eat toads, whereas toad naive quolls in the west (NT and WA) would happily attack toads (and usually die). This looked to be a genetic shift between QLD and the NT. Ella showed that it is possible to cross QLD and NT quolls and that there is no obvious outbreeding depression through three generations. Ella also undertook modelling indicating that targeted gene flow — introducing some QLD quolls into NT populations just before toads arrived — could make a huge difference to the survival of these populations and the preservation of their local genetic diversity. Essentially, targeted gene flow should work nicely in this situation.
Meanwhile, Naomi Indigo was working on the idea of training quolls to avoid eating toads. This involved feeding wild quolls a “toad sausage” laced with a nauseating chemical. She showed that quolls trained on the sausage would avoid toads in the following weeks. She also undertook some heroic field trials in the remote Kimberley which showed that baiting wild quoll populations with these toad sausages made absolutely no improvement to the survivorship of these populations. If anything, the “trained” populations did worse. It turns out that trained quolls actually forget their training pretty quickly. In other work she showed that the number of baits required to treat enough quolls was pretty daunting. So the idea of teaching quolls in the field was looking pretty shaky. We then followed up with some theoretical work showing that even if we could train animals before toads arrived, the population would still go extinct unless there was very high parent to offspring transmission of the lesson. Given the parents were forgetting the lesson themselves, this seemed a very unlikely hurdle to jump. Overall, and disappointingly, Naomi’s work showed that training quolls to avoid toads simply doesn’t work to protect quoll populations from toads.
While all this was happening, Chris Jolly was going off on his own tangent. He showed that a population of quolls that had been placed on an offshore island (as insurance against toads) had, in 13 generations, lost their recognition of important predators (dingos and cats). As a consequence, when these animals were trained to avoid toads and released in Kakadu National Park, most of them were killed by dingos. Chris also showed that introducing quolls to an island can set of complex trophic cascades, driven not just by a change in number of the quoll’s prey, but by a change in the prey’s behaviour. Chris’s observation on the loss of antipredator traits caused us to unearth an evolutionary explanation that could be applying in all conservation havens. This insight gave us immediate concern for the fitness of havened mammal populations around Australia.
Selected publications
Indigo, Naomi. L., Kelly, Ella, Smith, James, Webb, Jonathan. K., Phillips, Ben. L., Indigo, Naomi. L., Kelly, Ella, Smith, James, Webb, Jonathan. K., Phillips, Ben. L. (2023). Can conditioned taste aversion be deployed at a landscape level to mitigate the impact of invasive cane toads on northern quolls? Wildlife Research. **: .
Kelly, Ella, Rangers, Kenbi. Traditional. Owners. and, Jolly, Chris. J., Indigo, Naomi, Smart, Adam, Webb, Jonathan, Phillips, B (2021). No outbreeding depression in a trial of targeted gene flow in an endangered Australian marsupial Conservation Genetics. 22: 23–33.
Jolly, Chris. J., Smart, Adam. S., Moreen, John, Webb, Jonathan. K., Gillespie, Graeme. R., Phillips, Ben. L. (2021). Trophic cascade driven by behavioral fine-tuning as naïve prey rapidly adjust to a novel predator Ecology. 102: e03363.
Jolly, Chris. J., Phillips, Ben. L. (2021). Rapid evolution in predator‐free conservation havens and its effects on endangered species recovery Conservation Biology. 35: 383–385.
Indigo, Naomi. L., Jolly, Chris. J., Kelly, Ella, Smith, James, Webb, Jonathan. K., Phillips, Ben. L. (2021). Effects of learning and adaptation on population viability Conservation Biology. 35: 1245–1255.
Jolly, Chris. J., Webb, Jonathan. K., Gillespie, Graeme. R., Phillips, Ben. L. (2020). Training fails to elicit behavioral change in a marsupial suffering evolutionary loss of antipredator behaviors Journal of Mammalogy. 101: 1108–1116.
Kelly, Ella, Phillips, Ben (2019). How many and when? Optimising targeted gene flow for a step change in the environment Ecology Letters. 22: 447–457.
Jolly, Chris. J., Webb, Jonathan. K., Gillespie, Graeme. R., Hughes, Nelika. K., Phillips, Ben. L. (2019). Bias averted: personality may not influence trappability Behavioral Ecology and Sociobiology. 73: 129.
Jolly, Chris. J., Smart, Adam. S., Moreen, John, Webb, Jonathan. K., Gillespie, Graeme. R., Phillips, Ben. L. (2019). Trophic cascade driven by behavioural fine-tuning as naïve prey rapidly adjust to a novel predator bioRxiv. **: .
Indigo, Naomi, Smith, James, Webb, Jonathan. K., Phillips, Ben. L. (2019). Bangers and cash: Baiting efficiency in a heterogeneous population Wildlife Society Bulletin. 43: 669–677.
Kelly, E, Phillips, B. L (2018). Targeted gene flow and rapid adaptation in an endangered marsupial Conservation Biology. 33: 112–121.
Kelly, E. L, Phillips, B. L, Webb, J. K (2018). Taste overshadows less salient cues to elicit food aversion in endangered marsupial Applied Animal Behaviour Science. 209: 83–87.
Jolly, C. J, Webb, J. K, Phillips, B. L (2018). The perils of paradise: an endangered species conserved on an island loses antipredator behaviours within 13 generations Biology Letters. 14: 20180222.
Jolly, Christopher. J., Kelly, Ella, Gillespie, Graeme. R., Phillips, Ben, Webb, Jonathan. K. (2018). Out of the frying pan: Reintroduction of toad-smart northern quolls to southern Kakadu National Park Austral Ecology. 43: 139–149.
Indigo, Naomi, Smith, James, Webb, Jonathan. K., Phillips, Ben (2018). Not such silly sausages: Evidence suggests northern quolls exhibit aversion to toads after training with toad sausages Austral Ecology. 43: 592–601.
Kelly, E. L, Phillips, B. L (2017). Get smart: native mammal develops toad-smart behaviour in response to a toxic invader Behavioral Ecology. 28: 854–858.
Kelly, E. L, Phillips, B. L (2016). Targeted gene flow for conservation Conservation Biology. 30: 259–267.