Apologies in advance but if you don't read Part 1 and Part 2 then Part 3 is going to make no sense at all! Mind you, starting in the middle of the story did not seem to influence the popularity of Star Wars. As it annoys the crap out of me when Reno Rumble, My Kitchen Rules and I'm a Celebrity Get Me Out of Here repeat 75% of the story to date after every advertisement break (treating the audience like they are goldfish), I simply refuse to do it here. Suffice to say that it involves a planigale, a quoll and a toad (NB - no animals were harmed in the making of this blog). Oh........and a rat.
.....just give me a second as I flick back to Part 2 to see where I left off (goldfish syndrome).........Ok, here we go.
So, let us assume that the population of Northern Quoll on Koolan Island will be somewhat buffered from obliteration when the Cane Toad arrives by virtue of their smaller body size and their tendency to prey on smaller, less toxic toads. What this means is that there is at least some hope for the population.
Enter the hero (actually heroes) of our story: Planigales and Rock Rats.
Planigales are surprisingly smart, proving that intelligent things come in small packages. Recent studies by Llewelyn et al. (2010) and Webb et al. (2008) have shown that very few planigales die after they attack toads and that the survivors rapidly learn that toads are best avoided. Moreover, planigales living in areas where toads are present may actually develop a resistance to toad toxin.
Now dasyurids, including the Planigale, are known to be boom and bust breeders and that means that under favourable conditions their numbers can explode in a single breeding season. A massive reduction in predation pressure is definitely a catalyst for a population explosion and this is exactly what will happen when the Cane Toad arrives. The quoll population will have the snot knocked out of it, and the Planigale population will explode.
For the small number of quoll that do survive the toad invasion this should result in a buffet of food available to them for which they will not have to work very hard to acquire. As the quoll is also a Dasyurid, it has the same capacity to boom or bounce back in response to a rapid increase in prey availability.
Lingering around just left of centre stage is the Rock Rat, Zyzomys argurus. Based on the very recent work of Cabrera-Guzmn et al. (2015) at least three species of native Australian rodents, normally described as herbivorous, have been shown to actively pursue and prey on Cane Toads with no ill effects. So it is very likely indeed that the Rock Rat should be no different.
So, like Batman and Robin, the Planigale and the Rock Rat are going to come to the rescue of the Koolan Island Northern Quoll by combating (Bammmm...Powwww....KaPlunk) and consuming (Sluuurrpp, Shhhlllllooolllooooppp) the Cane Toad. Then they are going to make lots and lots of babies (I always wondered whether there was more to the relationship between Batman and Robin) due to the reduction in predation pressure from the decimated quoll numbers.
The newly abundant prey will then be the catalyst for a bounce back in the quoll population, , Coupled with the quoll's own capacity to learn to avoid toads, the population will be back to a new stable equilibrium in no time!
Presently, we view Koolan Island as a island ark, somewhat safe from the invasion of the Cane Toad as its population spreads west through the Kimberley. We anxiously await news on the toad front at the end of each wet season. They are in the Fitzroy River catchment now, which flows out through Derby and around the islands of the Buccaneer Archipelago, within which Koolan Island is located. One big flood and toads will spill out into King Sound and it is inevitable the individuals will wash up on the shores of Koolan Island.
But I am not worried! I think, thanks to the planigales, the rock rats and island dwarfism, I reckon they will be fine. Thoughts?
Planigales are surprisingly smart, proving that intelligent things come in small packages. Recent studies by Llewelyn et al. (2010) and Webb et al. (2008) have shown that very few planigales die after they attack toads and that the survivors rapidly learn that toads are best avoided. Moreover, planigales living in areas where toads are present may actually develop a resistance to toad toxin.
Now dasyurids, including the Planigale, are known to be boom and bust breeders and that means that under favourable conditions their numbers can explode in a single breeding season. A massive reduction in predation pressure is definitely a catalyst for a population explosion and this is exactly what will happen when the Cane Toad arrives. The quoll population will have the snot knocked out of it, and the Planigale population will explode.
For the small number of quoll that do survive the toad invasion this should result in a buffet of food available to them for which they will not have to work very hard to acquire. As the quoll is also a Dasyurid, it has the same capacity to boom or bounce back in response to a rapid increase in prey availability.
Lingering around just left of centre stage is the Rock Rat, Zyzomys argurus. Based on the very recent work of Cabrera-Guzmn et al. (2015) at least three species of native Australian rodents, normally described as herbivorous, have been shown to actively pursue and prey on Cane Toads with no ill effects. So it is very likely indeed that the Rock Rat should be no different.
So, like Batman and Robin, the Planigale and the Rock Rat are going to come to the rescue of the Koolan Island Northern Quoll by combating (Bammmm...Powwww....KaPlunk) and consuming (Sluuurrpp, Shhhlllllooolllooooppp) the Cane Toad. Then they are going to make lots and lots of babies (I always wondered whether there was more to the relationship between Batman and Robin) due to the reduction in predation pressure from the decimated quoll numbers.
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| The heroes of our story: The Planigale and the Rock Rat |
Presently, we view Koolan Island as a island ark, somewhat safe from the invasion of the Cane Toad as its population spreads west through the Kimberley. We anxiously await news on the toad front at the end of each wet season. They are in the Fitzroy River catchment now, which flows out through Derby and around the islands of the Buccaneer Archipelago, within which Koolan Island is located. One big flood and toads will spill out into King Sound and it is inevitable the individuals will wash up on the shores of Koolan Island.
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| Toads strategizing their invasion on Koolan Island |
References.
Cabrera-Guzmn, E., Crossland, M.R., Pearson, D., Webb, J.K. & Shine, R. 2014, 'Predation on invasive cane toads (Rhinella marina) by native Australian rodents', Journal of Pest Science.
Hayes, R. A., M. R. Crossland, M. Hagman, R. J. Capon, and R. Shine. 2009. Ontogenetic variation in the chemical defences of cane toads (Bufo marinus): toxin profiles and effects on predators. Journal of Chemical Ecology 35:391-399.
Llewelyn, J., J. K. Webb, L. Schwarzkopf, R. Alford, and R. Shine. 2010. Behavioural responses of carnivorous marsupials (Planigale maculata) to toxic invasive cane toads (Bufo marinus). Austral Ecology 35:560-567.
Webb, J. K., G. P. Brown, T. Child, M. J. Greenlees, B. L. Phillips, and R. Shine. 2008. A native dasyurid predator (common planigale, Planigale maculata) rapidly learns to avoid toxic cane toads. Austral Ecology 33:821-829.
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