You Could Be Your Worst Enemy's Best Friend - Part 1: The Planigale

I roused late one night and my mind too quickly escaped the restraints of fatigue; within seconds I was wide awake and I knew it was going to be a long night.

Immediately, my brain was a mangled mess of ecological questions without answers on the topic of island biogeography. I guess this should come as no great surprise because I was on an island and I was studying aspects of biogeography; I was doing the annual quoll monitoring survey on Koolan Island with Animal Plant Mineral.

That day I had caught a Planigale. Though I never tire of seeing these very cool little critters, a long-tailed planigale is not what I would normally consider a significant collection. However, on Koolan Island its capture was a somewhat special event.

Planigales are the tiniest of tiny (10grms) little dasyurid marsupials; not the smallest, that is the Pilbara Ningaui. They look like little mice but they have cat like teeth and they are ferocious predators with an insatiable appetite for almost all invertebrates and any small vertebrates that it can subdue. They have a metabolic rate that could power a small village. They are super cool tiny little Tassy Devils, if you like.

On Koolan Island we never catch Planigales. We have done hundreds upon hundreds (even thousands) of trapping nights (pit traps, funnels and pit traps) and from 2004 until today only four individuals have ever been captured, including this one. 

Within their known distribution they are not normally uncommon. So why are they such a rarity on Koolan Island? The answer lies in the belly of a close relative - literally. At nearly 50 times the size of a planigale the Northern Quoll tears the heads off live Planigales, eats them from the inside out and picks its teeth clean with the femur bone. 

It would be a gross understatement to say that the Northern Quoll is the Planigales worst enemy. But things may be about to get a whole lot worse for Mr Planigale. With the coming of the Cane Toad Mr Planigale may be the Northern Quoll's bestest friend and with friends like the Northern Quoll, who needs enemies????????

Read Part 2 of this blog to find out why.

References:

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.

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.