Marsupials have their very own Superhero

By Ingrid Crossing, 2019 Alumni 

You are a small marsupial, trembling in the red soil. Your fur stands on edge as the predator approaches, sniffing out your crevice in the dirt. Its paws are light, yet you can feel the vibrations pulsing through the ground – or is that your heart? Your ears twitch, waiting for the moment when its fangs will sink into your fleshy throat. You can smell it, creeping closer, and closer, and closer…

A red shape thrusts you into shadow as it soars over, tackling the hunter to the ground.  Your hero, the dingo, towers over the feline’s body – the feral cat, killer of native marsupials, destroyer of ecosystems, clutched in its strong jaws. You salute it, and it nods, before disappearing into the sunset.

Ok, so maybe that’s not quite how the ecosystem works. Dingoes don’t walk around in superhero capes defending Australia’s defenceless mammals, and small marsupials don’t exactly salute. But I promise there is some truth to it, and an interesting relationship that plays out between an introduced predator, and the Australian ecosystem.

Wait… dingoes aren’t native?

You’d be forgiven for thinking that such an iconic Australian animal was native. In fact, the dingo was introduced at least 3000 years ago, but estimates go all the way back to 14,000 years (look, archaeology isn’t perfect). The dingo currently has a bit of an identity crisis –  to some, they are pests terrorizing livestock, or fearsome predators. Yet they are also an icon of the Australian outback, and have had a long relationship with First Nations People. Some insist they’re a native species, whilst others still consider them introduced. Either way, they’ve definitely left their footprint – or pawprint – on the country.

So where did they come from?

Well, going way back in time, all dogs are believed to have descended from a single population of wolves, which then radiated pretty much worldwide. Considering the shortest distance between Australia and South-East Asia is 90km, it’s highly unlikely that the dingo’s ancestors just paddled across. Dingoes were brought to Australia by humans, possibly as pets or trade objects. Whether they were traded off, or if someone lost Fluffy in the outback, somehow the dingo ended up becoming a permanent resident.

Ok, so what does the dingo get up to now?

Remember the little marsupial, so bravely defended by its dingo hero? Well, there is a grain of truth to this tale of good and evil. While dingoes don’t actively go around saving tiny marsupials, they do prey on feral cats and foxes. Any guesses what these invaders prey on?

That’s right: small mammals.

So more dingoes = less cats and foxes = more small mammals. Dingoes are the apex predator, sitting at the top of the food chain. This means that whatever happens to dingo populations sends ripples through the ecosystem, in what’s known as a trophic cascade.

Although cat bits have been found in dingo poo (my condolences to the scientist who figured that out), they don’t just control feral predators through hunting them. Dingoes also act as guard dogs to the ecosystem. Cats actively avoid areas where dingoes are present, restricting them from prey – If you were a cat up against a canine 5 times your size, you’d probably avoid the neighbourhood too.

So when dingoes disappear, foxes and cats can flourish and destroy environments. Since European settlement, dingoes have been wiped out in much of the country. These same areas, where dingoes are scarce, have had a devastating loss of marsupials.

Cute and fluffy animals aren’t the only concern when dingoes are wiped out. Vegetation also has a place in the food chain. Particularly in arid areas, control of dingo populations by humans causes an increase in herbivores, both native  and introduced. Think rabbits. So many rabbits. Rabbits that breed like rabbits. These herbivores can quickly deplete a resource and eliminate vegetation in Australia’s arid areas.

A top predator is crucial for the regulation of the ecosystem. Africa has its fair share of lions and wild dogs. North America has bears and wolves. Australia is left only with its iconic dingo. If we lose them, the runner-up for largest predator is the spotted tail quoll, and… well, at 5kg, I don’t think he’ll be taking on foxes any time soon.