A new chance for native animals threatened by feral invaders

At first glance, you might think a remote corner of the hot and sandy Simpson Desert is all but lifeless. Yet research has been going on here for 28 years. Why? Because it’s teeming with life.

“There are not so much seasons here as long periods of dormancy interrupted by bursts of productivity,” says Professor of Ecology and Evolution, Glenda Wardle. Chris Dickman, Professor in Terrestrial Ecology, adds, “It’s a vast, expansive, open desert landscape. There are rich colours, red sand, green vegetation; and after rain, the yellow, the blue, the purple, the white – all the wildflowers that come up.” They're talking about Ethabuka Reserve in southwest Queensland, a one-time cattle station where the two professors and a support team of volunteers work up to four times a year.

There is life and beauty, but there are some wicked problems here too. Climate change is beginning to raise its ugly head, with early indications that rainfalls are becoming more intense and dry spells longer and hotter. But that’s not all. European settlement brought with it not just cattle grazing, but also foxes and cats – feral animals that have chewed through an entire strata of native animals. “Pretty much all the medium-sized fauna that used to occur through arid Australia, that’s gone,” Professor Dickman says.

The list of losses is long, from rat kangaroos to desert bandicoots, mostly from foxes and cats. Australia has lost 30 species of native mammals in the last 200 years; more than the rest of the world put together.

Controlling the foxes and cats has proved near impossible. Professor Dickman has trialled a highly targeted fox poison at Ethabuka, but to be effective, it requires consistent deployment over a much bigger area. Feral cats present extra problems because they’re not as tempted by baits, preferring live prey. After a big bushfire goes through (about every 25 years) and wipes out sheltering vegetation, the native mammals are left even more exposed to predation.

After many years fighting this losing battle against the invaders, Professor Dickman had a radical shift in thinking – instead of trying to eradicate the ferals, why not focus on protecting the native animals? He devised a surprisingly simple solution, constructing refuges of wire mesh – long, low, tunnel-like structures into which the small mammals might retreat when threatened by a fox or cat. The big question was, would they use them?

Turns out the answer is yes. “From what we can see using a variety of behavioural assays, the small animals are keenly aware that these things provide shelter. If you disturb them, they just head straight to the tunnels – there’s a very strong response,” Professor Dickman says.

Another indicator is that the native mammals are eating more food from dishes left near the refuges than dishes left out in the open.

It’s a thrilling result for Professor Dickman. “The shelters are being used by insectivorous mammals, hopping mice, mulgara, sandy inland mice, lizards, even some birds – button quails are running up and down inside them.”

Professor Wardle focuses her plant lens. “You know what Chris is really building out there?” she says. “Plants.” Like plants, the wire-mesh gives protection to the small mammals. “These shelters are important because dry spells are predicted to be longer, which will delay the return of protective plant cover after fires.”

The team supporting the professors on these expeditions includes their long-serving research personnel, Bobby Tomayo (BSc ’95) and Dr Aaron Greenville (BSc(Hons) ’01, PhD ’15), both of whose photos you see with this story, along with a clutch of PhD students and volunteers. All agree it’s a rewarding experience, and that looking after natural ecosystems ultimately adds to the wellbeing of people as well.

That said, the work isn’t for everyone. There’s the searing heat (up to 50 degrees in summer), relentless flies, flooding rains, dust storms, and bushfires sparked by lightning.

But for arid-zone ecologists, this is paradise. It has to be: a three-week stint at Ethabuka involves four-wheel drives packed to the gunwales with scientific equipment, personal belongings and food for the entire time, and 36 hours’ driving over three days just to get here. Water comes from bores. It’s about as far from five-star as you can possibly get.

Ethabuka was destocked of cattle in 2004. It is one of two cattle properties acquired by Bush Heritage Australia as a result of the team's findings; the other is Cravens Peak Reserve.

Let’s start with the plants, which Professor Wardle describes as “the backbone of biodiversity”. “If you go out there expecting a void with sand, the first shock you get is how vegetated it is,” she says. There’s spinifex, saltbush, gidgee trees and coolabah trees. After big rains (about once a decade), there's a great burst of herbs, peas, daisies and wildflowers.

Then we come to the small mammals: the mulgara (a carnivorous marsupial), dunnart (insectivorous marsupial), hopping mice, the sandy inland mouse and the long-haired rat. There are at least 50 species of snakes and reptiles, including geckos, dragons, skinks and goannas. They’re joined by insects and spiders, bees (one of Professor Wardle’s PhD students has named several new species), those ruthless flies, button quails, emus, echidnas, kangaroos and the occasional dingo. “Australia is home to world-record numbers of species in a very arid area,” Professor Dickman says.

In piecing together a holistic picture of this ecosystem, researchers have taken a clip from the ear of every mammal they’ve caught, and from the toe of every lizard, leading to a store of some 8000 tissue samples from 12 different sites. These samples are being used in a new study linking ecological and evolutionary processes in this dynamic system.

Combined, it’s a treasure trove of long-term information on the animals and plants of the Simpson Desert and how they change over time – invaluable data on species now facing rapid climate change.

Though conditions can be tough, these expeditions are rewarding for all who take part. Professor Dickman describes a culture of helping one another, come what may. Professor Wardle says each group of volunteers quickly get to know each other in a way city life precludes. Going home can be surprisingly difficult. People find the experience so profound they’ve been known to upend their lives: change relationships, jobs, even futures.

Perhaps it’s not so surprising in this changing environment that people change too.

Help this work continue

To support the research and animal protection work happening in the Simpson Desert, or to find out more, call +61 2 8627 8818, email development.fund@sydney.edu.au or make a gift online.

See more Aaron Greenville photography at his website.

Written by Monica Crouch (BA(Hons) ’95)
Photography by Dr Aaron Greenville (BSc(Hons) ’01 PhD ’15) and Bobby Tomayo (BSc ’95)