Australia’s semi-arid and arid rangelands have experienced an alarming trend of extinctions and declines of native animals, mainly due to feral cats and foxes, as well as altered fire regimes and inappropriate agricultural practices. But in Western Australia, a movement is underway to help our wildlife take back their place within the ecosystem.
Dr Judy Dunlop and Western Australia’s Department of Parks and Wildlife have been working to protect one of Australia’s most valuable ecosystems in Western Australia’s Pilbara region. The Pilbara’s remoteness is a key aspect of its significance. It is one of Australia’s oldest landscapes, and is separated from the Kimberley region by 500 kilometres of desert. The result for the northern quoll is a population with distinct genetics from its northern and eastern counterparts. And these unique genetics may make it important for the species’ long-term resilience to the extinction process. Despite the threats from feral predators, the northern quoll population has managed to survive, in part due to the high levels of ecosystem complexity found here.
Habitat modelling shows that quolls are strongly affiliated with complex habitats. The vast rocky outcrops of the Pilbara provide the steep terrain and crevices required to protect them from fox and cat predation – albeit at lower numbers. However, when the ground cover has been destroyed – for example, due to a large wildfire – cats and foxes have free range. A single event like this can devastate the population of natives due simply to the loss of coverage.
The Department of Parks and Wildlife’s Threatened Fauna Animal Science Program is working to address this threat with a feral cat baiting trial in the arid zone. Thousands of sausage baits laced with 1080 are aerially dropped at a research site, in an attempt to boost northern quoll survival by reducing feral cat numbers. Native species have a natural resistance to 1080, particularly in Western Australia, where the active ingredient of this poison
[fluoroacetate] is naturally found in local plants. The program also monitors quolls at 12 sites across the Pilbara to collect a wide range of data. Records from cameras and quoll scats show a diet rich in rodents, insects, and native figs and provides a visual record of their night time activity. DNA samples show how mobile northern quolls are; all northern quolls in the Pilbara are part of the same genetic group, indicating that they are highly mobile during the breeding season and genes flow across the entire region. Now, in its third year of monitoring, the program aims to create a data bank that covers 10 years of observation.
To have the best fighting chances against future threats, both known and unknown, this long-term data is essential. “Cane toads are due to arrive on their own in the next 15-20 years, but it could be even sooner if they hitch a ride.” This could be their greatest threat yet – where naïve quolls are pitted against toxic toads. Because all male quolls die when they are one year old after the mating season, they are a boom and bust population and thus even more vulnerable to interference. “Our best bet is going to be getting quolls to persist past the first wave toxic toads, so that they can at least cohabit.
It’s also hard to know what climate change will do—we just don’t know what impact that will have. It is the ultimate wild card.”
However heartbreaking these challenges might be, Dr Dunlop’s experience shows her that “you have to deal with things as they come up. Ecosystems are so complex. To work with them you have to reshape your ideas, you have to be adaptable and optimistic; you have to roll with it.” Hers is the ultimate Adaptive Management approach.
“Though it’s hard sometimes and you can feel like you’re fighting a losing battle, you also see great innovation and the enthusiasm of people trying hard with their particular patch or species. And because of that, we make progress.”