The Cane Toad has had a terrible impact on local species. Photo Cathy Zwick.
Australia’s isolation from other landmasses for millions of years since its separation from the Gondwanan continent allowed a unique group of animal species to evolve.
Since the arrival of Europeans many additional species have been introduced. Some of these have adapted and thrived so successfully that they now dominate and threaten many of our native species and ecosystems.
Feral predators like cats and foxes have a devastating impact on native wildlife and their impact is greatest where over-grazing or fire has left little vegetation in which native species can hide.
Twenty eight Australian mammal species are now extinct. Cats have been implicated in the demise of at least 20 mammal species and subspecies. Feral cat populations fluctuate between two and six million and consume between 100 million and 1.5 billion birds each year.
Feral pigs damage fragile wetlands with their hard hooves. Photo Leanne Hales.
Other species can have profound impacts on ecosystems in other ways. Cane Toads, which are poisonous, have caused a catastrophic decline in populations of native species such as goannas and quolls that naturally prey on native frogs. Starlings and Indian Mynas compete with native birds for nest sites, food and territory.
Water Buffalo create channels that allows saltwater to intrude into freshwater wetlands adjacent to northern Australian coasts. Feral pigs damage wetlands, tearing up vegetation in pursuit of roots and tubers and eating the eggs and young of birds and turtles.
Controlling feral predators
Felixer cat traps have been trialled. They spray cats with toxins.
Poison baits are a tool that we use reluctantly but which unfortunately in many circumstances are the only viable means by which we can reduce feral animal numbers enough to allow native species to survive and recover.
Where there are viable alternatives, then we use them. We deploy poison baits in ways that minimise the likelihood of native species being affected and are trialling alternative methods (such as Felixer cat traps) that further minimise the chances that non-target animals are impacted.
Monitoring and science
Luke Bayley and Tim Doherty fit a tracking collar to a cat to monitor its movements. Photo Annette Ruzicka.
Bush Heritage monitors native and feral species numbers on our reserves using multiple methods including motion sensing cameras, trapping, spotlighting and the use of sandpads to capture tracks.
This allows us to understand how our control programs are impacting on feral numbers and in turn how this is benefiting native species populations. This information is used in our planning to refine and prioritise out feral animal control efforts.
We collaborate with scientists and university students on research to understand the impact of ferals, the benefits to native speices of controlling them, and the best control methods.
The role of Dingoes as suppressors of ferals
A dingo on Carnarvon Reserve, Qld. Dingos play a protective role for native species in supressing cats and foxes. Photo Emma Burgess.
Dingoes are Australia's apex predator and are an important part of the ecology, keeping natural systems in balance. Perhaps counter-intuitively, a healthy Dingo population is good for small to medium-sized mammals (and reptiles and birds) because Dingoes suppress feral predators (cats and foxes) through direct predation and indirect interference (cats and foxes avoid them).
Unlike cats and foxes, Dingoes prefer larger prey (e.g. wallabies, kangaroos) so there's less predation pressure on small to medium fauna. Dingoes also regulate numbers of feral herbivores like goats, deer and rabbits, aiding in the survival of native species.