Feral cats and foxes now roam across almost all of Australia. These predators are a major reason why many species have been driven to extinction.
Author
- John Gould
Senior Research Assistant in Conservation Biology, University of Newcastle
In response, conservation groups and authorities have turned to safe havens - islands or large fenced-off areas on land. Well known havens include Newhaven in the Northern Territory and Faure Island off the coast of Western Australia.
After feral cats and foxes are removed, authorities can reintroduce endangered native mammals such as bilbies who can live their lives in the wild, rather than in zoos or captive breeding programs. Many are now flourishing, such as the brush-tailed bettong and greater bilby . These havens have become a powerful tool to pull many mammal species back from the brink.
Unfortunately, our new research shows mainland safe havens don't yet offer strong protection for many other groups of animals, such as frogs, reptiles, fish, birds and invertebrates. Many species from these groups are similarly threatened by introduced predators as well as other invasive threats, from black rats to deadly fungal infections.
This is because safe havens are often set up for mammals and don't protect the range of habitats other animal groups need or exclude their specific threats. We will need to create new safe havens for non-mammal species. We have pinpointed several priority areas on the mainland where future safe havens could extend protection.
Nowhere to hide
To test whether safe havens were protecting other animal groups, we examined the known ranges of 123 species of threatened reptiles, amphibians, birds and invertebrates considered highly susceptible to introduced species.
We found only two have populations currently inside existing safe havens - the great desert skink and western swamp tortoise. Some frog and fish species have specific havens, such as breeding sites fenced off to protect them from feral pigs or other threats.
Our research shows few current havens are likely to have suitable habitat for our target species in the future.
This means our current network of safe havens aren't enough. We need more in different locations and designed to counter different threats.
What's more, we will need to account for future shifts in where these threatened species will occur given human-induced climate change.
While existing safe havens can keep out cats and foxes, they're not designed to stop rats or birds. But these can pose real threats to threatened invertebrates and amphibians.
Location, location, location
Australia will need safe havens for the foreseeable future. It makes sense to ensure our network is inclusive and protects as wide a range of species as possible, beyond just threatened mammals.
We used models of where species are likely to be found in the future while accounting for future climate projections. This let us identify the top 1% of priority locations for new safe havens aimed at protecting non-mammal species most at risk from invasive species.
Many of these regions are in eastern Australia. They include the Victorian Alps, the Snowy Mountains in New South Wales, and Tasmania's Central Highlands.
Creating a robust network
There's no silver bullet to protect the many hundreds of Australian animal species at risk. Each often faces many different threats simultaneously in addition to invasive species.
As the safe haven network grows, it will be necessary to design some to respond to threats which cat and fox-proof fences don't protect against.
Finer-scale fencing or netting may be needed, or the creation of havens in natural refuges such as isolated waterways or islands.
If priority locations lie in tough terrain where extensive fencing is less viable, it may work to create mini havens protecting a smaller set of species.
For some species, it may work to have "leaky" havens where invasive species can't get in but threatened species can move in and out. This would help avoid genetic bottlenecks due to isolation.
For some species, fences won't work at all. For instance, the green and golden bell frog is threatened by both the lethal chytrid fungus and invasive fish such as mosquitofish, which eat its eggs. For this species, our earlier research suggests the best safe haven would likely be a wetland on a high plateau rather than a fence.
A similar option for other species is to use mesas - high, isolated landforms with flat tops - to keep invaders out . This could be a cost-effective solution, as these provide long-term refuges for such species to recover.
All havens have limits
Keeping threatened species in the wild rather than captivity has many benefits. Bringing animals back to the land restores their key ecological roles, such as digging through soil and spreading seeds.
Their presence benefits other native species who they have evolved alongside over millions of years, making ecosystems more functional.
Despite these benefits, havens are not a long term solution. Animals protected from predators and other threats lose their wariness. If they're released outside the fence, many are quickly eaten. Some researchers are exploring ways to expose animals to a few predators so that the wariest survive and breed. The point of safe havens is to buy time for scientists to find longer-term solutions.
Our research offers a blueprint for a new generation of climate-ready safe havens able to protect many more species and give many lesser-known species a fighting chance.
John Gould receives funding from the National Environmental Science Program.
