Last updated May 30, 2019 at 10:17 am
A Hunger Games-style experiment has shown that pitting them against predators can actually help endangered species, like the bilby, survive in the wild.
Exposure to predators can positively impact endangered species. Credit: Auscape/UIG via Getty Images)
Imagine The Hunger Games, but instead of being trapped in a dome with killer kids and lethal wasps, you’re locked in with a bunch of feral cats.
For the greater bilby, it’s probably one of the worst situations to find themselves in, but research has shown that this exposure can actually help them survive in the wild.
The experiment, overseen by Katherine Moseby, a UNSW ecologist, has looked into the effects of exposing these vulnerable species to an environment with predators, before releasing them back into the wild.
The study, published in the Journal of Applied Ecology, compared the behaviour and subsequent survival of two groups of bilbies from different scenarios.
The first scenario saw a group of bilbies that had been deliberately exposed to feral cats.
The second, a group that had not come into contact with predators before.
Predators can help the fate of endangered animals
The study is the first experimental test of predator exposure that shows the fate of animals could be improved by prior experience living with predators.
“Deliberately exposing threatened species to feral cats in a wild setting is risky but our research suggests that it leads to a significant improvement in anti-predator behaviour and survival,” says Moseby.
The team from UNSW, Arid Recovery and UCLA, conducted the experiment in the Arid Recovery Reserve – a 123 km2 network of fenced exclosures in arid South Australia.
Several locally extinct species have recently been re‐introduced into the Reserve, including the vulnerable greater bilby.
“The reserve is divided into paddocks, and we conducted the experiment in three paddocks: the predator‐free paddock, the predator‐exposed paddock, and the release site,” says lead author Aly Ross, also from UNSW.
Predator exposure shapes bilbies behaviour
Bilbies from the predator-exposed paddock had been living with five feral cats in the two years leading up to the experiment.
The bilbies from the predator-free environment had never encountered cats or other predators.
“First, we compared the behaviour of bilbies from the predator‐free and predator‐exposed populations in a small fenced pen of a bit over 50 m2 – primarily to see how they’d react to a new environment,” says Ross.
The team found that the behaviour of the animals that had previous predator exposure differed from the predator ‘novices’.
The study showed that predator exposure changed the behaviour of the bilby. Credit: JOUAN/RIUS/Gamma-Rapho via Getty Images
“Animals that had lived in an environment with predators moved less and sought cover more quickly,” says Ross.
“This shows that they were warier of potential threats, whereas the predator-free group of bilbies showed fewer signs of predator awareness.”
The fact that animal behaviour can be changed by predator training has been demonstrated before, but it’s what the group found next that is particularly interesting.
“In a second experiment, we released bilbies from the predator-exposed paddock and some from the predator-free paddock into a third paddock with some feral cats,” says Ross.
“Unfortunately, we found that 71 per cent of the predator‐free bilbies died in the week after release, but only 33 per cent of the predator‐exposed bilbies met the same fate – showing that the bilbies who had been exposed to the very real threat of predators already had benefitted from that experience.”
A different approach to conservation
The findings have important implications for the conservation of native animals and programs that seek to reintroduce species like the bilby.
“Our native animals did not evolve with introduced cats and foxes,” says Moseby.
“Isolating threatened animals from introduced predators on islands or inside fenced reserves exacerbates the issue of prey naivety. We are advocating for a different approach whereby threatened species are exposed to these predators in the wild under controlled conditions.”
Possible to make ‘better’ prey species
The research suggests that predator exposure improves survival in the first 40 days following translocation.
Species with predator training may be have a vital edge that increases the chance of creating a sustainable population in areas with some predators.
Mike Letnic from UNSW says that the research points out the importance of native animals tolerating introduced predators.
“Our research shows that it is possible to make ‘better’ prey species, because ultimately if native animals are to survive in the wild they need to be able to tolerate the threat posed by introduced predators.”
Moseby agrees that co-existence is important for the survival of native species.
“Although it may take decades or even centuries for our native species to develop the skills they need to combat feral cats and foxes, we need to be working towards that co-existence now,” she says.
