A pest expert has likened the ACT Government’s secret release of 30 rare eastern bettongs west of Canberra to offering up native animals as cat and dog food.
Almost two years of intensive fox control preceded the release in the Lower Cotter Catchment, but questions are being asked whether this is a waste of resources, leaving other areas across the territory short for pest and weed control.
Author with the CSIRO, adjunct professor in natural resource management and national expert on pest management Dr Mike Braysher said he believed the bettongs would be wiped out.
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“Even if they do survive it will require intensive fox control,” Dr Braysher said.
“Which begs the question, what pest and weed control will be done for the rest of the ACT?’’
Thirty of the rabbit-sized kangaroos have been set free in stages since September, raising hope of addressing Australia’s shocking record of losing mammal species.
But the release has angered critics of Mulligans Flat Woodland Sanctuary, where bettong numbers have exploded past 300, since an initial release of 30 in 2012.
Dr Braysher said under International Union for Conservation of Nature guidelines such a release would need a detailed plan on costs and benefits, and identification of all the risks, which had not been done. He said feral cats carried diseases that would endanger the bettongs.
The academic said a release of more than 1200 burrowing bettongs in South Australia in 2013 was unsuccessful, and that was done with aerial fox baiting, which was not possible in the Lower Cotter Catchment.
But ACT Parks and Conservation director Daniel Iglesias said as a land manager, the release in stages in September, and signs of some bettongs (Bettongia gaimardi) breeding were really exciting.
“Pure conservation is not just about protecting what we have, but replenishing what we don’t have and what we have lost in the past,’’ Mr Iglesias said.
“It is a brave new world for the ACT to contemplate the possibility we could be re-introducing animals that our forebears managed to allow go to extinction, it is a real paradigm shift, a real game changer in the way we look after our protected areas.
“Bettongs into the wild like this, it is the first in Australia that I know of,’’ he said.
Extinct on the mainland for about 100 years because of foxes and land clearing, bettongs are prolific breeders when protected from predators.
Those released into the Lower Cotter Catchment have collars emitting signals triggered by activity, and from being non-active. Six or seven of the creatures released in September have been taken by foxes. At least one has been killed by a feral cat, and one by an eagle.
The bettongs now face their most dangerous period, as foxes begin to force out their cubs to hunt separately.
“But interestingly, in the three months they have been out there, we already know the females are carrying young,’’ Mr Iglesias said.
“In our next lot of trapping over the next few months we will be able to catch a lot of them and check a lot of the females and I am suspicious a good proportion of those females will have young inside them.’’
Mr Iglesias says the ACT Government could not have arrived at this point without a partnership with the ANU Fenner School, CSIRO and Woodlands and Wetlands Trust.
Researchers had also relied on Dr Katherine Moseby, involved in releasing burrowing bettongs in arid South Australia. In that trial, no bettongs were detected at the main release site 42 days after the last release.
Research at Mulligans emboldened scientists to try again. A total of 3000 hours were spent on fox baiting.
“Going outside the fence is fraught with risk because what we are effectively doing is introducing a native population of animals into un-protected landscape,’’ Mr Iglesias said.
No more bettongs will be released until researchers know how they have fared against the changing fox population.
“It makes no sense to have a protected area for bettongs if it is going to cost us a fortune, we are not going to be able to maintain it.
“The interesting questions will be at what level do we adjust that? How many foxes are too much? And how many foxes are too little from our point of view because we don’t want to invest a lot of money getting rid of a lot of foxes if we don’t have to.’’
Mr Iglesias said in Tasmania, bettongs had thrived in the wild alongside feral cats.
“Eastern bettong have a high reproductive rate, that appealed to us because of their in-built resilience to predation, effectively what we are trying to do is discover at what level that predation can be sustained,’’ Mr Iglesias said.
Meanwhile, under the bushland soil abundant native truffles are available to feed bettongs, as well as seeds and insects. The little marsupials are called eco-system engineers.
“They dig up the soil, continually turning it over looking for seeds and things to eat,’’ Mr Iglesias said. “If you think about it, that element of the eco system has been missing from the Canberra regions for 100 years. You put them back again, they are digging the soil up, it is going to have a knock-on effect in the environment,’’ Mr Iglesias said.
He said understanding what level of fox control was needed to enable bettongs to thrive would be a great outcome.
Do you think the ACT Government should be funding a program to release bettongs in an area with a feral fox problem?