Revelations that 67 eastern bettongs had been killed in a release program devised in liaison with the government come as no surprise to academic Mike Braysher, who says he warned organisers.
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The animals had been wiped out from the Lower Cotter Catchment where they had been released between 2015 and 2017 by about March last year, manager of Mulligans Flat Woodland Sanctuary, Dr Will Batson, confirmed.
Most of them, taken from captivity in Mulligans Flat and Tidbinbilla Nature Reserve when they reached nine months, died immediately or shortly after they were released. The longest-surviving bettong died at 18 months.
Eastern bettongs generally have a lifespan of five years in the wild, Dr Batson said.
"We have really pushed the boundaries of what was thought of as possible outside these reserves," Dr Batson said.
"We kept adult bettongs alive for over 18 months, which gave females the time needed to produce multiple young, but what we suspect is happening is predation still affects the newly-born animals when they're in the growth phase."
The eastern bettongs were mostly killed by foxes when they got into the wild but the trial taught researchers that new technologies would be necessary to keep them at bay, Dr Batson said.
The release program used intensive baiting over 8000 hectares, supplemented with trapping and shooting. Eastern bettongs have long been extinct on mainland Australia, having only survived in the wild of fox-free Tasmania for 100 years. The bettongs at Mulligans Flat and Tidbinbilla had been introduced from Tasmania.
"We need to develop ... ways to make baits more attractive to the animals, bring them into specially designed traps ... and potentially improve the behaviour of the bettongs themselves," Dr Batson said.
Adjunct University of Canberra professor Mike Braysher, who published a book about pest control with the CSIRO in 2017, told researchers that the program was destined to fail, he says.
He was on the Woodlands and Wetlands trust when the organisation was devising the initiative with the ACT government and the Australian National University, which was given a grant to run the program.
The program was staffed by ACT Parks and Conservation. The ACT government did not say how much the program, which started in 2011, cost.
"We just can't eradicate foxes; we know that and it's well accepted. I told ACT Parks and the trust that this was the case ... and there are no new technologies to control them on the horizon," Dr Braysher said.
"It's bad science. Scientists should do their due diligence and check the background information before they start."
Dr Braysher resigned from the trust two years ago. Laying down fox baiting in a new area would just attract foxes and create a new "territory" for them that would be eventually overrun, he said.
The only way the animals could be effectively reintroduced to the wild was if a large population was put throughout the Namadgi national park and poisoning continued intensively, forever.
There are about 150 eastern bettongs at Mulligans Flat. Late in 2018, there were about 70 in Tidbinbilla.
"That's just not practical," Dr Braysher said.
"The sadness of it is is that we should be spending the financial and human resources we are spending on these programs - which we know aren't going to work - on the programs we need."
It was hoped that eastern quolls, which had also been released in Mulligans Flat, would too be reintroduced to the wild eventually, although their were no plans at this stage, Dr Batson said.
"We're only ever going to learn to how to successfully do these programs by exposing a certain number of those animals to those threats," Dr Batson said.
Cassandra Morgan
It has never been more important for Canberrans to be able to access reliable and accurate information about health. As The Canberra Times’ health reporter, I am committed to ensuring our readers have access to this. I, like many in the territory, have family members who work in the sector. Although providing comprehensive coverage on the coronavirus pandemic is obviously my number one priority, I aim to frequently shed light on the fantastic work our frontline professionals do, as well as the challenges they face. Email me tips and story ideas at: c.morgan@canberratimes.com.au.
It has never been more important for Canberrans to be able to access reliable and accurate information about health. As The Canberra Times’ health reporter, I am committed to ensuring our readers have access to this. I, like many in the territory, have family members who work in the sector. Although providing comprehensive coverage on the coronavirus pandemic is obviously my number one priority, I aim to frequently shed light on the fantastic work our frontline professionals do, as well as the challenges they face. Email me tips and story ideas at: c.morgan@canberratimes.com.au.
