a day ago
Professional shooters patrol parks in Canberra in search of persistent pests
Rabbits are being shot in the area of Lake Burley Griffin in Canberra's centre in an effort to keep their population under control.
The thermal-assisted rabbit control program has been used in the Mulligans Flat and Goorooyarroo nature reserves since 2014, and in Canberra Nature Park reserves since 2023.
"It's very carefully managed," Mark Sweaney of ACT Parks and Conservation said.
"It's done with air rifles, [so they're relatively low-powered], by professional shooters, that spend all their time undertaking rabbit control, so they've got techniques available that prioritise public safety."
The program is continuing amid fears rabbit numbers could be growing at a concerning rate.
"Australians don't have good memories of what really out of control rabbit populations are, but we could be on the brink of starting to see that," Invasive Species Council chief executive Jack Gough said.
There was a time when Australia was overrun with rabbits in plague proportions.
With only physical means to control them at that time, they caused widespread environmental, agricultural and economic destruction.
Previous virus releases, like myxomatosis and calicivirus, have brought rabbit numbers down to historic lows.
But experts say a new virus is needed every 10 to 15 years as rabbits build immunity.
As the effectiveness of the virus fades along with the memory of the destruction rabbits can cause, there are calls to fast-track and fund the next biocontrol.
Many Canberrans have noticed rabbits popping up in areas they've never been seen before — veggie gardens, local streets, and the lush lawns of Parliament House.
"What we're seeing is what happens when we have enough food and favourable seasons for rabbits," Mr Sweaney said.
"Rabbits start spreading and occurring in new places and return to where they already occurred."
In a good season, female rabbits can have three litters a year with up to eight rabbits per litter.
"Thousands of rabbits can come from few in a very short time," Mr Sweaney said.
Mr Gough said the "perfect storm" is a few good years followed by a drought.
"While rabbit numbers have been low, after a couple of very good seasons in a lot of Australia and as virus efficacy starts to drop off dramatically, this is going to start being an issue that turns up in the inboxes of politicians," Mr Gough said.
Rabbits breed like rabbits, and Mr Gough says to stop rabbit populations from increasing, you need to remove roughly 87 per cent of rabbits in an area each year.
Areas that are difficult to treat, or where the rabbits are resistant to the virus, become harbours for rabbits to breed and multiply.
Cooperation and coordination are needed to achieve success, but still, even with a Rabbit Control Working Group in the ACT — made up of ACT government departments, the National Capital Authority and the Department of Defence — there are areas that provide the perfect habitat for rabbits.
One example is the hedges around Lake Burley Griffin and Kings Avenue Bridge, a space that is making it harder to tackle the problem.
"We spend over $500,000 annually on rabbit control across the ACT. That's not including staff time," Mr Sweaney said.
"What we want to see more biocontrol in the pipeline, that's what really makes a difference. It's a real battle. We've got a lot of resources put toward rabbit control and there's still a lot of areas we can't get to."
While rabbits may appear harmless, CSIRO Health and Biosecurity senior principal research scientist Tanja Strive describes them as a "reverse keystone species" that has a devastating ecological impact far beyond what their size might suggest.
Beyond decimating agriculture industries and competing with native animals and plants for resources, large rabbit populations sustain significant numbers of feral cats and foxes, worsening those pest problems.
Controlling rabbits, therefore, delivers multiple biodiversity benefits across the landscape.
"One way of pulling down the fox numbers long-term is to actually control rabbits," said Dr Strive.
"If you do have to prioritise your biodiversity dollars, rabbits are really good targets because by targeting rabbits, you will achieve a lot of really positive impacts in all directions."
Dr Strive and her colleagues have been at the forefront of rabbit biocontrol research for decades.
Their work focuses on rabbit haemorrhagic disease virus (RHDV), a calicivirus that has been used to successfully manage rabbit populations in Australia since the 1990s, and they are working on the next generation of biocontrol.
"It has to be species-specific — obviously, that's the first priority. And it has to be [highly] effective at reducing population, and repeatable," Dr Strive said.
She says if the population reaches plague proportions again, not only will it take us back to where we were, but will destroy all the long-term biodiversity gains that have been made by the long-term suppression of rabbits.
"It's not about killing lots of rabbits. It's about keeping rabbit numbers low," Dr Strive said.
She emphasises that there must also be a vaccine ready to roll out to protect the domestic and farmed rabbit population against any new virus that is developed.
Dr Strive suggests that with rabbit numbers at historic lows for a decade, she suspects the issue has dropped down the priority list for funding and public attention.
"Biocontrol may have become a victim of its own success because numbers have been at historic lows for 10 years," she said.
"It's a bit out of sight, out of mind, and it might have been replaced as a top priority by other equally pressing issues."
There's an urgent imperative to develop the next generation of rabbit biocontrols before the current ones lose their effectiveness and Australia faces another rabbit population explosion.
"Up to now, we've been supported, we've had industry support for this work, and at the moment, we have federal funding to see us for the next little while, but not to the point where there is a new product ready for this.
"It's always a challenge in any field of science. Sustainable long-term funding is a problem."
Jack Gough puts it another way, saying "we are always going to be in a race with rabbits" to keep their population down.
"We're always going to need new innovations, whether it's new methods to distribute these biocontrols or entirely new biocontrols," Mr Gough said.
"If we take our foot off the pedal, which is what's happening right now, we will lose the race."
At CSIRO's Black Mountain laboratories in Canberra, Dr Strive and her team are working on new approaches to rabbit biocontrol.
These include genetic biocontrol, otherwise known as gene-drives, that could offer alternative, non-lethal methods for rabbit population control in the future.
"Gene-drives may be a tool that will get them to eventually breed themselves out of existence, in a very Australian specific manner," Dr Strive said.
"But that technology could be decades away.
"In the meantime, we need a virus or two or three."
