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ABC News
2 days ago
- Health
- ABC News
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."
ABC News
11-05-2025
- General
- ABC News
Thermal cameras helping aerial shooters 'effectively' cull feral deer and keep them out of Canberra
Rabbits may jump to mind when thinking of introduced pests causing problems in Canberra, but deer pose issues for the bush capital too. Feral deer can be found running wild not only in the ACT's Namadgi National Park and Tidbinbilla Nature Reserve, but also along river corridors and in nature reserves surrounding Canberra's southern and western suburbs. They're a problem not confined to the territory's borders, with deer having significant environmental, economic and social impacts across the country. But unlike some other urban centres, Canberra is ahead of the game, with the ACT government implementing a thermal-assisted aerial culling and monitoring program to keep deer numbers under control and out of the suburbs. Mark Sweaney, assistant director of invasive animals and overabundant wildlife programs, said the ACT was "very lucky" to be in the proactive stage of deer control. "Other parts of Australia are coping with peri-urban deer populations, where they've got established populations that they're having to do control within the urban area, which makes it very difficult," he said. "It presents all sorts of social and ecological issues, including traffic issues, animal welfare issues, the techniques that are available are a lot more limited." Given the layout of the bush capital, Mr Sweaney said it was essential deer were kept at bay, as their numbers could quickly multiply. "We're seeing early signs of deer spreading into town," he said. "It's really important that we keep the number of animals under control in these areas, so they don't become established in town. Keeping the deer numbers in check requires constant management, support and technology — and that's where thermal imaging has been a game changer. "We were one of the first to use thermal-assisted aerial control, and so far, it's proven very effective to help us maintain that control," Mr Sweeney said. "So we have relatively low densities of some of the worst species, like feral deer, feral pigs." Since 2021, ACT Parks and Conservation has been using thermal-assisted aerial control programs for detecting, culling and preventing the further spread of deer with "positive results". Mr Sweaney said the use of thermal camera technology significantly increased the effectiveness and efficiency of aerial shooting. "We have the shooter and the thermal camera operator sitting next to each other, and that means they're both looking at the same area of ground, and that increases the effectiveness." The crew takes to the air during the "most ideal conditions for thermal", being the first and final few hours of daylight, Mr Sweaney said. "We can't fly at night. That's only the military that can do that at the moment in Australia," he said. This year's cull is currently underway and will run through until May 30. There is no set quota ahead of each aerial cull season, with the objective being to reduce deer numbers with the time and funding available. In 2024, the program removed 771 vertebrate pest animals including 350 deer, while in 2023 there were around 500 animals removed. Mr Sweaney said camera monitoring was helping to assess how effective the control programs were, and whether animals were adapting to aerial shooting. "There is evidence that animals do learn, particularly feral pigs, about aerial shooting," he said. "So we're keeping a close eye on what's happening, particularly in Namadgi National Park." Deer were introduced to Australia in the 19th century as game animals, then later in the 1980s in a push to farm deer for venison. Australia is now home to six species of deer: fallow, red, chital, hog, rusa and sambar — and the wild ones are completely feral. ACT Parks and Conservation executive branch manager Michaela Watts said deer were becoming an emerging threat. "Especially in some of our endangered ecosystems in the high country alpine bogs and fens, but also in the peri-urban area," Ms Watts said. "We use this program to control the spread of feral species, and stop them from breaching other sensitive areas and the urban areas." Ms Watts said thermally-assisted aerial control programs were the most effective way to control feral species. "[They're] more effective than ground shooting by professionals," she said. "It's also humane for the animals that we'll be targeting as part of this program." Due to logistics and the remoteness of the operations, Ms Watts said the carcasses were not used but left in situ, with ground crews following up if an animal was at risk of contaminating waterways in the catchment. The Australian Deer Association (ADA) considers the deer a valuable resource, and it would like to build a collaborative relationship with governments and land management agencies to assist in culls and make use of the venison. ADA ACT-Snowy Mountains branch president Phoebe Youd has been hunting for 11 years. "We're using the natural resources around us, and I think that's really important, because we're part of the balance of the ecosystem." Beyond being recreation, it's also a passion that puts the problem onto the plate. "It's the shared passion and being able to feed the family knowing that what we're actually eating is quite literally free-range, organic fast food," Ms Youd said. In other parts of Australia, recreational shooters have been part of the control programs — but in the ACT there is no hunting on public land. Ms Youd would like to build a relationship between the local branch of the ADA and ACT Parks and Conservation. "We started, a couple of years ago, looking to collaborate in terms of how the deer people in the local area can be a useful resource for Parks and Conservation," she said. "Especially in being able to get into areas where the choppers can't get into … I think that we have a huge role to play in being able to assist further with their management." Ms Watts said she recognised the community of recreational shooters and acknowledged it was a valid pastime, but it was not part of the plan in tackling the emerging ecological crisis. "In the areas that we're covering, they're remote and rugged, and the densities of animals are also quite low," she said. "This is a program where we're trying to reduce the number of animals, so recreational hunting would be less desirable.
