The Black Summer bushfires of 2019–2020 that razed more than half of the landscape on Kangaroo Island in South Australia left an indelible mark on the island’s unique native biodiversity, which is still struggling to recover.
Flinders Chase National Park after the 2019-2020 Black Summer fires
" data-orig-size="4029,2751" sizes="(max-width: 510px) 100vw, 510px" data-image-title="KI fire scar" data-orig-file="https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg" style="width:840px;height:auto" data-image-description="CJA Bradshaw
" data-image-meta="{"aperture":"2.2","credit":"","camera":"iPhone 6s Plus","caption":"","created_timestamp":"1582728780","copyright":"","focal_length":"4.15","iso":"25","shutter_speed":"0.00054585152838428","title":"","orientation":"0"}" width="510" data-medium-file="https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=300" data-permalink="https://conservationbytes.com/2024/12/04/5000-piggies-500-piggies-100-piggies-and-there-there-was-none/ki-fire-scar/" alt="" height="348" srcset="https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=510 510w, https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=1020 1020w, https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=150 150w, https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=300 300w, https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=768 768w" class="wp-image-214085" data-large-file="https://conservationbytes.com/wp-content/uploads/2024/12/ki-fire-scar.jpg?w=510" />Flinders Chase National Park on Kangaroo Island after the 2019-2020 Black Summer fires (credit: CJA Bradshaw)However, one big bonus for the environment’s recovery is the likely eradication of feral pigs (Sus scrofa). Invasive feral pigs cause a wide range of environmental, economic and social damages. In Australia, feral pigs occupy about 40% of the mainland and offshore islands, with a total, yet highly uncertain, population size estimated in the millions.
Feral pigs are recognised as a key threatening process under the Environment Protection and Biodiversity Conservation Act 1999, with impacts on at least 148 nationally threatened species and eight threatened ecological communities. They are a declared invasive species and the subject to control programs in all Australian jurisdictions.
Motion sensing cameras deployed during the eradication program capture feral pigs using their snouts to search for soil-borne food. This behaviour, called rooting, creates large areas of disturbed soil, killing native vegetation and spreading invasive weeds and pathogens (credit: PIRSA).In a new article published in Ecosphere, a collaboration between PIRSA Biosecurity and the Global Ecology Laboratory at Flinders University analysed optimal strategies for culling feral pigs.
Lead author Peter Hamnett states that this could be helpful in Australia and elsewhere where feral pigs are a major environmental problem.
Globally, feral pigs cause extensive damage to biodiversity and agricultural land and infrastructure, so successes like this one are extremely important.
As well as likely having eradicated pigs entirely, the success of the program was even more astounding when you consider its rough terrain and large size — Kangaroo Island is Australia’s third-largest island at 4430 km2.
Kangaroo Island, showing its location relative to the Australian mainland. The orange area indicates the extent of the 2019–2020 bushfires. Black dots indicate the location of pig records 1928–2019 (ALA.org, 2024), and red dots indicate the location of pig culling events recorded after the 2019–2020 bushfires.Invasive species cost Australia around $25 billion/year in terms of management and economic losses, with reduction and eradication campaigns often ad hoc.
First introduced to the island in 1803, the feral pig population grew exponentially, mainly on the western end of the island where native flora and fauna attract tourists from around the world. Despite sporadic eradication efforts, the annual cost of feral pigs to farming and the economy on the island has run around $1 million.
The model gives important results, particularly when many attempt eradications of invasive species are prone to fail. It also was well-timed after the fires on Kangaroo Island already reduced the pig population by about 90%.
The program managed to kill 900 pigs in total, using the most advanced technology including trapping and thermal imaging from helicopters. Follow-up monitoring is checking whether any pigs remain.
Major investment from State, Commonwealth and other partners, totalling about $7 million, was another reason the Kangaroo Island program has been successful.
The paper assesses the costs and techniques that led to success, which will help land managers to select the most cost-effective control methods in the future.
The methods we applied will support decision-making in future feral animal eradication programs, allowing pest managers to identify the best control methods and estimate expenditure to achieve eradication in a realistic timeframe.
A motion-sensing camera captures a boar taking bait from a Hoggone® Feral Pig Bait Box, a feral pig-specific bait and dispenser (credit: PIRSA).More effective eradication strategies will give project investors, partners and local communities more confidence and, in turn, attract more support and help.
The eradication program was funded by the State and Commonwealth governments, Kangaroo Island Landscape Board, and the South Australian livestock industry.
The modelling article included collaborations with the Kangaroo Island Landscape Board, National Parks and Wildlife Service, Livestock South Australia, AgKI, Kangaroo Island Land for Wildlife, landholders, and tourism stakeholders.
Acknowledgements: Thanks to PIRSA’s Biosecurity Division, Invasive Species Unit for data access and support. We acknowledge the continued connection of Kaurna, Ngarrindjeri, and Narungga people to Karta (Kangaroo Island) and that we did this work on the unceded lands of the Kaurna.
