Australia’s forests are facing a growing threat from invasive animals. Feral pigs, goats, deer, horses, cats and foxes are damaging native ecosystems, threatening biodiversity, and undermining decades of forest management and restoration efforts. Their impacts are well-documented across government agencies and the scientific community, and they must be addressed as part of any holistic forest health strategy.
In fact, according to the CSIRO and the Australian Government’s State of the Environment report, invasive species are the biggest threat to native species and number one cause of extinction in Australia1,2.
Feral herbivores: damaging landscapes from the ground up
Hard-hoofed animals like deer, goats, pigs and horses physically disturb soils, trample regenerating vegetation, and degrade waterways. Feral pigs, for example, disrupt the ground layer through rooting, leading to erosion, spread of weeds, and destruction of native plant seedlings3,4.
Feral goats intensify erosion by overgrazing and browsing on native shrubs and grasses, especially in semi-arid and forest fringe environments. Their competitive impact on native herbivores such as wallabies has been observed across multiple regions5,6.
Feral deer populations are rapidly expanding in south-eastern Australia. Their browsing reduces forest understorey complexity, and their trails and wallows damage soil and water systems7. In Victoria, six deer species are now considered established and cause measurable impacts on forest structure, seedling recruitment, and fire behaviour.
Feral horses in alpine and subalpine areas, particularly in Kosciuszko National Park, trample sphagnum bogs, compact soils, and disrupt fragile wetland ecosystems—many of which are listed as endangered8,9.
Mesopredators: major threats to native fauna
Feral cats and red foxes are leading causes of faunal decline in Australia. Feral cats kill over 1.5 billion native animals annually, including mammals, birds, reptiles, and frogs10,11. Foxes, introduced in the 19th century, are responsible for regional extinctions and suppress recovery efforts for threatened species like bandicoots and quolls12.
These predators continue to thwart conservation initiatives, especially species reintroductions in unfenced or semi-wild habitats, unless comprehensive predator control is in place13.
The need for integrated, well-resourced control
Effective feral animal management includes lethal and non-lethal strategies: trapping, shooting, exclusion fencing, and targeted baiting. Yet, these measures are often fragmented, underfunded, and short-lived14. Without coordination, efforts fail to scale to the ecological breadth of the problem.
Several organisations—including research bodies, state agencies, Indigenous ranger groups, and advocacy groups like the Invasive Species Council—are doing important work to reduce the threat of pest animals. But more consistent national leadership, Indigenous-led co-management, and science-based investment are urgently needed15,16.
Healthy forests need fewer hooves and paws
At the Healthy Forests Foundation, we know that pest species control is a cornerstone of forest restoration. Forests cannot regenerate properly when young plants are grazed to the ground or when small mammals are missing from the ecosystem. Managing invasive species is not a side issue—it’s central to ecosystem repair, cultural healing, and climate resilience.
By supporting coordinated feral animal control as part of a broader forest recovery plan, we can create lasting, landscape-scale outcomes. Restoring healthy forests means restoring balance—hoof by hoof, paw by paw.
References
1 Sheppard, A. & Broadhurst, L., 2019. Invasive species are Australia’s number-one extinction threat. CSIRO. 28 May. Available at: CSIRO website.
2 Department of Agriculture, Water and the Environment 2021, Australia state of the environment 2021, independent report to the Australian Government Minister for the Environment, Australian Government, Canberra, viewed 20 June 2025, https:
3 Hone J. 2002, Feral pigs in Namadgi National Park, Wildlife Research, vol. 29, no. 6, pp. 525–530.
4 Department of Climate Change, Energy, the Environment and Water (DCCEEW) 2021, Australia’s Strategy for Nature, viewed 18 June 2025, https:
5 Parkes J., Henzell R. & Pickles G. 1996, Feral goat control, Bureau of Resource Sciences, Canberra.
6 NSW Threatened Species Scientific Committee 2004, Final Determination: Competition from feral goats, NSW Government, viewed 18 June 2025, https:
7 Davis N.E. et al. 2016, A systematic review of the impacts and management of introduced deer in Australia, Wildlife Research, vol. 43, no. 6, pp. 515–532,
8 Worboys G.L. et al. 2015, Environmental impacts of feral horses in the Australian Alps, Ecological Management & Restoration, vol. 16, no. 1, pp. 58–63,
9 NSW Office of Environment and Heritage 2016, Wild Horse Management Plan: Kosciuszko National Park, NSW Government, viewed 18 June 2025, https:
10 Doherty T.S. et al. 2017, Invasive predators and global biodiversity loss, Biological Conservation, vol. 213, pp. 85–94,
11 Woinarski J.C.Z. et al. 2017, How many birds are killed by cats in Australia?, Biological Conservation, vol. 214, pp. 76–87,
12 Kinnear J.E. et al. 2002, The red fox in Australia: an exotic predator turned biocontrol agent, Biological Conservation, vol. 108, no. 3, pp. 335–359,
13 Legge S. et al. 2011, The effectiveness of predator control and habitat restoration for the conservation of threatened mammals in the Kimberley, Austral Ecology, vol. 36, no. 7, pp. 730–740,
14 Department of Agriculture, Water and the Environment (DAWE) 2021, National Feral Animal Management Strategy, viewed 18 June 2025, https:
15 Invasive Species Council (ISC) 2023, Feral Animals and Forests Report, viewed 18 June 2025, https:
Forests' threats