Alpine and subalpine ecosystems are among the environments most vulnerable to climate change1. In Australia, rising temperatures, declining snowfall, prolonged droughts and increasingly frequent wildfires are transforming these fragile landscapes and placing unique wildlife under growing pressure.
A recent long-term study examined how fluctuations in snowpack and the occurrence of wildfire affected three native small mammals in the Australian Alps: the broad-toothed rat (Mastacomys fuscus), bush rat (Rattus fuscipes), and mainland dusky antechinus (Antechinus mimetes)2.
Historically, alpine snow covered the landscape for several months each winter creating an insulating layer that protects the subnivean space— the hollow air layer between the ground and the bottom of the snowpack in which animals can shelter and forage within tunnels and burrows. Concerningly, snow depth and persistence have declined over the past 50 years. Climate projections suggest that by 2050 the total area experiencing more than 60 days of snow each year could shrink by as much as 96%.
By monitoring alpine sites for between 19–43 years, Green and colleagues characterised how reduced snow cover negatively affected small mammal populations, particularly the broad-toothed rat and the dusky antechinus. Earlier snowmelt exposed these species to colder conditions during spring, while shallow snowpacks provided less insulation for nests and burrows. The broad-toothed rat was especially vulnerable because it nests on the ground in grass shelters, making it more susceptible to harsh weather and predators such as foxes. In contrast, bush rats, which have relatively flexible dietary requirements and high reproductive potential, were less affected by changes in snow conditions.
Wildfire had an even greater impact than declining snowpack. The extensive 2003 wildfire in the Australian Alps, which burnt over 1.73 million hectares3, decimated populations of all three species. Broad-toothed rats disappeared entirely from the main study sites for several years and had still not fully recovered by 2020. Although bush rats and dusky antechinus gradually returned, their recovery was slow. The authors believe these enduring negative impacts from the fires is likely attributed to the reduction of dense shrub vegetation that provides shelter, food and the structural conditions necessary for snow to accumulate.
These results are concerning given the existence of a positive feedback loop in which drier conditions, declining snow cover, and a lengthening growing season increase vegetation flammability and woody encroachment, thereby leading to longer wildfire seasons4. Indeed, less than two decades after the 2003 blaze, 33.5% of Kosciuszko National Park burned again in 2019–205. Green and co-authors noted that long-term monitoring and targeted conservation efforts, including habitat restoration, invasive species management, and improved fire planning, will be essential to protect Australia’s alpine biodiversity.
References
- Rowland, J. A., Walsh, J. C., Beitzel, M., Brawata, R., Brown, D., Chalmers, L., … & Moore, J. L. (2023). Setting research priorities for effective management of a threatened ecosystem: Australian alpine and subalpine peatland. Conservation Science and Practice, 5(3), e12891. ↩︎
- Green, K. P., Happold, D. C., Sanecki, G. M., & Dickman, C. R. (2026). Fire and Snow: Effects of Snowpack Variation and Wildfire on Small Mammal Dynamics in Sub‐Alpine Habitats. Ecology and Evolution, 16(4), e73525. ↩︎
- Worboys, G. (2003). A brief report on the 2003 Australian Alps bushfires. Mountain Research and Development, 23(3), 294-295. ↩︎
- Verrall, B., Norman, P., Mackey, B., Fisher, S., & Dodd, J. (2023). The impact of climate change and wildfire on decadal alpine vegetation dynamics. Australian Journal of Botany, 71(5), 231-251. ↩︎
- Kosciuszko National Park 2020 fire recovery. Available at: https://fnpw.org.au/project/kosciuszko-national-park-2020-fire-recovery/ (Accessed: 02 July 2026). ↩︎
This article was written by Cassandra Harvey, the Healthy Ecosystems Project Officer with the Nature Conservation Council of NSW
