9th May 2025. A long-term study aids understanding of the likely impact of climate change on Gariwerd’s small mammals
Associate Professor John White presented to 32 attendees recently on “How will little critters cope with Climate Change?’ The Grampians fire, climate and biodiversity project.
Climate Changes means fires, drought and floods and this project aims to look at how ecosystems are going to respond.
Over the past 20 years the Grampians has experienced hypervariable climatic conditions, including four mega fires since 2005. Major fires are now more frequent, more intense, and more devastating. Floods are becoming more frequent and severe with major damage from the 2010/2011 flood.
Photo Credit Leigh Douglas
Deakin University has established 36 survey sites and conducted extensive small mammal surveys since 2008. These surveys have tracked numbers of feral (house mouse and black rat) and native species. Native rodents include the heath mouse and swamp rat, while little native carnivores include Dunnarts and three species of Antechinus – dusky, agile and yellow footed. The study has also tracked numbers of the endangered Long Nosed Potoroos and Southern Brown Bandicoots.
Photo Credit Leigh Douglas
This is an extensive long-term study is one of the largest of its kind in Australia. Over this time the researchers have conducted 9340 trap nights of trapping per year, resulting in 10354 captures. The team have also conducted many thousands of nights of camera traps.
The study has conclusively shown that small mammal populations are sensitive to the interrelated variables of time since fire, rainfall (drought), and vegetation productivity. All three will and are being impacted by climate change. Over the last 20 years the Grampians have had the Millenium drought, followed by the big wet and then the last 3 years of ups and downs with a very bad dry spell and a recent fire at the moment.
John and his team have developed models looking at the response of all these small mammals post fires, drought and floods which has helped them to understand what has happened before and what can happen in the future. (Using models to look back in time at the Grampians). See this photo which shows how numbers vary – red is low and green is high.
Points
- 2 years post high rainfall periods there is a boom in animal numbers, such as in 2012 with the heath mouse and agile antechinus.
- The recovery of most native species after fire is very slow.
- House mouse numbers explode after fire due to no competition with natives, its ability to move into an area and the abundance of grass regeneration. Its numbers are initially high and then as the native species recover its numbers drop off.
- After 18-20 years there is peak species richness.
When rainfall is low there is a decline in all small mammal populations. More rain equals more natives.
It is not completely true that animals need fire. Most native animal species prefer long unburnt vegetation, but fire does help bring back some floristic diversity (Who drives post-fire recovery-our paper from the Grampians).
John’s team was also interested to know if there are areas in the Grampians offering drought microrefugia and studied an area between Lynch’s Crossing Road and Yarram Gap Road using cameras and processing over ½ million images. There was scientific evidence that areas with high vegetation (NVDI) cover provide drought microrefugia offering us hope in the face of increasing fire, drought and floods. The hope that in these microrefugia animals can shelter and then move out and breed once the conditions improve. Our paper from the Wannon looking at drought refugia (Can NDVI identify drought refugia for mammals and birds in mesic landscapes? – ScienceDirect).
However, the concern is that a continuing dry climate without rain is likely to lead to extinctions of fires keep occurring as regularly as they are now. For Gariwerd, long-term maintenance of species all depends on rain.
More information in this paper Diversity and Distributions – 2016 – Hale – Fire and climatic extremes shape mammal distributions in a fire?prone landscape