Delaney, L., Di Stefano, J. & Sitters, H. (in press). Mammal responses to spatial pattern in fire history depend on landscape context. Landscape Ecology.

http://link.springer.com/article/10.1007/s10980-020-01186-3

While kangaroos are easier to spot than many of Australia’s more secretive native species, a suite of threats currently face these magnificent animals.  The 2019-20 fire season was exceptional because, according to modern records, it consumed forests that had never before burnt at such vast scales.

More than 200,000 kangaroos are thought to have died during or soon after the fires in Victoria, where paradoxically, permits have been issued to kill almost 450,000 kangaroos since 2018. At that time, the state’s total population was estimated to be 1.4 million.

Although these figures are alarming, this is not another grim conservation tale.  This year, La Niña climate patterns have brought Victoria’s wildlife and fire crews some respite in the form of summer rain and cooler daytime temperatures. And the Victorian Government’s Department of Environment Land, Water and Planning has among the most sophisticated approaches to ecological fire management in the world, having forged partnerships with researchers and community groups over recent decades.

My team, including co-researchers Lauren Delaney and Dr Julian Di Stefano, works with land managers in Victoria and South Australia to find out where and when to apply planned fire for the benefit of kangaroos and other animals.  Our new research has found that kangaroos prefer a mix of long-unburnt and recently burnt areas within large expanses of woodland or forest.  It’s likely that kangaroos enjoy the shelter provided by shrubs and large trees in long-unburnt vegetation, alongside fresh, green ephemeral foods in recently burnt areas. 

However, the kangaroos’ preferences changed where remnant patches of vegetation were surrounded by pasture, crops or small towns.  In fragmented landscapes, kangaroos did not prefer a mix of fire ages, presumably because they substituted pasture grasses for post-fire ephemerals.  We found consistent patterns in four species: eastern grey kangaroo (Macropus giganteus), western grey kangaroo (Macropus fuliginosus), red-necked wallaby (Notamacropus rufogriseus) and - to our surprise - the yellow-footed antechinus (Antechinus flavipes), a 45-gram shrew-like marsupial.

The yellow-footed antechinus is famed for its unusual sexual exploits, involving the death of all males following an annual winter mating season. After the males die, pregnant females must search for a suitable den in a tree hollow or log where they rear their young.  Fire may cause a shortage of these den sites if it consumes big, old trees which provide lots of hollows. While females are fairly sedentary, a radio-tracking study showed that males live their short lives to the full and may leave the relative safety of native woodland to find food in nearby pasture.

Nonetheless, it was harder to wrap our heads around the notion that the dainty antechinus would venture into paddocks more often than the much larger and more mobile kangaroos and wallabies – but our results indicate that the four species share an ability to take advantage of a range of resources.

We used wildlife cameras to survey the animals on Gunditjmara Country in the heathy woodland of a quiet corner of southwest Victoria, where remnant vegetation is surrounded by pasture, pine and blue gum plantations.  Using a sprawling and dilapidated house in Casterton as a base for our fieldwork, we visited 70 sites and tied cameras near the base of two trees per site. The cameras are triggered automatically by motion and heat, and we placed a smelly bait mix of oats, peanut butter and golden syrup in front of the camera to encourage animals to hang out long enough for us to identify them with confidence.

After 25 days, we returned to pick up the cameras and celebrate our haul of tens of thousands of animal images.
For animals like koalas and echidnas, identification is easy – but Gunditjmara Country features several mammals that are very difficult to distinguish from one another.  Eastern and western grey kangaroos may look identical to the untrained eye, but with practice and help from kangaroo experts we gradually picked up the subtle differences in ear shape and fur colour.

We hope that the outcomes of the many days we spent scratching our heads while looking at grainy images will help land managers decide where and when to use planned fire (or fire suppression) to benefit kangaroos and other less-well-known species.  Although two kangaroos, the wallaby, and the antechinus are not currently listed as threatened or endangered, increasingly frequent wildfires, together with increases in the numbers of kangaroos that can be killed for commercial profit, are likely to be having dramatic impacts on population sizes.

Biodiversity conservation during this time of rapid environmental change can sometimes feel like trying to hold back a tsunami with the palm of your hand.  However, tailoring ecological fire management strategies according to whether native vegetation occurs as a large, continuous block or in fragmented remnants may help preserve one of Australia’s iconic species for generations to come.

​I’m currently working my way through 162 invertebrate samples from 27 sites in the Otway Ranges with the aim of understanding the effect fire has on flying insect population structure in Australia. Existing Australian studies on fire and insects have primarily focused on terrestrial and litter dwelling invertebrates, which may have a different response to fire than their flying counterparts. Studies that include flying insects have been conducted overseas in forests where the vegetation structure is very different to that of Australian forests.

​Right now I’m working through all of the beetle samples, the order in which we collected the highest number of individuals. My results will hopefully add to our knowledge of the current global pollinator decline, and aid future research on the recovery of insectivorous animals after fire. All the disruption from coronavirus has really slowed things down for me but I’ve finally gotten my hands on my insects again and can carry on while I work from home.

​As of last week, I have finished going through the vast numbers of images from my camera traps that I set between last October and March, and extracted all the data about what species were detected at each of my 129 sites (this is 3 less than I had previously, due to the Cudlee Creek fire and several missing cameras). 

Across both of my fieldwork seasons I have detected southern brown bandicoots (shown above) at 23 sites, mostly in Cleland, Belair, and Scott Creek/Mount Bold.  I’m currently starting to look at how the surrounding landscape, in terms of land use and past fire, might shape mammal community composition at each site. Early work suggests that more fragmented areas are more likely to be home to feral and disturbance-specialist species (e.g. black rats, kangaroos, brushtail possums), while more intact areas are where habitat specialists like native bush rats, bandicoots and antechinus are found.

I plan to look at how the fire mosaic affects mammal communities, and whether the influence of fire is dependent on habitat fragmentation or vice versa.  I hope to have my first chapter answering these questions completed in the next 3-4 months, before moving on to looking at individual species and habitat structure.

​Having successfully trialled the use of hair traps for collecting DNA from bandicoots (above left) my plans had a covid-shaped spanner thrown in the works. I’m still figuring out exactly what that portion of the project will look like, but I still plan to look at bandicoot habitat connectivity in some way.

LADIES AND GENTLEMEN, meet the dayang (Pseudomys shortridgei) – heath dweller, flower feaster and day napper. At a petite 9.5-12cm, this long-whiskered lovely is a member of the Old World rat family, which will no doubt send shivers down the spine of musophobes! But fear not rat haters, this bobble-eyed, endangered heath mouse is at the cutting edge of scientific research into the link between fire and native species’ survival.

As we all know, bushfires in Australia not only threaten human life and property, but cause significant changes to ecosystems. Increasingly, prescribed fire regimes are used to reduce dry fuel load as well as lower the intensity and spread of fires. 

Along with affecting wildlife populations directly, bushfires can also affect animals indirectly by changing the surrounding vegetation. This influences where habitat is available and how animals will respond to fire-induced changes depending on their habitat requirements.

The heath mouse lives in patches of treeless heath surrounded by woodland. Occurring in two geographically remote areas in south-western Western Australia and around the southern border of South Australia and Victoria, it’s sensitive to the effects of fire regimes on the small amount of available habitat left.

Scientists at the Fire Ecology and Biodiversity Lab at the University of Melbourne are mapping the DNA of heath mouse populations to discover how fire regimes affect their movement. 

“We hope to find out whether fire helps or hinders movement among these islands of treeless heath by catching the animals and taking DNA samples,” says Dr Holly Sitters, coordinator of the Fire and Fragmentation Project. 

“The ability of animals to disperse and breed is critical to the survival of populations under changing environmental conditions. By relating genetic information to fire history and other aspects of landscape structure, we’ll be able to help fire managers decide where and when to apply fire to promote population persistence in the long term.”

​Like any animal, heath mice require a minimum habitat area to meet their needs for food, shelter and breeding. 

Current ecological approaches to fire management involve the use of fire mosaics, however this presents several problems when it comes to preserving biodiversity; the effect of fire on how they move through their habitat and the significance of fire on their ability to find other mice to have sex with, a vital part of population survival. 

Their ability to connect affects genetic diversity, which is the basis of population health.

 “Currently, fire simulation is normally applied in the context of hazard reduction rather than biodiversity conservation, but there’s huge potential to use fire simulation in wildlife management,” says Holly. 

There is a capacity to use fire to influence wildlife movement patterns for the benefit of genetic diversity and the species survival such as the heath mouse, as well as the surrounding ecosystems. Holly says a shift in the focus of ecological fire management to consider functional connectivity (the connectivity between brain regions that share functional properties) could result in better conservation outcomes for all species facing a changing climate. 

“Genes are at the foundation of ecological function, and genetic diversity in populations is linked to ecosystem resilience, the capacity to adjust to environmental disturbances such as fire or drought,” she says.

Holly and her colleagues are leading a small army of students and volunteers to collect data on a variety of small lizard and bat species, as well as southern brown bandicoots and even a marsupial mouse, the yellow-footed antechinus. 

They’re hoping to use the genetic data they collect to map functional connectivity and assist fire managers to refine methods for promotion of long-term species persistence. 

“The combined use of fire simulation and empirical data could help us decide where and when to use prescribed fire for the benefit of wildlife populations at the scale of both fire events and fire regimes.”