Unburnt patches are expected to provide an important resource for fauna, potentially acting as a refuge from the direct effects of fire, and allowing animals to persist in burnt landscapes. Nevertheless there is little information about the way refugia are used by fauna and how populations may be affected by them.
In our new paper, we tested three alternative hypotheses relating to the abundance of two small mammal species, bush rat (Rattus fuscipes) and agile antechinus (Antechinus agilis), after a planned fire at Henderson Creek in the Otway Ranges:
We surveyed small mammals using Elliott Traps, and found that the two species responded differently to the presence of unburnt refugia in the landscape. Whilst fire resulted in reduced abundance of bush rats on burnt slopes, there was no change in gullies, suggesting that their use of refugia is passive. In contrast, agile antechinus abundance increased in gullies immediately post-fire, consistent with a shift of individuals from burnt parts of the landscape and suggesting active use of refugia.
Our work highlights that different species' responses to patchy disturbances are likely to be influenced by factors such as site fidelity, habitat use and intraspecific competition.
Find the paper in Early View:
Swan, M., Galindez-Silva, C., Christie, F., York, A. & Di Stefano, J. (in press). Contrasting responses of small mammals to fire and topographic refugia. Austral Ecology.
Small mammals select resources based on their requirements for food, shelter and protection from predators. Understanding the influence of fire on resource selection can help to guide species conservation and management.
Our new paper investigates the effects of a planned fire on resource selection, abundance, body condition, and movement pathways of a native rodent, the bush rat (Rattus fuscipes). This work formed Amber Fordyce's Honours thesis, and involved gathering data from 60 individuals fitted with spool-and-line tracking devices at Breakfast Creek in the Otway Ranges.
After the fire, rats selected patches of unburnt vegetation, and no rats were caught at a trapping site where most of the understory had been burnt. The fire also reduced bush rat abundance and body condition and caused movement pathways to become more convoluted. After the fire, some individuals moved through burnt areas but the majority of movements occurred within unburnt patches.
Our findings suggest the influence of planned fire on small mammals will depend on the resulting mosaic of burnt and unburnt patches and how well this corresponds to the resource requirements of particular species.
Thanks to Amber, Bronwyn and Julian for the photos. Find the paper here:
Fordyce, A., Hradsky, B.A., Ritchie, E. & Di Stefano, J. (2016). Fire affects microhabitat selection, movement patterns and body condition of an Australian rodent (Rattus fuscipes). Journal of Mammalogy. 97(1): 102-111
Our 2016 fieldwork program has already kicked off with a team of seven visiting the Otways to help Hilman and Natasha measure vegetation structure and trap small mammals.
Hilman is nearing the end of a mammoth effort to deploy camera traps and measure vegetation at 130 long-term monitoring sites spanning foothills forest, forby forest, tall-mixed woodland and heathland. His Masters research examines the influence of time since fire and habitat structure on the functional diversity of ground-dwelling mammals, and will reveal the attributes of prescribed burns that are likely to enhance ecosystem function.
Natasha has recently begun fieldwork for her Masters project which seeks to test species distribution models for mammals in heathland, where several species appear to have become locally extinct or persist in very small numbers. She is using Elliott traps to target small mammals, and plans to create new models of species' current distributions.
Please contact us if you are interested in joining a field trip as a volunteer. Our Otways fieldwork is finishing shortly, but several opportunities are coming up in the Central Highlands.
Many thanks to Matt and Natasha for these photos.
Fire Ecology and Biodiversity at UniMelb
Bushfire Behaviour and Management at UniMelb
Quantitative & Applied Ecology Group at UniMelb
Integrated Forest Ecosystem Research at UniMelb