The burning question—the effect of torpor on mammals during and after bushfires

Although several ecological studies have examined animal diversity and abundance before and after bushfires, the reasons why some species perform better than others have remained obscure.

Funded through the ARC Discovery Projects scheme, Professor Fritz Geiser, ARC Discovery Early Career Researcher Award (DECRA) recipient, Dr Clare Stawski, and their research team at the University of New England, have studied how small mammals, which have high rates of energy expenditure and food requirements, can survive bushfires and post-fire conditions.

Many mammals lower their body temperatures during a state of daily torpor or multiday torpor (hibernation) as an energy preserving mechanism to survive harsh conditions, like winter, or as a response to unpredictable events such as drought. Torpor may reduce energy use by up to 99%, but is risky during bushfires because torpid animals may not be able to rewarm in time to escape the fire, especially during ‘hazard reduction’ burns, which are lit in winter when animals are more likely to be hibernating.

The researchers have discovered that despite these risks, torpor does provide some species with an adaptive advantage compared to animals which have constant high body temperatures. Torpid mammals can respond to smoke and using torpor substantially reduces foraging requirements and therefore exposure to predators. Overall, the findings linked expression of mammalian torpor with a lower risk of extinction.

	Exploring the survival of animals during wildfire and fire management burns demonstrated how animals can cope in a post-fire environment where food and shelter are often reduced, and the pressure from predators is increased.

 

Image: A survivor of the wildfire, a common dunnart, Sminthopsis murina, with pouch young in spring 2013. This species uses daily torpor. Credit: Fritz Geiser.