Perfect storm: Demographic responses of an irruptive desert mammal to prescribed burns following flooding rain



Extreme climatic events are expected to increase in frequency and magnitude in future and to have powerful effects on the organisms and ecological communities that experience them. In arid Australia flooding rains trigger flushes in primary productivity that allow ephemeral irruptions of consumer organisms, but they also provide conditions for ‘perfect storms’: wildfires that are carried by flood-stimulated increases in fuel load. Here we describe demographic responses of the long-haired rat Rattus villosissimus to flood rains and prescribed burns in the Mitchell grass downs of central Queensland, Australia, during a broad-scale irruption of this species in 2011. Populations were sampled on three trapping grids on two occasions before and two occasions after control burns in April 2011, and compared with populations sampled at the same times on three further grids that remained unburnt. Rat populations declined temporarily just after the fires, but survival, sex ratio, body condition, reproduction and other demographic parameters remained unaffected by the burn treatment. The temporary declines in rat numbers on the burnt grids were probably caused by resource shortages, but subsequent increases in rat numbers suggest that these impacts were not severe. If small-scale prescribed burns reduce the chance of landscape-wide wildfires taking hold, we suggest that they should effectively allow long-haired rats to weather perfect storms in future.