The panzootic white-nose syndrome: an environmentally constrained disease?

White-nose syndrome (WNS) is an emerging disease of hibernating bats probably caused by a pathogenic fungus, Geomyces destructans. The fungus has dispersed rapidly in the Northeastern United States and Canada and is presently a serious risk to hibernating bats of the mid-southern United States. Our objectives were to investigate how the environmental factors of temperature and resources impact the physiology of bats and apply this to explore possible effects of the fungus G. destructans on bats. Using a dynamic, physiologically based model parameterized for little brown bats (Myotis lucifugus), we found that the survival region defined in terms of minimal and maximal cave temperatures and bat lipid reserve levels exhibits plasticity as a function of cave temperature. During the pre-hibernation period, constellations of increased availability of fall and winter prey, reduced energy expenditure and lipogenic factors provide fat deposition in hibernator species that engender survival throughout the hibernation period. The model-derived survival region is used to demonstrate that small increases in lipid reserves allow survival under increasing maximum temperatures, which provides flexibility of bat persistence at the higher cave temperature ranges that may occur in the Southern United States. Antipodally, the lower-temperature survival range is bounded with minimum temperatures. Our results suggest that there is an environmental distinction between survival of bats in Southern and Northern US states, a relationship that could prove very important in managing WNS and its dispersal.