The evolution of a bat population with white-nose syndrome (WNS) reveals a shift from an epizootic to an enzootic phase

White-nose Syndrome (WNS) is a mycosis caused by a cutaneous infection with the fungus ( ). It produces hibernation mortality rates of 75-98% in 4 bats: , , , and . These high mortality rates were observed during the first several years after the arrival of at a hibernation site. Mortality is caused by a 60% decrease in torpor bout duration, which results in a premature depletion of depot fat prior to spring. Little is known about the long-term effects of on torpor and mortality, thus we conducted a 9-year study on at 5 of the hibernation sites where first appeared in North America during the winter of 2007-08. The hibernating at one of these sites one year after the arrival of (2008-09) had: a) a mean torpor bout duration of 7.6 d, b) no depot fat reserves by March, and c) an apparent over-winter mortality rate of 88%. The hibernating at this same site 6-9 years after the arrival of , in contrast, had: a) a mean torpor bout duration of 14.7 d, b) depot fat remaining in March, and c) an apparent mortality rate of 50%. The number of hibernating at 2 of these sites has consistently increased since 2010 and is now more than 3.0-fold higher than the number remaining after the winter of 2008-09. These findings indicate that this population of has evolved mechanisms to hibernate well in the presence of , thus reducing over-winter mortality.