Unless the criteria for the diagnosis of WNS are met (confirmation by histo-pathology and PCR) [2] WNS should not be assumed as a cause of mortality in dead bats found in hibernacula of Europe.
Although rare, hibernacula of a few thousands and up to about 34,000 individuals are also known for species of Myotis in Europe [34], [35], [38], [39], [40], [41].
In addition to physiological changes, different species of bats have evolved different behavioral strategies to maximize survival during hibernation, such as selection of humid areas of hibernacula or dense clustering to conserve energy and decrease moisture loss [ 16- 18].
Potential control strategies include development of probiotic treatments (14 ) and alteration of hibernacula microclimates to make them cooler and drier (3, 15 ).
By the end of the second winter, 109 (98%) of 111 bats were positive for P. destructans, and P. destructans was present throughout the hibernacula (in 91% of samples from under bats, 66% of samples near bats, and 44% of samples far from bats).
It would be important to investigate whether bats carry spores out of hibernacula and as a result could possibly contaminate maternity roosts and maternity mates as suggested by Hallam and McCracken [28].
Conditions outside of hibernacula may influence disease outcome for bats that transiently emerge from hibernation during winter.
We also sampled the wall or ceiling of hibernacula under, near (10 20 cm), and far from (>2 m) roosting bats by using the same swabbing technique.
It may not be a coincidence that species that have lower reported mortality or more variable declines due to WNS (Myotis sodalis, Myotis leibii and Eptesicus fuscus) are those that seem less susceptible to EWL, often select drier areas of hibernacula, and are rarely, if ever, seen covered with condensation during hibernation [ 16].
lucifugus, Myotis septentrionalis and Perimyotis subflavus) are also those that consistently roost in the most humid parts of hibernacula and are often observed with condensation on their fur [ 16], suggesting that these species are more susceptible to EWL and have evolved compensatory behavioral strategies, such as roost selection or hibernation in tight clusters.
"In the Berkshires in Massachusetts, we are getting reports of dying/dead bats in areas where we do not have known bat hibernacula, so we may have more sites than we will ever be able to identify," said Susi von Oettingen, an endangered species biologist with the United States Fish and Wildlife Service.
