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White-nose syndrome (WNS) has rendered four of Ontario's species endangered, while leaving the other four species relatively unaffected. The causes and extent of the declines have been widely studied. The influence on remaining bat species has not. Comparing acoustic data recorded -10 years apart, we evaluated how species in southeastern Ontario, Canada, use different foraging habitats pre- and post-WNS detection. We observed activity declines in now-endangered species over open fields (small-footed myotis, Myotis leibii (Audubon and Bachman, 1842); little brown bat, Myotis lucifugus (Le Conte, 1831); northern myotis, Myotis septentrionalis (Trouessart, 1897); tricolored bat, Perimyotis subflavus (F. Cuvier, 1832)) and speculate that the reduction of the once most common species (M. lucifugus) may have resulted in other species searching for prey in habitat once dominated by M. lucifugus. That is, these changes may have allowed greater presence in open field and clutter or edge environments by the big brown bat (Eptesicusfuscus (Palisot de Beauvois, 1796)) and three migratory species (silver-haired bat, Lasionycteris noctivagans (Le Conte, 1831); red bat, Lasiurus borealis (Muller, 1776); hoary bat, Lasiurus cinereus (Palisot de Beauvois, 1796)). However, our results also suggest that (i) while the decline of most resident bat species due to WNS may have relaxed competition for relatively unaffected species in some, but not all habitats, that (ii) sensory and biomechanical constraints may limit prey exploitation by these less-affected bat species in these habitats. Key words: white-nose syndrome, Pseudogymnoascus destructans, niche release, interspecific competition, Myotis lucifugus, little brown bat, Eptesicus fuscus, big brown bat. Le syndrome du museau blanc (SMB) a mis quatre especes en voie de disparition en Ontario, les quatre autres especes etant relativement peu touchees. Si les causes et l'etendue de ces declins ont ete largement etudiees, l'influence du SMB sur les autres especes de chauves-souris ne l'a pas ete. En comparant des donnees acoustiques enregistrees a environ 10 annees d'intervalle, nous evaluons les utilisations faites par differentes especes dans le sud-est de l'Ontario (Canada) d'habitats d'approvisionnement avant et apres la detection du SMB. Nous observons des baisses d'activite au-dessus de champs ouverts chez les especes aujourd'hui en voie de disparition (chauve-souris pygmee, Myotis leibii (Audubon et Bachman, 1842); vespertilion brun, Myotis lucifugus (Le Conte, 1831); vespertilion nordique, Myotis septentrionalis (Trouessart, 1897); pipistrelle de l'Est, Perimyotis subflavus (F. Cuvier, 1832)) et postulons que le declin de l'espece auparavant la plus repandue (M. lucifugus) pourrait avoir mener d'autres especes a chercher des proies dans des habitats ou ce dernier etait autrefois dominant. Autrement dit, ces changements pourraient avoir permis une plus grande presence dans les milieux de champ ouvert et de fouillis ou de bordure de la serotine brune (Eptesicusfuscus (Palisot de Beauvois, 1796)) et de trois especes migratrices (chauve-souris argentee, Lasionycteris noctivagans (Le Conte, 1831); chauve-souris rousse, Lasiurus borealis (Muller, 1776); chauve-souris cendree, Lasiurus cinereus (Palisot de Beauvois, 1796)). Cependant, nos resultats indiqueraient aussi que (i) si le declin de la plupart des especes de chauves-souris residentes en raison du SMB pourrait avoir attenue la concurrence pour des especes relativement non affectees dans certains, mais non tous les habitats, (ii) des contraintes sensorielles et biomecaniques pourraient limiter l'exploitation de proies dans ces habitats par ces especes moins affectees. [Traduit par la Redaction] Mots-cles : syndrome du museau blanc, Pseudogymnoascus destructans, liberation de la niche, concurrence interspecifique, Myotis lucifugus, vespertilion brun, Eptesicusfuscus, serotine brune., Introduction Bat communities are rarely monospecific and local assemblages can include over 100 bat species in equatorial regions of Africa, Asia, and South America (Fenton and Ratcliffe 2010). Even in [...]

Fungal diseases of wildlife typically manifest as superficial skin infections but can have devastating consequences for host physiology and survival. White-nose syndrome (WNS) is a fungal skin disease that has killed millions of hibernating bats in North America since 2007. Infection with the fungus Pseudogymnoascus destructans causes bats to rewarm too often during hibernation, but the cause of increased arousal rates remains unknown. On the basis of data from studies of captive and free-living bats, two mechanistic models have been proposed to explain disease processes in WNS. Key predictions of both models are that WNS-affected bats will show 1 ) higher metabolic rates during torpor (TMR) and 2 ) higher rates of evaporative water loss (EWL). We collected bats from a WNS-negative hibernaculum, inoculated one group with P. destructans , and sham-inoculated a second group as controls. After 4 mo of hibernation, TMR and EWL were measured using respirometry. Both predictions were supported, and our data suggest that infected bats were more affected by variation in ambient humidity than controls. Furthermore, disease severity, as indicated by the area of the wing with UV fluorescence, was positively correlated with EWL, but not TMR. Our results provide the first direct evidence that heightened energy expenditure during torpor and higher EWL independently contribute to WNS pathophysiology, with implications for the design of potential treatments for the disease., (Copyright © 2017 the American Physiological Society.)