Raw microclimate data from caves and mines in New Brunswick, Canada

We document white-nose syndrome (WNS), a lethal disease of bats caused by the fungus Pseudogymnoascus destructans (Pd), and hibernacula microclimate in New Brunswick, Canada. Our study area represents a more northern region than is common for hibernacula microclimate investigations, providing insight as to how WNS may impact bats at higher latitudes. Hibernacula microclimate is important in hibernaculum selection by bats and may also be an important factor influencing WNS-associated bat mortality rates. To determine the impact of the March 2011 arrival of Pd in New Brunswick and the role of hibernacula microclimate on hibernating bat mortality, we surveyed bat numbers at hibernacula twice a year from 2009 – 2015. We also collected data from iButton temperature loggers deployed at all sites and gathered temperature and humidity data from HOBO loggers at three sites. Bat species found in New Brunswick hibernacula include Myotis lucifugus (Little Brown Bat) and M. septentrionalis (Northern Long-eared Bat), with small numbers of Perimyotis subflavus (Tricolored Bat). All known hibernacula in the province were Pd-positive with WNS-positive bats by winter 2013. A 99% decrease in the over-wintering bat population in New Brunswick was observed between 2011 and 2015. We did not observe P. subflavus during surveys 2013 – 2015 and the species appears to be extirpated from these sites. Bats did not appear to choose hibernacula based on winter temperatures, but dark zone (zone where no light penetrates) winter temperatures did not differ among our study sites, likely due to the geographically small sampling area. Dark zone temperatures did not vary among years, unlike hibernacula entrance temperatures, but both locations were affected by the presence of flowing water. Winter dark zone temperatures were warmer and less variable than entrance or above ground temperatures. We observed visible Pd growth on hibernating bats in New Brunswick during early winter surveys (November), even though hibernacula temperatures were colder (~ 4 – 5°C) than optimum for in vitro Pd growth (12.5 – 15.8°C). This suggests that cold hibernacula temperatures encountered near the apparent northern range limit for Pd do not sufficiently slow fungal growth to prevent the onset of WNS and associated bat mortality over the winter. As WNS continues to spread west across continental North America, the severity of WNS-related mortality may therefore be greater at northern latitudes where bat hibernation periods are longer, despite apparent suboptimal temperatures for Pd growth.