Bats of Skydusky Hollow, Bland County, Virginia

During the period 22 November 1999 – 11 October 2001, winter hibernacula surveys, spring staging/autumn swarming surveys, and summer surveys for bats were completed in caves of Skydusky Hollow, Bland County, Virginia. During winter, 12 caves were entered and 16,185 bats counted: 235 Myotis sodalis (Indiana bat), 14,475 Myotis lucifugus (little brown myotis), 12 Myotis septentrionalis (northern myotis), 7 Myotis leibii (eastern small-footed myotis), 1,441 Pipistrellus subflavus (eastern pipistrelle), and 15 Eptesicus fuscus (big brown bat). Myotis sodalis hibernated in thermally stable areas of 7 -9 ̊C. The largest concentration of M. lucifugus (n = 4,280) hibernated in an area that was cooler (6.5 ̊C) than areas used by M. sodalis. The remaining 6,300 M. lucifugus hibernated at temperatures similar to, or slightly cooler than, temperatures used by M. sodalis. Intra-cave (and possibly inter-cave) movements of M. lucifugus and M. sodalis during the season of hibernation concentrated bats in cooler areas of the caves. An unusually large concentration of P. subflavus (n = 920) hibernated in Coon Cave in a warm (8.6 – 9.7 ̊C, stable environment. Proportions of species of bats captured during spring staging and autumn swarming varied from proportions found during winter hibernation. Mating and perhaps other social functions affect patterns of autumn use. No concentration of bats used the caves during summer

Patterns of Heterogeneity within Phreatic Karst Aquifers of the Great Valley, Virginia and West Virginia: Evidence from Time Series Hydrologic Monitoring, Groundwater Chemistry, and Stygobite Site Occupancy

Phreatic karst waters in the Central Appalachian Great Valley are the subject of an ongoing habitat monitoring project across the geographic range of the federally threatened Madison Cave Isopod (MCI, Antrolana lira), a stygobitic crustacean previously documented at each monitoring site. Eight caves and five wells were monitored, via instrumentation, hourly from June, 2016 thru October, 2017 for water level (WL), temperature (T), and specific conductivity (Cs.) Sites were visited quarterly to download data, collect water samples, and deploy baited traps to assess occupancy by stygobitic fauna. Samples were analyzed for major ions, inorganic carbon, and stable water isotopes. Precipitation data from National Climate Data Center stations were used to evaluate response to precipitation events. There is significant variation between sites in water chemistry, in baseline WL, Cs, and T values, and in the response of these parameters to precipitation. Median temperatures varied from 11.6 to 13.8 °C, with ranges within sites of 0.7 to 15.5 °C. Median Cs values varied from 442 to 726 uS/cm at 25 °C, with ranges within sites of 16 to 573 uS/cm. Ranges of WL within sites varied from 0.9 to 9.6 m. Ten sites exhibited rapid WL increases following precipitation, accompanied by spikes and/or dips in Cs. Six of these sites exhibited significant T changes. Sites with negative Cs response typically exhibited T changes reflecting precipitation temperature, with several exhibiting a compound response to larger events. Samples analyzed as calcium-magnesium-bicarbonate type waters, with Ca:Mg ratios from 9 to 5.5:1 and Ca + Mg values from 1.8 to 4.1 mmol/l. Geochemical parameters grouped more by site than by season. Chloride, nitrate, sulfate and sodium levels at some sites suggest significant land use influence from agricultural and stormwater management practices. Average δ2H and δ18O compositions suggest winter-dominated (Nov-April) recharge. Over the course of the study, site occupancy of these known MCI sites ranged from 0 to 100%, both for MCI and other stygobitic invertebrates. Occupancy rates appeared unrelated to geochemical or hydrodynamic patterns. Data are consistent with a complex, compartmentalized phreatic aquifer, reflecting the folded, faulted, and fractured bedrock structure. Water levels determine inter-compartment connectivity, facilitating episodic migration of stygobitic species. Characterization of such a system to support groundwater and habitat management decisions would require a much higher spatial density of monitoring stations than presently exists in the Great Valley

Patterns of Heterogeneity within Phreatic Karst Aquifers of the Great Valley, Virginia and West Virginia: Evidence from Time Series Hydrologic Monitoring, Groundwater Chemistry, and Stygobite Site Occupancy

Phreatic karst waters in the Central Appalachian Great Valley are the subject of an ongoing habitat monitoring project across the geographic range of the federally threatened Madison Cave Isopod (MCI, Antrolana lira), a stygobitic crustacean previously documented at each monitoring site. Eight caves and five wells were monitored, via instrumentation, hourly from June, 2016 thru October, 2017 for water level (WL), temperature (T), and specific conductivity (Cs.) Sites were visited quarterly to download data, collect water samples, and deploy baited traps to assess occupancy by stygobitic fauna. Samples were analyzed for major ions, inorganic carbon, and stable water isotopes. Precipitation data from National Climate Data Center stations were used to evaluate response to precipitation events. There is significant variation between sites in water chemistry, in baseline WL, Cs, and T values, and in the response of these parameters to precipitation. Median temperatures varied from 11.6 to 13.8 °C, with ranges within sites of 0.7 to 15.5 °C. Median Cs values varied from 442 to 726 uS/cm at 25 °C, with ranges within sites of 16 to 573 uS/cm. Ranges of WL within sites varied from 0.9 to 9.6 m. Ten sites exhibited rapid WL increases following precipitation, accompanied by spikes and/or dips in Cs. Six of these sites exhibited significant T changes. Sites with negative Cs response typically exhibited T changes reflecting precipitation temperature, with several exhibiting a compound response to larger events. Samples analyzed as calcium-magnesium-bicarbonate type waters, with Ca:Mg ratios from 9 to 5.5:1 and Ca + Mg values from 1.8 to 4.1 mmol/l. Geochemical parameters grouped more by site than by season. Chloride, nitrate, sulfate and sodium levels at some sites suggest significant land use influence from agricultural and stormwater management practices. Average δ2H and δ18O compositions suggest winter-dominated (Nov-April) recharge. Over the course of the study, site occupancy of these known MCI sites ranged from 0 to 100%, both for MCI and other stygobitic invertebrates. Occupancy rates appeared unrelated to geochemical or hydrodynamic patterns. Data are consistent with a complex, compartmentalized phreatic aquifer, reflecting the folded, faulted, and fractured bedrock structure. Water levels determine inter-compartment connectivity, facilitating episodic migration of stygobitic species. Characterization of such a system to support groundwater and habitat management decisions would require a much higher spatial density of monitoring stations than presently exists in the Great Valley

Post-White-nose syndrome trends in Virginia’s cave bats, 2008-2013

Since its 2009 detection in Virginia hibernacula, the fungal pathogen Pseudogymnoascus destructans causing White-nose Syndrome (WNS) has had a marked impact on cave bats locally. From 2008-2013, we documented numeric and physiologic changes in cave bats through fall swarm (FS), early hibernation (EH), and late hibernation (LH) capture and banding surveys at 18 hibernacula in western Virginia. We coupled active surveys with passive biennial winter counts in 2009, 2011, and 2013. We compared individual body mass index (BMI) across years for FS, EH, and LH hibernation to determine if WNS impacts on extant bats would be manifested by changes in body condition (as anecdotally observed elsewhere for WNS-impacted bats) as well as a population reduction. To estimate percent declines in bat presence or relative activity, we used FS capture per-unit-effort data, and the winter hibernacula absolute counts. We captured 4,524 bats of eight species, with species-specific capture success declining by 75-100% post-WNS. Little brown bats (Myotis lucifugus) exhibited the greatest declines in winter hibernacula counts (AVG. = 99.0% decline), followed by tri-colored bats (Perimyotis subflavus; 89.5% decline) and Indiana bats (M. sodalis; 33.5% decline). Graphical analyses of captures-per-trap-hour in FS showed declines for little brown bats, tri-colored bats, and northern long-eared bats (M. septentrionalis), but suggest a modest rebound of Indiana bat numbers. Fall swarm trends in BMI suggested some drops post-WNS exposure, but these trends were not consistent across sexes or seasonal time blocks. Our inconclusive BMI metrics and little brown bat band recapture data suggest little competitive advantage or selection for surviving bats. Lesser (but apparent) declines in Indiana bat numbers mirrors trends seen elsewhere regionally, and band recoveries do show that some individuals are persisting. Additional surveys will determine if bats in Virginia will persist or face extirpation due to presumed low recruitment and survivorship

Post-White-nose syndrome trends in Virginia’s cave bats, 2008-2013

Since its 2009 detection in Virginia hibernacula, the fungal pathogen Pseudogymnoascus destructans causing White-nose Syndrome (WNS) has had a marked impact on cave bats locally. From 2008-2013, we documented numeric and physiologic changes in cave bats through fall swarm (FS), early hibernation (EH), and late hibernation (LH) capture and banding surveys at 18 hibernacula in western Virginia. We coupled active surveys with passive biennial winter counts in 2009, 2011, and 2013. We compared individual body mass index (BMI) across years for FS, EH, and LH hibernation to determine if WNS impacts on extant bats would be manifested by changes in body condition (as anecdotally observed elsewhere for WNS-impacted bats) as well as a population reduction. To estimate percent declines in bat presence or relative activity, we used FS capture per-unit-effort data, and the winter hibernacula absolute counts. We captured 4,524 bats of eight species, with species-specific capture success declining by 75-100% post-WNS. Little brown bats (Myotis lucifugus) exhibited the greatest declines in winter hibernacula counts (AVG. = 99.0% decline), followed by tri-colored bats (Perimyotis subflavus; 89.5% decline) and Indiana bats (M. sodalis; 33.5% decline). Graphical analyses of captures-per-trap-hour in FS showed declines for little brown bats, tri-colored bats, and northern long-eared bats (M. septentrionalis), but suggest a modest rebound of Indiana bat numbers. Fall swarm trends in BMI suggested some drops post-WNS exposure, but these trends were not consistent across sexes or seasonal time blocks. Our inconclusive BMI metrics and little brown bat band recapture data suggest little competitive advantage or selection for surviving bats. Lesser (but apparent) declines in Indiana bat numbers mirrors trends seen elsewhere regionally, and band recoveries do show that some individuals are persisting. Additional surveys will determine if bats in Virginia will persist or face extirpation due to presumed low recruitment and survivorship