Ecology & Conservation of Bats II

Contributed Oral Presentations

SESSION NUMBER: 38

Contributed paper sessions will be available on-demand for the duration of the conference, then again at the conclusion of the conference.

 

Total Decline and Community Composition Changes Observed in Summer Bat Field Surveys Since White-Nose Syndrome Arrived in North Carolina
Han Li; Katherine Etchison; Kevin Parker; Gabrielle Graeter; Kendrick Weeks; Matina Kalcounis-Rueppell
Epidemiological and physiological studies have shown that White-Nose Syndrome (WNS) has species specific mortality rates. Certain species such as big brown bats (Eptesicus fuscus) are less susceptible to WNS than other species (e.g. little brown bats, Myotis lucifugus). In contrast, some species such as eastern red bats (Lasiurus borealis) might not be affected by WNS. Evidence also suggests that empty niches of WNS affected species can be filled by other species. Therefore, community composition changes can be expected in local bat communities impacted by WNS over time whereas the total amount of bats might not change. Our goal was to investigate whether total bats indicated by captures and acoustic activities would change over time and whether community composition changes would be observed in a manner consistent with species-specific WNS mortality rates. We hypothesized that over time the absolute number of individuals/acoustic activities would not change, however, species less susceptible to WNS would increase proportionally as compared to species more susceptible to WNS. Our study took place in the North Carolina mountain region where WNS was first confirmed in the 2010-2011 winter. We examined mist-netting captures between 2001 and 2018 and two separate acoustic monitoring datasets (one between 2011 and 2018, one between 2015 and 2018). We found total bat decline and expected community compositional changes in captures and the 2011-2018 acoustic dataset. However, no decline or compositional change was found in the 2015-2018 acoustic dataset. Our results show that the impact of WNS is strongest in the first few years of its arrival and there might be a time lag to fill empty niches. Our study also shows a congruence between acoustic and capture data. We recommend that WNS treatments prioritize species that are more WNS susceptible.
Bat Tracker: A Volunteer-Led Acoustic Monitoring Program for Bats in the Chicago, Illinois Area
Elizabeth W. Lehrer; Maggie Jones; Mason Fidino; Seth Magle
Bats are facing multiple threats and we need more information about what factors influence their spatial distributions to better support them, especially in cities. At the same time, bats are of increasing public interest and advances in technology have made it easier, cheaper, and more accessible for community scientists to engage in bat research. As part of a region-wide effort, we established a volunteer-led acoustic monitoring project at parks and natural areas in the greater Chicago, Illinois area. Volunteers record bat echolocation calls using handheld acoustic equipment (Echo Meter Touch 2 Pro, Wildlife Acoustics) while walking transects around their selected sites during the spring (May), mid-summer (July), and fall (September) seasons, the period of highest bat activity in our study area. Echolocation calls are recorded, automatically identified to species, stored on the device, and then later reviewed by experts. Since the program began in 2018, over 20 volunteers have recorded over 3000 echolocation calls identified to 5 bat species across 7 sites in Chicago and surrounding Cook County with plans to expand. Benefits to volunteers include instant feedback about the species that are using their sites, learning about the ecology and call signatures of local bat species, and making important contributions to scientific research. By collaborating with volunteers, researchers are able to collect more data at a greater number of sites while engaging the public about urban ecology and the importance of bats. Data collected are part of a broader, regional bat monitoring program across five counties in the Chicago Metropolitan Area.
Lasting Effects of White-Nose Syndrome: Wing Damage and Reproductive Status of Little Brown Bats in New England
Olivia Paige Fortuna
White-nose Syndrome (WNS) is a disease caused by the accumulation of fungus (Pseudogymnoascus destructans) on the ears, nose and wings of numerous bat species in eastern North America during hibernation. As bats emerge from hibernation, their immune system reacts to the fungus, leading to wing damage. Wing damage includes thinning patagium and necrosis. Repairing this wing damage requires an elevated energy output. However, during this time females need all their energy for gestation. This study will examine how WNS is affecting the overall reproductive success of little brown bat (Myotis lucifugus) populations by examining wing damage and looking for correlations with the reproductive status of female bats. Seven existing colonies were selected throughout New England. During the summer of 2018 each site was visited four times. Individuals were trapped and analyzed for reproductive status and wing damage associated with WNS in the field. Wing damage scores were based off a 0-3 grading system in which 0 was no damage and 3 was severe damage. The results of this study show that females with a low wing damage score experienced unaltered reproductive health, whereas individuals with high wing damage scores experienced abnormal reproductive health, showing signs of gestation later in the summer than those with less damage. One potential explanation for this may involve bats ability to delay fertilization. Typically fertilization of an embryo is delayed until females congregate in their summer roosts. However, reversing the damage from WNS may be so energetically costly that fertilization may be delayed until the organism can biologically sustain a pregnancy. The findings of this study suggest that wing damage has the potential to alter reproductive output for the entire colony affected by WNS. This may help project the reproductive output for the season based on a wing damage index in proportion to entire colony.
Estimating the Total Number of Hibernating Bats in a Multi-Cave System
Theodore J. Weller; Katrina J. Smith; James A. Baldwin; Shawn C. Thomas
Effective conservation and management of mammals requires an accurate understanding of the size of a population and its trend over time. For temperate bat species, the most reliable method of assessing population size is via visual counts of bats in their hibernacula. But how do we efficiently determine population size and trend when there are many possible locations where bats may hibernate? Lava Beds National Monument provides hibernation habitat for the largest known population of Townsend’s Big-eared Bats in California. However, because there more than 800 caves in the park it is infeasible to survey all caves and, we presumed, all caves were not equal in the probability of providing hibernation habitat to bats. Beginning in 2013, we implemented an adaptive monitoring program to better understand the types of caves where bats hibernate and to estimate the full population of hibernating bats in the park. We assigned caves a probability of selection according to number of bats counted during previous surveys and randomly selected previously unsurveyed caves annually. Through 2019 we surveyed 311 unique caves and estimated that, on average, 2239 (SE = 132) bats hibernated throughout the cave complex. We found no evidence of a change in the population since 2013. We suggest that our methods could be used to improve estimates of bat population size and trend in other situations.
Bat Acoustic Activity Comparison between Anabat SD1 and SD2 Detectors Versus SM3BAT and SM4BAT Detectors at Wind Energy Facilities in the United States and Canada
Larisa J. Bishop-Boros
Standard pre-construction surveys at wind energy facilities often include the deployment of ultrasonic detectors for 3-12 months to assess bat activity at the project prior to construction. WEST has collected acoustic data using zero-crossing Anabat SD1 and SD2 (SD) detectors at wind projects for decades, however, with new technological advancements SD’s are being phased out. Full spectrum detectors such as the SM3Bat and SM4Bat (SM3/4) are generally expected to sample bat activity more effectively than SD’s but the empirical evidence supporting this contention is limited and contradictory. Regulatory agencies use these data to assess potential risk to bats and to make management decisions affecting how wind facilities operate. In Alberta, Canada, an autumn activity threshold of more than two migratory bat passes per detector-night classifies a project as high potential risk for bat fatalities. Preliminary work by WEST indicated that field-deployed SM3/SM4’s consistently detect more bat calls than SD’s. Intrinsic differences in bat activity rate estimations between detector types could make the interpretation of these data problematic. Activity thresholds established using one detector type may not be applicable to the other. Apparent changes in bat activity from one year to the next may be artifacts of the differences between detectors rather than actual changes in the bat community. The objectives of this study are to: 1) evaluate the practical differences in bat call detection rates between SD and SM3/4 detectors, and 2) make recommendations regarding how these data should be interpreted by biologists in management positions. WEST examined bat activity rates from paired SD and SM3/SM4 units at several wind Projects in the US and Canada from 2016 – 2019. This research allows biologists, regulatory agencies, and wind energy developers to relate and interpret activity rates from older studies using Anabat SD units to current and future studies using SM3/SM4’s.

 

Virtual
Location: Virtual Date: Time: -