Analyzes of bat echolocation calls enable to investigate diverse patterns of bat communities without the need for contact manipulation with individuals. The continuous all-night acoustic recordings provide standardised data open to quantitative comparisons and testing effects of diverse contextual factors upon bat community structure. The multidisciplinary project MOSAIK (Monitoring Savanna Biodiversity in Kruger NP) mapping patterns of variation in savanna communities under different spatial and temporal influences includes bats as one of the model groups. At standardized monitoring points of the project (covering 20 different areas, each containing triplet points differing in access to the water surface: permanent, seasonal and the crests without a water source), all-night acoustic recordings of bats were undertaken over two seasons (using Song Meter recorders SM4BAT). All records were analyzed with aid of Kaleidoscope Pro software and cluster identification technique (with an input database developed by Weier et al. 2018 and Taylor et al. 2020) controlled by manual checking. Multiple comparisons of diverse coenologic variables of the particular samples were performed together with testing effects of associated contextual variables (geographic setting and climatic currents, seasons, vegetation,...

Nightjars are a group of nocturnal and aerial insectivorous birds that have experienced long-term decline likely driven primarily by habitat loss and declines in prey populations. Eastern Whip-poor-will (Antrostomus vociferus) and Chuck-will’s-widow (Antrostomus carolinensis), two nightjar species native to Illinois, declined 69% and 58% since 1966, respectively. Although previous survey efforts have documented presence of Chuck-will’s-widow and Whip-poor-will, their current distribution in the state is not well known. Using Autonomous Recording Units (ARUs) deployed in a uniform, systematic grid, I surveyed 142 locations from May – July 2022 on public and private lands across the southern eleven counties of Illinois to assess Whip-poor-will and Chuck-will’s-widow distribution and estimate species occupancy. I estimated species relationships with proportion of landcover types, forest patch configuration, and proximity to other landcover types. Additionally, I quantified disturbances from the past 15 years to estimate species relationships to the severity and duration of disturbances. I deployed ARUs for 710 survey days collecting 170,400 minutes or 3,000 hours of recordings. Acoustic bird call identification software, BirdNet, was highly accurate at detecting focal species and greatly reduced the time spent manually reviewing acoustic data. BirdNet identified 43,922 calls of Whip-poor-will and 31,447 calls of Chuck-will’s-widow. I detected Whip-poor-will on 78 surveys with 100% accuracy and Chuck-will’s-widow on 75 surveys with 76% accuracy. Whip-poor-will were positively associated with forest patches with large core areas that neighbored pastures. Additionally, Whip-poor-will were likely to occupy landscapes that had experienced low to moderate disturbance within the previous 15 years. Covariates used to model Chuck-will’s-widow occupancy explained little variation in detection or occupancy and there were no significant relationships with any covariate. However, examining non-significant trends suggest similar relationships as Whip-poor-will in the area. Results highlight the efficiency of passive acoustic monitoring for these birds and the need for further investigation into Chuck-will’s-widow species-environmental relationships. In southern Illinois, Chuck-will’s-widow populations appears to be consistent with previous estimates from the 1990s while Whip-poor-will follow the broader trend of decline.

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White-nose syndrome (WNS), caused by the introduced fungal pathogen, Pseudogymnoascus destructans, has caused precipitous declines in bat populations including the now endangered northern long-eared bat (Myotis septentrionalis; NLEB). Remnant populations of NLEB have been found outside their traditional range in areas of the urbanized Piedmont and also the Coastal Plain of the mid-Atlantic region of the United States, where little is known about their summertime day-roost habitat needs. More broadly for the species, little research has examined the day-roost habitat use of both male and females. This information is vital to inform management and policy for the conservation of this endangered species. In this dissertation, I captured NLEB at three properties in eastern Virginia and Washington D.C. Captures at Marine Corps Base Quantico (MCBQ) and Prince William Forest Park (PRWI) in Virginia were male-biased and Rock Creek Park (ROCR) captures in D.C. were female-biased. I found that overall NLEB are associated with mature, deciduous forest. Males used red maples (Acer rubrum) in later decay stages and lower crown classes at MCBQ/PRWI. Females used taller oaks (Quercus) at ROCR. Differences between the two study areas may be an artifact of MCBQ/PRWI being an early mature forest whereas much of ROCR is approaching late mature to old-growth gap-phase conditions. Building off the fact that many WNS affected bat species are now substantially more difficult to detect on the landscape, I explored novel methods to help increase detection of bats during acoustic surveys. This included developing and testing an experimental ultraviolet (UV) light lure that attracted insects and thereby attracted bats. The lure increased overall bat feeding buzz calls and had a species-specific response, primarily attracting eastern red bats (Lasiurus borealis). The lure elicited an interesting negative response from NLEB within the illuminated area, but an increase above control conditions beyond the illuminated area. Overall, the UV lure shows promise for increasing detection of bats and warrants further research, however caution should be exercised as some bats showed a negative response. I also investigated the effects of environmental clutter on the reception of ultrasonic bat echolocation signals to help researchers better understand how different clutter types and configurations affect and potentially bias acoustic survey results. This is especially important when surveying for clutter-adapted bats, such as NLEB which are traditionally biased against in acoustic surveys due to their habitat associations and low detection probability. I found that the recording angle of the bat in relation to the microphone overshadowed most other effects. On-axis recording created the best quality recording and the signal rapidly degraded as the angle increased. Therefore, placement of microphones to where bats are expected to be flying is critical. Many small clutter objects, analogous to a young forest with a high stocking rate substantially degraded echolocation signals. Fewer, large objects, analogous to a mature forest with large trees and little understory actually generated echoes that were identifiable to species that would be beneficial to improving detection probability and occupancy estimates, but might generate bias by overcalculating activity estimates. / Doctor of Philosophy / A disease called white-nose syndrome (WNS), caused by the fungal pathogen, Pseudogymnoascus destructans, was introduced into the U.S. around 2006 and has decimated bat populations across much of the U.S. and Canada. Bats are responsible for providing important pest insect control services to the agriculture and forestry industries as well as helping to control disease carrying insects. Once particular species, the northern long-eared bat (Myotis septentrionalis; NLEB) has seen some of the heaviest declines. Once a common bat in forests across the eastern and mid-western portions of North America, the NLEB is now considered an endangered species. Recently, populations of this bat have been found in areas where they were previously not known to exist and they represent potentially important remnant populations with high conservation value. In order to protect these NLEB, scientists must understand their forest habitat needs for roosting during the day and rearing young. Most past studies have focused on female NLEB, so information on male roost use is also needed. I captured NLEB at Marine Corps Base Quantico (MCBQ) and Prince William Forest Park (PRWI) in Virginia as well as at Rock Creek Park (ROCR) in Washington, D.C. and tracked NLEB to their day-roosts to characterize their habitat needs at multiple scales ranging from the day-roost itself, the surrounding forest area, and the greater landscape around the bat roosting areas. I found that NLEB prefer to roost in older deciduous hardwood forests. Male NLEB used red maples (Acer rubrum) that were shorter and more decayed than surrounding trees at MCBQ/PRWI. Females used taller oak trees (Quercus) at ROCR. Differences observed in the analysis between the two study areas may be an artifact of MCBQ/PRWI being a younger forest whereas much of ROCR is approaching conditions of a very old forest. Building off the fact that many WNS affected bat species are now substantially more difficult to find out on the landscape, I explored new research methods to help increase detection of bats during acoustic surveys. Scientists often use acoustic recording devices to record ultrasonic (above human hearing) echolocation calls that bats use for navigation and hunting at night. Those calls can be identified as specific types of bats for use in environmental studies using automated computer programs. The problem however, is that bats must fly close to the microphone in order to record a clear sound file that can be identified by the software. I built and tested a device that uses ultraviolet (UV) "blacklights" to attract insects that bats eat and thereby attract bats to an array of recording devices. The lure device worked, but for individual species of bats rather than all bats. Of particular interest is that NLEB were repelled within the area illuminated by the UV light lure, but increased outside the illuminated area. Overall, a UV light lure shows promise for increasing detection of bats, but caution is recommended because some bats seemed to avoid the light. I also investigated how clutter around these recording devices, such as trees and branches, affects the quality of recorded sound files under controlled conditions. I found that the angle of the recording device microphone to the sound source (a bat) mattered the most. Many smaller objects between a bat and the microphone, such as many small trees in a young forest, resulted in the worse recordings. Fewer large objects, such as large, old trees, resulted in echoes of the bat calls being recorded and actually helped the software identify the calls to a specific type of bat. However, this also warrants caution, as those echoes could introduce bias into counts of nightly bat activity.