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.

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Northern long-eared bat (Myotis septentrionalis) populations have declined sharply in recent years due to the introduction and rapid spread of White-nose Syndrome. This has prompted an urgent need for a greater understanding of their natural history in order to support the conservation of extant populations, particularly where forested day-roost and foraging habitats are being fragmented by development. Prior to 2006, with other Myotis species on the endangered species list, northern long-eared bats were understudied. In recent years, with the pressing concern to document the ecology of all cave bats affected by White-nose Syndrome on the landscape, researchers have now prioritized northern long-eared bat habitat needs, day-roost use, social dynamics, and barriers to gene flow. A relatively new discovery has been the numerous coastal populations that occur in smaller forest patches often surrounded by anthropogenic development. The goal of my research is to aid in informing future monitoring and management protocols that are specific to northern long-eared bats, particularly as they may shift from Threatened to Endangered under the Endangered Species Act. The chapters of this dissertation explore (1) similarities and differences between coastal and more documented upland habitat associations for populations of northern long-eared bats throughout the summer months through the use of acoustic detectors; (2) relationships between acoustic activity patterns and weather on an hourly basis for several bat species on Long Island, New York; and (3–4) day-roost characteristics and social network dynamics of a coastal northern long-eared bat maternity colony on Long Island, New York. I found that northern long-eared bat colonies have larger spatial footprints in – and a moderate tolerance for – forests in anthropogenically-developed areas than previously believed, though many natural history aspects of the bat were similar among coastal and interior populations. Installation of artificial day-roost structures such as bat boxes would likely be used and highly beneficial to colonies in these conditions, particularly to offset the deleterious effects of stochastic disturbance events on day-roost availability and to support social cohesion (and, by extension, reproductive success) for coastal maternity colonies. Additionally, I found that acoustic activity increased in riparian areas, or at sites closer to water features, and as proportion of forest coverage increased at a broad scale. However, immediately around the detector this relationship was reversed. Taken together, this demonstrates that riparian corridors, water features, and forest structural heterogeneity should explicitly be included in management guidelines. / Doctor of Philosophy / White-nose Syndrome is a fungal disease that has killed millions of cave bats in North America, including the northern long-eared bat (Myotis septentrionalis) that during the spring through fall uses forests for roosting and foraging habitat. As the disease continues to spread, and as forests are increasingly being lost to urbanization, it is imperative for researchers and land managers to understand the landscape needs of this species so that they can retain those forests that are used by this species. In addition to broader landscape needs, it is important to understand what specific forest stand to tree features the bats are using, how their social dynamics support their reproductive success, and how to best support habitat conditions foster mating in the fall swarm to avoid inbreeding. In recent years, more northern long-eared bats have been documented in coastal landscapes, suggesting that these areas might be more important to the conservation of the species than previously believed. In this dissertation, my aim was to explore how or why the landscapes in these coastal areas were being used by these bats both during nightly foraging and during the day as resting areas (day-roosts). Additionally, I explored how multiple species of bats were responding to weather conditions on the coast across seasons. Overall, I found that complex forests continue to be an important resource for northern long-eared bats, as well as water features whereby the latter should be more explicitly included in conservation management plans. Northern long-eared bats also show an ability to successfully use small forest patches within a larger urbanized landscape, including using human structures for day-roosts. Human structures might provide reliable, multi-year day-roosts in areas where extreme coastal weather events (hurricanes) occur or increase or as natural processes reduce the suitability of these forests to provide day-roosts. These structures, particularly artificial roost boxes could also support the social network of reproductive northern long-eared bats and thus maintain population stability to some extent.

Day-roost use by northern long-eared bat (Myotis septentrionalis) maternity colonies on the Fort Knox military reservation, Kentucky, USA, resulted in formation of non-random networks of roosts that exhibited a trend toward centralization. Centralization of day-roost networks was reflected in the social structure of colonies, which were characterized by dense associations among individuals within colonies. Social structure varied among colonies and appeared to be related to reproductive condition; colonies exhibited greater cohesiveness during parturition and lactation. Northern long-eared bat maternity colonies appeared to be exclusive, occupying distinct roosting areas with one or several areas receiving intense use. Day-roost removal simulations suggested a linear relationship between colony fragmentation and roost loss, and that loss of >20% of roosts is required to initiate colony fragmentation. Experimental hierarchical removal of day-roosts yielded results consistent with simulations, as removal of the single most-central (primary) roost had no impact on colony fragmentation, whereas removal of 24% of less-central (secondary) roosts resulted in partial network fragmentation. Patterns of colony day-roost and space use were similar pre- and post-removal treatments. Day-roost removal did not alter the number of roosts used by individual bats, but distances moved between roosts were greater in the secondary roost-removal treatment group. Day-roost characteristics largely were consistent pre-post treatment for both treatment groups. Historical data from an Indiana bat (Myotis sodalis) maternity colony revealed that this species also exhibits a non-random social assorting dynamic. Non-random social assortment resulted in a closely connected centralized network of day-roosts. Individuals within the Indiana bat maternity colony exhibited close social connections with colony members, but subgroups likely existed within the colony. Indiana bat day-roosting ecology appears flexible, as patterns of roost and space use differed substantially between years. Development of specific, but tactical, management approaches for individual colonies of both northern long-eared and Indiana bats may be possible. Such approaches would allow land managers to manage for both northern long-eared bat habitat and other objectives. However, the nature of targeted management approaches employed likely will depend on the unique forest context and dynamic within which individual colonies reside. / Ph. D.

The endangered northern long-eared bat (<i>Myotis septentrionalis</i>) has experienced severe population declines since the 2007 introduction of <i>Pseudogymnoascus destructans</i>, the fungal pathogen that causes white-nose syndrome (WNS). Due to continued mortality, failed recruitment, and range fragmentation, effective species conservation would benefit from local and regional research related to habitat selection and suitability, seasonal activity, and large-scale estimates of continued occupancy across the post-WNS landscape. In this dissertation, I explored maternity colony home range size and habitat selection, both coastal and interior seasonal activity patterns, habitat suitability, and species occupancy trends in the Mid-Atlantic and Northeastern United States. Research from the Coastal Plain of North Carolina, based on diurnal roost locations, revealed that core and peripheral home range estimates were large but comparable to areas of contiguous forest cover in other regions of the species' range. Prior to juvenile volancy, female northern long-eared bats selected red maple (<i>Acer rubrum</i>), water ash (<i>Fraxinus caroliniana</i>), and loblolly pine (<i>Pinus taeda</i>) as day-roosts, but then used sweetgum (<i>Liquidambar styraciflua</i>), swamp bay (<i>Persea palustris</i>), and water tupelo (<i>Nyssa aquatica</i>) after juvenile volancy. At the second-order spatial scale (i.e., home range within a region), roosting home ranges were associated with woody wetlands farther from anthropogenic development and open water. However, within the third-order scale (i.e., core home range within a periphery), northern long-eared bats selected woody wetlands adjacent to intact upland forests, areas containing shorter trees and occurring proximal to open water. Research utilizing passive acoustic monitoring on the Coastal Plain of both Virginia and North Carolina found that northern long-eared bat relative activity was highest in areas containing greater proportions of woody wetlands and upland pine-dominated evergreen forests. Conversely, the likelihood to record northern long-eared bats was associated with smaller proportions of woody wetlands and open water resources, emphasizing the importance of upland forests adjacent to these features. I also observed a higher probability of recording northern long-eared bats during non-winter seasons and when temperatures were between 10 and 25 °C, potentially highlighting an optimal thermoneutral zone for the species regionally. Research using presence data from the Monongahela National Forest (MNF) in the Central Appalachians of West Virginia found that northern long-eared bat habitat, whether occupied or not, was abundant (43.1% of the MNF) and widely dispersed. Northern long-eared bat habitat on the MNF was often characterized as mature, interior mixed mesophytic forests. Research using passive acoustic surveys associated with hibernacula in western Virginia found that northern long-eared bats were most active near hibernacula during warmer weeks of the fall swarm and spring emergence, when rainfall was low. Similarly, the probability of northern long-eared bat activity was highest near hibernacula during the spring/summer season. However, unlike relative activity, the likelihood of recording northern long-eared bats was associated with more heterogeneous, interior forests. Finally, research using a combination of long-term repeated and single-season clearance survey data from New England found that northern long-eared bat occupancy was highest on steep hillsides in contiguous forested landscapes with minimal anthropogenic development. My results also indicated higher occupancy of northern long-eared bats in warmer regions, particularly along the New England coastline and offshore islands. These findings collectively stress the importance of managing areas of large core forest to promote sustainable roost formation and productive foraging areas, often associated with dynamic ecotones, to support the survival and recovery of northern long-eared bats in the post-WNS Mid-Atlantic and Northeast. / Doctor of Philosophy / The northern long-eared bat was once one of the most common bat species in North America. However, due to population impacts caused by white-nose syndrome (WNS) the species is now recognized as endangered by the United States Fish and Wildlife Service. In this dissertation, I explore habitat selection and suitability, seasonal activity, and occupancy trends of remnant populations of northern long-eared bats in the Mid-Atlantic and Northeast of the United States, representing approximately 25% of the species' historical range. Specifically, I examined home range size and habitat selection of a reproductively successful maternity colony on the Mid-Atlantic Coastal Plain, overwintering activity at both interior and coastal sites, habitat suitability in the Central Appalachians, and spatial occupancy trends across New England. My research found that reproductive northern long-eared bats actively selected for specific cover features and displayed notable shifts in roost tree selection throughout the maternity season on the Coastal Plain of North Carolina. My research also indicated that northern long-eared bats were more active during non-winter seasons, favoring moderate temperatures and areas of forested wetlands adjacent to evergreen forests in coastal North Carolina and Virginia. In Virginia, northern long-eared bat activity near mountain hibernacula was highest in areas of greater landscape richness prior to and after hibernation. Finally, my research from New England found that northern long-eared bat occupancy was highest in steeper, forested landscapes in the absence of human development. Overall, this research highlights the need to conserve and manage forest ecosystems to promote recovery of the endangered northern long-eared bat. Conservation and management efforts informed by population status, activity trends, and habitat associations will be invaluable in guiding species recovery efforts.