The endangered Indiana bat (Myotis sodalis) congregates in large hibernation groups in winter and travels after spring emergence to form summer maternity colonies, but information on migration behavior in this species remains limited to mostly band recovery observations. We tracked female Indiana bats in spring migration toward summer grounds using aerial radiotelemetry. Adult female Indiana bats were radiotagged in spring from 2009 through 2017, with 15 individuals successfully tracked to summer grounds and an additional 11 bats located in summer grounds via aerial telemetry after migration was complete. This resulted in the location of 17 previously unknown summer grounds for female Indiana bats, including adding Georgia, Alabama, and Mississippi to the summer maternity range. Two of the colonies identified in this study were south of the previously known southernmost colony in Tennessee, expanding the summer maternity range for the species by 178 km. Time-stamped location fixes along the migration path provided information about nightly and overall distances traveled, duration of travel, migration speed, and weather-related influences on bat behavior. Bats traveled 164.6 ± 26.2 km (± SE) on average from hibernacula to summer grounds and were migrating for an average of 7.3 ± 1.4 calendar nights. Bats alternated between foraging and traveling throughout each night of their migration route. Nightly migration rate was 9.9 ± 0.8 km/h and bats were active on the landscape for an average of 6.1 ± 0.4 h/night. Lower nighttime temperatures and lower barometric pressure correlated with use of layover areas during a migration night. Understanding bat behavior during migration can provide pertinent information for land managers to consider in efforts to conserve potential migration corridors, foraging areas, and roosting habitats of species in decline.

Mist nets are commonly used to capture free-flying bats; however, some bat species are very difficult to capture because of their flight behavior, habitat preferences, and ability to avoid nets. High-flying, open-space foragers are especially underrepresented by mist-net surveys. Few studies have investigated the effectiveness of using acoustic lures (playbacks of conspecific vocalizations) to increase capture success of bats in mist nets. We tested the efficacy of an acoustic lure to capture a high-flying rare molossid, the endangered Florida bonneted bat (Eumops floridanus), which had been captured only once away from a known roost prior to our research. We used a crossover experimental design with 2 lure treatments (nets with lures playing social call recordings from 2 different roosts) and 2 control nets (no lures) in 6 sites for 2 nights each. We captured 15 Florida bonneted bats in our treatment nets and 0 in our control nets. One lure had greater capture success (n ¼ 13) than the other (n ¼ 2), with a trend for greater captures of males (n ¼ 11) than females (n ¼ 4). We suggest that these differences were due to the social context in which the calls used in the lures were recorded. Our study demonstrated the utility of acoustic lures to capture Florida bonneted bats and expands research opportunities critical to the species' conservation, such as the ability to use radio telemetry to track captured bats to unknown roosting and foraging areas. Our study also lays the foundation for future research into social call playbacks as a technique to lure other high-flying and elusive bat species into mist nets. Ó 2017 The Wildlife Society.

Abstract. The federally endangered Indiana bat (Myotis sodalis) is a concern for development projects in nearly half of the United States. The species roosts and rears young under exfoliating bark of trees, which has put it at risk for incurring adverse impacts from most projects that require tree clearing throughout its summer range. Project proponents generally incorporate avoidance and minimization strategies into the planning process. These strategies, however, are not always compatible with project goals and objectives, and mitigation is often required to offset adverse impacts to the Indiana bat. BrandenBark™ is an artificial roost structure that mimics the natural roosting habitat of Indiana bats. To date, 69 BrandenBark™ structures have been installed in 7 states (IL, KY, LA, OH, PA, TN and WV). Of these, 59 (86%) structures have been used by 6 species of bats, including northern long-eared bats (proposed for federal listing) and little brown bats (under status review); however, the majority of use (85%) has been by maternity colonies of Indiana bats confirmed by radio telemetry, capture, or genetic analysis of guano. Of the structures used by Indiana bats at Fort Knox Military Installation (n=21) in north-central Kentucky, 120 emergence counts have been conducted with an average of 81.3±7.1 bats per roost. Although the roost area under BrandenBark™ is slightly warmer ( X = 24.6±7.2°C [SD]) than that of natural bark ( X = 23.1±6.5°C), the temperature difference between BrandenBark™ and ambient ( X = 2.1±2.7°C) is less variable than the temperature difference between natural bark and ambient ( X = 3.9±4.0°C), possibly indicating a more stable thermal environment. However, both roost types are warmer than corresponding ambient temperatures. BrandenBark™ provides instant long-lasting habitat commensurate with natural roosts, is easy to install and monitor, and does not require the purchase of additional land for placement when used as a mitigation option.

As bat (Chiroptera) populations continue to decline in the eastern United States due to threats such as white-nose syndrome and interactions with wind facilities, capturing already rare species such as the federally endangered Indiana bat Myotis sodalis to assess health and demographics has become increasingly difficult. Mist-nets are a standard method for capturing and studying bats, but bats have the ability to escape from or avoid mist-nets. Past research has shown that the use of acoustic lures may increase mist-net capture success. Using prerecorded Indiana bat social calls, we tested the effectiveness of acoustic lures on capture rates across 24 nights at 37 sites in summers 2013 and 2014 in north-central Kentucky. Each site consisted of two nets (treatment and control) placed >35 m apart: we placed an acoustic lure set 1 m in front of the treatment net, whereas the control net received no lure. At the species level, we recorded significantly more captures in treatment nets (n = 262) than in control nets [n = 128; t(36) = 5.08, P < 0.001]. However, although we found a trend toward higher Indiana bat captures, the only species' with significant positive responses were evening bats Nycticeius humeralis [t(15) = 6.25, P < 0.001] and eastern red bats Lasiurus borealis [t(36) = 3.60, P < 0.001]. Further study is required to determine whether modifications to lure settings or call types result in increased Indiana bat captures.

An increasingly popular mark–recapture method to study the ecology of bats is the use of passive integrated transponder (PIT) tags. Deployment of PIT reader arrays at entrances to caves and mines can yield insight into bat behavior during swarming, winter activity, and emergence. This application has the potential to address questions about bat activity at cave and mine entrances in response to white-nose syndrome or bat seasonal movements; however, no studies have examined the response of bats to these arrays. We describe bat response to placement of PIT tag reader arrays using camcorders and supplemental infrared illuminators at three cave entrances near Bloomington, Indiana, during spring 2006. A random subset of 5-min periods was viewed and bat behavior was classified. Circling represented >70% of all behavior noted for two caves but only represented approximately 30% of behavior at the third cave. Proportions of observed activity that resulted in contacts or landings were consistently low across the three caves (x̄  =  1.34%; range 0.5–3.0%), with most contacts causing bats to simply change course and fly away. Based on our observations, positioning reader PIT tag reader arrays at cave entrances to passively recapture PIT tags does not limit bat movements. However, video monitoring during initial sampling efforts of future projects should be conducted to verify appropriate placement and configuration of PIT tag reader arrays. This research provides data illustrating the lack of significant impact in using PIT tag reader arrays at cave entrances, thereby opening up the potential use of this technology to address issues of bats ecology that cannot be obtained with other marking techniques.