Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio-telemetry was used to locate bats in forest stands used for day-roosting. A roost’s forest stand was defined as a 50-m radius circle around a roost location, which was established in two ways: 1) a bat was tracked to a specific roost tree location using radio telemetry and/or visual confirmation of a bat’s presence was made, or 2) when a specific roost tree could not be identified, the multiple points and compass bearings recorded during radio-tracking were analyzed with LOAS software (version 4.0.3.8, Ecological Software Solutions LLC, Urnäsh, Switzerland) to estimate the X,Y coordinates of the bat's roosting location. A total of 45 bat day-roosts were identified to forest stand and used by 33 bats (23 male; 10 female; 32 adult; 1 juvenile). During the period of monitoring of telemetered bats (less than one month), eight bats used multiple forest stands. Twenty-six forest stands used for bat day roosts were located in Hawaii State administered lands, with the rest on private property. Forest stands ranged in elevation from 13 to 1654 m asl. Dominant canopy trees in forest stands used by roosting bats were primarily comprised of non-native plantation or invasive species, although native Metrosideros polymorpha was the dominant or co-dominant canopy tree in nine forest stands. Mean forest stand canopy height ranged from 11 to 44 m (mean = 23 m).

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. A total of 23 bat day-roosts were identified to tree and used by 18 bats (10 male; 8 female; 17 adult; 1 juvenile). Three maternity roosts were confirmed. One maternity roost was determined to be a bat that was not captured or radio-tagged but was visually located in a roost tree that was also in use by a radio-tagged bat. During the period of monitoring of telemetered bats (less than one month), multiple roosts were located for five bats. Twelve roost sites were located in Hawaii State administered lands, with the rest on private property. Trees used by roosting bats were primarily comprised of non-native plantation or invasive species, although native Metrosideros polymorpha was used in three cases. Tree height and canopy cover ranged from 9 to 56 m (mean = 21 m) and 3 to 97% (mean = 45%). Of the 13 bats visible at perch in the roost, metrics of roost perch canopy cover, perch height and perch aspect ranged from 4 to 98% (mean = 50%), 5 to 24 m (mean = 14 m), and 110 (east-southeast) to 334 (north-northwest) degrees (mean = 217 degrees [southwest]), respectively. Distance to the nearest tree ranged from 0.5 to 22 m (mean = 6 m).

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. A total of 23 bat day-roosts were identified to tree and used by 18 bats (10 male; 8 female; 17 adult; 1 juvenile). Three maternity roosts were confirmed. One maternity roost was determined to be a bat that was not captured or radio-tagged but was visually located in a roost tree that was also in use by a radio-tagged bat. During the period of monitoring of telemetered bats (less than one month), multiple roosts were located for five bats. Twelve roost sites were located in Hawaii State administered lands, with the rest on private property. Trees used by roosting bats were primarily comprised of non-native plantation or invasive species, although native Metrosideros polymorpha was used in three cases. Tree height and canopy cover ranged from 9 to 56 m (mean = 21 m) and 3 to 97% (mean = 45%). Of the 13 bats visible at perch in the roost, metrics of roost perch canopy cover, perch height and perch aspect ranged from 4 to 98% (mean = 50%), 5 to 24 m (mean = 14 m), and 110 (east-southeast) to 334 (north-northwest) degrees (mean = 217 degrees [southwest]), respectively. Distance to the nearest tree ranged from 0.5 to 22 m (mean = 6 m).

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2019 to October 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. In 2019, three maternity roosts were identified however only two were suitable for video recording. Thermal video recording at two maternal roosts was used to identify the time of bat departure and arrival at a roost. We examined an average of 2 hours during sunset and sunrise (range = 0.9 to 5.4 hours). The time of bat departure from a roost ranged from 53 minutes before sunset to 20 minutes after sunset (n = 48, mean = 2.7 minutes before sunset). The time of bat arrival at roost ranged from 41 minutes before sunrise to 11 minutes before sunrise (n = 40, mean = 22 minutes before sunrise). Departure and arrival times were positively correlated (r = 0.16); that is, earlier departures were generally associated with earlier arrivals at a roost the following morning. No potential predators (cats or rats) were seen during the period of video review.

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. Repeated visits to confirm bat presence were conducted until radio-tagged bats were no longer detected at roosts. A total of 56 bats (40 male; 16 female; 55 adult; 1 juvenile) were captured and radio-tagged, and of these, 33 were tracked to roost (23 male; 10 female; 32 adult; 1 juvenile) of either stand- or tree-level. For this subset of 33 bats, the number of distinct days with confirmed occupancy of a bat at roost at either the stand- or tree-level ranged from 1 to 15 days (mean = 5.0 days). The use of multiple roosts at the stand-level were observed for 8 bats; the remaining 25 were only observed at a single roost during the period of monitoring (i.e., until visually confirmed as absent or no radio-tag signal was detected from the roost). Of the subset of eight bats observed at multiple roosts, five were recorded at two roosts, two were recorded at three roosts, and one was recorded at four roosts. The observed frequency of alternating roost trees (“roost switching”) ranged from one (four bats), two (two bats), three (one bat) and eight (one bat).

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. Repeated visits to confirm bat presence were conducted until radio-tagged bats were no longer detected at roosts. A total of 56 bats (40 male; 16 female; 55 adult; 1 juvenile) were captured and radio-tagged, and of these, 33 were tracked to roost (23 male; 10 female; 32 adult; 1 juvenile) of either stand- or tree-level. For this subset of 33 bats, the number of distinct days with confirmed occupancy of a bat at roost at either the stand- or tree-level ranged from 1 to 15 days (mean = 5.0 days). The use of multiple roosts at the stand-level were observed for 8 bats; the remaining 25 were only observed at a single roost during the period of monitoring (i.e., until visually confirmed as absent or no radio-tag signal was detected from the roost). Of the subset of eight bats observed at multiple roosts, five were recorded at two roosts, two were recorded at three roosts, and one was recorded at four roosts. The observed frequency of alternating roost trees (“roost switching”) ranged from one (four bats), two (two bats), three (one bat) and eight (one bat).

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. In 2019, three maternity roosts were identified however only two were suitable for acoustic recording. Acoustic detectors were used to record acoustic activity (i.e., echolocation pulses) at two maternity roosts. Song Meter SM4BAT FS ultrasonic recorders (Wildlife Acoustics, Maynard, MA) with SMX-US ultrasonic microphones (Wildlife Acoustics, Maynard, MA) were deployed within 5-m of each maternity roost tree and configured for continuous (24-hr) data collection. Upon detection of a vocalizing bat, recording was triggered, and a call file was stored with the corresponding date and time. Recordings were analyzed with Kaleidoscope Pro version 5.1.9 (Wildlife Acoustics, Maynard, MA). All files were aurally and visually inspected for bat acoustic activity. A total of 2791 call files were proofed positive for bat calls. A total of 2657 bat call files were recorded from 18:00 to 05:59 (>95%). Less than 5% of call files containing bat calls were recorded from 06:00 to 17:59.

Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. Detection trials for roosting bats were conducted from June to October 2019. Bats confirmed as present at roosts were used as “targets” to evaluate the efficacy of detecting bats with thermal imaging, and when not effective (i.e., during hotter parts of the day when the technique could not discern bats from warm vegetation), visual searching with binoculars was also investigated. Most bat detection trials (48 of 95; 51%) were limited to searches of a single tree. The remaining trials involved searches of stands composed of 2 to 5 trees. Bats were detected in 30 of 95 (32%) trials. The time spent to detect a roosting bat ranged from 2 to 40 minutes (mean = 15 minutes). The height of a roost where bats were detected ranged from 4 to 24 m (mean = 16.8 m). Thermal imaging was used in 64 of 95 trials, of which 25 resulted in bat detection (40%). In contrast, thermal imaging was not used in 31 of 95 trials, of which 5 resulted in bat detection (16%). For trials where thermal imaging was used within 1 hour of sunrise, bats were detected in 15 of 27 trials (56%), whereas for trials conducted more than 1 hour past sunrise, bats were detected in 10 of 37 trials (27%). For bats at roost heights ≤15 m, use of thermal imaging detected bats in 10 of 23 trials (43%). For bats at roost heights >15 m, use of thermal imaging detected bats in 15 of 19 trials (79%). Bats were detected in 8 of 20 trials (40%) in trees or stands comprised of Eucalyptus species. Bats were detected in 22 of 75 trials (40%) in stands comprised of all other species besides Eucalyptus species. When bats were visually confirmed before the trial, 26 of 41 trials (63%) resulted in bat detection. Bats were detected in 9 of 31 trials (29%) conducted during periods of clear skies or few clouds. During cloudy, partly cloudy or periods with light rain, bats were detected in 21 of 64 trials (33%).

Hawaiian hoary bats (Lasiurus cinereus semotus) on Hawaii island were surveyed intermittently from 2004–2010. This data release is a single table of resulting bat location estimates, including date, time, coordinates for each location, and presumed bat activity at the time of collection. Nightly movements were documented for 30 Hawaiian hoary bats along the windward (eastern) side of the island of Hawaii. Each bat was fitted with a colored, split ring forearm band (Size X3; A. C. Hughes, Hampton Hill, United Kingdom) for long-term individual recognition and with a radiotransmitter (BD-2C model from Holohil Systems, Carp, Ontario, Canada). Bats were then released at the point of capture. Output from the transmitters was monitored with tracking receivers and 3-element Yagi antennae. Tracking stations were established at points within 5–300 m of activity centers for each bat and the tracking station coordinates recorded using Garmin GPS 12XL units (Garmin Corporation, Olathe, Kansas). Receiver stations were moved as necessary to improve reception. For a flying bat, bat locations were derived from a single bearing and signal strength (from Bonaccorso et al. 2015). Bonaccorso, F. J., C. M. Todd, A. C. Miles, and P. M. Gorresen (2015). Foraging range movements of the endangered Hawaiian hoary bat, Lasiurus cinereus semotus (Chiroptera: Vespertilionidae). Journal of Mammalogy 96:64–71.

Hawaiian hoary bats (Lasiurus cinereus semotus) on Hawaii island were surveyed intermittently from 2004–2010. This data release is a single table of resulting bat location estimates, including date, time, coordinates for each location, and presumed bat activity at the time of collection. Nightly movements were documented for 30 Hawaiian hoary bats along the windward (eastern) side of the island of Hawaii. Each bat was fitted with a colored, split ring forearm band (Size X3; A. C. Hughes, Hampton Hill, United Kingdom) for long-term individual recognition and with a radiotransmitter (BD-2C model from Holohil Systems, Carp, Ontario, Canada). Bats were then released at the point of capture. Output from the transmitters was monitored with tracking receivers and 3-element Yagi antennae. Tracking stations were established at points within 5–300 m of activity centers for each bat and the tracking station coordinates recorded using Garmin GPS 12XL units (Garmin Corporation, Olathe, Kansas). Receiver stations were moved as necessary to improve reception. For a flying bat, bat locations were derived from a single bearing and signal strength (from Bonaccorso et al. 2015). Bonaccorso, F. J., C. M. Todd, A. C. Miles, and P. M. Gorresen (2015). Foraging range movements of the endangered Hawaiian hoary bat, Lasiurus cinereus semotus (Chiroptera: Vespertilionidae). Journal of Mammalogy 96:64–71.