Hawaiian hoary bats ('ōpe'ape'a; Lasiurus semotus) were captured at 23 sites on Hawaiʻi Island from May 2018 through August 2021. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees or forest stands used for day-roosts. Repeated visits to confirm bat presence were conducted until radio-tagged bats were no longer detected. Of the total 148 captured bats we affixed 131 with radio transmitters and attempted to relocate 127 (38 female; 89 male; 120 adult; 7 juvenile) on subsequent days of tracking. Radio signals were not detected for 36 bats (6 female; 30 male). Of the 91 bats (32 female; 59 male) relocated, males retained transmitters longer than females with a mean low estimate of 9 ± 6 days for males and 6 ± 4 days for females (time from capture to the last day a signal was confirmed). This data file includes data related to dates of capture and subsequent tracking effort, sex and age of captured individuals, and tracking methods.

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 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.

‘Ōpe‘ape‘a (Hawaiian hoary bats; Lasiurus semotus) were surveyed at 23 sites on Hawaiʻi Island from 33 to 2,341 m elevation from May 2018 to August 2021. Of the 23 sites, 8 were established as fixed survey sites for sampling at repeated intervals from January 2019 through January 2021. We surveyed each fixed site at least once per four-month period (January–April, May–August, September–December), with a survey comprising one to three netting events. Additional opportunistic surveys were conducted at alternate sites or on alternate dates. We captured 138 unique bats (37 female, 101 male) and recaptured 10 bats over 224 mist-netting events. Of the total 148 captured bats we affixed 131 with radio transmitters and attempted to relocate 127 (38 female; 89 male; 120 adult; 7 juvenile) bats in trees or forest stands used for day roosts on subsequent days of tracking. Of 91 bats (32 female; 59 male) relocated, males retained transmitters longer than females with a mean low estimate of 9 ± 6 days for males and 6 ± 4 days for females (time from capture to the last day a signal was confirmed). This data release consists of three tabular datasets: (1) Hawaiʻi Island ʻōpeʻapeʻa mist netting effort, 2018–2021, (2) Hawai‘i Island ʻōpeʻapeʻa captures, 2018–2021, and (3) Hawaiʻi Island ʻōpeʻapeʻa transmitter retention, 2018-2021.

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 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).

‘Ōpe‘ape‘a (Hawaiian hoary bats; Lasiurus semotus) were surveyed at 23 sites on Hawaiʻi Island from 33 to 2,341 m elevation from May 2018 to August 2021. Bats were captured using mist nets; once detangled from mist nets, bats were secured in cloth holding bags for up to 10 min before collecting age, sex, reproductive condition, mass, forearm length, and biological samples and marking individuals with split ring bands and attaching very high frequency (VHF) radio transmitters. We captured 138 uniquely identified individuals (37 female, 101 male), of which 10 were recaptured (4 female, 6 male) and an additional 10 were ensnared in nets and escaped, for a total of 158. This data file includes data related to individual bats captured including sex, age and morphometrics of captured individuals, samples collected, markings applied, transmitter frequency, dates and generalized locations of capture.

‘Ōpe‘ape‘a (Hawaiian hoary bats; Lasiurus semotus) were surveyed at 23 sites on Hawaiʻi Island from 33 to 2,341 m elevation from May 2018 to August 2021. Bats were captured using mist nets; once detangled from mist nets, bats were secured in cloth holding bags for up to 10 min before collecting age, sex, reproductive condition, mass, forearm length, and biological samples and marking individuals with split ring bands and attaching very high frequency (VHF) radio transmitters. We captured 138 uniquely identified individuals (37 female, 101 male), of which 10 were recaptured (4 female, 6 male) and an additional 10 were ensnared in nets and escaped, for a total of 158. This data file includes data related to individual bats captured including sex, age and morphometrics of captured individuals, samples collected, markings applied, transmitter frequency, dates and generalized locations of capture.

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).