Technical Report HCSU-089

Hawaiian HoaRy baT aCoUSTiC moniToRing on U. S. aRmy o`aHU faCiliTieS

frank J. bonaccorso1, Kristina montoya-aiona1, and Corinna a. Pinzari2

1U.S. geological Survey, Pacific island ecosystems Research Center, Kīlauea field Station,

P.o. box 44, Hawai i national Park, Hi 967182Hawai i Cooperative Studies Unit, University of Hawai i at Hilo,

P.o. box 44, Hawai i national Park, Hi 96718

Hawai i Cooperative Studies UnitUniversity of Hawai i at Hilo

200 w. Kawili St.Hilo, Hi 96720

(808) 933-0706

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This product was prepared under Cooperative Agreement G14AC00392 for the Pacific Island Ecosystems Research Center of the U.S. Geological Survey.

This article has been peer reviewed and approved for publication consistent with USGS Fundamental Science Practices (http://pubs.usgs.gov/circ/1367/). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

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TABLE OF CONTENTS

List of Tables ..................................................................................................................... iii

List of Figures .................................................................................................................... iii

Abstract ............................................................................................................................ 1

Introduction ...................................................................................................................... 1

Methods ............................................................................................................................ 2

Results .............................................................................................................................. 6

Bat Distribution and Presence .......................................................................................... 6

Seasonal Bat Activity ....................................................................................................... 7

Foraging Activity ............................................................................................................12

Discussion ........................................................................................................................13

Acknowledgements ...........................................................................................................14

Literature Cited .................................................................................................................15

Appendices .......................................................................................................................17

LIST OF TABLES

Table 1. Hawaiian hoary bat survey effort on U.S. Army installations on O‘ahu. ....................... 4

Table 2. Summary of acoustic monitoring at 30 stations and 12 locations. .............................. 5

Table 3. Sampling effort by month 12 locations surveyed from 2015 through 2016. ................. 8

Appendix 2. Frequency of nightly bat detections by month and monitoring station. .................29

LIST OF FIGURES

Figure 1. Locations of 30 acoustic detector stations on U. S. Army installations, O‘ahu Island. .. 3

Figure 2. Spectrogram of search-phase call pulses followed by terminal-phase series of pulses. 6

Figure 3. Confirmed bat presence or presumed absence from 2015 through 2016.. ................. 7

Figure 4. Mean frequency of bat detections during the reproductive and fledging periods........10

Figure 5. Total number of acoustic call events by time of night. ............................................11

Figure 6. Hawaiian hoary bat foraging activity in the Schofield East and West Ranges in 2015. 13

Appendix 1. Aerial maps and habitat of Hawaiian hoary bat acoustic monitoring stations. .......17

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ABSTRACT

Acoustic sampling for occurrence of the endangered Hawaiian hoary bat (Lasiurus cinereus semotus) was conducted at 12 locations on U. S. Army installations on O‘ahu Island, Hawai‘i. Bats were confirmed as present at 10 of these locations: Dillingham Military Reservation, Helemano Military Reservation, Kahuku Training Area, Kawailoa Training Area, Mākua Military Reservation, Schofield Barracks East Range, Schofield Barracks West Range, Schofield Barracks (Mendonca Park Housing), Tripler Army Medical Center, and Wheeler Army Airfield. Our acoustic sampling did not record bat vocalizations at Fort DeRussy or Fort Shafter. Despite the presence of bats at the above 10 locations, foraging activity as identified from characteristic feeding buzzes was observed only at East Range and West Range of Schofield Barracks. Nevertheless, Hawaiian hoary bats were recorded actively searching for prey in airspace at 10 of the 12 areas during important periods of Hawaiian hoary bat life history, including periods of pregnancy, lactation, and pup fledging. Within-night bat activity pooled for all nights and detectors at each location showed bat activity was mostly confined to the first several hours of the night. This acoustic study detected bats at lower rates of occurrence (frequency of detection [“f”] = 0.07) compared to detection probabilities (“dp”) observed on the islands of Hawai‘i (dp = 0.56) and Maui (dp = 0.27), implying either behavioral differences or that they occur at lower densities on O‘ahu. The rate is also consistent with results from two previous acoustic studies conducted on O‘ahu; a year long monitoring study in the northern Ko‘olau Mountains in 2014 (dp = 0.08), and short-term seasonal Army monitoring efforts in 2012 (dp = 0.05 to 0.06).

INTRODUCTION

Also known as the ‘Ōpe‘ape‘a, the Hawaiian hoary bat (Lasiurus cinereus semotus) is the only extant native terrestrial mammal and sole bat species in Hawai‘i state. This endemic subspecies of hoary bat occurs on all of the major islands (Tomich 1986) and is listed by the U.S. Fish and Wildlife Service (USFWS) and the State of Hawai‘i Department of Forestry and Wildlife list as “Endangered”. The species is a habitat generalist with aerial-hawking foraging behavior and feeds primarily on Coleoptera and Lepidoptera captured and eaten while in flight (Whitaker and Tomich 1983, Belwood and Fullard 1984, Jacobs 1999). Individual bats are highly mobile and regularly forage in multiple disjunct feeding areas that may be up to 15 km in long axis across an individual’s foraging range, as demonstrated in radio-telemetry studies conducted on both Hawai‘i and Maui islands (Bonaccorso et al. 2015, D. Johnston, H.T. Harvey and Associates, pers. comm.).

Use of ultrasonic acoustic monitoring techniques have revealed this species’ seasonal presence and aspects of its behavior across many areas of the state (Gorresen et al. 2013, Pinzari et al. 2014, Todd et al. 2016); however, with the exception of Gorresen et al. 2015, there is relatively little published about populations and contemporary distributional range of this bat on O‘ahu. The objectives in this acoustic monitoring effort were to provide an assessment for U.S. Army facilities on O‘ahu of Hawaiian hoary bat occurrence and distribution during important life history periods, and evidence of foraging activity.

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METHODS

The study was conducted across 12 locations on U. S. Army installations on O‘ahu between 28 January 2015 and 23 March 2016 (Figure 1). We deployed SM2Bat+ Song Meter Digital Field Recorders (Wildlife Acoustics Inc., Concord, MA) capable of recording ultrasound between 10 and 100 kHz at 30 monitoring stations (Table 1). Each station consisted of a SM2Bat+in waterproof housing, 6V external battery, 6W solar panel, and SMX-US ultrasonic microphone (Wildlife Acoustics Inc., Concord, MA). Microphones were placed at the top of a metal conduit 2 to 3 m above the ground and connected by cable to the SM2Bat+ microphone port. These microphones are omnidirectional and capable of detecting bat calls at distances up to 30 m under ideal conditions (Adams et al. 2012). However, the range of call detection varies with weather conditions and orientation of the bat relative to the microphone. One to five stations per location, depending on Army installation size and accessibility, were placed in open areas or along vegetation edges (see Appendix 1) because Hawaiian hoary bats frequently fly and forage along edge/open areas and to ensure adequate sunlight to power solar panels and recharge batteries. Elevation at stations ranged between 1 and 552 m asl (Table 1). Stations were maintained for between 134 and 420 nights of recording (Table 2) except at Fort DeRussy, where a single station operated only for 53 nights because of technical and security issues. All sound files were recorded in the Waveform Audio File format (.wav) onto Secure Digital (SD) memory cards with corresponding times and dates. All detectors operated from one hour before local sunset until one hour after local sunrise. Recording units were checked at 2–3 month intervals to exchange SD data cards and test optimal battery and microphone function.

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Figure 1. Locations of 30 acoustic detector stations (red dots) on U. S. Army installations, O‘ahu Island.

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Table 1. Hawaiian hoary bat survey effort on U.S. Army installations on O‘ahu, including Universal Transverse Mercator (UTM) locations (Zone 4, datum WGS84), elevation, and operational dates for acoustic monitoring stations.

Installation Monitoring

Station UTM

Easting UTM

Northing Elevation

(m) Start Date End Date

Dillingham Military Reservation

DIL1 583839 2386391 1 2/3/2015 9/24/2015

DIL2 582900 2385660 6 2/3/2015 9/24/2015

DIL3 582296 2386399 1 2/3/2015 9/24/2015

Fort DeRussy FTDR 620935 2354031 2 8/27/2015 10/18/2015

Fort Shafter FTSH 616514 2361852 84 2/4/2015 9/12/2015

Helemano Military Reservation

HELE 601267 2381404 335 2/2/2015 3/22/2016

Kahuku Training Area

KAHU2 602915 2397606 165 2/3/2015 11/14/2015

KAHU3 604384 2394306 422 2/3/2015 2/17/2016

KAHU4 605056 2396846 170 2/3/2015 3/23/2016

Kawailoa Training Area

KAW1 603607 2385356 432 2/2/2015 1/23/2016

KAW2 602711 2385556 400 2/2/2015 3/22/2016

KAW3 602382 2387121 337 2/2/2015 10/12/2015

KAW4 602855 2387751 403 2/2/2015 9/25/2015

Mākua Military Reservation

MAKA1 581418 2380002 170 2/4/2015 3/23/2016

MAKA2 580914 2381036 45 2/4/2015 11/3/2015

MAKA3 581926 2380849 112 2/4/2015 6/17/2015

MAKA4 581700 2382283 240 2/4/2015 9/11/2015

Schofield Barracks (East Range)

ER1 604185 2376636 272 1/28/2015 9/4/2015

ER2 605005 2377023 333 1/28/2015 9/16/2015

ER3 605981 2377312 364 1/28/2015 3/22/2016

ER4 606893 2377511 432 1/28/2015 10/18/2015

Schofield Barracks (West Range)

WR1 591192 2376500 542 1/27/2015 9/3/2015

WR2 591083 2377444 552 1/27/2015 9/4/2015

WR3 591424 2378463 489 1/27/2015 3/21/2016

WR4 592267 2378977 497 1/27/2015 9/26/2015

WR5 592985 2376508 369 2/2/2015 11/7/2015

Schofield Barracks (Central–Canby,

CANB 597777 237442 260 2/3/2015 9/2/2015

Mendonca Park) MEND 599070 2376921 260 1/28/2015 2/17/2016

Tripler Medical Center

TRIP 615377 2362861 152 2/4/2015 1/18/2016

Wheeler Army Airfield

WHEE 599911 2374095 202 1/28/2015 12/1/2015

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Bat detections were verified by audio and visual inspection of echolocation recording spectrograms using Kaleidoscope 4.1.0 software (Wildlife Acoustics). We discarded call events not conforming to standard Hawaiian hoary bat vocalization parameters (see example in Figure 2). A call event was defined as a series of ≥ 3 echolocation pulses within a recording. The cumulative number of echolocation pulses for all call events was summed for each monitoring station and night within a month and classified as either search- or terminal-phase calls (“feeding buzzes”; Griffin 1958). The search-phase portions of calls were identified as a successive series of pulses separated by at least 100 ms (Barclay, Fullard, and Jacobs 1999). Terminal-phase calls were qualitatively distinguished from search-phase and approach-phase calls by a rapid increase in the call rate. Table 2. Summary of acoustic monitoring at 30 stations across 12 locations from January 2015 through March 2016.

Monitoring Station

Total Nights Sampled

Nights Bats Present (%)

Number of Call Events

Nights with Feeding Buzzes

CANB 0 1 - - - DIL1 134 1.5 2 0 DIL2 234 0 0 0 DIL3 223 5.4 15 0 FTDR 53 0 0 0 FTSH 183 0 0 0 HELE 383 1.6 6 0 KAH2 285 0.7 2 0 KAH3 351 0.9 3 0 KAH4 415 0.2 1 0 KAW1 356 0.8 1 0 KAW2 292 1.4 4 0 KAW3 253 0 0 0 KAW4 233 0.4 2 0 MAKA1 414 1.2 5 0 MAKA2 250 0.4 1 0 MAKA3 134 0 0 0 MAKA4 220 0 0 0 ER1 138 0 0 0 ER2 231 0 0 0 ER3 420 0.2 1 0 ER4 234 3.0 7 1 WR1 198 4.0 43 3 WR2 31 2 35.5 18 1 WR3 420 14.5 91 6 WR4 243 0 0 0 WR5 279 4.7 59 4 TRIP 351 0.6 2 0 MEND 361 1.4 5 0 WHEE 308 1.0 3 0

1 Unit only recorded first 3 hours of every night. No results are presented for this monitoring station. 2 Equipment failure limited number of recording nights.

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The detection history at monitoring stations was used to calculate the proportion of total nights with observed bat activity throughout the 15-month survey and the frequency of nightly samples with bat activity as averaged for the reproductive and fledging periods (May to October). Hawaiian hoary bat reproductive or “breeding” season (as adapted from Menard 2001) includes a pregnancy (May to June) and a lactation period (July to August). The remainder of the year includes a fledging/post-lactation period (September to October) and a pre-pregnancy period (November to March), the latter of which is referred to as the “non-reproductive” period. For the subset of stations with at least one detection, the frequency of detection (“f”) per month was calculated for each survey location as the total number of nights with detections divided by the total number of nights sampled (effectively weighting the values by sampling effort). The station-level values were averaged for locations with multiple stations to produce a pooled monthly index of the likelihood of observing bats at sites where the species had been recorded. Total counts of echolocation call events were used to examine nightly activity patterns at sites or clusters of sites for samples pooled for the duration of the survey.

Figure 2. Sample spectrogram of search-phase call pulses (left and center) followed by a terminal-phase series of pulses (“feeding buzz”; far right in red box) in one echolocation call event. The X-axis represents time in seconds and the Y-axis represents frequency in kilohertz (kHz).

RESULTS

Bat Distribution and Presence Hawaiian hoary bat occurrence was acoustically sampled for a total of 7,865 recording nights at 12 U. S. Army locations on O‘ahu Island in 2015 and 2016 (Table 2). Technical problems with the acoustic recorders at the Cantone station at Schofield Barracks (Canby) resulted in no recordings for this location, and only 31 nights of sampling at the WR2 station of Schofield Barracks (West Range).

Vocalizations of Hawaiian hoary bats were positively identified for 151 (2%) of all recording nights at 20 of 30 monitoring stations (67%). The proportion of total nights with bat presence for the 15-month survey period was relatively high only at Schofield Barracks (West Range)

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stations WR2 (35.5%) and WR3 (14.5%; Table 2). Bat acoustic activity was generally very low and exceeded 20 individual recording events only at Schofield Barracks (West Range), where four of the five monitoring stations exceeded that total. Confirmed feeding buzzes were observed at only five stations, all located at the West and East Ranges of Schofield Barracks, and were only rarely recorded (max = 6 events at WR3).

Seasonal Bat Activity Bat occurrence varied seasonally among survey locations as indicated by the distribution of monthly detections (Figure 3, Table 3). Schofield Barracks (West Range) was the only location at which bats were recorded year-round. Bat occurrence at other locations tended to be distributed irregularly or concentrated towards the beginning and middle of the year. Frequency of detection for all locations over the 15-month survey period averaged 0.08 (SD = 0.08) for the subset of months with at least one detection. However, although the monthly index was relatively low for most locations, all locations besides Ft. DeRussy and Ft. Shafter recorded bats during one or more months of the reproductive season.

Figure 3. Confirmed bat presence or presumed absence by survey month and survey location from January 2015 through March 2016. A solid circle indicates that bats were detected, hollow circles that no bats were detected, and asterisk that no data was collected in that month. Circles are colored to distinguish stages of the breeding season from pregnancy (May–June), lactation (July–August) through fledging (September–October).

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Table 3. Sampling effort by month at 12 locations surveyed from January 2015 through March 2016. Number of sampling stations (n) is listed under each installation name, and the first, second, and third row of numbers is the number of effective nights the detectors were operating that month (i.e., number of detectors multiplied by number of nights sampled per month), number of detections and monthly frequency of detection (f), respectively.

Survey

2015 2016 Location Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Dillingham 64 70 90 93 76 87 68 51

(n = 3) 2 0 1 1 1 5 3 1 0.07 0 0.03 0.03 0.03 0.08 0.10 0.03

Ft. DeRussy 5 30 18

(n = 1) 0 0 0 0 0 0

Ft. Shafter 11 7 30 31 30 31 31 12

(n = 1) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Helemano 17 9 30 31 30 31 31 30 31 30 31 31 29 22 (n = 1) 0 0 1 1 1 1 2 0 0 0 0 0 0 0

0 0 0.03 0.03 0.03 0.03 0.06 0 0 0 0 0 0 0

Kahuku 78 93 90 93 90 93 87 67 93 74 62 62 46 23 (n = 3) 2 0 0 0 0 0 4 0 0 0 0 0 0 0

0.07 0 0 0 0 0 0.04 0 0 0 0 0 0 0

Kawailoa 97 96 90 93 97 124 121 115 74 60 62 54 29 22 (n = 4) 3 0 0 0 0 3 1 0 1 0 0 0 0 0

0.05 0 0 0 0 0.05 0.03 0 0.03 0 0 0 0 0

Mākua 100 101 120 124 107 93 93 71 62 33 31 31 29 23 (n = 4) 0 1 1 1 0 0 1 2 0 0 0 0 0 0

0 0.03 0.03 0.03 0 0 0.03 0.07 0 0 0 0 0 0

Schofield 16 104 101 113 100 120 97 100 80 49 30 31 31 29 22 (East Range) 1 4 0 0 0 0 0 2 1 0 0 0 0 0 0

(n = 4) 0.20 0.07 0 0 0 0 0 0.06 0.03 0 0 0 0 0 0

Schofield 20 116 121 123 124 120 124 119 93 62 37 31 31 29 21 (West Range) 5 6 10 4 5 7 11 10 14 4 2 5 4 5 1

(n = 5) 0.50 0.05 0.11 0.04 0.16 0.12 0.18 0.08 0.16 0.13 0.07 0.16 0.13 0.17 0.03

Schofield (central - 4 28 23 18 31 29 31 27 30 31 30 31 31 17

Mendonca Park) 1 1 1 1 1 0 0 0 0 0 0 0 0 0

(n = 1) 0.20 0.04 0.03 0.03 0.03 0 0 0 0 0 0 0 0 0

Tripler 25 31 30 31 30 31 31 30 31 30 31 21

(n = 1) 0 0 0 0 0 0 1 0 0 1 0 0

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Survey

2015 2016 Location Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

0 0 0 0 0 0 0.03 0 0 0.03 0 0

Wheeler 4 28 31 30 31 30 31 31 30 31 30 1

(n = 1) 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0.03 0.03 0.03 0 0 0 0 0 0 0

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The frequency of bat detections during the reproductive and fledging periods (May–October) exhibited considerable variation at the level of the sampling station even among proximate stations (Figure 4, Appendix 2). For example, frequency of nightly detections per month for the five Schofield Barracks (West Range) stations range from 0% to 23%. Eleven of the 30 stations recorded no bat presence during these periods, and the overall frequency for all stations averaged only 3%.

Figure 4. Mean monthly frequency of bat detections during the reproductive and fledging periods (May–October) at 30 acoustic detector stations on O‘ahu. Data tabulated in Appendix 2.

Acoustic monitoring at Dillingham Military Reservation indicated bat presence in all months sampled except March (Figure 3). The highest levels of bat detectability at Dillingham were recorded in July and August during the lactation season for hoary bats (Table 3). Within-night bat activity pooled for all nights and detectors at Dillingham showed bat activity was mostly confined to the first five hours of the night (≤ 300 minutes after sunset; Figure 5).

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Figure 5. Total number of acoustic call events by time of night recorded for the entire sampling period at each survey location where bats were detected. To account for seasonal changes in the length of night, the time of detection was standardized relative to sunset time.

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Acoustic monitoring at Helemano Military Reservation demonstrated bat presence only during the period from April through August 2015, the period of hoary bat pregnancy and lactation (Figure 3, Table 3). Within-night activity pooled for all sampling nights was confined to the first half of the night with no distinct peak (Figure 5). At Kahuku Training Area, bat activity was observed only in February and August 2015 (Figure 3, Table 3). Within-night bat activity at Kahuku, pooled over all sampling nights, was irregularly distributed throughout the night (Figure 5). Acoustic monitoring at Kawailoa Training Area detected bat vocalizations in February, July, August, and October 2015 (Figure 3, Table 3). Within-night bat activity pooled for all detectors and all sampling nights at Kawailoa occurred during both the first and last hours of night (Figure 5).

Bat acoustic activity at Mākua Military Reservation was detected from March through May and during August and September, the latter period coincides with the lactation and fledging season for hoary bat pups (Figure 3, Table 3). Within-night activity pooled for all sampling nights at Mākua occurred irregularly throughout the night (Figure 5). Acoustic monitoring at Schofield Barracks (East Range) recorded bat activity only in January, February, August and September 2015 (Figure 3, Table 3). Within-night bat activity was concentrated primarily in the first several hours of the night (Figure 5). In contrast, bat activity at Schofield Barracks (West Range) was recorded in every month of the 15-month survey (Figure 3, Table 3) and throughout the night, with peak activity in the first few hours of the night (Figure 5). Acoustic monitoring at Schofield Barracks (Mendonca Park) recorded bat vocalizations from January through May 2015, but bats were not detected for the subsequent 9 months. Within-night bat activity at Mendonca occurred between 2000 and 0200 (Figure 5).

Acoustic bat activity at Tripler Army Medical Center from January 2015 to January 2016 was restricted to August and November 2015 (Figure 3, Table 3), and all records occurred in the middle of the night (Figure 5). Acoustic monitoring at Wheeler Army Airfield was conducted between January and November 2015 (Figure 3). Bat vocalizations recorded at Wheeler Army Airfield were confined to March through May 2015 and the first half of the night (Figure 5).

Foraging Activity Although bats were recorded at 10 of the 12 locations, foraging activity as indicated by feeding buzz detections was observed infrequently and only at Schofield Barracks East and West Ranges (Figure 6). Four of five sampling stations recorded feeding buzzes on 14 nights at the West Range, and one station recorded feeding buzzes on a single night at the East Range. Peak foraging activity was observed in August and September, a period coinciding with hoary bat fledging in Hawai‘i.

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Figure 6. Hawaiian hoary bat foraging activity in the Schofield East and West Ranges in 2015 (monitoring station codes as in Table 1).

DISCUSSION

Acoustic monitoring confirmed that Hawaiian hoary bats were present in 2015 on 10 of 12 U. S. Army locations on O‘ahu Island during the Hawaiian hoary bat summer/fall pregnancy and pup rearing (lactation and fledgling) seasons. Bat occurrence tended to be distributed irregularly or concentrated towards the beginning and middle of the year, and mostly confined to the first several hours of the night. Schofield Barracks (West Range) was the only location at which bats were recorded year-round and throughout most of the night. Moreover, the frequency of bat occurrence was generally very low across the 30 monitoring stations, averaging 0.08 (SD = 0.08) for the subset of months with at least one detection. These results are comparable to that recorded during 2013–2014 across the northern Ko‘olau Mountains of O‘ahu, which sampled some of the same locations within the Kahuku and Kawailoa Army Training Areas (Gorresen et al. 2015). Acoustic surveys, using similar equipment and settings, in the Kahuku and Kawailoa Training Areas and Schofield Barracks East Range from September 2010 to October 2011 also documented bat activity at the three locations, with a peak in activity in August (Oahu Army Natural Resource Program and Pacific Cooperative Studies Unit 2012). However, overall bat detection events were very low with bats detected on only 6% of the total recording nights at Kahuku and 5% of recording nights at Schofield East Range (Kawailoa data was not fully included in the report). However, it is important to note that detection of bat presence by acoustic sampling can be problematic. Acoustic detectors are known to have a fairly limited detection range (generally less than 40 m; Adams et al. 2012) and may not record bats flying at higher heights. Recent studies also indicate that Hawaiian hoary bats may use sight more than expected and may fly quietly when transiting between foraging areas (Gorresen et al. 2017). Therefore, although detection rates were low, the results indicate that bats do occur in and

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make use of habitats within the installations monitored, even within urban environments (e.g., Tripler Army Medical Center).

Bat foraging activity as indicated by feeding buzz detections was observed infrequently, and mostly limited to August and September, a period coinciding with hoary bat fledging in Hawai‘i. Although feeding buzzes are unambiguous indicators of prey targeting and possible feeding, these types of calls are typically emitted at a much lower intensity than search or approach phase calls (e.g., Corcoran and Conner 2017). As such, feeding buzzes are more difficult to detect in the field. Therefore, using these calls as a measure of feeding may greatly under-represent its occurrence compared to tallies obtained from the acoustics of bats simply searching for prey. Future studies using improved acoustic equipment may result in higher detection rates. This could also allow for better characterization of seasonal and nightly patterns of occurrence, as well as confirmation of feeding activity that current technology samples poorly.

Acoustic monitoring confirmed that Hawaiian hoary bats were present during the Hawaiian hoary bat summer/fall gestation and pup rearing season. The season begins during pregnancy (May) and continues through fledging and maternal care, a period that includes knowledge transfer from mother to volant juveniles as they forage in tandem after the initial juvenile fledging (October). July–August is the most critical time for mothers with pups because this tree roosting species may be unable to effectively relocate pups should a roosting tree be disturbed or felled. This is particularly the case in late July and early August when pups are no longer carried by a mother and are approaching adult body mass, yet cannot fly. While we did not search for roost trees during this study, roosting mothers with pups might be present on any of the installations in this study during the reproductive season. Caution in conducting habitat alterations during July and August is a consideration where bat presence has been determined.

ACKNOWLEDGEMENTS

We thank M. Burt and H. K. Kawelo, field staff from the O‘ahu Army Natural Resources group, D. Montoya-Aiona, and S. Moura, for assistance with survey logistics on O‘ahu. This report was improved by critical reading and suggestions from D. Johnston, J. Jacobi and M. Reeves. Editorial assistance was provided by J. Rowe.

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LITERATURE CITED

Adams, A. M., M.K. Jantzen, R. M. Hamiliton, and M.B. Fenton. 2012. Do you hear what I hear? Implications of detector selection for acoustic monitoring of bats. Methods in Ecology and Evolution 3: 992–998. Barclay, R. M. R., J. H. Fullard, and D.S. Jacobs. 1999. Variation in the echolocation calls of the hoary bat (Lasiurus cinereus): influence of body size, habitat structure, and geographic location. Canadian Journal of Zoology 77: 530–534.

Belwood, J. J. and J. H. Fullard. 1984. Echolocation and foraging behavior in the Hawaiian hoary bat, Lasiurus cinereus semotus. Canadian Journal of Zoology 62: 2113–2120. 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. Corcoran, A. J. and W. E. Conner. 2017. Predator counteradaptations: stealth echolocation overcomes insect sonar-jamming and evasive-manoeuvring defences. Animal Behaviour 132:291–301. Gorresen, M. P., F. J. Bonaccorso, C. A. Pinzari, C. M. Todd, K. Montoya-Aiona, and K. Brinck. 2013. A five-year study of Hawaiian hoary bat (Lasiurus cinereus semotus) occupancy on the Island of Hawai‘i. Technical Report 41, Hawai‘i Cooperative Studies Unit, University of Hawai‘i at Hilo, HI. 48 pp. Gorresen, P. M., P. M. Cryan, M. Huso, C. Hein, M. Schirmacher, J. Johnson, K. Montoya-Aiona, K. W. Brinck and F. J. Bonaccorso. 2015. Behavior of the Hawaiian hoary bat at wind turbines and its distribution across the North Ko‘olau Mountains, O‘ahu Technical Report 64, Hawai‘i Cooperative Studies Unit, University of Hawai‘i at Hilo, HI, 69 pp.

Gorresen, P. M., P. M. Cryan, K. Montoya‐Aiona, and F. J. Bonaccorso. 2017. Do you hear what

I see? Vocalization relative to visual detection rates of Hawaiian hoary bats (Lasiurus cinereus semotus). Ecology and Evolution 7: 6669–6679.

Griffin D. R. 1958. Listening in the dark: The acoustic orientation of bats and men. New Haven: Yale University Press. Jacobs D. S. 1999. The diet of the insectivorous Hawaiian hoary bat (Lasiurus cinereus semotus) in an open and a cluttered habitat. Canadian Journal of Zoology 77: 1603–1608. Menard, T. 2001. Activity patterns of the Hawaiian hoary bat (Lasiurus cinereus semotus) in relation to reproductive time periods. Master’s Thesis. University of Hawai‘i, at Mānoa, Honolulu, HI.

O‘ahu Army Natural Resource Program U.S. Army Garrison, Hawai‘i and Pacific Cooperative Studies Unit. 2012. Chapter 5: Ōpe‘ape‘a (Hawaiian Hoary Bat) in Mākua and O‘ahu Implementation Plan Status Report. , Schofield Barracks, HI. http://manoa.hawaii.edu/hpicesu/DPW/2012_YER/default.htm.

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Pinzari, C. A., F. J. Bonaccorso, and K. Montoya-Aiona. 2014. Hawaiian Hoary bat occupancy at Kaloko-Honokōhau National Historical Park. Report 51, Hawai‘i Cooperative Studies Unit, University of Hawai‘i at Hilo, HI, 15 pp.

Todd, C. M., C. A. Pinzari, and F. J. Bonaccorso. 2016. Acoustic surveys of Hawaiian hoary bats in Kahikinui Forest Reserve and Nakula Natural Area Reserve on the island of Maui. Report 78, Hawai‘i Cooperative Studies Unit, University of Hawai‘i at Hilo, HI, 22 pp.

Tomich, P. Q. 1986. Mammals in Hawai‘i. Second edition. Bishop Museum Press, Honolulu, HI. 375 pp. Whitaker J. O. Jr, and P. Q. Tomich. 1983. Food habits of the hoary bat, Lasiurus cinereus, from Hawaii. Journal of Mammalogy 64: 150–151.

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APPENDICES

Appendix 1. Aerial maps and habitat of Hawaiian hoary bat acoustic monitoring stations.

Dillingham Military Reservation

Appendix Figure 1. Dillingham Military Reservation acoustic monitoring stations (white dots).

Appendix Figure 2. Dillingham Military Reservation acoustic monitoring station DIL1 and habitat representative of three recording stations at this facility.

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Fort DeRussy

Appendix Figure 3. Fort DeRussy acoustic monitoring station (white dot).

Kahuku Training Area

Appendix Figure 4. Kahuku Training Area acoustic recording stations (white dots).

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Fort Shafter

Appendix Figure 5. Fort Shafter with acoustic monitoring station (white dot).

Appendix Figure 6. Fort Shafter acoustic recording station and habitat.

20

Helemano Military Reservation

Appendix Figure 7. Helemano Military Reservation aerial map with acoustic monitoring station (white dot).

Appendix Figure 8. Helemano Military Reservation acoustic monitoring station.

21

Kawailoa Training Area

Appendix Figure 9. Kawailoa Training Area with acoustic monitoring stations (white dots).

Appendix Figure 10. Kawailoa Training Area acoustic monitoring stations and habitats (top left to right; KAW1, KAW2, bottom left to right; KAW3, KAW4).

22

Mākua Military Reservation

Appendix Figure 11. Mākua Military Reservation acoustic monitoring stations (white dots).

Appendix Figure 12. Mākua Military Reservation acoustic monitoring stations (top left to right; Maka1, Maka2, bottom left to right; Maka3, Maka4).

23

Schofield Barracks East Range

Appendix Figure 13. Schofield Barracks East Range acoustic monitoring stations (white dots).

Appendix Figure 14. Schofield Barracks East Range Training Area acoustic monitoring station habitats (left to right: ER1, ER2, ER4; ER3 not pictured).

24

Schofield Barracks West Range

Appendix Figure 15. Schofield Barracks West Range acoustic monitoring stations (white dots).

Appendix Figure 16. Schofield Barracks West Range Training Area acoustic monitoring station habitats (top left to right; WR1, WR2, bottom left to right; WR3, WR4; not pictured, WR5).

25

Tripler Army Medical Center

Appendix Figure 17. Tripler Army Medical Center acoustic monitoring station (white dot).

Appendix Figure 18. Tripler Army Medical Center acoustic monitoring station (left) and habitat (right).

26

Schofield Barracks Canby Housing Area

Appendix Figure 19. Schofield Barracks Canby Housing Area acoustic monitoring station (white dot).

Appendix Figure 20. Schofield Barracks Canby Housing Area acoustic monitoring station (left) and habitat (right).

27

Schofield Barracks Mendonca Park Housing

Appendix Figure 21. Map with acoustic monitoring station at Schofield Barracks Mendonca Park Housing.

Appendix Figure 22. Schofield Barracks Mendonca Park Housing Area acoustic monitoring station (left) and habitat (right) near the adjacent Wahiawa Reservoir.

28

Wheeler Army Airfield

Appendix Figure 23. Wheeler Army Airfield acoustic monitoring station (white dot).

Appendix Figure 24. Wheeler Army Airfield acoustic monitoring station (top) and habitat bottom).

29

Appendix 2. Frequency of nightly bat detections by month and monitoring station.

Recording

2015

2016

May -

station Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Oct avg

DIL1

0 0 0 0.03 0 0.04 0 0

0.01

DIL2

0 0 0 0 0 0 0 0

0

DIL3

0.08 0 0.03 0 0.06 0.13 0.10 0.04

0.06

FTDR

0 0 0

0

FTSH

0 0 0 0 0 0 0 0

0

HELE

0 0 0.03 0.03 0.03 0.03 0.06 0 0 0 0 0 0 0 0.03

KAH2

0 0 0 0 0 0 0.06 0 0 0

0.01

KAH3

0.08 0 0 0 0 0 0.04 0 0 0 0 0 0

0.01

KAH4

0 0 0 0 0 0 0.03 0 0 0 0 0 0 0 0.01

KAW1

0 0 0 0 0 0.03 0.03 0 0.03 0 0 0

0.02

KAW2

0.13 0

0 0.06 0 0 0 0 0 0 0 0 0.01

KAW3

0 0 0 0 0 0 0 0 0

0

KAW4

0.04 0 0 0 0 0 0 0

0

MAKA1

0 0.03 0.03 0 0 0 0.03 0.07 0 0 0 0 0 0 0.02

MAKA2

0 0 0 0.03 0 0 0 0 0 0

0.01

MAKA3

0 0 0 0 0

0

MAKA4

0 0 0 0 0 0 0 0

0

ER1 0 0 0 0 0 0 0 0 0

0

ER2 0 0 0 0 0 0 0 0 0

0

ER3 0 0.04 0 0 0 0 0 0 0 0 0 0 0 0 0 0

ER4 0.25 0.15 0 0 0 0 0 0.06 0.03 0

0.02

WR1 0 0.11 0 0 0 0 0.06 0.10 0.33

0.10

WR2 0.60 0.20 0.44 0.33

0.20 0.25

0.23

WR3 0.40 0.04 0.06 0.07 0.16 0.13 0.29 0.10 0.40 0.13 0.07 0.16 0.13 0.17 0.05 0.20

WR4 0 0 0 0 0 0 0 0 0

0

WR5

0.04 0.13 0.03 0 0.10 0 0.13 0 0 0

0.04

TRIP

0 0 0 0 0 0 0.03 0 0 0.03 0 0

0.01

MEND 0.25 0.04 0.04 0.06 0.03 0 0 0 0 0 0 0 0 0

0.01

WHEE 0 0 0.03 0.03 0.03 0 0 0 0 0 0 0

0.01