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Special Publications Title Special Publications From Field to Laboratory: A Memorial Volume In Honor of Robert J. Baker Edited by

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  Special Publications Museum of Texas Tech University  Number xx xx XXXX 2010 Title     Special Publications Museum of Texas Tech University  Number 71 11 October 2019 From Field to Laboratory: A Memorial Volume In Honor of Robert J. Baker Edited by Robert D. Bradley, Hugh H. Genoways, David J. Schmidly, and Lisa C. Bradley   T EMPORAL  P ATTERNS   OF  B AT  A CTIVITY   ON   THE  H IGH  P LAINS   OF  T EXAS  J  ULIE   A. P   ARLOS   , M   ACY   A. M   ADDEN   , L  IZETTE   S   ILES   , F   AISAL  A  LI   A  NWARALI   K   HAN   , C   IBELE   G. S  OTERO -C   AIO  ,  K   ENDRA  L. P   HELPS   , R OBERT   J. B  AKER  ,  AND  R OBERT   D. B  RADLEY  A BSTRACT Texas is home to more wind turbines and more bat species than any other state in the United States. Insectivorous bats provide an important economical ecosystem service in this region through agricultural pest regulation. Unfortunately, bats can be impacted negatively by wind turbines, and migratory bat species particularly so. To understand how bat activity changes throughout the year in western Texas, activity was monitored through echolocation calls and opportunistic mist-netting efforts over a  period of four years (2012–2015). Peaks in activity were observed from March through April, and again in September, which coincides with previously documented migra - tory periods for many species native to the High Plains of Texas. Findings presented herein suggest that urban habitats are preferred stopover sites for migratory bat species while traversing arid regions such as those occurring in western Texas. In addition to human-made structures, urban habitats harbor non-native trees that provide suitable roost sites, aggregations of insect prey swarming outdoor light sources, and articial water sources. It is important to understand bat activity in western Texas, not only for the benet of agricultural pest suppression, but also to predict how the expansion of wind energy may affect bat populations in this region. Key words:   active monitoring, agriculture, driving transect, echolocation calls,  passive monitoring, West Texas, wind energy I NTRODUCTION The High Plains ecoregion of western Texas is characterized by a relatively at topography, an arid climate with scarce water sources, and a shortgrass  prairie habitat that is largely depauperate of trees (Price et al. 1997; Grifth et al. 2007). Many bat species na- tive to Texas are dependent on trees as roosting sites (Schmidly and Bradley 2016), thus the nearly treeless landscape of the High Plains may deter bats from using Lubbock and surrounding counties as stopover sites during migration; some bat species appear to migrate through the High Plains instead of inhabiting the region year-round. Moreover, as much as 80% of the High Plains ecoregion has been converted to agricultural lands, which contributes to the loss of native prairie habitats and reduction in water resources available for wildlife due to irrigation demands (Schmidly 2002).Despite these inhospitable conditions, over a third of all bat species native to Texas (i.e., 12 of 33 species) have been recorded in Lubbock and adjacent counties (Ammerman et al. 2012). Museum records of three migratory bats that occur in western Texas (  Aeo-restes cinereus ,  Lasiurus borealis , and  Lasionycteris noctivagans ) suggest a seasonal peak in the presence of these species likely occurs across the High Plains (Cryan 2003). Although another bat species, Tadarida brasiliensis , also is migratory (Glass 1982),  A. cinereus ,  Lasiurus borealis , and  Lasionycteris noctivagans  are the more frequent species found to collide with turbines (Arnett et al. 2008). Though museum records do not specify whether bats were caught in urban areas or not, one potential explanation for peaks in seasonal activity of migratory bats could be the availability of atypical roost sites in the region, specically planted trees in urban green spaces (e.g., parks, golf courses, residential yards). Many bat species, including migratory species, also have been documented to roost in occupied and abandoned human-made structures, such as buildings 275  276 S PECIAL  P UBLICATIONS , M USEUM   OF  T EXAS  T ECH  U NIVERSITY and homes (McGuire et al. 2012; Schmidly and Bradley 2016). Coleman and Barclay (2012) reported higher bat activity in the urban environments of Alberta, Canada, versus the surrounding non-urban landscapes; Alberta, Canada, is located in the northern Great Plains ecore - gion and is an environment similar to western Texas. Furthermore, playas and dammed reservoir lakes in the Great Plains provide water sources known to be used by migratory birds as stopover sites (Davis and Smith 2001) and could feasibly be used as migratory stopovers by insectivorous bats, as well. Whereas urban environments provide suitable roost sites and water sources, expanding agricultural  production in the region provides native bats with ad - ditional food resources. Insectivorous bats consume agricultural pests (Cleveland et al. 2006; Kunz et al. 2011), including cotton bollworms that contribute to economic losses for local farmers exceeding millions of dollars in recent years (USDA 2019). However, along with the agricultural expansion, there has been a marked increase in the installation of wind turbine farms in western Texas. The High Plains ecoregion is ideal for wind turbines due to its consistently high wind speeds (AWS Truepower and National Renew - able Energy Laboratory 2010), yet there is mounting evidence that wind turbines have negative effects on wildlife, including mortality in bats and birds (Arnett et al. 2007, 2008; Baerwald et al. 2008; Arnett and Baerwald 2013). Declining bat populations in the High Plains could result in an increase in agricultural pests, making it more costly for farmers to achieve protable yields (Cleveland et al. 2006). Although bats play a critical role in suppressing agricultural pests in western Texas, the rapid expansion of wind energy installations potentially could threaten the long-term viability of resident and migratory bat  populations. To date, however, bats largely have been understudied in the region compared to central and east - ern Texas (Cleveland et al. 2006; Boyles et al. 2011). Challenges associated with capturing free-ying, highly maneuverable bats in open space habitats characteristic of the High Plains ecoregion likely contributes to the limited research effort on bats in western Texas. Much of our current knowledge about bat species in the Texas Panhandle is based on dead and live bats recovered by local citizens and submitted to the Texas Department of Health for rabies testing and/or bats deposited in natural history museums, including the Natural Sci - ence Research Laboratory at the Museum of Texas Tech University. To improve our understanding of the bat species native to the High Plains of western Texas, an ecoregion that has undergone historic and ongoing conversion of native prairie to agricultural croplands and wind energy installations, this study employed diverse methods to inventory species present in Lubbock and surrounding counties. Moreover, the study sought to understand if  bat activity varied throughout the year using passive and active acoustic monitoring, which allows identi -cation of seasonal peaks in activity corresponding with known migratory periods of native bat species. Bat activity is hypothesized to vary seasonally within Lubbock County; specically, a greater number of bat calls were expected to be detected during early spring (i.e., March to May) and fall (i.e., August to November), corresponding with previous records of seasonal migra - tory patterns of native species (Cryan 2003). Taken together, ndings from this study will guide develop- ment of comprehensive recommendations to mitigate  bat mortalities attributed to wind energy installations during migratory periods when bat activity is greatest,  particularly with respect to nearly treeless ecoregions expected to be inhospitable to bats. M ETHODS Study areas.—  Bat monitoring activities were conducted at two sites located within the High Plains and Rolling Plains ecoregions of Texas (Fig. 1). The rst site, Reese Technology Center (RTC), is located approximately 5 km west of Lubbock, Texas. The RTC, constructed in 1941, served as a United States Air Base (Reese Air Force Base) until 1997 when it was targeted for closure and the property was trans - ferred to the Lubbock community. The RTC contains numerous buildings (occupied and abandoned), hang - ers, runways, a water tower, a weather tower, parks and green areas with mature trees, and an adjacent  P ARLOS   ET   AL .—B AT  A CTIVITY   ON  T EXAS  H IGH  P LAINS  277 golf course with a permanent water source. One wind turbine was installed prior to the initiation of the survey and functioned intermittently. Three additional wind turbines were installed but were not yet functional during the study period; therefore, bat deaths due to wind turbines was not the focus of the study reported herein. Given that the primary objective of the study was to identify bat activity patterns, the RTC formed the basis for most of the activities conducted. Monitor  - ing was concentrated around wind turbine locations,  buildings, permanent water sources, and other sites likely to harbor bats.A second study site was comprised of a driving transect survey that extended from the northeastern  portion of the city of Lubbock, through the Canyon Lakes (CL) system, and terminated at Buffalo Springs and Ransom Canyon (approximately 20 km east of Lubbock, Texas). The CL system was established in 1971 and consists of a series of impoundments along the Yellowhouse Canyon system located in the northeastern portions of Lubbock. These man-made structures produce a series of eight lakes that not only serve as a valuable water source but also support a substantial number of large trees, which are rare in the High Plains ecoregion. This site was selected to be a  pseudo-replicate of activities being conducted at RTC. Both sites were located in or on the fringe of a large urban area that was surrounded by agricultural activities (primarily cotton production).  Mist-netting for presence of bats.—  Mist-net surveys were used to determine the current bat species  present at study sites. Attempts were made to mist-net  bats at RTC from March 2012 through June 2014. Six mist-nets were set up around the Reese Golf Center (golf course) next to vegetation corridors and ponds. Multiple mist-nets (lengths 9 m to 18 m) and mist- netting methods were utilized in an attempt to improve capture success, including arranging mist-nets in an Figure 1. Study sites in Lubbock County. The area with diagonal lines indicates Reese Technology Center (RTC) and the black line indicates roads driven during the driving transect (48 km in length).  278 S PECIAL  P UBLICATIONS , M USEUM   OF  T EXAS  T ECH  U NIVERSITY “L-shaped” formation and employing a triple high net system (BatNets.com) extending almost 7.5 m above the ground. Mist-netting was conducted twice per month from April to October, but were deployed only during periods when temperatures were above freez - ing during the winter months of November through March. Mist-nets were opened within 30 mins of sunset for a period of four to six hours and performed when weather conditions permitted, excluding evenings when temperatures decreased below freezing, rain occurred, or wind speeds exceeded 80.7 kmh. Additional mist- netting efforts were conducted elsewhere in Lubbock County and other locations across the High Plains to obtain reference echolocation calls not included in Adams (2003).  Acoustic monitoring of bat activity.—  Anabat SD2 detectors (Titley Scientic, Columbia, Missouri) were used to establish four stationary (passive) acoustic monitoring stations at RTC from January 2012 through May 2015. Three Anabat detectors were set up at struc - tures around RTC at the following locations: weather tower (approximately 50 m above the ground); water tower (approximately 40 m above the ground); and one  building (approximately 20 m above the ground). The fourth Anabat detector was near a man-made pond at the golf course (approximately 2 m above the ground) which contained water year-round. The detector located at the building was connected directly to an outlet; others were powered by rechargeable 12-volt  batteries attached to solar panel charging units. All detectors and batteries were protected against weather and solar inuence by being placed inside an ammuni- tion box. Anabat extension cables were used to set up microphones, which were placed parallel to the ground and protected with a plastic cover. Because bat species stratify by altitude, microphones were located at dif  - ferent heights to register as many species as possible in the study area. The detectors were congured to record bat calls from 1800 h to 0600 h. The four Anabat units were checked at least once a month (more frequently during severe weather periods such as high winds), and les were downloaded and analyzed using AnalookW call analysis and data man - agement software. Echolocation calls at both sites were evaluated for species identication following Adams (2003). In AnalookW, an “allbats.abf” lter was used to exclude all the noise from the les (i.e., wind, insects, machines). Bats were identied to species manually using search-phase calls and the following parameters: shape, duration, and frequencies (maximum, minimum, and characteristic). These parameters were compared to published records by Adams (2003), reference calls obtained from captured bats, and online libraries that were available at the time of this study (e.g., bat call library at Museum of Southwestern Biology and Bat Sound Services). In May 2015, record-high monthly rainfall (30.8 cm) caused water damage to, and loss of, the Anabat detector at the golf course. The rainfall caused techni - cal problems with the remaining three microphones, resulting in loss of data and cessation of data collection at RTC. Attempts were made to resolve the technical issues, but the damaged equipment was not replaced as this event occurred near the conclusion of the survey. Acoustic monitoring with an Anabat SD2 with a PDA kit (Titley Scientic, Columbia, Missouri) also was conducted during all mist-netting activities at RTC, in an effort to determine if bats were in the area but were not netted. In addition to the acoustic monitoring at RTC, a driving transect was conducted to examine bat activity on the eastern side of Lubbock, which followed the CL system and continued to Buffalo Springs Lake (Fig. 1). The 48-km transect route was selected to maximize the detection of bats by choosing wooded areas or es - tablished water sources (i.e., CL and Buffalo Springs Lake). Driving transect surveys occurred during two  periods: June 2012 through June 2013, excluding July 2012 and February 2013; and January 2014 through September 2015. The rst 12-month period was used to gather preliminary data before deciding to continue with a second study period. The driving transect was conducted using the Anabat SD2 with PDA kit and car mount following guidelines provided by Georgia Department of Natural Resources (Britzke and Herzog n.d.). Driving transects were conducted while traveling at a maximum speed of 32 kmh once per month when weather conditions were suitable. Evenings when the temperature decreased below freezing, rain occurred, or wind speeds exceeded 80.5 kmh were deemed poor weather conditions not conducive to active monitoring.
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