2008 NORTHEASTERN NATURALIST 15(2):263–274 Netting Surveys for Bats in the Northeast: Differences Associated with Habitat, Duration of Netting, and Use of Consecutive Nights Lisa Winhold1,2 and Allen Kurta1,* Abstract - Using results from a three-year mist-netting survey of bats in Michigan, we examined effects of three aspects of netting protocols on number of bats caught, relative abundance of species, species diversity, and species evenness. Netting for a second consecutive night at the same location led to a 40% reduction in number of bats captured, although relative abundance, diversity, and evenness were not affected. Proportionately fewer bats were caught during the 5th h after sunset compared with the first 4 h in a night; however, diversity and evenness were greater in the 5th h compared with the first 4 h. Diversity, evenness, and number of bats captured in nets set over wooded areas on land did not differ from nets set over water, but relative abundance differed between habitats. Even slight variations in netting protocols can lead to quantitative differences in the description of a local assemblage of bats. Introduction Surveys to determine presence of a particular species or to assess composition of an assemblage are essential components of any strategy for wildlife conservation (Wilson et al. 1996). Different types of animals require different approaches to surveys, and for small bats in summer, acoustic detection and mist-netting are the two most common sampling techniques (Kunz and Kurta 1988). Each method has advantages over the other, and consequently, they often are used in tandem (Murray et al. 1999). Although a myriad of papers are devoted to the nuances of acoustic detection and interpretation of resulting data (e.g., Broders 2003, Hayes 1997, Larson and Hayes 2000, Sherwin et al. 2000, Tibbels 1999), surprisingly little information is available comparing different netting protocols, implying that all netting studies are alike. Mist-netting for bats in the Northeast often is associated with surveys attempting to establish the presence of Myotis sodalis Miller and Allen (Indiana bat), an endangered species (Hutson et al. 2001, Kurta and Kennedy 2002). Although Indiana bats are the impetus for such projects, the resulting data frequently are used to characterize entire assemblages of bats (e.g., Brack and Whitaker 2004; Brack et al. 1984, 2004; Carroll et al. 2002; Hoffman et al. 2006; Kessler et al. 1981; Kurta et al. 1989; Lacki and Bookhout 1983; Lacki and Hutchinson 1999; Sparks et al. 1998; Ulrey et al. 2005; Whitaker and Gummer 2001; Whitaker et al. 2005). However, 1Department of Biology, Eastern Michigan University, Ypsilanti, MI 48197. 2Current address - BHE Environmental, Inc., 11733 Chesterdale Road, Cincinnati, OH 45246. *Corresponding author - akurta@emich.edu. 264 Northeastern Naturalist Vol. 15, No. 2 methods used for these surveys have differed in numerous ways, such as habitat in which nets are placed, number and height of nets, composition of netting material (e.g., braided vs. monofilament threads), number of nights that each site is netted, and nightly duration of netting. Protocols commonly vary between and even within studies. Brack et al. (2004), for example, combine netting data obtained from dusk to dawn, dusk to 0200 hours, and dusk to midnight when describing the bat assemblage in the Hoosier National Forest of Indiana. In recent years, the search for Indiana bats has become standardized and follows a protocol formulated by the US Fish and Wildlife Service (1999, 2007). Surveys for Indiana bats now require two large mist-netting systems (typically 6.5–9 m tall) that are spaced at least 30 m apart and positioned so that the nets reach into the forest canopy. Netting can occur only on warm (≥10 °C), dry nights and must last from sunset until at least 5 h after sunset. Furthermore, each site must be surveyed for two nights, which are usually consecutive, and netting can occur only between 15 May and 15 August, which represents the maternity period for Indiana bats and most other species in the East. We recently completed a three-year mist-netting survey of bats in southern Lower Michigan (Winhold 2007), seeking Indiana bats and generally following the guidelines of the US Fish and Wildlife Service (1999, 2007). Herein, we use subsets of that data to examine three aspects of netting protocols and their potential effect on perceived relative abundance of species, species diversity, and species evenness (Brower and Zar 1984) of a regional assemblage. We examine specifically whether our quantitative description of the bat assemblage in southern Michigan changes if netting occurs for 4 h rather than 5 h after sunset, takes place on one versus two nights at the same location, and involves nets placed in upland wooded sites or wooded areas near streams and ponds. Although the present paper is based on data obtained with the current protocol recommended for Indiana bats (US Fish and Wildlife Service 1999, 2007), our results have ramifications for the design of surveys for other bat assemblages, as well as interpretation of previously completed studies and comparisons among them. Methods Study area We predominantly netted bats at rural sites in the southern four tiers of counties in Michigan (Winhold 2007). Southern Lower Michigan is composed of lake plains and moraines that are fine-to-coarse textured and characterized by low relief, with a maximum elevation of ca. 250 m (Albert et al. 1986). Although the land mostly was covered by deciduous forest at the time of European settlement, agriculture is the dominant land use today, and significant urban sprawl is occurring in some areas; consequently, remaining patches of forest are small and fragmented, and most land is privately owned. Small streams, lakes, and ponds are abundant (Albert et al. 1986, 2008 L. Winhold and A. Kurta 265 Winhold 2007). Only one small cave, ca. 60 m long, occurs in this glaciated region (Davies 1955, Kurta et al. 2007). Netting and handling techniques Netting occurred between 15 May and 15 August 2004–2006. Most nets were made from 50-denier, braided nylon (Avinet, Dryden, NY), and a typical netting system was 9 m high and either 9 or 13 m wide. Two netting systems were used at most sites, with individual nets placed about 100 m apart. Netting took place at most sites on two nights, usually consecutively, with nets remaining in the same position for the second night. We netted from sunset to ca. 5 h after sunset and checked each net at least every 15 min. Nets were stretched across potential foraging/commuting corridors, such as county roads, primitive roads (two-tracks), pipeline corridors, woodland edges, and streams. Indiana bats roost and forage predominantly in deciduous woodlands (Gardner et al. 1991, Kurta 2005, Sparks et al. 2005, US Fish and Wildlife Service 2007), and consequently, all our netting sites were in areas of mature deciduous woods. Potential netting areas were identified from topographic maps, county maps, and aerial photographs, and actual sites were chosen primarily based on land-owner cooperation and presence of a suitable flight corridor. Captured bats were identified to species and either punch-marked (Bonaccorso and Smythe 1972) or banded (Lambournes, Ltd., Leominster, Middlesex, UK) before release for future identification. Marked bats occasionally were recaptured later in the same evening (6.3%) and even more rarely on the second night (1.3%) (Winhold 2007), but to preserve independence, these repeat captures were not used in any analysis. On some dates, cold ambient temperatures (<10 °C) or prolonged rain dramatically shortened the duration of netting, and these data also were eliminated from all analyses to be consistent with the protocol recommended by the US Fish and Wildlife Service (2007). Statistical techniques We characterized the assemblage of bats by calculating a value for species diversity and evenness. As a measure of diversity, we used Simpson’s index, which is equal to: 1 - [ Σ ni (ni - 1)] / N (N - 1), where ni is the number of individuals from each species and N is the grand total of captured individuals (Brower and Zar 1984). We compared values of diversity using a t-test with infinite degrees of freedom (Brower and Zar 1984). Evenness was calculated by taking the ratio of observed diversity and maximum possible diversity for an assemblage with a given number of individuals and species (Brower and Zar 1984). Maximum diversity was calculated as: [(s - 1) / s] * [N / (N - 1)], where s equals number of different species in the sample and N represents the grand total of captured individuals. For the data retained for analysis, each species was included in calculations of diversity and evenness, and no species were deleted or combined. 266 Northeastern Naturalist Vol. 15, No. 2 We generally used t-tests to analyze differences in number of bats caught per night and chi-squared tests to examine differences in relative abundance of species. We eliminated three morphologically dissimilar species from statistical analyses of relative abundance because of an extremely small number of captures (see Results). These species were Lasionycteris noctivagans (Le Conte) (silver-haired bat), Lasiurus cinereus Palisot de Beauvois (hoary bat), and Nycticeius humeralis (Rafinesque) (evening bat). In addition, we combined three morphologically similar species of Myotis—M. lucifugus (Le Conte) (little brown bat), M. septentrionalis (Trouessart) (northern bat), and Indiana bat—into one category for analyses of relative abundance. Although combining all Myotis into a single group may obscure ecological differences within the genus, such consolidation is a common procedure for acoustic surveys in the Northeast (e.g., Furlonger et al. 1987, Jung et al. 1999, Krusic and Neefus 1996, Reynolds 2006, Zimmerman and Glanz 2000) and also was necessary to avoid small expected values when analyzing our data using chi-squared tests. Hence, tests of relative abundance used a 3-by-2 contingency table, with Eptesicus fuscus Palisot de Beauvois (big brown bat), Lasiurus borealis Müller (eastern red bat), and Myotis as the three categories. If the null hypothesis of no change in relative abundance was rejected, we used the sum of the partial chi-squared value for each group as an indication of which group was most responsible for the overall change (Steele and Torrie 1980). Calculations were performed using a standard spreadsheet (Excel, Microsoft, Redmond, WA). Alpha was set at 0.05 for all statistical tests. Means are presented with the associated standard error. Results Overall captures During 2004–2006, we netted bats on 135 calendar nights, for 266 net-nights, at 75 sites. Overall, we captured 948 bats from eight species (Table 1). Big brown bats were the most commonly netted species and Table 1. Number and percentage of bats captured in southern Lower Michigan during a netting survey on 135 calendar nights, for 266 net-nights, at 75 sites, between 15 May and 15 August 2004–2006. Species Number of bats Eptesicus fuscus (big brown bat) 768 (81.0%) Lasionycteris noctivagans (silver-haired bat) 1 (0.1%) Lasiurus borealis (eastern red bat) 116 (12.2%) Lasiurus cinereus (hoary bat) 7 (0.7%) Myotis lucifugus (little brown bat) 37 (3.9%) Myotis septentrionalis (northern long-eared bat) 6 (0.6%) Myotis sodalis (Indiana bat) 12 (1.3%) Nycticeius humeralis (evening bat) 1 (0.1%) Total 948 2008 L. Winhold and A. Kurta 267 represented 81% of the catch. Red bats were second most abundant at 12%. All other species were uncommon and contributed less than 4% each to the total. All species known to exist in the area were captured, except a new immigrant, Perimyotis subflavus (Kerr) (eastern pipistrelle); a few individuals of this migratory species recently began hibernating in a small cave in the extreme southwestern corner of the state, but where they spend the summer is unknown (Kurta et al. 2007). Netting over land versus over water Two major types of wooded habitat were sampled in this study: terrestrial locations (roads and trails through woods not associated with ponds or streams, edges of woodlots) and sites that were over or adjacent to water (perennial streams, edges of ponds, natural corridors through riparian forest). For a few bats, the specific net in which the animal was captured was not recorded. Consequently, we eliminated 35 bats (4%) from the analysis, which left 913 bats from 72 sites. Of the 253 net-nights in this modified data set, 131 were over water, and 122 were over land. Number of bats captured per night over water (3.9 ± 0.4 bats) was not significantly (t251 = 1.06; P = 0.15) greater than number of captures over land (3.3 ± 0.4 bats). There was, however, a significant difference (χ2 2 = 27.78; P < 0.001) in relative abundance between habitats (Table 2). Although big brown bats comprised ca. 80% of total captures in either Table 2. Number and percentage of bats captured in various habitats, at different times of night, and on different days during a netting survey in southern Lower Michigan, between 15 May and 15 August 2004–2006. Habitat Time of night Repeat netting Species Land Water First 4 h Fifth h Night 1 Night 2 Eptesicus fuscus 332 414 680 69 447 261 (82.2%) (79.9%) (83.3%) (69.7%) (82.5%) (80.3%) Lasionycteris noctivagans 1 1 1 (0.2%) (0.1%) (0.3%) Lasiurus borealis 62 50 97 18 61 38 (15.3%) (9.7%) (11.9%) (18.2%) (11.3%) (11.7%) Lasiurus cinereus 2 5 4 3 3 4 (0.5%) (1.0%) (0.5%) (3.0%) (0.6%) (1.2%) Myotis lucifugus 37 22 3 18 17 (7.1%) (2.7%) (3.0%) (3.3%) (5.2%) Myotis septentrionalis 3 3 3 2 5 1 (0.7%) (0.6%) (0.4%) (2.0%) (0.9%) (0.3%) Myotis sodalis 4 8 8 4 8 2 (1.0%) (1.5%) (1.0%) (4.0%) (1.5%) (0.6%) Nycticeius humeralis 1 1 1 (0.2%) (0.1%) (0.3%) Total 404 518 816 99 542 325 268 Northeastern Naturalist Vol. 15, No. 2 habitat, Myotis was encountered more frequently over water, and red bats were slightly more common over land, as suggested by the magnitude of the individual contributions to overall χ2 (Table 3). Species diversity (Simpson’s index) over land (0.30) was significantly lower (t∞ = 2.43; P < 0.01) than over water (0.35), and evenness was 10% lower over land (0.36) than over water (0.40). Netting in the 5th h versus the first 4 h after sunset Most previous netting in Michigan (Kurta 1980, Kurta and Teramino 1992, Kurta et al. 1989) was performed for only 4 h after sunset, whereas the current protocol recommended by the US Fish and Wildlife Service (2007) requires netting for 5 h after sunset. Can our new data be compared directly with earlier results, or does the longer duration of netting affect the resulting picture of the bat assemblage? If the data are comparable, then diversity, evenness, and relative abundance in the 5th h after sunset during the present study should be statistically indistinguishable from diversity, evenness, and relative abundance that are calculated using only data for the first 4 h after sunset. During our study, time of night at which a bat was captured occasionally was not recorded, so we removed 42 individuals (4.4%) from this analysis, which left 906 bats from 75 sites. A significant difference (χ2 2 = 9.82; P < 0.001) in relative abundance was detected (Table 3). This difference was mostly attributable to a doubling of the proportion of Myotis in the last hour. In addition, red bats increased their contribution from 12% of the catch in the first 4 h to 18% in the 5th hr. As one might surmise from these changes in relative abundance, species diversity was significantly higher (t∞ = 5.18; P < 0.001) in the 5th h (0.48) compared with the first 4 h (0.29) after sunset, and evenness was almost twice as great in the 5th h (0.57) than earlier in the evening (0.33). Netting on the first night versus the second night at a site If netting occurs at a site on one night closely followed by a second night at the same site, does the extra night of netting influence number of individuals that are caught or quantitative descriptions of the assemblage, Table 3. Comparison of relative abundance determined by various netting procedures used during 2004–2006, after deleting uncommon species and combining all species of Myotis. Time of night Habitat First Fifth Repeat netting Species Land Water χ2 4 h h χ2 Night 1 Night 2 χ2 Eptesicus fuscus 332 414 0.10 680 69 1.51 447 261 0.03 Lasiurus borealis 62 50 5.95 97 18 3.10 61 38 0.06 Myotis 7 48 21.73 33 9 5.20 31 20 0.09 Total 401 512 27.78A 810 96 9.82A 539 319 0.18B A2 d.f.; P < 0.001. B2 d.f.; P > 0.05. 2008 L. Winhold and A. Kurta 269 i.e., are there differences in relative abundance, diversity, or evenness between nights? To answer these questions, we examined our data after excluding 15 sites at which netting occurred on only one night. At the remaining 60 sites, 542 bats were captured on the first night, and 325 bats were taken on the second night, indicating a 40% decline in number of animals caught (Table 2). An average of 9.0 ± 1.1 bats was netted on the first night, but only 5.4 ± 0.7 individuals were caught during the second evening (paired t59 = 4.50; P < 0.0001). Although number of captures was different between nights, relative abundance did not differ (χ2 2 = 0.18; P > 0.75; Table 3). Similarly, diversity during the first night (0.31) was indistinguishable (t∞ = 1.71; P > 0.05) from that on the second night (0.34), and evenness also varied little between nights (0.37–0.39). Nevertheless, netting for a second night did lead to increased species richness at some individual sites. Big brown bats, for example, were caught at a total of 58 sites, and at six (10%) of these locations, they were encountered only on the second night. Similarly, number of sites that yielded red bats only on the second night was seven (17%); hoary bats, four (57%); silver-haired bats, one (100%); northern bats, one (17%); and evening bats, one (100%). The protocol established for Indiana bats (US Fish and Wildlife Service 1999, 2007) requires two nights of netting to establish presence/absence of the species, but all sites (n = 5) that yielded Indiana bats in our study happened to do so on the first night. Discussion The guidelines for netting Indiana bats (US Fish and Wildlife Service 1999, 2007) have been the basis for two other recent papers that have broad applicability for netting protocols. MacCarthy et al. (2006) indicated that number of captures could be increased by checking nets more frequently than the recommended 15 minutes, and Carroll et al. (2002) showed that relative abundance differs, depending on whether nets are set in the interior of forests or on woodland edges and across wooded corridors. Our data also indicate that different quantitative results are obtained when using the recommended protocol, depending on timing of netting and location of nets (Tables 2 and 3). For example, species diversity, evenness, and relative abundance of bats caught during the 5th h after sunset are significantly different from results obtained during the first 4 h (Table 3). Although relative abundance of bats that are captured might be affected by distance between the netting site and a roost, particularly for colonial species (Fenton 1970, Kunz 1973), this problem is most likely to cause bias when only one or a few sites are netted. We had no knowledge of the location of any roost of any species when selecting our 75 netting sites, and based on the size of our sample, we assumed that the observed changes in diversity, evenness, and relative abundance in the 5th h resulted from species-specific patterns of nocturnal behavior (Kunz 1973) that are typical of southern Michigan. 270 Northeastern Naturalist Vol. 15, No. 2 These significant temporal differences (Tables 2 and 3) indicate that we cannot directly compare our results to earlier studies in Michigan that lasted for only 4 h after sunset (Kurta 1980, Kurta et al. 1989), and we suggest that other biologists should not compare or combine relative abundance, diversity, or evenness of different assemblages if duration of netting differs (e.g., Baker and Lacki 2004, Brack et al. 2004, Sparks et al. 1998, Ulrey et al. 2005), even by as little as 1 h. Furthermore, we question use of protocols that require netting to end at a specified time, such as midnight or 0200 hours (e.g., Duff and Morell 2007, Whitaker et al. 2005), because duration of netting necessarily would vary depending on date (shorter near the summer solstice) and location (shorter in summer to the north and west within the same time zone). Within our study area, differences in netting effort could amount to almost 1 h per night, if a specific ending time were used. For example, if a survey begins at local sunset and ends at 0100 hours, duration of netting on 15 August at Luna Pier, Monroe County, would be 4.43 h, whereas duration of netting on 22 June at Grand Haven, Ottawa County, would be only 3.53 h (US Naval Observatory 2007). Although netting for an additional hour affects overall results, netting for a second, consecutive, 5-h night has little impact on quantitative descriptors of the regional assemblage (Tables 2 and 3). In southern Michigan, species diversity, evenness, and relative abundance of the assemblage do not change on the second night, even though species that are not captured on the first night at individual locations occasionally are netted on the second night, as one would predict from site-specific species-accumulation curves (Moreno and Halffter 2000, Weller and Lee 2007). However, total number of bats caught declined by 40%, from 9.0 to 5.4 bats/night (Table 2). The decrease in number of animals captured suggests that bats learn the position of a net and avoid it on the second evening or that disturbance involved with netting causes bats to change the location of their activity (Kunz and Brock 1975). Netting at a greater number of sites throughout a region, rather than repeat netting at each site, obviously yields a greater number of individuals from the assemblage (Table 2) and may be more efficient in detecting uncommon species (Weller and Lee 2007), such as the endangered Indiana bat. Netting wooded corridors and edges over land yields the same number of bats per night as does netting at wooded sites over or adjacent to open water in our area, but differences in relative abundance exist between these two broadly defined habitats (Table 3). Although the big brown bats are ubiquitous, a significantly greater proportion of red bats were caught over land, and Myotis was encountered more commonly over water (Table 2). Our results are consistent with those of Furlonger et al. (1987), who relied on acoustic detection of flying bats, rather than netting captures, to detect differences in activity by big brown bats, red bats, and Myotis among habitats in a similar landscape in nearby southern Ontario. Such differences in use of wooded habitats likely reflect, at least partly, dietary differences and location of suitable prey. Little brown bats, for 2008 L. Winhold and A. Kurta 271 example, feed primarily on insects with aquatic larval stages (Anthony and Kunz 1977, Brack et al. 1984), such as caddisflies (Trichoptera) and mayflies (Ephemeroptera), so it is not surprising that our Myotis sample, which is dominated by little brown bats, is more common over or near water. Red bats, on the other hand, typically include fewer of these small insects in their diet, often concentrating instead on moths and bugs (Homoptera; Brack et al. 1984, Mumford and Whitaker 1982). Whatever the cause of these habitat differences in capture success, our results suggest that studies that target red bats or little brown bats should preferentially sample terrestrial or aquatic habitats, respectively, but any netting survey in the Northeast that attempts to document an entire assemblage should include nets across corridors in both types of wooded habitats, as well as locations within forest interiors (Carroll et al. 2002). Furthermore, biologists should be wary of combining data obtained from unequally sampled habitats or comparing studies that have not sampled the available habitats in the same way (e.g., Whitaker et al. 2005). Our study shows that even small differences in netting protocols can lead to statistically significant changes in number of bats captured and relative abundance of species (Table 3), which in turn affects indices of diversity and evenness. Understanding these effects could result in the design of more reliable and efficient studies, whether they target specific species or are intended as broad surveys. More importantly, our data quantitatively show that use of differing protocols may confound comparison of bat assemblages, such as those in different geographic areas or at different points in time (e.g., Baker and Lacki 2004, Sparks et al. 1998, Winhold 2007). Comparisons between studies should only be made if netting protocols are sufficiently described and known to be substantially similar (see also Weller 2007). Acknowledgments Field work was funded by grants to L. Winhold from Bat Conservation International and to A. Kurta from the State Wildlife Grants Program, Michigan Department of Natural Resources. We thank M. Becker, M. Camilleri, K. Clinansmith, J. Dudak, M. Farmer, R. Foster, K. Foster, S. Friedl, M. Gorecki, E. Hough, T. Jones, M. Kurta, M. Luelleman, S. Miller, L. Peter, H. Rice, M. Sauter-Portelli, D. Starkey, B. Wilson, K. Winhold, T. Winhold, and E. Winterhalter for help with field work. Literature Cited Albert, D.A., S.R. Denton, and B.V. Barnes. 1986. Regional Landscape Ecosystems of Michigan. University of Michigan, School of Natural Resources, Ann Arbor, MI. 32 pp. Anthony, E.L.P., and T.H. Kunz. 1977. Feeding strategies of the little brown bat, Myotis lucifugus, in southern New Hampshire. Ecology 58:775–786. Baker, M.D., and M.J. Lacki. 2004. Forest bat communities in the East Cascade Range, Washington. Northwest Science 78:234–241. Bonaccorso, F.J., and N. Smythe. 1972. Punch-marking bats: An alternative to banding. Journal of Mammalogy 53:389–390. 272 Northeastern Naturalist Vol. 15, No. 2 Brack, V., Jr., and J.O. Whitaker, Jr. 2004. Bats of the Naval Surface Warfare Center at Crane, Indiana. Proceedings of the Indiana Academy of Science 113:66–75. Brack, V., Jr., S. Taylor, and V.R. Holmes. 1984. Bat captures and niche partitioning along portions of three rivers in southern Michigan. Michigan Academician 16:391–399. Brack, V., Jr., J.O. Whitaker, Jr., and S.E. Pruitt. 2004. Bats of Hoosier National Forest. Proceedings of the Indiana Academy of Science 113:76–86. Broders, H.G. 2003. Another quantitative measure of bat species activity and sampling intensity considerations for the design of ultrasonic monitoring studies. Acta Chiropterologica 5:235–242. Brower, J.E., and J.H. Zar. 1984. Field and Laboratory Methods for General Ecology. Wm. C. Brown, Dubuque, IA. 226 pp. Carroll, S.K., T.C. Carter, and G.A. Feldhamer. 2002. Placement of nets for bats: Effects on perceived fauna. Southeastern Naturalist 1:193–198. Davies, W.E. 1955. Caves and related features of Michigan. National Speleological Society Bulletin 17:23–31. Duff, A.A., and T.E. Morell. 2007. Predictive occurrence models for bat species in California. Journal of Wildlife Management 71:693–700. Fenton, M.B. 1970. A technique for monitoring bat activity with results obtained from different environments in southern Ontario. Canadian Journal of Zoology 48:429–444. Furlonger, C.L., H.J. Dewar, and M.B. Fenton. 1987. Habitat use by foraging insectivorous bats. Canadian Journal of Zoology 65:284–288. Gardner, J.E., J.D. Garner, and J.E. Hofmann. 1991. Summer-roost selection and roosting behavior of Myotis sodalis (Indiana bat) in Illinois. Illinois Natural History Survey, Champaign, IL. 56 pp. Hayes, J. P. 1997. Temporal variation in activity of bats and the design of echolocation- monitoring studies. Acta Chiropterologica 2:225–236. Hofmann, J.E., J.F. Merritt, J.M. Mengelkoch, and S.K. Carpenter. 2006. A mistnetting survey for bats in northeastern Illinois. Illinois Natural History Survey Technical Report 2006(6):1–18. Hutson, A.M., S.P. Mickleburgh, and P.A. Racey. 2001. Microchiropteran Bats: Global Status Survey and Conservation Action Plan. International Union for the Conservation of Nature and Natural Resources, Glan, Switzerland. 268 pp. Jung, T.S., I.D. Thompson, R.D. Titman, and A.P. Applejohn. 1999. Habitat selection by forest bats in relation to mixed-wood stand types and structure in central Ontario. Journal of Wildlife Management 63:1306–1319. Kessler, J.S., W.M. Turner, and L. Morgan. 1981. A survey for the Indiana bat, Myotis sodalis, on Knob Creek, Bullitt County, Kentucky. Transactions of the Kentucky Academy of Science 42:38–40. Krusic, R.A., and C.D. Neefus. 1996. Habitat associations of bat species in the White Mountain National Forest. Pp. 185–198, In R.M.R. Barclay and R.M. Brigham, (Eds.). Bats and Forest Symposium. British Columbia Ministry of Forests, Victoria, BC, Canada. 292 pp. Kunz, T.H. 1973. Resource utilization: Temporal and spatial components of bat activity in central Iowa. Journal of Mammalogy 54:14–32. Kunz, T.H., and C.E. Brock. 1975. A comparison of mist nets and ultrasonic detectors for monitoring flight activity of bats. Journal of Mammalogy 56:907–911. 2008 L. Winhold and A. Kurta 273 Kunz, T.H., and A. Kurta. 1988. Capture methods and holding devices. Pp. 1–29, In T.H. Kunz (Ed.). Ecological and Behavioral Methods for the Study of Bats. Smithsonian Institution Press, Washington, DC. 533 pp. Kurta, A. 1980. The bats of southern Lower Michigan. M.Sc. Thesis, Michigan State University, East Lansing, MI. 147 pp. Kurta, A. 2005. Roosting ecology and behavior of Indiana bats (Myotis sodalis) in summer. Pp. 29–42, In K.C. Vories and A. Harrington (Eds.). The Indiana Bat and Coal Mining: A Technical Interactive Forum. Office of Surface Mining, US Department of the Interior, Alton, IL. 229 pp. Kurta, A., and J. Kennedy (Eds.). 2002. The Indiana Bat: Biology and Management of an Endangered Species. Bat Conservation International, Austin, TX. 253 pp. Kurta, A., and J.A. Teramino. 1992. Bat community structure in an urban park. Ecography 15:257–261. Kurta, A., T. Hubbard, and M.E. Stewart. 1989. Bat species diversity in central Michigan. Jack-Pine Warbler 67:80–87. Kurta, A., L. Winhold, J.O. Whitaker, Jr., and R. Foster. 2007. Range expansion and changing abundance of the eastern pipistrelle (Chiroptera: Vespertilionidae) in the central Great Lakes region. American Midland Naturalist 157:404–411. Lacki, M.J., and T.A. Bookhout. 1983. A survey of bats in the Wayne National Forest, Ohio. Ohio Journal of Science 83:45–50. Lacki, M.J., and J.T. Hutchinson. 1999. Communities of bats (Chiroptera) in the Greyson Lake region, northeastern Kentucky. Journal of the Kentucky Academy of Science 60:9–15. Larson, D.J., and J.P. Hayes. 2000. Variability in sensitivity of Anabat II bat detectors and a method of calibration. Acta Chiropterologica 2:209–213. MacCarthy, K.A., T.C. Carter, B.J. Steffen, and G.A. Feldhamer. 2006. Efficacy of mist-net protocol for Indiana bats: A video analysis. Northeastern Naturalist 13:25–28. Moreno, C.E., and G. Halffter. 2000. Assessing the completeness of bat biodiversity inventories using species accumulation curves. Journal of Applied Ecology 37:149–158. Mumford, R.E., and J.O. Whitaker, Jr. 1982. Mammals of Indiana. Indiana University Press, Bloomington, IL. 537 pp. Murray, K.L., E.R. Britzke, B.M. Hadley, and L.W. Robbins. 1999. Surveying bat communities: A comparison between mist nets and the Anabat II bat detector system. Acta Chiropterologica 1:105–112. Reynolds, D.S. 2006. Monitoring the potential impact of a wind-development site on bats in the Northeast. Journal of Wildlife Management 70:1219–1227. Sherwin, R.E., W.L. Gannon, and S. Haymond. 2000. The efficacy of acoustic techniques to infer use of habitat by bats. Acta Chiropterologica 2:145–154. Sparks, D.W., J.A. Laborda, and J.O. Whitaker, Jr. 1998. Bats of the Indianapolis International Airport as compared to a more rural community of bats at Prairie Creek. Proceedings of the Indiana Academy of Science 107:171–179. Sparks, D.W., J.O. Whitaker, Jr., and C.M. Ritzi. 2005. Foraging ecology of the endangered Indiana bat. Pp. 15–27, In K.C. Vories and A. Harrington (Eds.). The Indiana Bat and Coal Mining: A Technical Interactive Forum. Office of Surface Mining, US Department of the Interior, Alton, IL. 229 pp. Steele, R.G.D., and J.H. Torrie. 1980. Principles and Procedures of Statistics: A Biometrical Approach. McGraw-Hill, New York, NY. 235 pp. Tibbels, A. 1999. Do call libraries reflect reality? Bat Research News 40:153–155. 274 Northeastern Naturalist Vol. 15, No. 2 Ulrey, W.A., D.W. Sparks, and C.M. Ritzi. 2005. Bat communities in highly impacted areas: Comparing Camp Atterbury to the Indianapolis Airport. Proceedings of the Indiana Academy of Science 114:73–76. US Fish and Wildlife Service. 1999. Indiana bat (Myotis sodalis) revised recovery plan. Agency draft. Fort Snelling, MN. 60 pp. US Fish and Wildlife Service. 2007. Indiana bat (Myotis sodalis) draft recovery plan: First revision. Fort Snelling, MN. 258 pp. US Naval Observatory. 2007. Table of sunset/sunrise times for an entire year. Available online at http://aa.usno.navy.mil/data/. Accessed 17 September 2007. Weller, T.J. 2007. Assessing population status of bats in forests: Challenges and opportunities. Pp. 263–291, In M. Lacki, J. Hayes, and A. Kurta (Eds.). Bats in Forests: Conservation and Management. Johns Hopkins University Press, Baltimore, MD. 329 pp. Weller, T.J., and D.C. Lee. 2007. Mist-net effort required to inventory a forest bat species assemblage. Journal of Wildlife Management 71:251–257. Whitaker, J.O., Jr., and S.L. Gummer. 2001. Bats of the Wabash and Ohio River basins of southwestern Indiana. Proceedings of the Indiana Academy of Science 110:126–140. Whitaker, J.O., Jr., C.L. Gummer, A. Howard, W.A. Ulrey, and V. Brack, Jr. 2005. Bats of Camp Atterbury in south-central Indiana. Proceedings of the Indiana Academy of Science 114:216–223. Wilson, D.E., F.R. Cole, J.D. Nichols, R. Rudran, and M.S. Foster (Eds.). 1996. Measuring and Monitoring Biological Diversity: Standard Methods for Mammals. Smithsonian Institution Press, Washington, DC. 409 pp. Winhold, L. 2007. Community ecology of bats in southern Lower Michigan, with emphasis on roost selection by Myotis. M.Sc. Thesis. Eastern Michigan University, Ypsilanti, MI. 133 pp. Zimmerman, G.S., and W.E. Glanz. 2000. Habitat use by bats in Maine. Journal of Wildlife Management 64:1032–1040.