2012 NORTHEASTERN NATURALIST 19(4):665–672 Food Habits of Myotis leibii along a Forested Ridgetop in West Virginia Joseph S. Johnson1,*, Luke E. Dodd1, James D. Kiser2, Trevor S. Peterson3, and Kristen S. Watrous3 Abstract - Data on food habits of Myotis leibii (Eastern Small-footed Myotis) are scarce. We dissected 172 fecal samples collected from 75 adult (29 males and 46 females) and 2 juvenile (1 male and 1 female) Eastern Small-footed Myotis, captured in mist nets along a forested ridge in northeastern West Virginia in 2008. Fecal samples were dissected and prey items identified to the level of taxonomic order and, when possible, to family. Eastern Small-footed Myotis consumed eight orders of arthropods from 11 families. Lepidoptera (moths) composed 41.5% (± 1.9 SE) of adult fecal volume and were found in samples of all 75 adults. Coleoptera (beetles) contributed 30.6 ± 1.7% to adult fecal volume and were detected in samples of 97.3% of adults (n = 73). Diptera (flies) composed 16.9 ± 1.9% of adult fecal volume and were found in samples of 82.7% of adults (n = 62). Fecal samples of adult females contained a higher percent volume of Lepidoptera (45.9 ± 2.4%, n = 46) than samples of adult males (34.6 ± 3.2%, n = 29). These data provide evidence of moderate dietary specialization on Lepidoptera and demonstrate dietary variation between sexes. Data also indicate Coleoptera and Diptera as important taxonomic groups in the diet of Eastern Small-footed Myotis . Introduction Myotis leibii Audubon and Bachman (Eastern Small-footed Myotis) is a small, forest-dwelling bat found uncommonly in much of the eastern United States (Barbour and Davis 1974, Best and Jennings 1997, Erdle and Hobson 2001). The Eastern Small-footed Myotis is currently listed as rare or imperiled throughout its range and is one of several species of bat currently affected by White-nose Syndrome (NatureServe 2011, Turner et al. 2011). Little data on the ecology of Eastern Small-footed Myotis have been available until recently. Although several studies support the long-held belief that this species relies heavily on rocksubstrate or similar anthropogenic structures, such as bridges, for day roosting (Barbour and Davis 1974, Johnson and Gates 2008, Johnson et al. 2011), maternity roosts inside wooden man-made structures are also reported (O’Keefe and LaVoie 2011). Data from West Virginia show that Eastern Small-footed Myotis consistently day-roost in well-defined patches of rocky habitat and have small home ranges compared to other North American species of bat (Johnson and Gates 2008; Johnson et al. 2009, 2011; Lacki et al. 2007a). Recent studies suggest that the Eastern Small-footed Myotis consumes a variety of insects, with moderate specialization for Lepidoptera (moths), as well as 1University of Kentucky, Lexington, KY 40546. 2Stantec Consulting, Louisville, KY 40223. 3Stantec Consulting, Topsham, ME 04086. *Corresponding author - joseph.johnson@ uky.edu. 666 Northeastern Naturalist Vol. 19, No. 4 frequent consumption of Coleoptera (beetles) and Diptera (flies) (Johnson and Gates 2007, Moosman et al. 2007). Limited evidence suggests this species may be capable of gleaning or opportunistically feeding while day-roosting (Johnson and Gates 2007, Moosman et al. 2007). It is not clear if diet varies seasonally or is influenced by a bat’s sex or reproductive condition in this species. Moosman et al. (2007) did not observe any difference between diets of adult males and adult females but did find a significantly lower percent volume of beetles in the diet of juveniles compared to adults. The objectives of our study were to describe the food habits of Eastern Small-footed Myotis in West Virginia and to test the hypothesis that percent volume of important prey taxa do not differ among sex and reproductive classes. Study Area and Methods Our study took place along New Creek Mountain (39.2538° N, 79.1112° W) in Grant and Mineral counties, WV. New Creek Mountain is located at the western edge of the Appalachian Ridge and Valley Physiographic Province, within the Ridge and Valley Section of the Oak-Chestnut (Quercus spp.-Castanea spp.) Forest Region, as described by Braun (1950). New Creek Mountain is predominantly forested, although patches of exposed sandstone talus occur along the western side and southern terminus of the ridge. This talus was used as day-roosting habitat by Eastern Small-footed Myotis, and an extensive description of the study area can be found in Johnson et al. (2011). Capture and handling techniques followed the guidelines of the American Society of Mammalogists for the use of animals in research (Gannon et al. 2007). We captured bats in 75-denier polyester mist nets, with a mesh size of 38 mm (Avinet, Inc., Dryden, NY). We placed nets over ridge-top roads and ponds at 12 distinct locations, and we sampled twice at each site during spring (18 April through 15 May), summer (26 May through 5 July) and fall (September) 2008. We deployed two nets at each location. Nets were opened from approximately 30 min before sunset to 5 h after sunset. We recorded age, sex, reproductive condition, mass, and length of the right forearm for each bat. Bats were determined to be adult or juvenile by examining ephiphyseal-diaphyseal fusions (calcification) of long bones in the wing (Brunet-Rossinni and Wilkinson 2009). Females were categorized as non-reproductive, pregnant, or lactating based on the presence of a fetus or condition of the teats, and males were classified as non-reproductive or scrotal based on swelling of the epididymis (Racey 2009). Captured bats were held in cloth bags for <15 min until they could be measured and released. Fecal pellets produced by bats during this time were collected and frozen for later analysis. Pellets were dissected, as described by Whitaker et al. (2009), with remains identified to taxonomic order and, when possible, to the level of family. Items that could not be identified were classified as unknown. The percent volume of each taxonomic group, unknown material, hair, and vegetation detected in a pellet was estimated to the nearest 5%. We analyzed up to 3 pellets per bat and calculated average percent volumes for each bat for subsequent 2012 J.S. Johnson, L.E. Dodd, J.D. Kiser, T.S. Peterson, and K.S. Watrous 667 analyses (Lacki et al. 2007b). We calculated frequency of occurrence of each taxonomic group in the overall diet, based on the diet of individual bats and not individual pellets. We tested for differences in percent volume of Coleoptera, Diptera, and Lepidoptera— the three most common orders in the diet—between all adult males and females using a Wilcoxon rank-sum test. We also tested for differences in percent volume of each of these three orders among non-reproductive, pregnant, and lactating females, using Kruskal-Wallis tests followed by pair-wise comparisons (χ2 test statistics; SAS Institute 2002). Samples from bats captured during the fall were not included in statistical analyses due to an insufficient number of captures (n = 2), but these data are reported in overall summaries. All means are given as ± 1 SE. Results We dissected 172 fecal pellets from 77 Eastern Small-footed Myotis (Table 1). Samples from non-reproductive females (n = 21 bats, 56 pellets) were only Table 1. Mean ± SE percent volume (percent frequency) of prey identified in fecal samples of Eastern Small-footed Myotis captured in the Appalachian Ridge and Valley Physiographic Province of West Virginia in 2008. Numbers of bats are in brackets. “Other” includes the sum of hair, plant material, and unidentifiable prey items. Item Juveniles [2] Adult females [46] Adult males [29] All adults [75] Lepidoptera 53.8 ± 3.8 (100) 52.8 ± 2.4 (100) 35.6 ± 3.7 (100) 41.5 ± 1.9 (100) Coleoptera 30.2 ± 2.2 (95.6) 31.2 ± 2.6 (100) 30.6 ± 1.7 (97.3) Unknown 21.9 ± 1.9 (100) 28.5 ± 2.1 (95.6) 30.9 ± 2.6 (100) 29.4 ± 1.6 (97.3) Carabidae 0.7 ± 0.7 (6.5) 0.4 ± 0.4 (4.0) Chrysomelidae 0.5 ± 0.4 (8.7) 0.3 ± 0.3 (3.44) 0.5 ± 0.3 (6.7) Scarabidae 0.5 ± 0.4 (4.3) 0.3 ± 0.3 (2.7) Diptera 15.5 ± 2.3 (84.7) 19.1 ± 3.2 (79.3) 16.9 ± 1.9 (82.7) Unknown 9.4 ± 9.4 (50.0) 15.0 ± 2.2 (84.7) 19.0 ± 3.2 (79.3) 16.5 ± 1.9 (82.7) Culicidae 0.3 ± 0.2 (8.7) 0.1 ± 0.1 (6.9) 0.2 ± 0.1 (8.0) Dolicopodidae 0.1 ± 0.1 (4.3) 0.1 ± 0.1 (2.7) Tipulidae 0.1 ± 0.1 (2.2) 0.1 ± 0.1 (3.4) 0.1 ± 0.1 (2.7) Neuroptera 2.1 ± 0.7 (36.9) 2.6 ± 1.2 (27.5) 2.3 ± 0.6 (33.3) Unknown 1.4 ± 0.5 (30.4) 1.0 ± 0.6 (20.6) 1.3 ± 0.4 (26.7) Chrysopidae 0.7 ± 0.5 (4.3) 0.8 ± 0.8 (3.4) 0.7 ± 0.4 (4.0) Hemerobiidae 0.1 ± 0.1 (4.3) 0.8 ± 0.6 (10.3) 0.4 ± 0.2 (6.7) Hemiptera 2.6 ± 1.0 (21.7) 4.7 ± 1.5 (37.9) 3.4 ± 0.8 (28.0) Unknown 5.0 ± 5.0 (50.0) 1.1 ± 0.6 (15.2) 2.9 ± 1.2 (27.5) 1.8 ± 0.6 (20.0) Delphacidae 0.5 ± 0.5 (2.2) 0.3 ± 0.3 (1.3) Lygaeidae 1.0 ± 0.6 (8.7) 1.8 ± 0.9 (13.7) 1.3 ± 0.5 (10.7) Hymenoptera 0.9 ± 0.5 (10.8) 0.3 ± 0.2 (6.9) 0.7 ± 0.3 (9.3) Unknown 0.8 ± 0.5 (8.7) 0.3 ± 0.2 (6.9) 0.6 ± 0.3 (8.0) Ichneumonidae 0.2 ± 0.1 (4.3) 0.1 ± 0.1 (2.7) Trichoptera 1.4 ± 0.7 (10.8) 2.6 ± 1.5 (24.1) 1.9 ± 0.7 (16.0) Araneae 0.1 ± 0.1 (3.4) 0.1 ± 0.1 (1.3) Other 10.0 ± 10.0 (50.0) 1.3 ± 1.0 (17.3) 4.8 ± 2.2 (31.0) 2.9 ± 1.1 (22.7) 668 Northeastern Naturalist Vol. 19, No. 4 collected during spring, while samples from pregnant females (n = 13 bats, 29 pellets) and males (n = 29 bats, 54 pellets) were obtained during spring and summer. Samples from lactating females (n = 12 bats, 30 pellets) were only collected during summer netting. We also dissected 3 pellets collected from one juvenile male and one juvenile female during fall netting (Table 1). Fecal samples contained insects from 7 orders, Araneae (spiders), hair, and vegetation (Table 1). Three taxonomic families previously unrecorded in the diet of Eastern Small-footed Myotis were identified (Diptera: Dolicopodidae, Hemiptera: Lygaeidae, and Neuroptera: Chrysopidae; Tables 1, 2). Coleoptera, Diptera, and Lepidoptera combined to form >85% of the volume of prey. Lepidoptera (100% occurrence) and Coleoptera (97%) were generally present in adult diets, while Diptera was found somewhat less frequently (83%). Other taxa (Araneae, Hemiptera, Hymenoptera, Neuroptera, and Trichoptera) occurred less often and at lower volumes (Table 1). A summary of percent volume and frequency occurrence for all prey items and a comparison with other published data is included in Table 2. Fecal samples of adult females contained a higher percent volume of Lepidoptera than samples from adult males (W = 847.5, P = 0.006; Table 1). No difference in percent volume of Coleoptera (W = 1113.5, P = 0.90) or Diptera (W = 1191.0, P = 0.95) was found between males and females (Table 1). No statistical difference in percent volume of Lepidoptera (χ2 = 4.6, P = 0.09), Coleoptera (χ2 = 0.18, P = 0.91) or Diptera (χ2 = 0.99, P = 0.61) was found among female reproductive classes (Fig. 1). Discussion We present data on food habits of Eastern Small-footed Myotis, demonstrating differences in consumption of Lepidoptera between adult males and females. Although differences in consumption of Lepidoptera were not detected among reproductive classes of adult females, we postulate that differences would have Table 2. Mean percent volume (percent frequency) of prey identified in fecal samples of Eastern Small-footed Myotis in our study compared to other recent reports. Note that Hemiptera in our study includes taxa identified as Homoptera by Moosman et al. (2007). Numbers of bats are in brackets. Item Johnson and Gates (2007) [44] Moosman et al. (2007) [39] This study [77] Araneae 6.4 (10) 0.1 (0.1) Coleoptera 5.5 (46) 19.1 (56) 30.4 (97) Diptera 24.7 (66) 18.6 (46) 16.7 (82) Hemiptera 1.0 (5) 5.2 (21) 3.4 (29) Homoptera less than 0.1 (3) Hymenoptera 5.4 (27) 0.1 (3) 0.7 (9) Lepidoptera 58.5 (98) 46.2 (85) 41.8 ± (100) Neuroptera 1.6 (7) 2.3 ± (32) Orthoptera 0.1 (3) Psocoptera 3.4 (16) Trichoptera 2.0 (8) 1.8 ± (16) 2012 J.S. Johnson, L.E. Dodd, J.D. Kiser, T.S. Peterson, and K.S. Watrous 669 been observed if sample sizes for pregnant (mean percent volume = 41%, n = 13) and lactating (53%, n = 12) females were greater. A possible increase in lepidopteran consumption by lactating females could reflect a response to changing nutritional and energetic needs associated with the high energetic demands of lactation (Anthony and Kunz 1977, Kurta et al. 1989, Racey and Speakman 1987), although an increase in consumption of Lepidoptera by lactating females also could reflect seasonal differences in lepidopteran abundance, which generally increases after May in eastern deciduous forests (Dodd 2010, Summerville and Christ 2003). Interestingly, the mean percent volume of Lepidoptera in fecal pellets from males collected concurrently with samples from lactating females (48%, n = 6) was similar to the mean volume observed for lactating females. These data highlight the need for sampling the availability of insect prey when assessing the food habits of insectivorous bats. Overall, both males and females were well represented during spring (males: n = 8, females: n = 25) and summer (males: n = 21, females: n = 21) sampling, suggesting that the observed differences in percent volume of Lepidoptera between sexes reflected true differences in consumption of Lepidoptera by males and females, despite our lack of data on abundance of insects. Stronger preference for Lepidoptera by females suggests that these prey may be more profitable for females, which face high energetic demands during reproduction (Anthony and Kunz 1977, Kurta et al. 1989, Racey and Speakman 1987). Figure 1. Percent volume of major prey items in fecal samples of adult female Eastern Small-footed Myotis captured in West Virginia in 2008. Numbers of bats are in parentheses. 670 Northeastern Naturalist Vol. 19, No. 4 The results of our study were similar to other dietary studies of Eastern Smallfooted Myotis, although there were some notable differences (Table 2). Johnson and Gates (2007) reported greater volumes of Lepidoptera (58.5%) and Diptera (24.7%) than our study (41.8% and 16.7%, respectively), while we found a greater volume of Coleoptera (30.4% versus 5.5%). We also found that Coleoptera were consumed more frequently (97% versus 46%). Although Johnson and Gates (2007) also obtained fecal pellets from bats in West Virginia, their samples were collected during the fall swarming period. We suggest that diet of Eastern Smallfooted Myotis varies seasonally, leading to the observed differences between this study and Johnson and Gates (2007). This concept is corroborated by summer data from New Hampshire, where percent volumes of prey taxa were similar to those in our study (Moosman et al. 2007; Table 2). Although we observed no difference in consumption of Coleoptera (30.4% volume) or Diptera (16.7%) among sex or reproductive classes, the consistency and prominence of these taxa reaffirm their importance in the diet of Eastern Small-footed Myotis. We identified 8 orders of prey in the diet of these bats, similar to Johnson and Gates (2007) and Moosman et al. (2007), who discovered 7 and 8 orders, respectively. Three taxonomic families previously unrecorded in the diet of Eastern Small-footed Myotis were also found in this study, indicating that further studies are likely to identify additional taxa below the ordinal level in the diet of this bat. As with previous studies (Johnson and Gates 2007, Moosman et al. 2007), our finding of Araneae as prey, as well as vegetation in fecal samples, suggests that Eastern Small-footed Myotis glean prey. However, we observed spiders or vegetation in just 2 bats in our study, providing only limited support for the hypothesis of Moosman et al. (2007) that Eastern Small-footed Myotis both glean and hawk prey. Alternatively, spiders may have been captured while ballooning at night, or they may have been consumed opportunistically during the day if they entered roosts. Our data show that Eastern Small-footed Myotis exhibit moderate dietary specialization on Lepidoptera but also emphasize the importance of Coleoptera and Diptera. Consumption of Lepidoptera by females was greater than by males, illustrating variation in diet within the population. Dietary studies of the Eastern Small-footed Myotis remain scarce, however, highlighting the need for additional research into the natural history of this little-studied species. Acknowledgments This project would not have been possible without the help of H. Peters, who worked long, hard hours in the field. Thanks also go to M. Dionne and N. Gikas, for assistance in the field, and to M. Lacki and D. Saugey, for comments on earlier versions of this manuscript. Laboratory facilities and support were provided by the University of Kentucky, College of Agriculture. This investigation is connected with a project of the Kentucky Agricultural Experiment Station (KAES 11-09-097) and is published with the approval of the director. 2012 J.S. Johnson, L.E. Dodd, J.D. Kiser, T.S. Peterson, and K.S. Watrous 671 Literature Cited 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 Barbour, R.W., and W.H. Davis. 1974. Mammals of Kentucky. University Press of Kentucky, Lexington, KY. 286 pp. Best, T.L., and J.B. Jennings. 1997. Myotis leibii. Mammalian Species 547:1–6. Braun, E.L. 1950. Deciduous Forests of Eastern North America. Blakiston Company, Philadelphia, PA. 596 pp. Brunet-Rossinni, A.K., and G.S. Wilkinson. 2009. Methods for age estimation and the study of senescence in bats. Pp. 315–325, In T.H. Kunz and S. Parsons (Eds.). Ecological and Behavioral Methods for the Study of Bats. 2nd Edition. Johns Hopkins University Press, Baltimore, MD. 900 pp. Dodd, L.E., M.J. Lacki, E.R. Britzke, D.A. Buehler, P.D. Keyser, J.L. Larkin, A.D. Rodewald, T.B. Wigley, P.B. Wood, and L.K. Rieske. 2012. Forest structure affects trophic linkages: How silvicultural disturbance impacts bats and their insect prey. Forest Ecology and Management 267:262–270. Erdle, S.Y., and C.S. Hobson. 2001. Current status and conservation strategy for the Eastern Small-footed Myotis (Myotis leibii). Virginia Department of Conservation and Recreation, Division of Natural Heritage, Natural Heritage Technical Report 00–19–1-34. Richmond, VA. Gannon, W.L., R.S. Sikes, and the Animal Care and Use Committee of the American Society of Mammalogists. 2007. Guidelines of the American Society of Mammalogists for the use of wild mammals in research. Journal of Mammalogy 88:809–823. Johnson, J.B., and J.E. Gates. 2007. Food habits of Myotis leibii during fall swarming in West Virginia. Northeastern Naturalist 14:317–322. Johnson, J.B., and J.E. Gates. 2008. Spring migration and roost-selection of female Myotis leibii in Maryland. Northeastern Naturalist 15:453–460. Johnson, J.B., J.E. Gates, and W.M. Ford. 2009. Notes on foraging activity of female Myotis leibii in Maryland. Research Paper, US Department of Agriculture, Forest Service, Northern Research Station, Newton Square, PA. NRS–8:1–8. Johnson, J.S., J.D. Kiser, K.S. Watrous, and T.S. Peterson. 2011. Day-roosts of Myotis leibii in the Appalachian Ridge and Valley of West Virginia. Northeastern Naturalist 18:95–106. Kurta, A., G.P. Bell, K.A. Nagy, and T.H. Kunz. 1989. Energetics of pregnancy and lactation in free-ranging Little Brown Bats (Myotis lucifugus). Physiological Zoology 62:804–818. Lacki, M.J., S.K. Amelon, and M.D. Baker. 2007a. Foraging ecology of bats in forests. Pp. 83–128, In M.J. Lacki, J.P. Hayes, and A. Kurta (Eds.). Bats in Forests: Conservation and Management. Johns Hopkins University Press, Baltimore, MD. 329 pp. Lacki, M.J., J.S. Johnson, L.E. Dodd, and M.D. Baker. 2007b. Prey consumption of insectivorous bats in coniferous forests of north-central Idaho. Northwestern Naturalist 3:199–205. Moosman, P.R., Jr., H.H. Thomas, and J.P. Veilleux. 2007. Food habits of Eastern Small-footed Bats (Myotis leibii) in New Hampshire. American Midland Naturalist 158:354–360. NatureServe. 2011. Version 7.1. Arlington, VA. Available online at: http://www.natureserve. org/explorer. Accessed 25 February 2012. 672 Northeastern Naturalist Vol. 19, No. 4 O’Keefe, J.M., and M. LaVoie. 2011. Maternity colony of Eastern Small-footed Myotis (Myotis leibii) in a historic building. Southeastern Naturalist 10:381–383. Racey, P.A. 2009. Reproductive assessment of bats. Pp. 249–364, In T.H. Kunz and S. Parsons (Eds.). Ecological and Behavioral Methods for the Study of Bats. 2nd Edition. Johns Hopkins University Press, Baltimore, MD. 900 pp. Racey, P.A., and J.R. Speakman. 1987. The energy costs of pregnancy and lactation in heterothermic bats. Symposium of the Zoological Society of London 57:107–125. SAS Institute. 2002. Version 9. Cary, NC. Summerville, K.S., and T.O. Crist. 2003. Determinants of lepidopteran community composition and species diversity in eastern deciduous forests: Roles of season, ecoregion, and patch size. Oikos 100:134–148. Turner, G.G., D.M. Reeder, and J.T.H. Coleman. 2011. A five-year assessment of mortality and geographic spread of white-nose syndrome in North American bats and a look to the future. Bat Research News 52:13–27. Whitaker, J.O., Jr., G.F. McCracken, and B.M. Siemers. 2009. Food habits analysis of insectivorous bats. Pp. 567–592, In T.H. Kunz and S. Parsons (Eds.). Ecological and Behavioral Methods for the Study of Bats. 2nd Edition. Johns Hopkins University Press, Baltimore, MD. 900 pp.