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Bat Use of Edge and Interior Habitat in Managed Forest. A.J. Mengel1, J.E. Duchamp1
Department of Biology, Indiana University of Pennsylvania1
Introduction
Comparisons of Bat Activity Among Different
Silvicultural Treatments
Objectives
Methods
Conclusions
References
Acknowledgements
Comparisons of Bat Activity Among
Edge and Interior Habitats The foraging ecology of bats has attracted more research attention as bat populations continue to decline. Forest management can have a positive impact on the foraging activity of most bat species (Dodd et al. 2012, Menzel et al. 2002) and can improve habitat suitability by emulating a natural disturbance. With the spread of threats such as White-Nose Syndrome and the increasing development of wind energy harvesting, bat populations are continuing to decrease significantly (Francl et al. 2012, Jameson and Willis 2012) and are even becoming regionally extirpated in some areas (Dobony et al. 2011). Maintaining and improving quality habitat is one part of a strategy to help slow and reverse these declines. However, more information is needed on bat foraging ecology in order to better understand how to manage forests so as to benefit bat species.
• Compare the activity of bats in forests after different forest management practices.
• Compare use by bats of edge vs. interior habitats within harvested forests.
• To provide management recommendations to help improve conditions for bat populations.
Study Area: • Mixed Deciduous Forest Habitat • Pocono Mountain Range • Pike and Monroe Counties, PA
Sample Locations: • 6 Shelterwoods (Average size = 35.4
± 17.6 hectares) • 6 Overstory Removals (Average size
= 40.1 ± 15.7 hectares)
Surveys: • Anabat SD1 and SD2 detectors • Microphones were elevated 1.5 m
off the ground • Sampled for 6 nights at each
sampling location • Recorded at 24 locations for a total
of 150 sample nights • Vegetation was sampled at every
site
Call Identification: • Calls were identified using Analook and neural networks in Program R
(Britzke et al. 2011) • At least 5 call pulses and 60% belonging to the same species were
needed to obtain identification. • The call library was restricted to the 9 resident species
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Edge Interior
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Detector Location
Eptesicus fuscus Big brown bat
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Edge Interior
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Detector Location
Lasiurus borealis Eastern red bat
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Edge Interior
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Detector Location
Myotis leibii Small-footed bat
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Edge Interior
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Detector Location
Myotis lucifugus Little brown bat
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Edge Interior
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s Detector Location
Myotis sodalis Indiana bat
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Edge Interior
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l Min
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Detector Location
Perimyotis subflavus Tri-colored bat
• A total of 1118 calls and 815 call minutes were recorded over the course of this study. • Three species of bats were not recorded often enough for analyses of habitat selection (northern long-eared bats (Myotis septentrionalis), hoary
bats (Lasiurus cinereus), and silver-haired bats, (Lasionycteris noctivagans)). • The use of edge vs. interior habitat was compared using a chi-squared analysis. • Among the species analyzed for habitat selection, the most call minutes were recorded for Big brown bats (471) while Indiana Bats were recorded
for the fewest minutes (15). • Within harvests, Big brown bats selected interior habitat while red bats and Indiana bats selected edge habitats.
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Overstory Removal Shelterwood
Cal
l Min
ute
s
Treatment
Eptesicus fuscus Big Brown Bat
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Overstory Removal Shelterwood
Cal
l Min
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s
Treatment
Lasiurus borealis Eastern Red Bat
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Overstory Removal Shelterwood
Cal
l Min
ute
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Treatment
Myotis leibii Small-footed bat
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35
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Overstory Removal Shelterwood
Cal
l Min
ute
s
Treatment
Myotis lucifugus Little brown bat
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Overstory Removal Shelterwood
Cal
l Min
ute
s
Treatment
Myotis sodalis Indiana Bat
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Overstory Removal Shelterwood
Cal
l Min
ute
s
Treatment
Perimyotis subflavus Tri-colored bat
• Use of overstory removal vs. shelterwood treatments were compared using a Chi-squared analysis. • Big brown bats, little brown bats, and tri-colored bats selected overstory removal treatment over shelterwood treatments. • Eastern red bats and small-footed bats selected shelterwood treatments when compared to overstory removals. • Indiana bat selection of overstory removal was not found to be statistically significant. • Three species of bats were not recorded often enough for analyses of habitat selection (northern long-eared bats (Myotis septentrionalis), hoary bats
(Lasiurus cinereus), and silver-haired bats, (Lasionycteris noctivagans)).
P < 0.001 P < 0.001 P = 0.405
P = 0.527 P < 0.001 P = 0.738
P < .001 P < .001 P = 0.002
P = .027 P = .071
P = 0.046
Bat species in this study demonstrated differences in their use of both edge vs interior habitat and overstory removal vs shelterwood management. Big brown bats and eastern red bats were recorded more often than any other species and are not suspected to be under an immediate conservation threat. These species contrasted in their habitat selection with big brown bats selected interior habitats of a harvest and overstory removal treatments and eastern red bats selected edge habitat and shelterwood treatments. Among species that are of conservation concern in the region, most were recorded much less often which lowers the power of any statistical analyses. With the exception of small-footed bats, most species were recorded more often in overstory removal harvests when compared to shelterwood cuts. All of these species used both edge and interior habitats of harvests. However , the Indiana bat selected edge habitat of harvests rather than the interiors. Ground-level acoustic recordings do not necessarily reflect the total bat activity in an area. The activity within and above the canopy is mostly unaccounted for. However, based on our results it appears that a mixture of harvest types would benefit bat diversity and that Indiana bats would benefit from a more complex edge to increase foraging habitat.
I would like to thank the Indiana University of Pennsylvania Biology Department for providing me with the funds to complete this study. I would also like to thank Dr. Larkin and my advisor, Dr. Duchamp, for all of their help and guidance while conducting this research. And finally, I would like to thank Leandra Boodoo, Andrew Marmo, Renee Poole, Joey Smithmeyer, Wendy Leuenberger, and D.J. McNeil for their hard work and labor in helping me to complete this project.
Example of a Big Brown bat call (left).
Britzke, E. R., Duchamp, J. E., Murray, K. L., Swihart, R. K., & Robbins, L. W. (2011). Acoustic identification of bats in the eastern United States: A comparison of parametric and nonparametric methods. The Journal of Wildlife Management, 75(3), 660-667. Dodd, L. E., Lacki, M. J., Britzke, E. R., Buehler, D. A., Keyser, P. D., Larkin, J. L., ... & Rieske, L. K. (2012). Forest structure affects trophic linkages: how silvicultural disturbance impacts bats and their insect prey. Forest Ecology and Management, 267, 262-270. Francl K. E., W. M. Ford, D. W. Sparks, and V. Brack Jr. 2012. Capture and Reproductive Trends in Summer Bat Communities in West Virginia: Assessing the Impact of White-Nose Syndrome. Journal of Fish and Wildlife Management 3: 33-42. Grindal, S.D. 1996. Habitat use by bats in fragmented forests. eds R.M. R. Barclay & R.M. Brigham: 260–272. Jameson J. W. and C. K. R. Willis 2012. Bat Mortality at a Wind Power Facility in Central Canada. Northwestern Naturalist 93:194-202. Menzel, M. A., Carter, T. C., Menzel, J. M., Mark Ford, W., & Chapman, B. R. (2002). Effects of group selection silviculture in bottomland hardwoods on the spatial activity patterns of bats. Forest Ecology and Management, 162(2), 209-218.
Anabat detector recording a shelterwood. Photo taken by Adam Mengel.
Detector setup. Photo taken by Adam Mengel.
Aerial image of an overstory removal cut. Aerial image of a shelterwood cut.
Photo of an Overstory Removal. Photo taken by D.J. McNeil (right).
