AVAILABILITY AND SEASONAL USE OF DIURNAL ROOSTS BY RAFINESQUE’S BIG-EARED BAT AND SOUTHEASTERN MYOTIS IN BOTTOMLAND HARDWOODS OF MISSISSIPPI By Candice LeeAnn Stevenson A Thesis Submitted to the Faculty of Mississippi State University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Wildlife and Fisheries Science in the Department of Wildlife and Fisheries Mississippi State, Mississippi December 2008 AVAILABILITY AND SEASONAL USE OF DIURNAL ROOSTS BY RAFINESQUE’S BIG-EARED BAT AND SOUTHEASTERN MYOTIS IN BOTTOMLAND HARDWOODS OF MISSISSIPPI By Candice LeeAnn Stevenson Approved: _________________________________ _________________________________ Jeanne C. Miller Associate Professor of Wildlife and Adjunct Assistant Professor of Wildlife Fisheries and Fisheries (Director of Thesis) (Committee Member) _________________________________ _________________________________ David M. Vilella Adjunct Assistant Professor of Wildlife Professor of Wildlife and Fisheries and Fisheries (Committee Member) (Committee Member) _________________________________ _________________________________ Bruce D. Hopper Professor and Head of Wildlife and Dean of the College of Forest Resources Fisheries Graduate Coordinator (Committee Member) Name: Candice LeeAnn Stevenson Date of Degree: December 12, 2008 Institution: Mississippi State University Major Field: Wildlife and Fisheries Science Major Professor: Dr.
Jeanne Jones Title of Study: AVAILABILITY AND SEASONAL USE OF DIURNAL ROOSTS BY RAFINESQUE’S BIG-EARED BAT AND SOUTHEASTERN MYOTIS IN BOTTOMLAND HARDWOODS OF MISSISSIPPI Pages in Study: 109 Candidate for Degree of Master of Science Rafinesque’s big-eared bat (Corynorhinus rafinesquii) and southeastern myotis (Myotis austroriparius) are listed as species of concern in Mississippi. They use bottomland hardwood forests for roosting habitat; however, much of these forests in Mississippi have been lost or degraded. I seek to characterize availability and evaluate use of diurnal tree roosts for these presumably rare bats. Approximately 1,250 ha of bottomland hardwood forest on Noxubee National Wildlife Refuge were surveyed.
I measured characteristics of 622 cavity trees. Analyses revealed that these bats most often used cavities of large diameter trees (>70 cm DBH). Rafinesque’s big-eared bat and southeastern myotis roosted commonly in baldcypress (Taxodium distichum), black tupelo (Nyssa sylvatica), and American sycamore (Platanus occidentalis). This research will be used to provide guidance for management plans to conserve these bats and their habitat.
Key words: Rafinesque’s big-eared bat, southeastern myotis, cavity tree DEDICATION This work is dedicated to my husband Stacy and my daughter Cheyenne. Your sacrifice made this possible. ii ACKNOWLEDGEMENTS There are numerous students and faculty at the College of Forest Resources that contributed to this research. I appreciate the CFR staff for their support through the years, and especially Dr.
Bruce Leopold for welcoming me to the CFR family and giving me a chance. I offer my deepest thanks to my major professor, Dr. Jeanne Jones who served as a mentor and friend for many years. Thank you for sharing your knowledge and appreciation of natural resources, your passion for conservation, and for those moments when we could let our hair down! I will carry these lessons throughout my career.
I would not have had this project if it were not for Wildlife Biologist Dave Richardson. Thank you for your dedication and attention to this project and for showing me an example of a phenomenal biologist. I was fortunate enough to receive support from the entire Noxubee Refuge staff. You are all great people, and I felt like part of a family while working there.
I knew I could call any of you for help at any time, thank you for everything. I would like to thank my remaining committee members, Dr. Francisco Vilella and Dr. Darren Miller for their support and guidance.
Thank you for your superior and thoughtful suggestions that made this project excellent. I am grateful to the student workers who helped me with field work, they were: Scotty Coffman, Austin Merritt, Lewis Bradford, Steven Lewis, Lauren White, Amanda Deese, Erin Adams, Amber iii Breland, and Nicole Hodges. I owe an enormous debt of gratitude to Amber and Nicole for their hard work, passion, and dedication to the bat project. Thank you for spending endless hours looking for bat trees, following me through “deepest, darkest, Africa” and making me laugh in soaring temperatures and thickets of Rubus and buttvine! I can’t tell you how much your friendship means to me, and I am so proud of your accomplishments.
Deepest thanks go to Jarrod Fogarty for assistance with statistical analyses. I greatly appreciate your patience and knowledge of statistics that kept me sane through this process. This research could not have been possible without financial contributions and in- kind services for which I am grateful. Contributing organizations and agencies were Mississippi State University, Bat Conservation International, U.
Geological Survey Biological Resources Division, and U. Fish and Wildlife Service. iv TABLE OF CONTENTS DEDICATION. iii LIST OF TABLES.
viii LIST OF FIGURES. RESEARCH DESCRIPTION AND METHODOLOGY .15 Cavity tree measurements .17 Forest stand composition .21 Surveys for cavity tree use by bats .22 Hypothesis Testing and Analysis. CAVITY TREE AVAILABILITY WITHIN FORESTED STUDY SITES .26 Forest stand measurements .26 Cavity tree availability .29 Forest stand composition .29 Cavity tree availability .41 Future study recommendations. ROOST CHARACTERISTICS AND USE .49 Cavity tree measurements .51 Forest stand measurements .52 Landscape measurements of cavity trees .52 Cavity tree use.53 Seasonal use of cavity trees .56 Cavity tree measurements .57 Understory characteristics surrounding cavity trees .59 Forest stand measurements .60 Cavity tree use.62 Seasonal use of cavity trees .68 Bat use of artificial structures .70 Cavity tree characteristics .70 Cavity tree use by bats .79 Cavity Producing Tree Species and Use by Bats .79 Habitat Management Recommendations .83 Considerations for Landscape Characteristics .88 Cavity Tree Characteristics .89 Roost Site Use between Rafinesque’s big-eared bat and southeastern myotis .92 Use of Artificial Roosts.
DENSITY TABLES FOR PRISM CRUISES AND CAVITY TREE SURVEYS. STAND COMPOSITION, CAVITY TREE AVAILABILITY, AND BAT USE .107 vii LIST OF TABLES 3.1 Density of trees categorized in 5 cm diameter at breast height (DBH) size classes located by 10-factor prism cruises performed in four study sites at Noxubee National Wildlife Refuge, Mississippi during 2005-2007.2 Study site comparison of basal area (m2/ha) calculated from prism cruises conducted in four study sites at Noxubee National Wildlife Refuge, Mississippi during 2005-2007.3 Density (trees/ha) and number (n) of cavity trees categorized by 5 cm diameter at breast height (DBH) size classes on four study sites at Noxubee National Wildlife Refuge, Mississippi during 2005-2007.4 Percentage of the densities of trees found with and without cavities at Noxubee National Wildlife Refuge, Mississippi. Percentage compares cavity trees located in plot surveys to trees found during prism cruises in four study sites during 2005-2007.1 Results of logistic regression analysis used to compare use and non-use cavity tree characteristics for roosting Rafinesque’s big-eared bat at Noxubee National Wildlife Refuge during 2005-2007.2 Results of logistic regression analysis used to compare use and non-use cavity tree characteristics for roosting southeastern myotis at Noxubee National Wildlife Refuge during 2005-2007.3 Average percent coverage calculated from line intercepts performed around cavity trees used by Rafinesque’s big-eared bats and southeastern myotis at Noxubee National Wildlife Refuge during 2005-2007.4 Summary of statistics from logistic regression analysis of measured landscape characteristics and their relation to cavity tree use by Rafinesque’s big- eared bat and southeastern myotis at Noxubee National Wildlife Refuge during 2005-2007.5 Manly’s alpha selectivity index for cavity tree species used by Rafinesque’s big- eared bat as roosting habitat at Noxubee National Wildlife Refuge in Mississippi during 2005-2007.6 Manly’s alpha selectivity index for cavity tree species used by southeastern myotis as roosting habitat at Noxubee National Wildlife Refuge in Mississippi during 2005-2007.7 Cavity trees used for colony roosting by Rafinesque’s big-eared bat (RBEB) and southeastern myotis (SEM) at Noxubee National Wildlife Refuge (2005-2007).1 Number (n) and density (trees/ha) of trees categorized by species found from prism cruises conducted in four study sites at Noxubee National Wildlife Refuge during 2006-2007.2 Number of cavity trees and density (trees/hectare) by tree species from survey plots in four study sites at Noxubee National Wildlife Refuge, Mississippi during 2005-2007.3 Species and number of ancillary cavity trees found in or around four designated study sites in bottomland hardwood forest habitat at Noxubee National Wildlife Refuge, Mississippi during 2005-2007.1 Comparison of cavity tree species used by Rafinesque’s big-eared bat (RBEB) and southeastern myotis (SEM) as roosts to the availability of cavity trees found by plot surveys, and the overall stand composition measured by 10-factor prism cruise surveys conducted on four bottomland hardwood study sites at Noxubee National Wildlife Refuge, Mississippi during 2005 – 2007.108 ix LIST OF FIGURES 2.1 Noxubee National Wildlife Refuge located in Oktibbeha, Winston, and Noxubee counties in Mississippi in 2007.2 Study sites for cavity tree surveys conducted on Noxubee National Wildlife Refuge in northeast Mississippi. The four study sites were located within bottomland hardwood forested areas during 2005-2007.3 Site 1 overlaid with systematic grid generated using ArcView® in 2005 to locate starting point of plot surveys with a handheld GPS unit.
Four study sites were located at Noxubee National Wildlife Refuge in Mississippi.4 Diagram of plot survey design for locating cavity trees at Noxubee National Wildlife Refuge, Mississippi during 2005-2007. Lines represent path of surveyors and circles represent plot center of two 10-factor prism cruises conducted. Surveyors looked for cavity trees within the two outside lines.1 Average density (trees/ha) of all trees found in prism cruises conducted in four bottomland hardwood forest habitat sites at Noxubee National Wildlife Refuge, Mississippi during 2005-2007. Data were recorded in 5 cm diameter at breast height (DBH) size classes.2 Average density (number of trees/ha) of cavity trees found in fixed plot surveys conducted at Noxubee National Wildlife Refuge, Mississippi during 2005-2007.
Four study sites were surveyed in bottomland hardwood forest habitat. Data were recorded in 5 cm diameter at breast height (DBH) size classes.3 A ratio of the average density (trees/ha) of cavity trees found in fixed plot surveys to trees located in 10-factor prism cruises shown in 5 cm diameter at breast height (DBH) size class. Surveys were conducted in four bottomland hardwood forest study sites at Noxubee National Wildlife Refuge during 2005-2007. Ratio was calculated as follows: cavity tree density/cruise tree density.
The ratio shows that the number of cavity trees increases in larger size classes in relation to trees found in prism cruises.1 Relative frequency of cavity tree use per size class (DBH) for Rafinesque’s big- eared bat (RBEB) and southeastern myotis (SEM) at Noxubee National Wildlife Refuge during 2005-2007.2 Cavity tree use within different size classes grouped according to use (solitary, n < 4 and colony, n >5) by Rafinesque’s big-eared bat (RBEB) and southeastern myotis (SEM) at Noxubee National Wildlife Refuge in Mississippi during 2005-2007.67 xi CHAPTER I INTRODUCTION Bats serve a variety of ecological roles such as insect predators, prey, pollinators, and seed dispersers. As a taxonomic group, bats serve as indicators of forest health (Fenton 2003) because of their sensitivity to pollution (Hickey et al. 2001) and habitat disturbances (Medellin et al. However, research on bats has been limited in the field of wildlife management and conservation.
Miller et al. (2003) reported that only 56 studies concentrating on habitat management for forest-roosting bats have been published from 1980 to 2001. This paucity of research on forest-dwelling bats is most likely due to their elusive behavior that makes them difficult to find and easily overlooked. In comparison, O’Shea et al.
(2003) documented an increasing interest in bats in scientific research. They found 29 articles concerning bats published in “The Journal of Wildlife Management” and “The Wildlife Society Bulletin” between 1992 and 2001, of which, 22 were published from 1999 to 2001. This increase in publications could allow researchers to understand and identify life requirements and habitat use by bats, increasing likelihood of more efficient conservation planning for the species. To meet requirements for biodiversity management in forested systems, increased information is needed on ecological aspects that retain or create habitat components needed by bats and other wildlife species.
For more effective conservation of forest dwelling bats, additional 1 information is needed on development of cavity trees and use of these trees by bats as roost sites.