IDENTIFYING AND CHARACTERIZING ROOSTS OF SOUTHERN AND NORTHERN YELLOW BATS (LASIURUS EGA AND LASIURUS INTERMEDIUS) A Thesis Presented to the Faculty of the College of Graduate Studies of Angelo State University In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE by PATRICIA CITLALLY JIMENEZ May 2016 Major: Biology IDENTIFYING AND CHARACTERIZING ROOSTS OF SOUTHERN AND NORTHERN YELLOW BATS (LASIURUS EGA AND LASIURUS INTERMEDIUS) by PATRICIA CITLALLY JIMENEZ APPROVED: Dr. Loren K. Ammerman Dr. Robert C. Dowler Dr. Ben R. Skipper Dr. Biqing Huang April 5, 2016 APPROVED: Dr. Susan E. Keith Date Dean, College of Graduate DEDICATION This thesis is dedicated to my family, my future husband James Kiser, and my forever adorable yellow bats; “I can do all things through Him who gives me strength.” Using palm fronds as roosts, Yellow bats await. Hide-and-seek on the loose, Is the game that they play. iii ACKNOWLEDGMENTS I wish to start by thanking my thesis committee. I thank Dr. Ammerman for her never ending patience with my naivety and kookiness throughout this project, for her determination and knowledge to mold my skills to become a good researcher, and for teaching me how a strong work ethic, perseverance and a little creativity can lead to success. I thank Dr. Dowler for his reassurances and for always ensuring I produced quality work. I thank Dr. Skipper for being the best committee cheerleader a graduate student could ever hope for; without his guidance, understanding, and positive encouragement, I would still be stumbling through this project. And lastly, I’d like to thank Dr. Huang, who assured that I was never beat too badly by the rest of my committee. I also want to express my appreciation to those who graciously shared their wisdom and resources when I asked for help: Roger Rodriguez for providing contacts for sites where I could conduct my research, to Pablo Deyturbe and Stephanie Galla from Resaca de la Palma State Park, for granting the time and space to search for these yellow bats; John Karges and Max Pons from The Nature Conservancy for his knowledge and help finding the bats and identifying some key characteristics of yellow bat roosts; to the managers and staff of Sabal Palm Sanctuary, especially Seth Patterson and Guillermo Aguilar, for their invaluable willingness to open their doors to us and offering their time to facilitate this project; to Dr. Negovetich for advising in the initial understanding of the confusing world of statistics; and to Dr. Dixon, for his guidance and ‘outside-the-box’ thinking that spurred different aspects of this project. iv I am indebted to my funding sources that permitted every facet of this project: Head of the River Ranch Grant, Angelo State University’s Graduate Research Fellowships, and the Bob Berry Holohil Grant from the Western Bat Working Group. But I also would not have been able to complete any data-gathering without the priceless time given, (and sometimes suffered), by my volunteers. Words cannot describe how thankful I feel towards you, my sweet friends, who were willing to withstand long hours in the hot and humid, mosquito and hornet’s nest ridden, and sometimes bat-less nights during my field season. Thank you Max Abrahamson, Loren Ammerman, Shelby Bessette, Kylie Vincent Briggs, Gwyn Carmean, Linette Castañeda, Krysta Demere, Catheline Froehlich, Stephanie Galla, Malorri Hughes, Becca Thomas-Kuzilik, Stephanie Martinez, Isidro Montemayor, Seth Patterson, Max Pons, Greta Schmidt, Alison Shepherd, Ben Skipper, Christrina Straway, Craig Tipton, Juliet Vallejo, Ullisa Uribe-Zepeda, and Jaime Zepeda. To all those aforementioned, I owe a debt of gratitude for your encouragement and support throughout the journey to the completion of this project. v ABSTRACT Previous research has demonstrated the southern yellow bat (Lasiurus ega) to roost in the dead fronds of native palms (Sabal mexicana) and non-native palms (Washingtonia robusta). Roost use by the northern yellow bat (L. intermedius) is similar, with the addition of Spanish moss (Tillandsia spp.). Quantitative assessments of these roosting substrates, however, are lacking. My objective was to identify and quantitatively characterize the diurnal roosts of L. ega and L. intermedius in the Lower Rio Grande Valley of Texas. Through radio- telemetry from May – November of 2015, I located a total of 20 roosts in S. mexicana palms used by 8 yellow bats. Comparison of characteristics between roosts and randomly selected palms showed that yellow bats selected sabal palms with significantly taller, thicker frond skirts and smaller trunk diameters. A predictability model was subsequently constructed to aid in the management of roosting habitat for these species of yellow bats. vi TABLE OF CONTENTS Page DEDICATION ................................................................................................................... iii ACKNOWLEDGMENTS ................................................................................................. iv ABSTRACT ....................................................................................................................... vi TABLE OF CONTENTS .................................................................................................. vii LIST OF FIGURES ......................................................................................................... viii LIST OF TABLES ............................................................................................................. ix INTRODUCTION .............................................................................................................. 1 MATERIALS AND METHODS ........................................................................................ 6 Study sites ........................................................................................................................ 6 Sampling strategies .......................................................................................................... 6 Bat capture and radiotracking .......................................................................................... 8 Roost site characterization ............................................................................................... 9 Data analysis .................................................................................................................. 10 RESULTS ......................................................................................................................... 13 DISCUSSION ................................................................................................................... 23 LITERATURE CITED ..................................................................................................... 28 APPENDICES .................................................................................................................. 36 BIOGRAPHY ................................................................................................................... 42 vii LIST OF FIGURES FIGURE 1. Proportion of bats submitted to the Texas Department of State Health Services annually that were a yellow bat species encountered in Texas. In total, 780 out of 18,342 submissions were yellow bats across all years (2005 – 2014). ........................................... 3 FIGURE 2. Map of Cameron County (black outline) in Texas indicating the three study sites used to research the southern and northern yellow bats: Green – Resaca de la Palma, Orange – Southmost Preserve, Blue – Sabal Palm Sanctuary ......................................................... 7 FIGURE 3. Diagram of measurements taken for each roost and random palm using a clinometer at ground level from 5 m away, or from a distance where palm was in visible. Total palm height was taken from the tallest live frond of the palm; the height at the top of the skirt was taken from the topmost dried frond of the skirt; the height of the bottom of the skirt was taken from the bottommost dried frond of the skirt, whose stem attachment to the trunk was measured. Thickness of the dried frond skirt was calculated by subtracting the bottommost dried frond height from the topmost dried frond .......................................... 11 FIGURE 4. Radio-tagged bats, 6 Lasiurus ega (LAEG) and 2 L. intermedius (LAIN) were tracked to 20 roosts in Sabal mexicana palms within Sabal Palm Sanctuary in Brownsville, Texas from May 2015 – November 2015 ......................................................................... 15 viii LIST OF TABLES TABLE 1. Summary of bat captures for three sites in Brownsville, Texas (Cameron County) over a total of 23 trapping nights, shown in parentheses for each site, from November 2014 – November 2015. ................................................................................................................ 14 TABLE 2. The sexes, number of roosts used, number of days tracked, mean number of days per roost of radio-tagged Lasiurus ega (LAEG) and L. intermedius (LAIN) at Sabal Palm Sanctuary, Brownsville, Texas. ........................................................................................ 17 TABLE 3. Measurements of characteristics of roost and random Sabal mexicana palms used by both Lasiurus ega and L. intermedius. Numbers are means ± SD. .............................. 20 TABLE 4. Comparison of candidate models for Lasiurus ega or L. intermedius roost selection in Sabal mexicana based on AIC (Akaike information criterion scores), AICc (second