Do Bats use Olfactory Cues to Find Roosts? Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Bridget Kay Gladden Brown Graduate Program in Evolution, Ecology, and Organismal Biology The Ohio State University 2020 Thesis Committee Gerald G. Carter, Advisor Rachelle M. M. Adams Ian M. Hamilton 1 Copyrighted by Bridget Kay Gladden Brown 2020 2 Abstract Understanding how bats select roosts is crucial to their management and conservation. One way that bats can locate new roosts is by using cues from conspecifics. Research on this use of social information has mostly focused on conspecific calls. In many species, bats will move toward conspecific echolocation and social calls, which can help bats find new roosts faster. However, many roosts also have olfactory cues from guano and urine. Bat conservationists have long debated whether guano and urine can be used to attract bats to new roosts. If chemical cues can act as an effective bat lure, this would aid in efforts to exclude bats from buildings and attract them to artificial roosts in protected areas like state parks or wildlife preserves. In my thesis, I ask if bats use olfactory cues from guano and urine to locate potential roosts. In Chapter 1, I summarized research to date on the topic of the use of olfaction by roost-searching bats and I discuss reasons that bats might, or might not, use scent to locate roosts. From this research, results are consistent with the hypothesis that guano and urine are not strong enough lures to attract bats to new roosts. In Chapter 2, I describe experiments with three bat species given choices between a roosting area treated with guano and urine and an untreated control roosting area in captivity and in the field. This chapter describes experiments done by me (field experiments 1 and 2, captive experiments 4 and 6) and by other researchers (captive experiments 1, 2, 3, and 5). In field experiment 1 and 2, I used ii acoustic-based bat detectors to measure bat visits and nearby bat activity at paired treated and untreated artificial roosts for one week deployments at 16 sites in Panama (13 weeks) targeting velvety free-tailed bats (Molossus molossus) and at 7 sites in Ohio (17 weeks) targeting big brown bats (Eptesicus fuscus). Only one visit was detected, and the activity did not show an effect of the treatment. In the captive experiments, I tested vampire bats (Desmodus rotundus) using paired roost tubes (n=5 bats), using surfaces with different improved test procedures (n=20, n =22, n =33), and using a y-maze that compared their scent response to that of sound cues or the combination of sound and scent cues. I also tested captive velvety free-tailed bats instead (n=18). The overall effect size of scent cues on roost selection by captive bats was near zero. Ultimately, this indicates that guano and urine are not a strong enough lure to consistently draw bats into a roosting area. Key Words: bats; multimodal; replication; roosting ecology; sensory ecology iii Dedication I would like to dedicate my thesis to my husband, Tyler Brown, who provided unconditional support and countless edits to my work during my thesis. iv Acknowledgments First and foremost, I would like to express my sincere gratitude to my adviser, Dr. Gerald Carter, for his guidance and support during my master’s thesis. His knowledge and enthusiasm were a crucial resource for my master’s research. I would also like to thank the rest of my thesis committee, Dr. Ian Hamilton and Dr. Rachelle Adams, for their useful advice and constructive criticism. Besides my committee, I would also like to thank my field assistants, Jessica Nystrom, Jennifer Stancourt, and Morgan Little, for carrying out the field experiment in Ohio while I was in Panama for the summer. The preliminary experiments conducted that aided in the creation of my experiments were also done by other research interns. I would like to thank Lauren Leffer, Yesenia Valverde, Nia Toshkova for their contributions. Part of my project required the procurement of bat guano and knowledge of roosting sites, so I would like to thank the following people for their assistants with these aspects: The Ohio Wildlife Center, Columbus and Franklin County Metro Parks Staff (particularly Carrie Morrow), Lisa Cooper at NEOMED, and Jenna Kohles in Panama. While in Panama, I received assistance with mist-netting, resource acquisition and transportation from the Rachel Page Lab at the Smithsonian Tropical Research Institute. I would like to extend my appreciation to the following people for being an unparalleled v resource while I was there: Dr. Rachel Page, Gregg Cohen, May Dixon, Alexis Heckley, Camila Santiago, and Sebastian Stockmaier. I also thank my fellow labmates at Ohio State, Imran Razik, Simon Ripperger, David Girbino, and Emma Kline, for their assistance in modifying ideas and plans, editing proposals and papers, and extra hands in the field. Finally, I would like to thank the organizations that provided financial support for me during my thesis: Sigma Xi Grants-in Aid of Research and Ohio State’s Critical Difference for Women Professional Development Grant. vi Vita Personal Information May 2012……………………………………………………..…Beavercreek High School December 2015…………………..…B.S. Organismal Biology, The Ohio State University 2016-2018………………………………………………..…...…..Bat Survey Coordinator, Ohio Division of Wildlife 2019-present……………………………….Graduate Teaching Associate, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University Fields of Study Major Field: Evolution, Ecology, and Organismal Biology vii Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iv Acknowledgments............................................................................................................... v Vita .................................................................................................................................... vii List of Figures ..................................................................................................................... x Chapter 1. Do Bats Use Scent to Find or Select Roosts? A Literature Review .................. 1 INTRODUCTION .......................................................................................................... 1 FUTURE RESEARCH AND FURTHER QUESTIONS ............................................. 14 Chapter 2. The Role of Scent Cues in Roost-Finding by Bats.......................................... 17 ABSTRACT .................................................................................................................. 17 INTRODUCTION ........................................................................................................ 18 METHODS ................................................................................................................... 22 Ethics Statement........................................................................................................ 22 Panama Field Experiment ......................................................................................... 22 Ohio Field Experiment .............................................................................................. 25 Field experiment statistical analysis ......................................................................... 26 Captive Experiment One: Preliminary trials of bats choosing refuges (n=5 bats) ... 27 Captive Experiment Two: Zoo vampire bats (n=20) choosing sides ........................ 28 Captive Experiment Three: Wild-born and captive-born vampire bats (n=22) choosing sides ........................................................................................................... 29 Captive Experiment Four: Wild-born vampire bats (n=33) choosing sides ............. 30 Captive Experiment Five: A y-maze with acoustic cues, scent cues, and multimodal cues (n=45) ............................................................................................................... 32 Captive Experiment Six: Velvety free-tailed bats (n=18) choosing sides ................ 34 Captive experiment statistical analysis ..................................................................... 35 Comparing scent, sound and bimodal treatments in Captive Experiment Five ........ 35 RESULTS AND DISCUSSION ................................................................................... 36 Field Experiments ..................................................................................................... 36 viii Captive Experiments ................................................................................................. 38 CONCLUSION ............................................................................................................. 43 Bibliography ..................................................................................................................... 46 Appendix A: Maps of Roost Locations for Field Experiments ........................................ 55 ix List of Figures Figure 2.1. Paired test boxes used in the field experiments. ............................................. 25 Figure 2.2. Test chambers for Captive Experiment One and Captive Experiment Two and Three. ...............................................................................................................................