The Foraging Ecology of Fruit Bats in the Seasonal Environment of Central Zambia
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THE FORAGING ECOLOGY OF FRUIT BATS IN THE SEASONAL ENVIRONMENT OF CENTRAL ZAMBIA By HEIDI V. RICHTER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2004 Copyright 2004 by Heidi V. Richter ACKNOWLEDGMENTS Many people and organizations contributed financially, logistically, or personally to the success of this project. The Lubee Foundation provided funding and Dr. Allyson Walsh was fundamental in securing those research funds. This research was also supported in part by a David H. Smith Fellowship awarded by The Nature Conservancy to Dr. Graeme Cumming. I thank John Seyjaget for initially sparking my interest in fruit bats, and helping me get the funding to follow through on my project. In Zambia, I would like to thank the Kasanka Trust as well as Edmund and Kim Farmer for allowing me to live, work and conduct research at Kasanka National Park. The Zambian Wildlife Authority was extremely helpful in issuing the necessary permits for this research. I thank Julian and Kelly Green for their hospitality when I was in Lusaka and Tadg Wixted and his office for logistical support. Changwe Kenneth Yotamu and Clifford Kandonga were of particular value in catching bats, identifying trees and keeping me safe from harm. I thank Christopher Miselo, Christopher Mwape, Nyambe, Kennedy, Benson, Robert Chisenga, Paul, Friday Bwanga, Boas Mwape, Brighton, BV, Timothy Ndashe, Able, Shebbie, Kebby, Edson Chipale, Chibesa Mwaba, J. Mwewa, and Haggai Mwape for their help in collecting data. I thank Kennedy and George for their early morning help when I returned from a long night of mist-netting. Robin Lentz, Charlie Bear and Donna Bear–Hull were invaluable assistants in the field, and contributed an amazing amount during their stay in Zambia. I cannot thank iii them enough for traveling to Africa to assist with this project. I thank Charlie for providing me with his photographs from Zambia and allowing me to use them in my presentations. Alastair provided entertainment on some long mist netting nights. Cristina Evangelista was very supportive of my research, traveling to Zambia to help with fieldwork and assisting with editing in the U.S. Without her initial influence I never would have ended up in Africa. My husband, John Howard, has been extremely supportive of my working in far away places. I thank my labmates, especially Jeremy Dixon, Elina Garrison, Arpat Ozgul, and Melissa Moyer, for their help, understanding, and guidance whenever I had questions and for their daily support and friendship. Dr. Katie Sieving, Dr. Colin Chapman and Dr. Tom Kunz also deserve thanks for serving on my committee and providing comments on my methodology and manuscripts. I thank Dr. Madan Oli for not only serving as a de factor committee member but also for spending his free time teaching statistics. I thank my advisor and chair, Dr. Graeme Cumming, for supporting me with funding so that I could pursue this project. I would also like to thank him for his advice and guidance throughout this process. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iii LIST OF TABLES........................................................................................................... viii LIST OF FIGURES ........................................................................................................... ix ABSTRACT....................................................................................................................... xi CHAPTER 1 INTRODUCTION ........................................................................................................1 Megachiropteran Assemblages.....................................................................................2 Effects of Seasonality in Resources..............................................................................3 Migration Strategies in Fruit Bats.................................................................................3 Resident and Migratory Species Interactions ...............................................................4 Project Objectives.........................................................................................................5 2 FOOD AVAILABILITY AND ANIMAL MIGRATIONS: THE BEHAVIOR OF THE STRAW–COLORED FRUIT BAT AT KASANKA NATIONAL PARK, ZAMBIA.......................................................................................................................7 Methods ......................................................................................................................10 Study Species.......................................................................................................10 Study Site.............................................................................................................10 Vegetation Monitoring ........................................................................................13 Results.........................................................................................................................15 Species Results ....................................................................................................15 Vegetation Results...............................................................................................16 Discussion...................................................................................................................23 Summary of Results ............................................................................................23 Alternative Hypotheses .......................................................................................24 Conservation Implications...................................................................................28 3 DISTINGUISHING MEGACHIROPTERAN SPECIES USING MORPHOLOGICAL CHARACTERISTICS IN KASANKA NATIONAL PARK, ZAMBIA.....................................................................................................................30 v Methods ......................................................................................................................32 Study Site.............................................................................................................32 Mist Netting Methods..........................................................................................32 Analysis of Species Data.....................................................................................34 Results.........................................................................................................................35 Capture Data........................................................................................................35 Megachiroptera Species Identification................................................................37 Species assignments .....................................................................................37 Summary of group analysis..........................................................................38 Palate Data...........................................................................................................40 Discussion...................................................................................................................43 Identification of Sympatric Species.....................................................................43 Mathematical Methods in Species Discrimination..............................................45 Research Needs ...................................................................................................45 4 THE RESPONSE OF FRUIT BATS TO CHANGING RESOURCE AVAILABILITY IN KASANKA NATIONAL PARK, ZAMBIA...........................48 Methods ......................................................................................................................50 Study Site.............................................................................................................50 Mist Netting Methods..........................................................................................50 Bat Species Data..................................................................................................51 Vegetation Methods.............................................................................................51 Capture Rates.......................................................................................................53 Results.........................................................................................................................54 Bat Species Data..................................................................................................54 Vegetation Analysis.............................................................................................54 Analysis of Capture Rates ...................................................................................57 Capture rates and food availability...............................................................57 Analysis of variance.....................................................................................59 Mantel test results.........................................................................................59 Discussion...................................................................................................................63 Additional Influences on Assemblage Structure .................................................64