STATUS, DISTRIBUTION, HABITAT REQUIREMENTS, AND FORAGING ECOLOGY OF THE JABIRU STORK (Jabiru mycteria) IN NORTHERN AND CENTRAL BELIZE, CENTRAL AMERICA By ALEJANDRO JOSE PAREDES BORJAS 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 Alejandro José Paredes Borjas ACKNOWLEDGMENTS The successful completion of this project was due to the support of family, friends, professors, and organizations in Central America and the United States. Firstly, I feel indebted to Omar Figueroa and his parents, Don Azuceno and Doña Jeannette, for giving me their support while I was conducting field research in Belize. The Figueroa family kindly provided me with a warm, hospitable place from the moment I arrived in their country. Omar, in particular, helped me arrange logistics and provided useful technical and contact information. Their support was key to the success of this project. I would also like to thank Wilver Martinez, Raynold Cal and Mario Tehul for their help, peer support, and long-lasting coffee breaks. I also thank pilot Frank Plett, whose experience, skills and motivation have been instrumental for conservation of waterbirds in Belize. Thanks also go to the Belize Audubon Society, who granted me permission to do research in Crooked Tree Wildlife Sanctuary. I am grateful to my friends in Graduate school: Santiago Espinosa, Amy Duchelle, Rafael Reyna and Edith Rojas, Mutsuo Nakamura, Ivan Diaz, Olga Montenegro, Luis Ramos, Percy Peralta, Sonia Canavelli and Marcela Machicote, who assisted me with data analyses and provided feedback that proved extremely useful for the development of this project. Special thanks go to Charlotte Skov and Debra Anderson for their encouragement and unconditional support. iii Thanks go to my committee members (Dr. Peter Frederick, Dr. George Tanner and Dr. Ken Meyer) for providing ideas and revising the manuscript. This thesis was possible thanks to financial support provided by the Compton Foundation’s grant for Tropical conservation and development. Finally, I would like to thank my family: my mother, Martha; my sister Martha Judith; and my brother, Ricardo. They have always encouraged me to find a balance between the consistent mind and the kind heart. All my endeavors are kindly dedicated to them. iv TABLE OF CONTENTS Page ACKNOWLEDGMENTS ................................................................................................ iii LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii LIST OF OBJECTS .............................................................................................................x ABSTRACT....................................................................................................................... xi CHAPTER 1 INTRODUCTION ........................................................................................................1 Threats to Central American Wetlands.........................................................................1 Influence of Wetland Hydrology in the Natural History of Wading Birds ..................2 Influence of Spatial Heterogeneity and Hydrological Fluctuations on the Natural History of Wading Birds..........................................................................................4 The Study Species: The Jabiru Stork............................................................................8 2 STUDY AREA AND METHODS .............................................................................13 Study Area ..................................................................................................................13 Methods ......................................................................................................................16 Landscape Data and Population Estimates..........................................................16 Microhabitat data and Observations on Foraging Behavior................................19 Analysis of Data ..................................................................................................20 3 RESULTS...................................................................................................................24 Abundance of Jabiru Storks........................................................................................24 Spatial Distribution.....................................................................................................24 Habitat Use .................................................................................................................26 Habitat Use According to Ecosystem Classification...........................................26 Habitat Use According to Land Use Classification.............................................28 Use of Water Bodies............................................................................................28 Features of Foraging Microhabitat ......................................................................29 Diet Composition........................................................................................................29 Foraging Behavior ......................................................................................................30 v Walking and Searching for Food.........................................................................30 Capturing and Handling Prey ..............................................................................32 Prey Piracy...........................................................................................................34 Loafing and Social Interactions...........................................................................35 4 DISCUSSION.............................................................................................................50 Rainfall Pattern in Central and Northern Belize.........................................................50 Abundance of Storks in Response to Local Hydrology..............................................50 Spatial Distribution and Habitat Use ..........................................................................53 Foraging Ecology........................................................................................................55 Conservation...............................................................................................................57 5 CONCLUSIONS ........................................................................................................60 APPENDIX A MAPS OF STUDY AREA .........................................................................................62 B ROUTES OF SURVEY FLIGHTS ............................................................................65 LIST OF REFERENCES...................................................................................................69 BIOGRAPHICAL SKETCH .............................................................................................75 vi LIST OF TABLES Table page 1 Total number of Jabirus observed in survey flights .................................................47 2 Number of Jabirus in relation to habitat types. ........................................................48 vii LIST OF FIGURES Figure page 1 Map of Belize. ..........................................................................................................21 2 Map showing the components of the hydrological system in central Belize.. .........22 3 Map of study area.....................................................................................................22 4 Map showing of foraging areas................................................................................23 5 Variation of foraging sociality of Jabiru. .................................................................36 6 Spatial distribution of Jabirus: survey 1...................................................................37 7 Spatial distribution of Jabirus: survey 2...................................................................38 8 Spatial distribution of Jabirus: survey 3...................................................................39 9 Spatial distribution of Jabirus: survey 4...................................................................40 10 Spatial distribution of Jabirus: survey 5...................................................................41 11 Summary of spatial distribution of Jabiru................................................................42 12 Readings of water levels recorded from 6 water stages. ..........................................43 13 Ecosystems used by foraging Jabirus.......................................................................44 14 Habitat used by Jabirus. ...........................................................................................45 15 Water bodies used by foraging Jabirus. ...................................................................46 16 Proportion of prey items of the Jabiru......................................................................46 17 Satellite image of CTWS and New River Lagoon area............................................62 18 Map of ecosystems of Belize, northern Belize.........................................................63 19 Map of ecosystems of Belize, central Belize. ..........................................................64