RETURNING MATERIALS: PV1ESI.J Place in book drop to ”BRARIES remove this checkout from .-;_—. your record. FINES wi'l] be charged if book is returned after the date stamped be10w. SEP25 2008 HA9 15 I99§ WM“ ‘ . M D at: '.3(, ECOLOGY AND BEHAVIOR OF THE BLACK-AND-NHITE CASQUED HORNBILL (WWW) IN KIBALE FOREST, UGANDA By Jan Kalina A DISSERTATION Submitted to - Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Fisheries and Wildlife 1988 5". ABSTRACT ECOLOGY AND BEHAVIOR OF THE BLACK-AND-NHITE CASOUED HORNBILL BXQANLSIES SUBQILINDRIQQS SQBQQADBAIQS) IN KIBALE FOREST, UGANDA By Jan Kalina The ecology and behavior of the black-and-white casqued hornbill (Bycanistgs subgyliggricus subguagggtgs) was studied in logged and unlogged areas of Kibale Forest, Uganda (June l981-June l984; l986 and 1987 breeding seasons). Hornbill (family Bucerotidae) breeding behavior differs from that of other birds in that the nest cavity entrance is sealed, with the female and young imprisoned inside. This was the first long-term, intensive study of an African forest hornbill species. Hornbill movements, spatial dispersion, and habitat use varied seasonally. Hornbills were present in selectively logged areas but in lower numbers than in primary forest in the core of the Reserve. Hornbill movements were closely related to their diet. Particularly during the dry seasons, hornbills traveled long distances (> 6 km) in search of fruiting trees. These birds fed on at least 67 fruit species. Fruits comprised 90% of the diet by volume, with Eigus spp. comprising 57% of the volume of all fruits. Seeds from most species of fruits were either regurgitated or Jan Kalina defecated and dispersed intact. Hornbills, therefore, mediated seed dispersal of rainforest trees. Hornbills required very large trees (> 3 m circumference; n = 45) for nesting. Trees had large (> 25 cm depth), naturally formed cavities at a minimum height of 8 m above ground. Hornbill nest densities were highest in primary forest in .the center’ of the Reserve, where the density of trees > 3 m circumference was greater and where the trees were, on average, much larger. The number of young fledged per unit area was also highest in primary forest in the core of the Reserve. Reasons for nest failures were varied, but intrusions at nests by conspecifics often caused resident birds to abandon their nests. Competition for nest sites by hornbills was high. In this study, the nest-seal appeared to function primarily to prevent intra-specific competitors from entering the nest. Three other hypotheses concerning the function of nest-sealing are discussed. Based on findings in this study, general lrecomnendations are made concerning timber-management practices which seem likely to affect the conservation of forest hornbills in Uganda and elsewhere in the tropics. Copyright by JAN KALINA 1988 Dedicated to my family and the memory of Rebekah D. Fischer. iv ACKNOWLEDGMENTS I wish to acknowledge the President’s office, Uganda National Research Council, and the Uganda Forest Department for permission to work in Kibale Forest. The New York Zoological Society, Sigma Xi, and the American Museum of Natural History’s Frank M. Chapman Memorial Fund provided financial support. Much of this thesis was written at the U.S. Forest Service’s Institute of Tropical Forestry in Puerto Rico. A return research trip to Uganda was also funded by the U.S. Forest Service. My husband, Tom Butynski, contributed to every phase of this study through his advice, encouragement, and field assistance. His companionship and knowledge of the forest helped make completion of this work possible. My research and dissertation benefited from suggestions by nw' doctoral committee members: Professors George Petrides (chairman), Don Beaver, Niles Kevern, John King, and Peter Murphy. I am thankful to them for their guidance, accessibility, and support. I am grateful to Dr. Petrides for providing the opportunity for students of diverse backgrounds and nationalities to pursue their interests in wildlife ecology and conservation tn1 an international' scale. Perhaps more important than the structured education at Michigan State University was the inspiration gained from these other graduate students. I am especially thankful for the friendships of fellow students: Stan Koster, Heidi Grether, and John and Terese Hart. In Kibale Forest, Tom Struhsaker and Lysa Leland provided logistical support and made available their observations and comments. Joseph Skorupa, Lynne Isbell, Matti Nummelin, and Isabirye Basuta also shared information from 'their own studies. Everyone at Kibale helped locate hornbill nests. Steven Yongili, John Kyalimpa, Nyakairu Godfrey, John Rwagara, and Lawrence Rusoke were particularly successful nest-finders and were enthusiastic assistants in the field. This work would not'have been possible without their cooperation. Senior Game Guard Alfred Otim and his family also offered help freely. During trips to Kampala, Oscar and Linda Rothen kindly welcomed us into their home. Anthony Katende, curator of the Makerere University Herbarium, identified many plants. Identifications of hornbill foods were made by John Njoroge (National Museum of Kenya), John Corner, and Johnathan Baranga. Alan Kemp, Steve Martindale, and Mike Underwood offered valuable coments on observations and manuscripts. Betsy Anderson drew hornbill Figure 5.1. Mark Ritchie provided information on insects. Dr. Peter G. Waterman of the University of Strathclyde analyzed fruit samples. My sister, brother, and parents were the first to teach me how to find and observe wild animals. My greatest appreciation goes to family and friends who encouraged me to continue in graduate studies and who have reliably provided moral support and warm welcomes after vi long absences. My parents, Joseph and Celeste Kalina, handled financial and other obligations at home while I was in Uganda. Margie, Bob, and Rob Blake; Joe and Kim Kalina; Rebekah D. Fischer; JoAnne Fischer; Patty Cohen; Teresa Dorn; Jill Keilblock; Joyce Manko; and Barbara Rowe also sent much-needed mail and packages to us in Uganda. vii TABLE OF CONTENTS LIST OF TABLES ....................... LIST OF FIGURES ....................... Chapter I. INTRODUCTION .................... Reasons for Study ................. Study Animals ................... Study Areas .................... Methods ...................... REFERENCES .................... II. BLACK-AND-HHITE CASOUED HORNBILL DENSITIES IN KIBALE FOREST, UGANDA: SEASONAL AND HABITAT VARIATIONS Introduction ................... Study Area .................... Methods ...................... Resident Hornbill Densities ........... Development of the Census Method ........ Line-Transect Censuses ............. Calling-Rate Index (CRI) ............ Relative Abundances Based on a Total Detection Index ..................... Results/Discussion ................ Confidence in Census Results .......... Relative Abundance of Hornbills in Different Habitats ................... Seasonal Trends in Habitat Use ......... Overall Hornbill Numbers in Kibale ....... Conclusions .................... REFERENCES .................... APPENDICES Z-A. Calling Rate Index (CRI) Data Collected During lS-Second Scans at S-Minute Inter- vals During Transects Censusing Bycanistgs Hornbills in Ngogo, Kibale Forest, Uganda (1983-84) ......... 43 viii Page 2-8 Calling Rate Index (CRI) Data Collected During 15-Second Scans at S-Minute Inter- vals During Transects Censusing Byganistgs n ' Hornbills in K-30, Kibale Forest, Uganda (1983-84) ......... 44 Z-C Calling Rate Index (CRI) Data Collected During lS-Second Scans at 5-Minute Inter- vals During Transects Censusing Bygagistgs subgylingriggs Hornbills in K-15, Kibale Forest, Uganda (1983—84) ......... III. DIET OF BYCANISIES SQBCILINQBIQUS, HITH EMPHASIS ON THE NESTING SEASON ............... Introduction ................... Methods ...................... Opportunistic Observations ........... Nest-Hatches .................. Nest-Trap Data ................. Nutritional Analysis .............. Fruit Morphology ................ Results and Discussion .............. Foods and Foraging ........ ‘ ....... Nest-Hatch Data ................. Nest-Hatch Size Categories ........... Nest-Trap Data ................. Nutrition .................... Conclusions .................... REFERENCES .................... APPENDICES 3-A A Systematic List of All Food Items Recorded in the Diet of Byganistgs sub- gylindrjggs ................ 7O 3-B Description of Fruits in the Diet of Byganistgs subcylindriggs Hornbills in Uganda .................. 75 3-C Chemical Analysis of Some Byganistes 5gb_ cylindnigus Food Items (Analysis by P. Haterman) ................. 77 3-D Chemical Analysis of Some Byganjstgs sub- ;yljndrjggs Food Items (Analysis by Colo- rado State Univ.) ............. 78 ix IV. BREEDING BIOLOGY OF THE BLACK-AND-HHITE CASOUED HORNBILL (BIQANISTES SUBQILINDBLQUS) IN KIBALE FOREST, UGANDA .................. 79 Introduction ................... 79 Methods ...................... 80 Results ...................... 83 Timing of Nesting ................ 83 Courtship and Nesting Behavior ......... 83 Nest-Site Characteristics ............ 89 Density of Nests ................ 90 Nesting Success ................. 90 Sex-Ratio Bias in Fledglings .......... 96 Discussion/Recommendations for Further Study . 98 REFERENCES .................... 101 APPENDICES 4-A Characteristics of Byganjstgs subcyljndzi- cg; Nest Sites