Ecological Role of Dry-Habitat Chimpanzees (Pan Troglodytes Schweinfurthii)

Ecological Role of Dry-Habitat Chimpanzees (Pan troglodytes schweinfurthii) at Issa, Ugalla, Tanzania by Samantha M. Russak A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved April 2013 by the Graduate Supervisory Committee: Kaye Reed, Chair Gary Schwartz Leanne Nash ARIZONA STATE UNIVERSITY May 2013 ABSTRACT Identifying the ecological role, or niche, that a species occupies within their larger community elucidates environmental adaptability and evolutionary success. This dissertation investigates the occupied niche of chimpanzees (Pan troglodytes schweinfurthii) living in an open, dry savanna-woodland environment by examining patterns of resource use and interspecific interactions. Data were collected October 2010—November 2011 at Issa, in the Ugalla region of western Tanzania, which is one of the driest, most open, and seasonal habitats inhabited by chimpanzees. Unlike most primatological studies which employ methods that include focal follows, this study focused instead on observing ‘resource patches’ for chimpanzees. Patch focals allow for the observation of all animals within a study area; capture resources that are not used by the study species; and are particularly well suited for unhabituated communities. In order to better understand relationships between environment and behavior, data collected at Issa are compared with published data from other chimpanzee populations. Issa chimpanzees were expected to have broader resource use than forest chimpanzees, as well as increased competition with other fauna, due to fewer available resources. However, in contrast to the assumption of food scarcity in dry habitats, dietary resources were available throughout the year. Like other populations, the diet of Issa chimpanzees consisted of mostly fruit, but unlike at other sites, the majority of plants consumed were woodland species. Additionally, although chimpanzees and other fauna i shared spatial and dietary resources, there was only nominal overlap. These results point to extremely low levels of indirect competition between chimpanzees and other fauna. Despite extensive study of forest chimpanzees, little is known about their role within their faunal community in open, dry habitats, nor about how greater seasonality affects resource use. This project addresses both of these important issues and fosters novel approaches in anthropological studies, especially in reference to chimpanzee ecology and evolution. Understanding current chimpanzee behavioral relationships with their environments shapes hypotheses about their pasts, and also informs predictions about behaviors of similar taxa in paleo-environments. Lastly, examining the ecological role of chimpanzees within their larger communities will influence the formation of, as well as evaluate, conservation strategies. ii For my mother, who never stopped encouraging me to ask questions, and who wholeheartedly supports all of my scientific endeavors, no matter how far from home they may take me iii ACKNOWLEDGEMENTS First and foremost, I would like to thank my advisory committee Kaye Reed, Leanne Nash, and Gary Schwartz for their patience, support, and guidance throughout my entire graduate career. I am especially grateful to my chair, Kaye Reed, for the immediate responses to late night emails, long-distance support while either one or both of us were in the field, and for helping keep my mother sane while I spent a year in Africa. I would also like to express my deepest gratitude to my undergraduate advisors, Bill McGrew and Linda Marchant, who steered me towards the exciting field of primatology, and who continue to be inspirational mentors and colleagues. My dissertation research would not have been possible without the help and support of the amazing IHO and SHESC staff here at ASU, including Lindsay Mullen, Julie Russ, Chelle Brookes, Philomena Bell, Tae O’Connor, and Georgianna Miller. Funding was generously provided by IHO, GPSA, ASU Graduate College, SHESC, and a NSF Graduate Research Fellowship (DGE-0802261). Many thanks also go to the Max Planck Institute for Evolutionary Anthropology for supplying camera traps. My research would not have been possible without the permission of TAWIRI or COSTECH (permit # 2010-323-NA-2010-59). For allowing me to conduct research at their study site, I am deeply indebted to the Ugalla Primate Project. Alex Piel and Fiona Stewart, in particular, have been invaluable collaborators and I look forward to continuing to work with them. My sincerest gratitude goes to my field assistants Shedrack Lucas, Busoti Juma, Msigwa Rashid, Ndai Samwely, Joffrey Lucas, and Mlela Juma; I could not have asked for a better team of assistants, who never once complained iv about their unappealing tasks of “watching trees” and collecting fecal samples. Many thanks also go to Caspian Johnson for providing levity during stressful times and for being another English-speaking person with whom I could converse. For providing logistical help and guidance while in Tanzania, I thank the staff at the Jane Goodall Institute, including Shadrack Kamenya, Mary Mavanza, and Emmanuel Mtiti. A special thanks goes to Dr. Anthony Collins who introduced me to the wonderful people of Kigoma and Ujiji, to the chimpanzees of Gombe, and to my childhood inspiration Dr. Jane Goodall. My trips to Kigoma would not have been the same without the friendship of John Kerkering, who also gave me much-needed GIS help, and Mr. Salim, who supplied me with much-needed chocolate candy bars. I am forever appreciative for the advice, support, and commiseration of my fellow graduate students, particularly Stephanie Meredith, Kristi Lewton, Thierra Nalley, Terry Ritzman, Teague O’Mara, Laura Bidner, Jeremiah Scott, Lynn Lucas, Amy Shapiro, and my “best officemate” Laura Stroik. I cannot thank Jess Libman and the rest of the Libmans enough for adopting me into their family and making sure that I had a life outside of graduate school. Much love and gratitude also go to my brothers, aunts, cousin, and grandparents on the East coast for their long-distance support and encouragement. Last, but not least, I cannot express how grateful I am for my parents, who always gave me opportunities “to do science” and feed my intellectual curiosity. But most of all, I feel extremely privileged and loved to have parents who are constantly encouraging me to be independent and pursue my dreams, even when those dreams mean sending their only daughter to the remote jungles of Central America and Africa. v TABLE OF CONTENTS Page LIST OF TABLES ................................................................................................................xii LIST OF FIGURES.............................................................................................................. xiv CHAPTER 1 INTRODUCTION............................................................................................... 1 2 BACKGROUND................................................................................................ 5 Community Ecology....................................................................................... 5 Some important ecological factors ................................................................. 6 Habitats ...................................................................................................... 6 Resource Distribution ................................................................................ 9 Temporal distribution ........................................................................... 9 Spatial distribution.............................................................................. 11 What is a Community? ................................................................................. 12 Open and Closed Communities............................................................... 12 Community Features................................................................................ 13 Species diversity and richness ............................................................ 13 Measures of diversity and richness..................................................... 14 General patterns of diversity and richness ......................................... 15 Interspecific Interactions ......................................................................... 16 Neutralism........................................................................................... 17 Mutualism/Cooperation/Commensalism............................................ 18 vi CHAPTER Page Predation ............................................................................................. 19 Competition......................................................................................... 20 Coexistence of Species ................................................................................. 23 Competitive Exclusion Principle............................................................. 23 Niches and Ecological Roles ................................................................... 24 Fundamental versus realized niche..................................................... 24 Ecological role .................................................................................... 25 Niche Overlap .......................................................................................... 25 Niche Differentiation ............................................................................... 27 Summary of Community Ecology...............................................................

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