Cover page Faculty of Medicine and Pharmacy Ecological and Anthropogenic factors of Cross River gorilla (Gorilla gorilla diehli) survival at Mawambi Hills, southwest Cameroon. Thesis submitted in fulfillment of the requirements for the degree of Doctor (PhD) in Human Ecology by Denis Etiendem Ndeloh Prof. Dr. Debby Mangelings, promotor Dr. Nikki Tagg, promotor Dr. Zjef Pereboom, co-promotor Brussels, September 2013 Examination committee: Prof. Dr. Colin Chapman (McGill University, Canada) Prof. Dr. Emmanauel Boon (VUB, Belgium) Prof. Dr. Ronald Buyl (VUB, Belgium) Dr. Celine Devos (ULg, Belgium) Prof. Dr. Debby Mangelings (VUB, Belgium) Dr. Nikki Tagg (RZSA, PGS, Belgium/Cameroon) Dr. Zjef Pereboom (RZSA, Belgium) Cover photographs Front: A lone Cross River gorilla (Gorilla gorilla diehli) in captivity (Nyango) enjoys a meal of Aframomum sp. at the Limbe Wildlife Centre © limbewildlife.org Back : A Cross River gorilla (Gorilla gorilla diehli) tree nest in the Mawambi Hills © Denis Etiendem Ndeloh ISBN University Press, Zelzate Author's email address [email protected] Please refer to this work as: Etiendem, DN (2013). Ecological and anthropogenic factors of Cross River gorilla (Gorilla gorilla diehli) survival at Mawambi Hills, southwest Cameroon. PhD thesis, Vrije Universiteit Brussels. To Ymke i One of the joys of completing a PhD thesis is that you can look over the journey past and remember all the people who have helped and supported you along the tedious but fulfilling road. Over the past four years I have benefited from the support and guidance of funders, supervisors, other academics, colleagues, and family, to whom I would like to say thank you. But before I do so, permit me to reflect on the darkest day of my entire PhD life; the day I questioned the purpose of life in general, and the usefulness of academic achievement in particular. The idea to do a PhD in gorilla ecology was borne out of a discussion I had with one of my Master thesis supervisors, Dr. Ymke Warren, during the XXII International Primatological Society Congress, Edinburgh UK in 2008. In the months that followed, we both worked very hard to raise the initial funds and to fine-tune the research questions in collaboration with my other supervisors. The field work eventually started in November 2009 and we were all excited about the potential outcome of the study. But barely eight months into the 2 year project on the 29th of June 2010, was Dr. Warren brutally murdered in her Limbe residence in Cameroon. Her untimely death was devastating in every sense of the word and there were moments when I did not see how and why the project should continue. So let me begin this acknowledgement by thanking those who supported us during these difficult moments, and whose words and deeds enabled the project to come to a successful end. It is needless to say Ymke’s memory is threaded through every sentence in this thesis, and that her aspiration to nurture the next generation of African field conservationists must now be my motto. Thank you so much YM for everything. This thesis is yours too. Adieu. This research project was generously funded by the Flemish Interuniversity Council - University Development Cooperation PhD scholarship program (VLIR), the National Geographic Conservation Trust, the Centre for Research and Conservation - Royal Zoological Society of Antwerp (CRC- RZSA), the Gorilla Foundation, the Biosynergy Institute, and IDEA WILD. I am grateful to the Cameroon Ministries of Forestry and Wildlife and Scientific Research and Innovation for permission to work at the Mawambi Hills. I would like to express my heartfelt gratitude to Professor Luc Hens, Professor Debby Mangelings, Dr. Nikki Tagg, and Dr. Zjef Pereboom, who are not only mentors but dear friends. I could not have asked for better role models, each inspirational, supportive, and patient in their own way. Thank you very much Luc for accepting me as your PhD student in the first place and for your guidance over the years. I am eternally grateful to you and your wife for the love and friendship you have shown to my family. I could not be prouder of you Nikki for your everyday (yes I really mean everyday) guidance, selflessness and care. Your continuous reassurance that this was indeed possible is what kept me from quitting. Zjef, I thank you a million times for inviting to join the CRC lab and for providing all the logistic, financial and academic support through the CRC. It was invaluable and I could not have asked for more. I want to thank Debby so much for accepting to step in and help me complete this work when Luc had to retire. Even though we have known each other for only a few months, your words of encouragement and no-nonsense requirement that I adhere to deadlines is what pushed me across the finish line. Thanks again. ii I would also like to thank the chair of the examination and defence commission Professor Koen Putman and all my examiners: Professor Emmanuel Boon, Professor Ronald Buyl, Professor Colin Chapman, and Dr. Celine Devos, who provided encouraging and constructive feedback. It is no easy task, reviewing a 170+ page thesis, and I am grateful for your thoughtful and detailed comments. Before acting as chair of the jury, Koen helped me find a new supervisor (Debby) when Luc was retiring. I want to thank you sincerely for all your efforts and for assuring me that all will be okay. I really needed that assurance. To the many reviewers of published and unpublished articles, I want to thank you for helping to shape and guide the direction of the work with your careful and constructive comments. This includes a few colleagues and friends who helped to proofread some of my manuscripts. Thank you to Bethan M.J., Aaron N., Juliet R., Micheal W., Jude M., Aloysius A., Philippe H. and Tony R.A. I am thankful to the director of WCS, Dr. Roger Fotso, and to the entire staff of WCS Cameroon who supported me immensely during my fieldwork at Mawambi. I could not have found a more professional and accommodating group of collaborators, and for this, I am truly grateful. Members of CRC Lab at Antwerp Zoo also deserve my sincerest thanks. Your friendship and assistance has meant more to me than I could ever express. I’ll never forget your hospitality, all the useful discussions about science, and the many wonderful lunches at the zoo restaurant (Flamingo). In particular, I wish to express my gratitude to Dr. Peter Galbusera, and Dr. Philippe Helsen. Philippe especially for accepting that I test all my ideas on you first, for getting me started with genetic lab work, and for all your statistical advice. I could not complete my work without your invaluable friendly assistance which made me feel at home. Also worthy of great appreciation is Garoua Wildlife College, Cameroon, and it’s Director Mr. Francis Tarla. I want to thank you immensely for agreeing to my proposal for the college to serve as the host institution in Cameroon within the framework of VLIR PhD scholarship and your timely response to the numerous emails request. The success of this project was in significant part due to the hard work and dedication of my Cameroonian staff: Abang Patrick, Anya Fidelis, Eyoung Ferdinand, Etchu Hillary, Okun Felix, Ncha Raphael, Wenja John, and Ndive Elais, and all other service providers. Your willingness to work under extremely hard field conditions is what led to the success of this work. I am also grateful for the kindness of the people of Assam, Awuri, and Takpe villages. Behind-the-scenes, the love and support of my parents who instilled in me admirable qualities and gave me a good foundation with which to meet life was invaluable. Dad passed two years ago. I still dearly miss him and wished he could have lived another few years for my graduation. To my brothers: Thomas, Columbus, Felix, Jenarius, Derrick, Elvis, and Desmond and sisters: Julie, Alice, Canny, Bridget, and Mispa, who have stood by me and supported me despite my weird decision to move into the forest and study animals, I want to say thank you for your love. But at the same time I must warn you that having a PhD does not mean that I will not sleep in the forest anymore. Instead it means I have become professional at it. The best outcome from these past four years is the act of finding my best friend, soul-mate, and wife, who has enabled me to spread my genes into two immaculate children Ymke and Calin. My wife is the only extant human primate who can appreciate my weirdness and sense of humour and there are no words to convey how much I love her. She has been a true supporter and has unconditionally loved me through difficult times especially when I stayed in the field for months on end. Only she could sacrifice her own career to take care of our two angels while I pursue mine. My three year old (Ymke) has also been affected by the uneasy ride of the past year. I am so sorry YM and I promise I will make it up to you (someday!!!!). iii Chapter I General introduction p.1 p.21 Chapter II Impact of human activities on Cross River gorilla habitats Habitat suitability and vulnerability of Cross River gorillas Chapter III p.43 to anthropogenic disturbance Nesting behaviour of Cross River gorillas: The role of Chapter IV topography, season and vegetation type on nest site selection and nest construction efforts p.59 p.75 Feeding ecology of Cross River gorillas and the influence Chapter V of resource seasonality p.101 Chapter VI General discussion p.117 References p.151 Appendices p.167 Abstract p.168 List of publications iv List of Acronyms and Abbreviations a.s.l above sea lavel CAR Central African Republic CRG Cross River Gorilla DRC Democractic Republic of Congo FAO Food and Agriculture Organisation of the United Nation GIS Geographic Information System GPS Global Positioning Unit IUCN International Union for the Conservation of Nature and Natural Resources RZSA Royal Zoological Society of Antwerp MPI-EVA Max Planck Institute for Evolutionary Anthropology NCC Nigeria-Cameroon Chimpanzee NGO Non-Governmental Organisation NTFP Non-Timber Forest Product pers.