Colobus Guereza Guereza) from Wof-Washa Natural and Plantation Forest, Central Highland Ethiopia
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Population estimate and behavioural ecology of Omo River guereza (Colobus guereza guereza) from Wof-Washa Natural and plantation forest, central highland Ethiopia By Dereje Yazezew Mammo A Thesis Submitted to the School of Graduate Studies of the Addis Ababa University, Department of Zoological Sciences in Fulfilment of the Requirements for the Degree of Doctor of Philosophy in Biology (Ecological and Systematic Zoology Stream) Advisor: Professor Afework Bekele Addis Ababa University Addis Ababa, Ethiopia December, 2018 Addis Ababa University School of Graduate Studies Department of Zoological Sciences This is to certify that the dissertation prepared by Dereje Yazezew Mammo, entitled: Population estimate and behavioural ecology of Omo River guereza (Colobus guereza guereza) from Wof-Washa Natural and plantation forest, central highland Ethiopia and submitted to the School of Graduate Studies of Addis Ababa University in fulfillment of the requirements for the degree of Doctor of Philosophy in Biology (Ecological and Systematic Zoology Stream) complies with the regulation of the university and meets the accepted standard with respect to originality and quality. Signed by Examining Committee: Examiner_______________________ Signature_________ Date ____________ Examiner_______________________ Signature _________ Date ____________ Advisor ________________________Signature __________Date ____________ _____________________________________________ Chair of Department or Graduate Program Coordinator ABSTRACT Population estimate and behavioural ecology of Omo River guereza (Colobus guereza guereza) from Wof-Washa Natural and plantation forest, central highland Ethiopia Dereje Yazezew Mammo, PhD Thesis, Addis Ababa University February 2019 Omo River guereza (Colobus guereza guereza) is a subspecies of eastern black and white colobus monkeys endemic to the western Rift Valley forests of Ethiopia. No detailed published information is available on this subspecies and it remains one of the least studied primates in Africa. With the current increasing habitat loss and degradation across its geographic range, data on the current conservation status and behavioural ecology are essential to design a management plan. This study therefore aims to provide data on the population estimate and behavioural ecology of Omo River guereza. Vegetation surveys were conducted within each group’s home range to quantify the overall vegetation composition. A total of 2 with 400-500 m long and 10 m wide vegetation transects were laid out and sampled the diversity of big trees ≥ 10 cm diameter at breast height (DBH= 1.3 m above ground). Phenological data were analyzed from 13 plant species: 10 trees, two shrubs and one climber. A total of 39 censuses from 1.5 to 3 km transects were conducted with a cumulative distance of 88.5 km in four different habitat types. The activity budget, feeding ecology and ranging behaviour were studied in two neighbouring groups for five minutes with 15 minutes interval scan sampling for 12 month study period. Plant species with DBH ≥ 10 cm in the range of natural forest group (N) had higher stem density (780 stems/ha) than plantation group’s (P) (600 stems/ha). Plant species diversity and evenness were higher and dominance was lower in the natural forest (N) than in plantation forest (P). Young and mature leaves were the most abundant plant parts throughout the year while fruit was the least abundant. There were statistical differences in food availability indices of young leaves (Mann Whitney U; Z=-4.16, P<0.001) and mature leaves (Mann Whitney U; Z =-4.15, P<0.001) between the two guereza groups across months. Out of the total 140 Omo River guereza groups sighted, the highest encounter rate was recorded in the undisturbed natural forest (3.11 groups/km) transect while the lowest were in the Erica- Juniperus mixed forest and disturbed natural forest. The total population estimate of the study species was 2947 individuals. Out of the average individual number (317) of Omo River guereza sighted during the three-census period, 56.3±17.1 (71%) were adult and 17.3 ±5.6 (21.8%) were subadult of both sexes. Guerezas spent 43.1% of their time resting, 31.8% feeding 12.9% moving, 5.1% grooming and 4.8% performing other activities. Guerezas were observed feeding on 31 plant species belonging to 26 families. Overall, guerezas diet constituted 56.44% young leaves, 26.59% mature leaves, 10.8% fruits and 6.17% was from other food items. The top five species from five different families comprised 83% (group P) and 70% (group N) of Omo River guereza diet of which leaves of Maesa lanceolata contributed 23.2% of the overall diet. Kernel density estimate revealed that group P shared 19.1% of its home range with group N while group N shared 10.6% of its home range with group P. Further study should be carried out to work out a proper management plan and minimize human interference. Keywords: Activity budget, feeding ecology, habitat use, population estimate, WWNSF. iii ACKNOWLEDGEMENTS Above all, from the deepest of my soul, I praise Almighty God who stands against all obstacles and enabled me to bring this thesis to its completion. Many people and organizations have supported this thesis project and I am pleased to acknowledge their support, guidance and encouragement throughout this doctoral journey. Hence, this acknowledgement is not merely some formal thanks note; it is the best way I could attempt to convey my sincere gratitude and respect for those who have been indispensable in completing this project. First of all, acknowledgments themselves appear casual and say very little about my thesis advisor Professor Afework Bekele, who had devoted his precious time and knowledge to give me constructive and valuable suggestions. I would like to express my profound veneration and deep sense of gratitude to him for instilling the confidence in me through his inspirational words and providing me with invaluable comments and criticism on many issues. His keen interest in the problems treated in this study and his generosity and patience served me as a source of constant enlightenment and encouragement. He is always available to answer my questions and provide me with assistance I requested. I would like to thank Addis Ababa University and Debre Berhan University for financial and logistical support. My research project was supported by Thematic Research on Animal Diversity (Grant number TR-010-CNS), Primate Conservation Incorporated (PCI), Rufford Small Grant Foundation and International Foundation for Science (IFS), and this study would not have been possible without generous financial support of these organizations. I would like to thank for their generous support. I would like to appreciate and thank also IDEA WILD http://www.ideawild.org/ specially Ann Marie Gage (project iv Director), for material support for the field work without which the work was impossible. We are grateful to the Ethiopian Wildlife Conservation Authority, the Amhara Region Forest and Wildlife Enterprise, and District Agriculture Offices (Tarmaber and Ankober) for granting permission to conduct this study. My gratitude also extends to the Ethiopian Meteorology Agency for meteorological data of Debre Birhan area without payment. I am also profoundly grateful to the following individuals:Professor Nga Nguyen, Dr. Addisu Mekonnen, Dr. Ryan Burke, Professor Peter J. Fashing, Dr. Ivan Norscia, Dr. Elisabetta Palagi, Dr. Zewdu Kifle and Hussein Ibrahim for their indispensable assistance in numerous ways. I thank the research assistants, Lema Mamuye, Kura Kassa, Mamuye Gizaw, Getnet Haile for their valuable help in this project. I would also like to thank the following local guides and camp attendants: Wondosen Getahun, Demisew Techale and Mindahun Mekoya. v TABLE OF CONTENTS Page LIST OF FIGURES ......................................................................................................... IX LIST OF TABLES ........................................................................................................... XI LIST OF PLATES .......................................................................................................... XII LIST OF APPENDICES ............................................................................................... XIV ABBREVATIONS AND ACRONYMS ......................................................................... XV 1. INTRODUCTION ....................................................................................................... 1 1.1. Background .............................................................................................................. 1 1.2. Statement of the Problem ......................................................................................... 6 1.3. Study objectives, hypotheses and research questions .............................................. 7 1.3.1. General objective .............................................................................................. 7 1.3.2. Specific objectives ............................................................................................ 7 1.3.3. Research hypotheses ......................................................................................... 8 1.3.4. Research questions ........................................................................................... 8 2. LITERATURE REVIEW .......................................................................................... 10 2.1. Distribution and biology of colobus monkeys ......................................................