To Migrate or to Forage? The Where, When and Why Behind Grevy’s Zebra Movement Nika Levikov September 2014 A thesis submitted in partial fulfilment of the requirement for the degree of Master of Science and the Diploma of Imperial College London DECLARATION OF OWN WORK I declare that this thesis, “To Migrate or to Forage? The Where, When and Why Behind Grevy’s Zebra Movement,” is entirely my own work and that where material could be construed as the work of others, it is fully cited and referenced and/or with appropriate knowledge given. Signature Name of student: Nika Levikov Names of Supervisors: Dr. Marcus Rowcliffe Belinda Low Dr. Sarah Robinson 1 Contents Abstract ................................................................................................................................................... 5 Acknowledgements ................................................................................................................................. 6 1. Introduction ........................................................................................................................................ 8 1.1 Problem Statement ....................................................................................................................... 8 1.2 Aim and Objectives ..................................................................................................................... 10 1.3 Hypotheses ................................................................................................................................. 11 2. Background ....................................................................................................................................... 11 2.1 Grevy’s Zebra .............................................................................................................................. 11 2.1.1 Background and Ecology ...................................................................................................... 11 2.1.2 Threats and Legal Status ...................................................................................................... 12 2.2 Methods Approach ..................................................................................................................... 14 2.2.1 Normalized Differential Vegetation Index ........................................................................... 14 2.2.2 Dynamic Brownian Bridge Movement Model...................................................................... 15 2.3 Animal Movement ...................................................................................................................... 17 2.3.1 Understanding Movement and Utilization Distribution ...................................................... 17 2.3.2 Movement Research for Conservation Planning ................................................................. 17 2.4 Study Area ................................................................................................................................... 19 3. Methods ............................................................................................................................................ 20 3.1 Methodological Framework ........................................................................................................ 20 3.2 Data Collection ............................................................................................................................ 20 3.3 Data Analysis ............................................................................................................................... 22 3.3.1 Movement Modelling .......................................................................................................... 22 3.3.2 Core Foraging Areas and Priority Corridors ......................................................................... 25 3.3.3 Generalized Additive Model ................................................................................................ 26 4. Results ............................................................................................................................................... 28 4.1 Vegetation Driver ........................................................................................................................ 28 4.2 Utilization Distribution, Core Foraging Areas and Corridors ...................................................... 30 4.3 Generalized Additive Model ....................................................................................................... 31 5. Discussion .......................................................................................................................................... 36 5.1 Significance of Core Foraging Areas and Priority Movement Corridors ..................................... 36 5.2 Effects From Movement Drivers ................................................................................................. 39 5.2.1 NDVI Value Associations Between Foraging and Migratory Behaviour ............................... 39 5.2.2 Presence/Absence Response to NDVI .................................................................................. 40 5.2.3 Presence/Absence Response to Water Points and Human Settlements ............................. 40 5.3 Application to Future Threats ..................................................................................................... 42 5.3.1 Increased Human Wildlife Conflicts ..................................................................................... 42 5.3.2 Infrastructure Planning and Oil Pipelines ............................................................................ 43 5.4 Future Research Recommendations ........................................................................................... 44 References ............................................................................................................................................ 47 Appendix I ............................................................................................................................................. 52 Appendix II ............................................................................................................................................ 53 Appendix III ........................................................................................................................................... 54 Appendix IV ........................................................................................................................................... 56 Appendix V ............................................................................................................................................ 59 3 Acronyms AIC Akaike’s Information Criteria BBMM Brownian Bridge Movement Model CA Core Area(s) CITES Convention on International Trade in Endangered Species of Wild Fauna and Flora dBBMM dynamic Brownian Bridge Movement Model GAM Generalized Additive Model GE Google Earth GIS Geographic Information System GLEWS Global Livestock Early Warning System GPS Global Positioning System GZT Grevy’s Zebra Trust IUCN International Union for the Conservation of Nature LAPSSET Lamu Port and South Sudan Ethiopia Transport MODIS Moderate Resolution Imaging Spectroradiometer MV Motion Variance NDVI Normalized Difference Vegetation Index PA Protected Area(s) UD Utilization Distribution Abstract Biodiversity loss from habitat fragmentation and degradation continues to threaten much of Eastern Africa. Migratory ungulates face added pressure from fragmentation and land-use conversion due to increased agricultural expansion and infrastructure development, which may disrupt important movement corridors and migration pathways. For the endangered Grevy’s zebra (Equus grevyi), additional threats from limited natural resources make the future of this species uncertain. To develop appropriate conservation initiatives in light of present and future threats, it is vital to understand how and where Grevy’s zebra move. This study analyses three previously identified drivers of movement: vegetation, water availability and human settlements, to understand which of them has a greater effect by running a generalized additive model. Additionally, through the incorporation of the dynamic Brownian bridge movement model that estimates utilization distribution, core foraging areas and priority movement corridors are identified. This approach has not been used before and results indicate that it is more accurate in analysing space use than previous methods such as kernel densities. Results also found that vegetation explains little of Grevy’s zebra movements, but distance to settlements and water points have a greater effect. The probability of zebra presence according to core areas increases closer to water and away from settlements, suggesting a minimum distance threshold of 20km to water. In addition, it is suggested that Grevy’s zebra will migrate long distances only when natural resources become limiting and will keep further from water sources to avoid livestock and settlements. This study concludes that all identified core foraging areas occur outside of protected areas and mainly within conservancies that are managed by communities. Recommendations are made for management and monitoring of this species as well as for surrounding wildlife, livestock and pastoralist communities. Future research recommendations are also discussed. Word Count: 14,383 5 Acknowledgements I would like to