Spatial memory, search images and environmental cues: how do frugivores find ripe mistletoes fruits? A thesis submitted to the University of Technology Sydney in partial completion of the degree of Master of Science (Research) Melinda Elizabeth Cook BSc (Environmental Biology), University of Technology Sydney Faculty of Science, School of Life Sciences University of Technology Sydney August 2017 Supervisors Assoc. Prof. Andrea Leigh (UTS) Prof. Dave Watson (CSU) Dr. Brad Murray (UTS) Certificate of original authorship I certify that the work in this thesis has not previously been submitted for a degree nor has it been submitted as part of requirements for a degree except as fully acknowledged within the text. I also certify that the thesis has been written by me. Any help that I have received in my research work and the preparation of the thesis itself has been acknowledged. In addition, I certify that all information sources and literature used are indicated in the thesis. Signature of Student: Date: 13th July 2017 I Acknowledgements This thesis could not have been completed without the unconditional support of my long suffering parents! Thank you also to that ambiguously blessed request to ‘save the trees’ at Illabunda that has taught us all to soldier on and stay positive even when it all seems impossible, it’s just a plot twist. To my primary supervisors who are superstars, there are not enough adjectives in the world to describe how amazing they are! For believing in my ability to develop and grow as a researcher, writer and presenter; for encouraging me to take on challenges and extend my limits, and for reviewing my work from a wider viewpoint that made all the difference – thank you AndyPandy and Dr Dave! Brad, my co-supervisory superstar, thank you for squeezing me into your busy schedule to answer my sometimes inane questions about stats – you have been the light shining in the darkness, when all hope was all but lost. To Birdlife Australia, the Ecological Society of Australia and UTS, thank you for seeing the potential in my research and acting on it by funding my fieldwork and conference attendance and helping out with the logistics of fieldwork. My wonderful vollies Clarissa, Doug, Mitch, Brendon and Mickey, you made the experimental work of this study possible – thank you for sacrificing your precious summer days to spend tedious hours watching mistletoes for visiting birds! To my friends, family and fellow HDRs who listened to my talks, provided helpful feedback and learnt far more about mistletoes than they ever really wanted to know – thank you for your patience and opportune confidence boosts. And finally, to Neo, my crazy cockatiel – thank you for continually surprising me and challenging my perception of your perception of the world. You are the one. II Contents CERTIFICATE OF ORIGINAL AUTHORSHIP ................................................................................................ I ACKNOWLEDGEMENTS ......................................................................................................................... II LIST OF FIGURES .................................................................................................................................... V LIST OF TABLES .................................................................................................................................... VII ABSTRACT ............................................................................................................................................ IX 1 CHAPTER 1: INTRODUCTION ......................................................................................................... 1 1.1 OVERVIEW ..................................................................................................................................... 2 1.2 FORAGING ...................................................................................................................................... 3 1.3 SEARCH IMAGES .............................................................................................................................. 5 1.4 SEARCHING FOR PATCHY RESOURCES: FRUITS AND THEIR ASSOCIATED FRUGIVORES ........................................ 7 1.5 SEED DISPERSAL PATTERNS ................................................................................................................. 8 1.6 MISTLETOE ..................................................................................................................................... 9 1.7 MISTLETOE SEED DISPERSAL ............................................................................................................. 11 1.8 ROADSIDE ENVIRONMENTS .............................................................................................................. 12 1.9 SIGNIFICANCE AND RESEARCH CONTEXT .............................................................................................. 14 1.10 THESIS STRUCTURE ......................................................................................................................... 15 2 CHAPTER 2: THE ROLE OF LEAVES IN FORAGING STRATEGIES ......................................................17 2.1 INTRODUCTION ............................................................................................................................. 18 2.2 METHODS .................................................................................................................................... 21 2.2.1 Site and species description .................................................................................................. 21 2.2.2 Experimental procedure ....................................................................................................... 22 2.2.3 Data analysis ........................................................................................................................ 26 2.3 RESULTS....................................................................................................................................... 26 2.3.1 Proportional visits for dietary guild ...................................................................................... 27 2.4 DISCUSSION .................................................................................................................................. 28 3 CHAPTER 3: ‘CUT-AND-PASTE’ MISTLETOE RELOCATION..............................................................30 3.1 INTRODUCTION ............................................................................................................................. 31 3.1.1 Foraging strategies ............................................................................................................... 31 3.1.2 Spatially aggregated, temporally variable mistletoes .......................................................... 32 3.2 METHODS .................................................................................................................................... 34 3.2.1 Site and species description .................................................................................................. 34 3.2.2 Experimental procedure ....................................................................................................... 34 3.2.2.1 Selection of plants and their relocation ......................................................................................35 3.2.2.2 Observations ...............................................................................................................................37 3.2.3 Statistical analysis ................................................................................................................ 39 3.3 RESULTS....................................................................................................................................... 41 3.3.1 Bird visitation........................................................................................................................ 41 3.3.2 Mistletoe and vegetation characteristics ............................................................................. 41 3.3.3 Treatment effects ................................................................................................................. 42 3.3.4 Dietary guilds, resource use and influences over foraging strategies .................................. 43 3.4 DISCUSSION .................................................................................................................................. 45 3.4.1 Foraging strategies ............................................................................................................... 46 3.4.2 Foraging strategies influenced by dietary guild ................................................................... 47 III 3.4.3 Vegetation characteristics influencing foraging strategies .................................................. 48 3.4.4 Implications for the seed dispersal of mistletoe ................................................................... 49 4 CHAPTER 4: HABITAT COMPARISON: CONTINUOUS FOREST VERSUS ROADSIDE VEGETATION ....51 4.1 INTRODUCTION ............................................................................................................................. 52 4.2 METHODS .................................................................................................................................... 55 4.2.1 Site and species description .................................................................................................