The Effects of Landscape Structure and Climate Change on The
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The Effects of Landscape Structure and Climate Change on the Movement, Connectivity, and Population Viability of the Hawaiian gallinule (Gallinula galeata sandvicensis) A dissertation submitted by Charles Barteld van Rees In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology TUFTS UNIVERSITY May 2018 ADVISOR: Dr. J. Michael Reed i Abstract This dissertation examines the effects of anthropogenic landscape change on the population structure, functional connectivity, and extinction risk of the Hawaiian gallinule (Gallinula galeata sandvicensis), an endangered subspecies of waterbird endemic to Hawai`i. Through a combination of field work, population genetic analysis, geospatial analysis, simulation modeling, and meta-analysis of published and unpublished work, I elucidate the behavioral and ecological mechanisms by which landscape structure impacts Hawaiian gallinule populations persisting on the island of O`ahu, Hawai`i. Hawaiian gallinules exhibited severe population declines throughout the late 19th to mid-20th century, a period coinciding with substantial development and reclamation of wetland habitat throughout Hawai`i. Their population on O`ahu has been slowly increasing since the late 1970’s, and remaining populations persist in a fragmented, urbanized landscape. I quantified the extent of wetland loss across the archipelago, and investigated the population genetic impacts of this landscape fragmentation, as well as the recent population bottleneck, on the population structure of O`ahu’s gallinule population. O`ahu had the greatest extent of wetland loss (in excess of 65%), concentrated particularly in the coastal lowlands, and sampled gallinule subpopulations across O`ahu showed moderately high genetic differentiation (overall microsatellite FST = 0.098, mtDNA FST = 0.248) across small spatial scales (1-35km). Using these genetic data, I tested a variety of biologically- informed movement hypotheses for how gallinules navigate the island’s landscape. Models that treated water features like rivers, streams, and drainage canals as corridors for gallinule movement greatly outperformed other potential ii movement models across different molecular markers, simulation methods, and statistical tests. I next combined my own field observations with previous work from government reports, Masters theses and Doctoral dissertations to generate the first comprehensive review and estimation of the vital rates of Hawaiian gallinules. Finally, I used an individually-based, spatially explicit population model to explore the climate and landscape change impacts on the viability of O`ahu’s gallinule population. Sensitivity analysis highlighted the importance of juvenile and adult survival for overall population persistence, and the importance of dispersal in mediating source-sink dynamics on the island. I estimated that O`ahu’s major gallinule habitats could lose >40% of their carrying capacity under sea level rise conditions predicted for the next century. iii Oli Kia`i Manu Oli of the Bird Observer E nā `aumākua To the family guardians E nā kūpuna To the ancestors E nā akua ē To the gods Eia mai he kanaka holokai Here stands a travelling man aloha i ka`āina who loves the land E hō mai ka `ike Grant me knowledge E hō mai ke ao Give me enlightenment E hō mai nā mea huna Show me the hidden details o nā manu ē of the birds Eia mai he kia`i Here stands a protector I ka meheu in the footsteps o nā kia manu ē of the ancient feather-gatherers E hō mai Grant me knowledge E ola ai So that the birds may live on forever E manu aku ē Hawaiian Waterbird Research Oli (spiritual chant), composed in 2017 and edited for C. van Rees by Kumu Henani Enos and Martha Kawasaki iv Acknowledgements It is with a sense of great humility and gratitude that I reflect on the professional and personal journey that has led me to draft this dissertation, into which I have poured the better half of a decade of curiosity, learning, and effort. I find that my thoughts do not dwell long on my own accomplishments, but are continually drawn to what many others have done for me throughout this process, and how deeply thankful I am for the guidance, companionship, camaraderie, and support I have received from many people who I consider myself fortunate to know. I am deeply indebted to my advisor, Professor Michael Reed, for his constant, sincere, and patient mentorship and guidance. The selfless generosity with which he spent his time and energy (both of which were in constant, high demand!) on my behalf is something I will never take for granted. To this day I am astonished and grateful at the hours (plural) he took to chat with a sputtering avian ecology intern at an AOU meeting in Jacksonville, Florida seven years ago, and at the unflagging support that I have received since. Michael has guided me through my PhD research with a combination of intellectual excitement and personal concern that has at once made me feel like a respected colleague and member of a family. He always found as much time as was needed to provide guidance and mentorship, and he did so with an honesty and level-headedness that helped me guide my own decisions in the future. Michael has calmly dispensed helpful—at times critically important—advice on everything from field research techniques to qualifying exam subjects, to crockpot recipes and what earbuds to v buy for the clearest sound, and always with a genuine interest in my well-being. He has enthusiastically supported even my strangest project ideas, and reminded me constantly to enjoy the process of research, forcing me to lighten up when I became bogged down by my own seriousness. I have treasured lab meetings, Reeding group sessions, take-out dinners before Nuttall talks, birding trips, and spontaneous office conversations, and have been proud to be part of the lab. It is no exaggeration to say that working with Michael has dramatically changed my life; I have gained much more from him than a rotten sense of humor and a tendency to answer questions with “You bet!”, and I am honored to have him as a mentor. I also give my thanks to the rest of my graduate committee (Professors Colin Orians, Elizabeth Crone, Erik Dopman, and outside member Professor Brian Olsen). Many thanks to Colin, Elizabeth, and Erik for what they taught me in courses I took with them; these helped solidify the foundations of my disciplinary knowledge and gave me confidence to pursue it on my own. I would also like to thank them for serving on my qualifying exam committee, for outlining the core readings I would need to pursue my graduate work, and for challenging me to deepen my thinking and reflect deeply on my research topics. I am additionally grateful for their career advice and willingness to meet, often at short notice, both individually and as a group, as I progressed through my chaotic and travel-filled graduate tenure. I thank Colin for helping me add to my international conservation and ecology experience with not one but two trips to Costa Rica, and am grateful to Elizabeth for patiently talking me through vi statistical concepts and the interpretations of my results on multiple occasions. I also thank Erik for helping me direct my own learning in population genetics and for recommending helpful texts on the subject. My sincere thanks to Dr. Olsen for his willingness to remotely attend my dissertation defense despite its inflexible schedule; what he may see as a somewhat minor act was for me a heroic contribution. I am grateful to Professor Michael Romero, who from the beginning of my time in the Reed research group has been a cheerful, encouraging, and interested presence, always willing to share his enthusiasm and extensive expertise, and to hear about my work. Michael’s presence was always uplifting, and he came to every lab meeting and conversation with infectious curiosity and an easy laugh that reminded me of why I love science. I found my head spinning with ideas after many a quick hallway chat with him. Finally, I cannot stress enough how much I have enjoyed our sessions of pun exchange; my sincerest apologies to anyone who has been cort in the middle over the years. I owe my sincere thanks to Professor George Ellmore, who had a great and positive influence on my first year at Tufts by taking the chance in inviting me to join his research trip to Vietnam. Five years later, this remains one of the most influential and memorable trips I have ever taken, and a highlight of my time as a graduate student. George granted me this and other opportunities for international travel (like Hummingbird Cay in the Bahamas), and in so doing sparked my interest in international conservation, which continues to shape my career trajectory and professional decisions. George is an astoundingly knowledgeable vii naturalist, and I have enjoyed the opportunity to learn from him in these diverse settings. His entertaining stories and nuggets of useful advice—be they for science, life in general, or otherwise—have contributed an alternative perspective to my graduate training, and one that I value. I will treasure my years at Tufts University among the best years of my life, and I am thankful to a great many people who contributed to the welcoming and supportive academic atmosphere in which I have been immersed for the last 5 ½ years. I thank Michael Doire and Mike Grossi for their tireless and patient assistance with years of field season logistics and money transfers. I am additionally grateful to Eileen Magnant, Elizabeth Palmer and Dee McCann for gracefully resolving my frequent crises with space reservations, printing, card access, and so on, always with no small degree of kindness, understanding, and maternal concern over my myriad ineptitudes.