BREEDING ECOLOGY OF PIGEON GUILLEMOTS (CEPPHUS COLUMBA) ON ALCATRAZ ISLAND, CALIFORNIA A thesis submitted to the faculty of San Francisco State University A S In partial fulfillment of the requirements for polfc the Degree - Masters of Arts In Geography: Resource Management and Environmental Planning by Victoria Leslie Seher San Francisco, California August 2016 Copyright by Victoria Leslie Seher 2016 CERTIFICATION OF APPROVAL I certify that I have read Breeding Ecology of Pigeon Guillemots (Cepphus columbaj on Alcatraz Island, California by Victoria Leslie Seher, and that in my opinion this work meets the criteria for approving a thesis submitted in partial fulfillment of the requirement for the degree Master of Arts in Geography: Resource Management and Environmental Planning at San Francisco State University. Benjamin Becker, Ph.D. National Park Service BREEDING ECOLOGY OF PIGEON GUILLEMOTS (CEPPHUS COLUMBA) ON ALCATRAZ ISLAND, CALIFORNIA Victoria Leslie Seher San Francisco, California 2016 This study compared the breeding ecology and diet of Pigeon Guillemots (Cepphus columba) from an urban estuarine colony (Alcatraz Island) and a remote oceanic colony (Southeast Farallon Island) to better understand how spatial differences and current management influence the two colonies. I used video cameras inside nest sites to help monitor the breeding phenology, reproductive success, and prey delivered to chicks on Alcatraz Island in 2015 and 2016. Data collected in this study were compared with data collected by Point Blue Conservation Science on Southeast Farallon Island. Results show similarities in breeding phenology between the two colonies, although the breeding start date was earlier on Alcatraz in 2016 by 12 days. Productivity was higher on Alcatraz in both years with 0.73 and 0.83 fledged chicks/pair while productivity dropped on Southeast Farallon Island from 0.65 fledged chicks/pair in 2015 to 0.30 fledged chicks/pair in 2016. Chick diets on Southeast Farallon Island were dominated by juvenile rockfish in both years, while the main prey items fed to chicks on Alcatraz switched from flatfish in 2015 to sculpin in 2016. Warmer ocean temperatures and a large ENSO event in 2016 may have created poor conditions for seabirds breeding offshore, while seabirds breeding in San Francisco Bay were buffered by these environmental conditions leading to higher reproductive success. I certify that the abstract is a correct representation of the content of this thesis. Date ACKNOWLEDGEMENTS I would first like to thank my thesis advisor, Dr. Barbara Holzman, Professor of Geography & Environment, for her invaluable guidance and dedication to this study. Barbara’s reminders to stop and breathe enabled the successful completion of this thesis. My sincere thanks also goes to Dr. Ellen Hines, Professor of Geography & Environment, for her insightful comments and last minute edits, and Dr. Ben Becker, National Park Service, for his support with statistical analysis. Ben’s patience and kindness allowed me to learn and understand the analytical process of this study. I would like to thank Dr. Jaime Jahncke, Pete Warzybok, and Russel Bradley with Point Blue Conservation Science for sharing their data and expertise about the PIGU population on Southeast Farallon Island and on general PIGU ecology. I am especially appreciative for their time spent answering questions, providing comments to this thesis, and reviewing video to help identify prey species. Without the support from my supervisor, Dr. Bill Merkle, Golden Gate National Recreation Area, this project would not have been possible. I am grateful for Bill’s encouragement and commitment to my academic and professional growth. I am indebted to the interns who spent many hours analyzing video or helping with equipment including Patrick Mullins, Sarah Williams, Audrey Martin, Logan Porrazzo, Lena Geupel, Emma Lord, Lisa Rachal, Meghan Cook, and Jessie Vogt. I am also grateful to Heather Robinson, Farallon Institute, for her help in prey identification. I would like to acknowledge my mentor, Steve Thompson, posthumously. Steve inspired me to attend graduate school, taught me not to take life so seriously, and instilled the value of always carrying a field notebook when I explore our natural world. Finally, I would like to express my profound gratitude to my wife, Suzanne Goodman, for providing me with unfailing support and continuous encouragement. Financial support for this study was provided by Golden Gate National Recreation Area and Golden Gate National Parks Conservancy. TABLE OF CONTENTS List of Tables.............................................................................................................vii List of Figures...........................................................................................................viii Introduction..................................................................................................................1 Methods.......................................................................................................................8 Study Area.................................................................................................................. 8 Nest Monitoring.................................................................................................. 9 Breeding Phenology and Reproductive Success........................................... 11 Chick Diet and Delivery Rates......................................................................... 11 Statistical Methods............................................................................................12 Results........................................................................................................................13 Alcatraz Island...................................................................................................13 Southeast Farallon Island................................................................................ 15 Breeding Phenology......................................................................................... 15 Reproductive Success......................................................................................16 Chick Diet.......................................................................................................... 17 Delivery Rates...................................................................................................18 Discussion..................................................................................................................19 Conclusion.................................................................................................................31 Literature Cited..........................................................................................................33 LIST OF TABLES Table Page 1. Type of active sites monitored on Alcatraz and SEFI in 2015 and 2016......................................................................................................................39 2. Clutch size and number of fledged chicks from active sites on Alcatraz and SEFI in 2015 and 2016.................................................................40 3. Mean, standard error (SE) and range of days for egg laying, hatching, fledging, incubation, and days to fledge for Alcatraz and SEFI in 2015 and 2016....................................................................................... 41 4. Ranking of generalized linear models used to analyze start of breeding season (lay date) and reproductive success.....................................................42 5. Generalized linear model results showing relationship between start of breeding season (lay date) and predictor variables: year and colony.............43 6. Reproductive performance (hatching success, fledging success, productivity) on Alcatraz and SEFI in 2015 and 2016...................................... 44 7. Generalized linear model results showing relationship between reproductive success and predictor variables: year and colony......................45 8. Results from Adonis test showing relationship between diet and predictor variables: year and colony.................................................................. 46 9. Generalized additive model results showing significance for both daily (ChickAge) and hourly (Hours) prey delivery rates on Alcatraz.......................47 10. Ranking of generalized additive models for delivery rate per day and per hour................................................................................................................48 LIST OF FIGURES Figures Page 1. Map with arrows pointing to Alcatraz Island and Southeast Farallon Island (SEFI), San Francisco County, California.............................................. 49 2. Map of year-round range of Pigeon Guillemot population in North America.. 50 3. Map provided by the National Park Service showing all confirmed nest sites for Pigeon Guillemots on Alcatraz Island in 2015 and 2016................... 51 4. Map of Alcatraz Island showing active crevice and artificial nest box sites monitored in 2015 and 2016, including sites with and without video cameras......................................................................................................52 5. Map of monitored nest sites on Alcatraz Island showing successful (fledged at least one chick) and failed (no fledged chicks) nest sites in 2015..................................................................................................................53