Temporal Population Dynamics of Important Black Skimmer (Rynchops Niger) and Least Tern (Sternula Antillarum) Colonies in Lee An
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Temporal population dynamics of important Black Skimmer (Rynchops niger) and Least Tern (Sternula antillarum) colonies in Lee and Collier County, Florida ______________________________________________________________________________ A Thesis Presented to The Faculty of the College of Arts and Sciences Florida Gulf Coast University In Partial Fulfillment Of the Requirement for the Degree of Master of Science By Courtney E. Kern 2020 ii Florida Gulf Coast University Thesis APPROVAL SHEET This thesis is submitted in partial fulfillment of the requirements for the degree of Master of Science ________________________________ Courtney E. Kern ________________________________ Kara Lefevre, Ph.D., Advisor ________________________________ Brian Bovard, Ph.D, Committee Member ________________________________ Edwin M. Everham III, Ph.D, Committee Member ________________________________ Adam DiNuovo, Outside Reader The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above-mentioned discipline. 1 Acknowledgements I wish to thank all the people whose assistance helped me complete this project. Firstly, I am indebted to Dr. Kara Lefevre, who worked with me from beginning to end with my research. Kara has taken every opportunity to help me succeed. I am incredibly grateful to have her as a mentor, advisor, and friend. I would also like to thank Dr. Brian Bovard and Dr. Win Everham for providing me with the proper guidance throughout not just my research, but my career as a young environmental scientist. Dr. Bovard spent countless hours helping me understand JMP and my data analyses, and Dr. Everham gave me vital feedback on the design of my study. Additionally, seabird biologist Adam DiNuovo was instrumental in providing crucial background information about the skimmer colonies of Southwest Florida across the timespan of this study. I also wish to express my appreciation to the Florida Fish and Wildlife Conservation Commission and Audubon Florida for making it possible to visit these colony sites and be able to work alongside wonderful employees and volunteers. This project would not have been possible without the many members of the Florida Shorebird Alliance. The data collected by this team of biologists and community volunteers is crucial for the understanding of Black Skimmer and Least Tern ecology. Thank you to the FGCU Whitaker Center for STEM Education and Audubon Society of Southwest Florida for providing me with the funding that helped me complete my coursework and this project. Finally, thank you Chad Evers, Brenda Thomas, and Patty Krupp, for being mentors to me throughout my experience at FGCU. I am tremendously grateful for the love and support provided by my parents, Bob and Diane Kern, my sister Maddie Kern, and my fiancée Matt 2 Ramsey. Matt, you have put a smile on my face when I stressed over deadlines and you helped me get through the thick of it. I am so thankful for you! 3 Abstract Beach-nesting seabirds are particularly susceptible to environmental changes along coastlines, such as development, beach erosion, human interaction, predation, cyclonic storms, and sea level rise. Measuring all components within an ecosystem is impossible, therefore, selecting components that serve as indicators can provide insight to larger-picture conditions. Birds have been widely used as biological indicators. Studying populations of imperiled species is essential for understanding long-term trends and creating effective management plans, to achieve conservation goals. Without a baseline assessment of abundance and distribution, it is impossible to determine population status, monitor trends, or support management plans. This study focuses on populations of Rynchops niger (Black Skimmers) and co-nesting Sternula antillarum (Least Terns) due to their vulnerability to coastal land loss, sea level rise, and other human-caused impacts in Southwest Florida. Southwest Florida was selected as the focal area of this study because the region supports a majority of the state’s Black Skimmer population. 16 key sites in Lee County and Collier County have proven to be biologically important for Black Skimmer and Least Tern colonies due to their ecological characteristics that sustain seabird colonies. The Florida Shorebird Database (FSD) is a partner-led program created by the Florida Shorebird Alliance (FSA) for monitoring that consolidates survey effort by a mix of professionals and volunteers, to expedite the evaluation of population goals and management practices. The goal of this study was to gather nest, adult, and fledged chick population data for both seabird species between 2011-2019 to better understand Black Skimmer and Least Tern population dynamics along the Florida Gulf of Mexico Coast. The analysis of Black Skimmer and Least Tern breeding data compiled for 2011-2019 showed that Collier County and Lee County differed in total nest counts per year. Lee County did not experience as dramatic of peaks 4 and declines compared to Collier County, and Lee experienced more of a steady increase in nests over the years. Consequences of varying rates of reproductive success within the region include: potential population decreases in the future in some areas versus increases in other areas; steady regional populations with some sites contributing recruitment to other sites that have lower reproductive success; abandonment of sites with low reproductive success; and merging of colonies into sites with high reproductive success. As development continues to expand along coastal areas, it is critical that large, ecologically important nesting sites be constantly monitored and maintained. Monitoring is crucial in order to measure the success of management plans and conservation objectives. 5 Table of Contents Abstract ........................................................................................................................................... 3 List of Tables .................................................................................................................................. 6 List of Figures ................................................................................................................................ 7 Introduction .................................................................................................................................... 8 Standard Methods of Analyzing Population Data ............................................................... 18 Standard Measures of Productivity ...................................................................................... 23 Methods ........................................................................................................................................ 25 Breeding Bird Protocol Description ...................................................................................... 25 Study Area ............................................................................................................................... 25 The Florida Shorebird Database ........................................................................................... 28 Results........................................................................................................................................... 36 Relationships Between Nesting .............................................................................................. 36 Spatiotemporal Dynamics Between Counties ....................................................................... 36 Peak Counts of Nests, Fledglings, and Adults ...................................................................... 38 Peak Count Windows ............................................................................................................. 39 Discussion..................................................................................................................................... 48 Methodological Considerations ............................................................................................. 48 Implications for management ................................................................................................ 53 Reproductive success ........................................................................................................... 53 Juvenile rates of survival and dispersal ............................................................................. 53 Managing Critical Habitat ................................................................................................... 54 Recommendations for Future Research ................................................................................ 56 Closing Notes ........................................................................................................................ 56 Literature Cited ............................................................................................................................ 58 APPENDIX A ............................................................................................................................... 65 APPENDIX B ............................................................................................................................... 68 APPENDIX C ............................................................................................................................... 71 APPENDIX D .............................................................................................................................