Ecology, Morphology, and Behavior in the New World Wood Warblers A dissertation presented to the faculty of the College of Arts and Sciences of Ohio University In partial fulfillment of the requirements for the degree Doctor of Philosophy Brandan L. Gray August 2019 © 2019 Brandan L. Gray. All Rights Reserved. 2 This dissertation titled Ecology, Morphology, and Behavior in the New World Wood Warblers by BRANDAN L. GRAY has been approved for the Department of Biological Sciences and the College of Arts and Sciences by Donald B. Miles Professor of Biological Sciences Florenz Plassmann Dean, College of Arts and Sciences 3 ABSTRACT GRAY, BRANDAN L., Ph.D., August 2019, Biological Sciences Ecology, Morphology, and Behavior in the New World Wood Warblers Director of Dissertation: Donald B. Miles In a rapidly changing world, species are faced with habitat alteration, changing climate and weather patterns, changing community interactions, novel resources, novel dangers, and a host of other natural and anthropogenic challenges. Conservationists endeavor to understand how changing ecology will impact local populations and local communities so efforts and funds can be allocated to those taxa/ecosystems exhibiting the greatest need. Ecological morphological and functional morphological research form the foundation of our understanding of selection-driven morphological evolution. Studies which identify and describe ecomorphological or functional morphological relationships will improve our fundamental understanding of how taxa respond to ecological selective pressures and will improve our ability to identify and conserve those aspects of nature unable to cope with rapid change. The New World wood warblers (family Parulidae) exhibit extensive taxonomic, behavioral, ecological, and morphological variation. Ever growing museum collections, life history data availability, citizen science-collected behavior data availability, advances in statistical techniques, and advances in Parulid warbler phylogenetic relationships prime the family for modern ecomorphological and functional morphological study. I combined morphological and migration distance data from museum specimens and ecological data from the literature to explore ecomorphological patterns in a phylogenetic 4 context at the level of the Parulidae. Morphological similarity among warblers mirrors genetic similarity except for traits associated with flight. Wing aspect and tail length have been shown to be influenced by both migration distance as well as foraging habitat structural openness. Selective pressures encountered during migration may drive a wing shape less suited for locomotion within the breeding and wintering environments and the shapes of modern migrant wings may represent functional trade-offs. Many warbler species and subspecies are underrepresented in museum collections and ecological data are severely lacking for many taxa. Traditional ecomorphological ideology posits intraspecific phenotypic variation is minimal relative to interspecific phenotypic variation. However, the degree to which intraspecific variation in ecology and morphology varies among taxa and can be extensive. Studies which quantify the intraspecific variation in ecology and morphology for individual species will inform future ecomorphological study and inform conservation decisions by identifying those taxa with limited variation. The Hooded Warbler (Setophaga citrina) is considered a monotypic species within the Parulid family which exhibits well-characterized sex- specific habitat segregation. Using museum specimens, I explore the spatial and temporal variation in morphology across the species’ breeding range. Only males show a weak temporal shift in wing morphology with wing length increasing relative to wing width over the last century. The species exhibits age and sex-specific south to north, female to male, and young bird to old bird shifts in morphology consistent with migration distance, age, and sex patterns seen in other Parulid warblers and other small passerines. 5 Studies linking morphology and ecology with performance is crucial to our understanding of morphological evolution. Functional morphological relationships are rarely assessed in wild individuals due to temporal, financial, and practicality constraints. However, captive performance studies may provide a biased view of functional morphological relationships. We used flight tunnel and video recording in the field to assess how wing size and shape influence flight speed in a wild population of Hooded Warblers breeding near the northern limits of the species’ breeding range. Bird mass, wing area, and wing aspect interact to predict maximum takeoff flight speed attained during the first 2m of escape flight in the Hooded Warbler. For birds with low wing loading, wing aspect is positively related to maximum flight speed. At high wing loading, however, high aspect wings perform inferiorly to low aspect wings. This study supports a form-function relationship in the Hooded Warbler and provides a benchmark data set from wild, untrained individuals against which future captive and field-based studies can compare. Results presented in this dissertation support individual-level, species-level, and family level ecomorphological and functional morphological patterns in a model avian system and expand our understanding of ecomorphological and functional morphological associations. Including a broader taxonomic and morphological sample of the warbler family has uncovered novel ecomorphological patterns in this well-studied avian system. Additional fine-scale ecomorphological research is needed to better understand individual model taxa and to better understand discrepancies in ecomorphological patterns seen across taxonomic studies. 6 DEDICATION For my family 7 ACKNOWLEDGMENTS I thank my adviser, Donald Miles, for his mentorship and help developing my research and teaching interests; providing resources for my work; providing feedback for grant proposals; and for his patience, support, and advice regarding this dissertation. I also thank my dissertation committee members Kelly Williams, Viorel Popescu, and Harvey Ballard for their patience and guidance. I thank Kelly Williams for teaching me the ways of the Hooded Warbler; for helping develop my field, lab, and statistical skillsets; for providing resources for this and other Hooded Warbler projects; and for collaborative support. I thank Michelle Ward, Ryan Dorkoski, Kelly Williams, Debbie Walter, Kyle Brooks, Cassie Thompson, Derrick Gray, Linn Keyser, and Max Groff for countless hours of philosophical discussion and dissertation critique. Funding for these projects was provided by three Ohio University Graduate Student Senate Original Work Grants, an Ohio University Student Enhancement Award, and a Kirtland Bird Club Ohio Avian Project Initiative award. I thank Michelle Ward and Kelly Williams for assistance collecting museum and field morphological data. I thank the 2014-2017 Hooded Warbler field teams (the “chip chasers” and “HOWA hunters”) and HOWA lab members for field data collection assistance and data entry. Finally, I thank my family for supporting and encouraging my love of nature and pursuit of knowledge. 8 TABLE OF CONTENTS Page Abstract ............................................................................................................................... 3 Dedication ........................................................................................................................... 6 Acknowledgments............................................................................................................... 7 List of Tables .................................................................................................................... 11 List of Figures ................................................................................................................... 12 Chapter 1: Introduction ..................................................................................................... 14 Ecological Morphology .............................................................................................. 14 Ecology, Morphology, and Performance .................................................................... 15 Scale in Ecomorphological Studies ............................................................................ 16 Ecology and Avian Wing Morphology ....................................................................... 18 The New World Wood Warblers (Family Parulidae) ................................................. 22 Chapters ...................................................................................................................... 25 Chapter 2: Ecology and Morphology of the New World Wood Warblers ....................... 26 Abstract ....................................................................................................................... 26 Introduction ................................................................................................................. 27 Migration............................................................................................................... 27 Functional Morphological Trade-offs ................................................................... 31 Ontogenetic and Sex Polymorphism ..................................................................... 33 Parulidae ..............................................................................................................