University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2015 Predation Risk and Vegetation Effects on Avian Diversity, Species Turnover, Reproduction, and Fitness Joseph Anthony LaManna Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation LaManna, Joseph Anthony, "Predation Risk and Vegetation Effects on Avian Diversity, Species Turnover, Reproduction, and Fitness" (2015). Graduate Student Theses, Dissertations, & Professional Papers. 10868. https://scholarworks.umt.edu/etd/10868 This Dissertation is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. PREDATION RISK AND VEGETATION EFFECTS ON AVIAN DIVERSITY, SPECIES TURNOVER, REPRODUCTION, AND FITNESS By JOSEPH ANTHONY LAMANNA M.S. Natural Resources, Humboldt State University, Arcata, California, 2010 B.A. English Literature, University of Michigan, Ann Arbor, Michigan, 2003 Dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Wildlife Biology The University of Montana Missoula, Montana August 2015 Approved by: Sandy Ross, Dean of The Graduate School Graduate School Thomas E. Martin, Chair Montana Cooperative Wildlife Research Unit Ragan M. Callaway Wildlife Biology Mark Hebblewhite Wildlife Biology John L. Maron Wildlife Biology Douglas J. Emlen Organismal Biology and Ecology © COPYRIGHT by Joseph Anthony LaManna 2015 All Rights Reserved ii ABSTRACT LaManna, Joseph, Ph.D., August 2015 Wildlife Biology Predation risk and vegetation impacts on avian diversity, species turnover, reproduction, and fitness Chairperson: Thomas E. Martin Vegetation is the habitat that underlies animal distributions. Yet mechanisms by which dynamic changes in vegetation affect animal fitness, distributions, and communities remain unclear. For example, animal richness and species composition often change with decreased forest structural complexity associated with anthropogenic disturbance, but differences in latitude and vegetation effects on reproductive success may influence species responses to vegetation changes. My global meta-analysis of logging effects on bird communities revealed substantial species loss in tropical but not temperate forests. This suggests tropical birds exhibit greater habitat specialization than their temperate relatives. My meta-analysis also suggested that changes in reproductive success can influence how animals distribute themselves in response to vegetation change. I examined this hypothesis with an in-depth observational study and landscape-scale experiment. Habitat use and nest predation rates were examined for 16 bird species that breeding along a deciduous to coniferous vegetation gradient and with experimental conifer removal from aspen stands. For most bird species, decreasing abundance was associated with increasing predation risk along both natural and experimentally modified vegetation gradients. This landscape-scale approach strongly supports the idea that vegetation- mediated effects of predation risk are associated with animal distributions and species turnover. While direct predation mortality clearly has effects on animal population dynamics, the risk of predation alone may have equally large effects on reproduction and, ultimately, fitness. Yet the severity and generality of such demographic ‘costs of fear’ is unknown across species. I tested phenotypic responses to risk and associated demographic costs for 10 songbird species breeding along natural nest predation gradients and by experimentally increasing risk for four species. Parents decreased offspring development periods, reducing time-dependent nest mortality with natural and experimental increases in risk. Reproductive output from nests in the absence of direct predation generally declined along risk gradients, but the severity of this cost varied across species. Ultimately, demographic costs of fear reduced fitness across bird species, but not as strongly as direct predation mortality. These landscape and experimental tests suggest that vegetation affects the perceived risk of predation, and thereby strongly influences avian behaviors, fitness, distributions, and community assembly. iii ACKNOWLEDGEMENTS I am very grateful to have had the opportunity to pursue my Ph.D. with the Martin Lab in the beautiful state of Montana. First and foremost, I thank Tom Martin for bringing me into his graduate lab and putting his faith in me. Tom is exceptionally demanding and brilliant, and I am a far better scientist, writer, and thinker because of his efforts. For all this, plus my four years in Missoula and my amazing field sites, I thank my Ph.D. advisor. I am also very grateful for current and past members of the Martin graduate lab who have helped me in innumerable ways, especially Juan Oteyza, Riccardo Ton, Karolina Fierro, Andy Boyce, James Mouton, Adam Mitchell, Sonya Auer, Ron Bassar, Dan Barton, William Blake, Jen Olson, Julia Brandauer, Megan Jankowski, Ahvi Potticary, and Amy Hemenway. I am, of course, very grateful to the funders of my research during my time in Montana. This includes the Bair Foundation for 6 years of generous support for my research teams in Montana, and the Environmental Protection Agency’s Science to Achieve Results (STAR) Fellowship for supporting me during three years of my Ph.D. This work would not be possible without their gracious support. I also thank my committee: John Maron, Ragan Callaway, Doug Emlen, and Mark Hebblewhite. They, too, have demanded my very best work and have always pushed me to do and be a better scientist. I am also thankful for the broader community of both Wildlife Biology and OBE graduate students here at the University of Montana, especially Loralee Larios, Mandy Slate, Katie and Zach Baer, Sara Williams, Lauren Waller, Nicole Hupp, Theresa Laverty, Keaton Wilson, Maggie Riordan, Jema Rushe, Brett Addis, and Tom Brekke. Additionally, I would not have this dissertation without iv the help of many field technicians over my four summers here. I would like to especially thank John Schoen, Joe Hughes, Ryan Steiner, Matt Hemenway, Chelsea DeMarco, and Justin Broderick. I have had a long and winding journey to this point. I received a bachelor’s degree in English literature, but have always had a great love for the natural world and for science. After moving from Michigan to California, I worked in the Sierra Nevada Mountains leading wildlife biology field crews for the Forest Service. I am grateful to those who urged me to pursue graduate work in wildlife biology, especially Wick Prichard, Rachel Veal, Caryn Beiter, Brett Vivyan, Joy and Paul Barney and Adam Rich. I am also exceptionally thankful for my two master’s advisors, Matthew Johnson and Luke George, and my graduate student compadres at Humboldt State University, especially Bob Dillman and Marleen Wagner. James Saracco and Dave DeSante at the Institute for Bird Populations have also contributed greatly to my early wildlife career. Last, but certainly not least, I am eternally grateful for my wonderful and loving family. I thank my parents, William and Brenda LaManna, who taught me the value of hard work and that anything is possible if you only put your mind to it. I am also very grateful for my sister, Angie Hatfield, and her family, Jason, David, and Annabelle, for always being there when I need support. Finally, I dedicate this dissertation to my new baby daughter, Elena, and most importantly to Jennifer, my amazing wife, for all her love, patience, assistance, caring, and for being the most compassionate person I have ever met. I would not be who or where I am today without her love. v PREFACE Vegetation provides the habitat that underlies many animal distributions. Yet the specific mechanisms by which changes in vegetation affect animal fitness, distributions, and communities remain unclear. For example, changes in vegetation may alter fitness (i.e., reproduction and survival) sufficiently enough that animal species evolve preferences for habitat associated with high fitness (Fretwell and Lucas 1969, Pulliam 2000). These population processes may then scale up to influence changes in animal species richness and species turnover along vegetation gradients. But whether vegetation-mediated effects of predation on fitness are substantial enough to influence distributions and traits of animal species remains unknown. Alternatively, vegetation may influence predation risk, but impacts on fitness may not be strong or predictable enough to affect the behaviors, distributions, and species composition of animal species. Thus, the mechanisms by which vegetation influences animal fitness, behaviors, populations and communities remain uncertain despite their potential importance to explaining the evolution of traits or the conservation of animal populations in an era of global change. This dissertation examines one key potential mechanism by which changes in vegetation may influence animal behaviors, species richness, species composition, and demography: reproductive success. I examine ways in which changes in vegetation structure and composition alter avian reproductive success, and how those