University of Arkansas, Fayetteville ScholarWorks@UARK Theses and Dissertations 5-2013 Ecology and Flock-Following Behavior of the Wedge-Billed Woodcreeper in Eastern Ecuador Abigail Darrah University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/etd Part of the Behavior and Ethology Commons, Poultry or Avian Science Commons, and the Terrestrial and Aquatic Ecology Commons Recommended Citation Darrah, Abigail, "Ecology and Flock-Following Behavior of the Wedge-Billed Woodcreeper in Eastern Ecuador" (2013). Theses and Dissertations. 807. http://scholarworks.uark.edu/etd/807 This Dissertation is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. ECOLOGY AND FLOCK-FOLLOWING BEHAVIOR OF THE WEDGE-BILLED WOODCREEPER IN EASTERN ECUADOR ECOLOGY AND FLOCK-FOLLOWING BEHAVIOR OF THE WEDGE-BILLED WOODCREEPER IN EASTERN ECUADOR A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology by Abigail Darrah Ohio University Bachelor of Science in Biology, 2003 University of Arkansas Master of Science in Biology, 2006 May 2013 University of Arkansas ABSTRACT The wedge-billed woodcreeper (Glyphorynchus spirurus) is a common understory suboscine passerine of lowland Neotropical rainforests. It frequently joins mixed-species understory flocks but also regularly forages alone, and thus is an excellent model species on which to conduct comparative behavioral observations to examine the hypothesized costs and benefits of flock- following. Individuals exhibit variable flocking propensities (proportion of time spent with flocks), and thus observing the correlations between flocking propensity and physical and environmental factors can provide further insight into the importance of flock-following to the ecology of this species. Despite its abundance at many sites and its wide geographic range, surprisingly few studies have focused on the ecology and behavior of this species; previous observations suggested that this species occupies large, overlapping home ranges, which has important implications for intraspecific interactions and flock-following behavior. This study had three primary objectives: 1) to compare the foraging behavior and movement patterns of the wedge-billed woodcreeper in and out of flocks to examine the importance of hypothesized costs and benefits of flock-following for this species; 2) to determine which physical and environmental factors have the greatest influence on individual flocking propensity; and 3) to quantify the extent of home range overlap among individuals and to examine the influence of this overlap on space use and flock-following behavior. Wedge-billed woodcreepers used more open microhabitats in flocks than alone, supporting an anti-predator hypothesis for the benefit of flocking behavior. A decrease in time spent per trunk in flocks than alone, and a decrease in time spent with a flock with increasing movement rate, suggests an energetic cost associated with following flocks. Average flocking propensity was 32% in 2011 and 20% in 2012, considerably lower than previously reported in the literature and predicted under the assumption that individuals always join a flock when one is present in the home range. Body mass was the strongest predictor of individual flocking propensity, with larger individuals spending more time in flocks, and the correlation between the differences in body mass and flocking propensities of overlapping neighbors suggests that larger individuals may exclude smaller individuals from flocks. The distribution of flock-following locations was not influenced by the space use of larger neighbors, although a rigorous examination of simultaneous space use, coupled with a genetic analysis to determine if any overlapping neighbors are genetically related, would be necessary to provide a robust test of this hypothesis. Home ranges overlapped extensively in this study, thus the wedge-billed woodcreeper does not appear to defend exclusive home ranges at this site, unlike most other understory insectivores including other woodcreepers. Finally, in order to provide additional information about the behavior and natural history of this species, this dissertation includes a chapter that describes a previously known display behavior and provides notes about incubation and fledgling care. This dissertation is approved for recommendation to the Graduate Council. Dissertation Director: ________________________________________ Dr. Kimberly Smith Dissertation Committee: ________________________________________ Dr. Bette Loiselle ________________________________________ Dr. Gary Huxel ________________________________________ Dr. Douglas James DISSERTATION DUPLICATION RELEASE I hereby authorize the University of Arkansas Libraries to duplicate this dissertation when needed for research and/or scholarship. Agreed ____________________________________ Abigail Darrah Refused ____________________________________ Abigail Darrah ACKNOWLEDGMENTS I would like to thank Drs. Bette Loiselle and John Blake for their invaluable comments and logistical assistance in the field, and for permitting me to use their plots for this study. They graciously allowed me to accompany them during their yearly mist-netting efforts on their plots, which greatly facilitated my ability to capture enough wedge-billed woodcreepers for this study. I thank them for continuing to color-band the woodcreepers after my departure from the field in 2010. I am grateful for their efforts to teach me how to extract difficult birds from the nets and for allowing me to practice extraction techniques. I thank the staff of Tiputini Biodiversity Station for their support during my stays at the station, particularly on-site managers Diego Mosquera and Eduardo Mora. I am especially grateful for their efforts to provide comfort and transportation to a doctor when my husband and I were ill. I thank Consuelo de Romo for arranging transportation to and from the field station every year, and I thank David Romo Vallejo and María José Rendón for their assistance in obtaining research permits from the Ecuadorian Ministry of Environment. I thank Noah Strycker and Rebekah Rylander for volunteering their time to travel to Tiputini and help with field data collection. I thank the current and former students of the Smith Lab for their support and advice, particularly Jeff Kimmons, Maureen McClung, Jason Luscier, and Thea Kristensen. I am grateful to my committee members, Drs. Gary Huxel, Doug James, and Bette Loiselle, and to my advisor, Dr. Kimberly Smith, for their support. I thank three anonymous reviewers of a manuscript based on chapter 2 of this dissertation, whose comments were useful in improving that chapter. I thank the University of Arkansas Graduate School and the Arkansas Audubon Society Trust for providing funding for this project. Finally I thank my husband Tom Millican for his love and support throughout my endeavors. DEDICATION I dedicate this dissertation to my mother, Beverly Craig, whose hard work and achievements inspired me to test my limits and strive to excel in academia. TABLE OF CONTENTS CHAPTER 1. INTRODUCTION....................................................................................................1 Literature Cited....................................................................................................................8 CHAPTER 2.COMPARISON OF FORAGING BEHAVIORS AND MOVEMENT PATTERNS OF THE WEDGE-BILLED WOODCREEPER (GLYPHORYNCHUS SPIRURUS) TRAVELING ALONE AND IN MIXED-SPECIES FLOCKS IN AMAZONIAN ECUADOR ........................................................................................................................................................12 Abstract..............................................................................................................................13 Introduction........................................................................................................................13 Methods..............................................................................................................................17 Results................................................................................................................................22 Discussion..........................................................................................................................23 Literature Cited..................................................................................................................29 CHAPTER 3.ECOLOGICAL CORRELATES OF FLOCKING PROPENSITY IN THE WEDGE-BILLED WOODCREEPER (GLYPHORYNCHUS SPIRURUS) IN EASTERN ECUADOR....................................................................................................................................38 Abstract..............................................................................................................................39 Introduction........................................................................................................................39 Methods..............................................................................................................................43 Results................................................................................................................................49