Florida International University FIU Digital Commons FIU Electronic Theses and Dissertations University Graduate School 6-14-2013 Factors Influencing Movements and Foraging Ecology of American Alligators (Alligator mississippiensis) in a Dynamic Subtropical Coastal Ecosystem Adam Rosenblatt Florida International University, [email protected] DOI: 10.25148/etd.FI13080511 Follow this and additional works at: https://digitalcommons.fiu.edu/etd Part of the Behavior and Ethology Commons Recommended Citation Rosenblatt, Adam, "Factors Influencing Movements and Foraging Ecology of American Alligators (Alligator mississippiensis) in a Dynamic Subtropical Coastal Ecosystem" (2013). FIU Electronic Theses and Dissertations. 900. https://digitalcommons.fiu.edu/etd/900 This work is brought to you for free and open access by the University Graduate School at FIU Digital Commons. It has been accepted for inclusion in FIU Electronic Theses and Dissertations by an authorized administrator of FIU Digital Commons. For more information, please contact [email protected]. FLORIDA INTERNATIONAL UNIVERSITY Miami, Florida FACTORS INFLUENCING MOVEMENTS AND FORAGING ECOLOGY OF AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) IN A DYNAMIC SUBTROPICAL COASTAL ECOSYSTEM A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in BIOLOGY by Adam E. Rosenblatt 2013 To: Dean Kenneth G. Furton College of Arts and Sciences This dissertation, written by Adam E. Rosenblatt, and entitled Factors Influencing Movements and Foraging Ecology of American Alligators (Alligator mississippiensis) in a Dynamic Subtropical Coastal Ecosystem, having been approved in respect to style and intellectual content, is referred to you for judgment. We have read this dissertation and recommend that it be approved. _______________________________________ Maureen Donnelly _______________________________________ Craig Layman _______________________________________ Rene Price _______________________________________ Frank Mazzotti _______________________________________ Michael Heithaus, Major Professor Date of Defense: June 14, 2013 The dissertation of Adam E. Rosenblatt is approved. _______________________________________ Dean Kenneth G. Furton College of Arts and Sciences _______________________________________ Dean Lakshmi N. Reddi University Graduate School Florida International University, 2013 ii iii © Copyright 2013 by Adam E. Rosenblatt All rights reserved. iv DEDICATION To my mother and father, Ann Freedman and Rand Rosenblatt, for encouraging me to pursue my passions even when those passions scared the crap out of them. To my brother, David Rosenblatt, for leading by example. And to my wife, Rachel Decker, for her patience, kindness, insight, and love. v ACKNOWLEDGMENTS Almost no scientific work is accomplished alone, and my dissertation research is no different. Many people and organizations assisted and supported me during my studies and they are acknowledged at the end of each chapter. However, a number of people deserve specific thanks. First and foremost, I thank Mike Heithaus, my major advisor, for guiding me through the complexities of being a scientist, supporting and encouraging me through the good times and the bad, providing me with endless professional opportunities, and introducing me to alligators and the Everglades, both of which I now adore. I also thank the members of my committee, Maureen Donnelly, Craig Layman, Frank Mazzotti, and Rene Price, for their generous donations of expertise and time during my research. I am deeply indebted to many of my fellow graduate students for their support, assistance, and insight over the years, especially my current and former lab mates Cindy Bessey, Derek Burkholder, Katy Cameron, Diana Churchill, Meagan Dunphy-Daly, Kirk Gastrich, Jeremy Kiszka, Phil Matich, Shomen Mukherjee, Rob Nowicki, Robin Sarabia, Jordy Thomson, Jeremy Vaudo, Beth Whitman, and Aaron Wirsing. I was also helped in the field and the lab by a fantastic group of undergraduates, including Cynthia Aceves, Max Lowenstein, Jenn Meyer, Greg Mineau, Melissa Pimentel, Fernanda Velasco, Carlos Villegas, and Rebecca Wallace. During my research I was generously supported by Florida International University through a Teaching Assistantship and a Dissertation Year Fellowship. vi ABSTRACT OF THE DISSERTATION FACTORS INFLUENCING MOVEMENTS AND FORAGING ECOLOGY OF AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) IN A DYNAMIC SUBTROPICAL COASTAL ECOSYSTEM by Adam E. Rosenblatt Florida International University, 2013 Miami, Florida Professor Michael Heithaus, Major Professor Top predators can have large effects on community and population dynamics but we still know relatively little about their roles in ecosystems and which biotic and abiotic factors potentially affect their behavioral patterns. Understanding the roles played by top predators is a pressing issue because many top predator populations around the world are declining rapidly yet we do not fully understand what the consequences of their potential extirpation could be for ecosystem structure and function. In addition, individual behavioral specialization is commonplace across many taxa, but studies of its prevalence, causes, and consequences in top predator populations are lacking. In this dissertation I investigated the movement, feeding patterns, and drivers and implications of individual specialization in an American alligator (Alligator mississippiensis) population inhabiting a dynamic subtropical estuary. I found that alligator movement and feeding behaviors in this population were largely regulated by a combination of biotic and abiotic factors that varied seasonally. I also found that the population consisted of individuals that displayed an extremely wide range of movement and feeding behaviors, indicating that individual vii specialization is potentially an important determinant of the varied roles of alligators in ecosystems. Ultimately, I found that assuming top predator populations consist of individuals that all behave in similar ways in terms of their feeding, movements, and potential roles in ecosystems is likely incorrect. As climate change and ecosystem restoration and conservation activities continue to affect top predator populations worldwide, individuals will likely respond in different and possibly unexpected ways. viii TABLE OF CONTENTS CHAPTER PAGE PREFACE ............................................................................................................................1 I. GENERAL INTRODUCTION ......................................................................................2 Literature Cited ..........................................................................................................6 II. SLOW ISOTOPE TURNOVER RATES AND LOW DISCRIMINATION VALUES IN THE AMERICAN ALLIGATOR: IMPLICATIONS FOR INTERPRETATION OF ECTOTHERM STABLE ISOTOPE DATA .......................................................................8 Abstract ......................................................................................................................9 Introduction ..............................................................................................................10 Materials and Methods .............................................................................................12 Results ......................................................................................................................18 Discussion ................................................................................................................23 Acknowledgements ..................................................................................................33 Literature Cited ........................................................................................................33 III. DOES VARIATION IN MOVEMENT TACTICS AND TROPHIC INTERACTIONS AMONG AMERICAN ALLIGATORS CREATE HABITAT LINKAGES? ......................................................................................................................41 Abstract ....................................................................................................................42 Introduction ..............................................................................................................43 Materials and Methods .............................................................................................46 Results ......................................................................................................................54 Discussion ................................................................................................................69 Acknowledgements ..................................................................................................78 Literature Cited ........................................................................................................79 IV. INTRAPOPULATION VARIATION IN ACTIVITY RANGES, MOVEMENT RATES, AND HABITAT USE OF AN AMERICAN ALLIGATOR POPULATION IN A SUBTROPICAL ESTUARY .........................................................................................84 Abstract ....................................................................................................................85 Introduction ..............................................................................................................86 Materials and Methods .............................................................................................89