FLORIDA SCRUB-JAY MOVEMENT THROUGH UNSUITABLE HABITAT AND ITS RELATIONSHIP TO OCCUPANCY IN OCALA NATIONAL FOREST By AMANDA M. ABEL A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2014 © 2014 Amanda M. Abel To my Mom who has always encouraged me to be a lifelong learner ACKNOWLEDGMENTS I would like to begin by thanking my family and friends for their support and encouragement throughout my time at the University of Florida. I thank my advisor, Katie Sieving, and committee members, Karl Miller and Tom Hoctor, for helping me develop a well thought out thesis project. I thank Liz White for helping me with field work in Ocala National Forest. I thank Jennifer Gillett-Kaufman and Thomas Walker for hiring me as a graduate assistanct at the Natural Area Teaching Lab. Lastly, I thank the School of Natural Resources and Environment for the tuition waivers and the Provost for the stipend I received for my graduate assistantship. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF FIGURES .......................................................................................................... 7 LIST OF ABBREVIATIONS ............................................................................................. 8 ABSTRACT ..................................................................................................................... 9 CHAPTER 1 INTRODUCTION .................................................................................................... 11 2 MOVEMENT THROUGH UNSUITABLE HABITAT................................................. 13 Research Design .................................................................................................... 15 Study Species: Florida Scrub-jay (Aphelocoma coerulescens) ........................ 16 Study Site: Ocala National Forest .................................................................... 17 Methods .................................................................................................................. 18 Sampling Design .............................................................................................. 18 Field Techniques .............................................................................................. 19 Remote Sensing and Land Cover Classification .............................................. 20 Calculation of Percent Pine, Oak, and Open Space Within Stands .................. 20 Data Analysis ................................................................................................... 21 Results .................................................................................................................... 22 Discussion .............................................................................................................. 23 3 CLEAR-CUT PATCH OCCUPANCY ...................................................................... 30 Research Design .................................................................................................... 31 Study Species: Florida Scrub-jay (Aphelocoma coerulescens) ........................ 32 Study Site: Ocala National Forest .................................................................... 33 Methods .................................................................................................................. 34 Survey Stand Identification and Definition of Suitable Stands .......................... 34 Data Analysis ................................................................................................... 37 Results .................................................................................................................... 38 Discussion .............................................................................................................. 38 4 CONCLUSIONS ..................................................................................................... 46 LIST OF REFERENCES ............................................................................................... 47 BIOGRAPHICAL SKETCH ............................................................................................ 51 5 LIST OF TABLES Table page 2-1 Sampling Design ................................................................................................ 27 2-2 Predictor (X) and Response (Y) Variables in Analyses ...................................... 27 2-3 Principal Components Variance Explained and Loadings for Matrix Vegetation and Age ............................................................................................ 27 2-4 Principal Component Variance Explained and Loadings for Habitat Vegetation and Age ............................................................................................ 28 2-5 Logistic Regression of Enter/Not Enter (Seasons Combined) ............................ 28 2-6 Linear Regression on Distance Followed (Seasons Combined) ......................... 28 3-1 Predictor (X) and Response (Y) Variables of Occupancy Study ......................... 42 3-2 Logistic Regression of Patch Occupancy ........................................................... 42 6 LIST OF FIGURES Figure page 2-1 Examples of clustered and isolated functional patches.. .................................... 29 3-1 Demonstration of verifying unoccupied stands, functional stands, and distance to closest optimal patch ........................................................................ 43 3-2 Classification and regression tree analysis (CART) of stands before merging to make "functional patches" .............................................................................. 44 3-3 Classification and regression tree analysis (CART) of the functional patches with all predictor variables included .................................................................... 45 7 LIST OF ABBREVIATIONS DFP Distance to closest functional patch DFPDP Distance to closest functional patch in the direction being pulled FLSJ Florida scrub-jay Functional Patch Stands which are presumably suitable for FLSJ occupancy ONF Ocala National Forest Stand Forest management units for logging activities YSH Years since last harvest 8 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science FLORIDA SCRUB-JAY MOVEMENT THROUGH UNSUITABLE HABITAT AND ITS RELATIONSHIP TO OCCUPANCY IN OCALA NATIONAL FOREST By Amanda M. Abel December 2014 Chair: Kathryn E. Sieving Major: Interdisciplinary Ecology For this study we used Florida Scrub-jay (FLSJ) survey data and behavioral experiments to determine how occupancy and movement through harvested clear-cut stands in Ocala National Forest (ONF) is affected by characteristics of the stands and surrounding stands. We conducted a replicated playback study utilizing territorial calls of FLSJ to elicit approach and following responses in target jay groups. In this way we could compare birds’ willingness to enter and move through adjacent stands exhibiting a range of age, vegetation structure, and other stand metrics using a standardized motivation to approach a potential intruder. We found that many FLSJ in ONF were willing to move into stands unsuitable for FLSJ occupancy (the matrix). Regression models showed us that FLSJ are more likely to enter a matrix stand which is relatively old, has high percent pine, and low percent oak and open space. Importantly, the distance to the nearest suitable habitat patch was also a significant factor. Playback ‘pulls’ into matrix stands which had suitable habitat nearby elicited longer movements into the matrix, suggesting that FLSJs are aware of habitat availability and configuration outside of their own occupied stand. Next, we used clear-cut patch occupancy survey data to create statistical models to determine characteristics which most affect 9 occupancy. We found that occupancy of clear-cut stands in ONF is negatively related to distance to the closest stand suitable for occupancy, positively related to area, and negatively related to edge:area ratio (a reflection of shape). A classification and regression tree analysis of survey data allowed us to create recommendation for ONF forest managers. We recommend that clear-cut stands should be within 540 meters of other suitable stands. If stands exceed this distance, they should be greater than 26 hectares in size. As edge:area ratio negatively affects occupancy, creating stands with small edge:area ratios (large core space) may positively FLSJ occupancy. As ONF is home to the largest remaining population of this federally threatened species, effective management this habitat is essential to the species persistence. We believe the findings of this study may help forest managers more effectively manage FLSJs in this ecosystem. 10 CHAPTER 1 INTRODUCTION Ocala National Forest (ONF) protects the largest contiguous sand pine scrub forest and is home to the largest population of Florida scrub-jays (FLSJ). Sand pine scrub ecosystems are adapted to a cycle in which wildfires kill all vegetation above ground, the vegetation grows back, and burns again in 20 to 80 years. Native species, such as the FLSJ, depend on this cycle of opening and regrowth. Natural wildfires are suppressed in ONF and openings are created primarily by timber harvesting. Timber harvest clear-cutting