HABITAT SELECTION AND MOVEMENT PATTERNS OF AMPHIBIANS IN ALTERED FOREST HABITATS by GABRIELLE JOY GRAETER (Under the Direction of J. WHITFIELD GIBBONS) ABSTRACT I released adult southern leopard frogs (Rana sphenocephala), marbled salamanders (Ambystoma opacum), and southern toads (Bufo terrestris) on forest/clearcut edges to examine the effects of forest management on amphibian habitat selection and movement behavior. Salamanders selected habitat at random, toads preferred clearcuts, and frogs initially selected clearcuts but ultimately chose forests. All three species made more turns in clearcuts than forests, and toads and frogs moved farther in forests. Frogs and toads moved without regard to environmental conditions, but salamanders were influenced by soil moisture. I also examined the efficacy of fluorescent powder as an amphibian tracking technique and found that some colors were easier to detect when paths were long, that heavy rainfall truncated path length, and that effectiveness varied among species, habitat, and region. Such knowledge of individual and species-level responses to terrestrial habitat alteration will facilitate development of forest management plans that enhance persistence of amphibian populations. INDEX WORDS: Ambystoma opacum, Bufo terrestris, Rana sphenocephala, marbled salamander, southern toad, southern leopard frog, habitat fragmentation, forest management, amphibians, movement, migration, habitat selection, permeability, fluorescent powder, tracking, clearcut, amphibian conservation HABITAT SELECTION AND MOVEMENT PATTERNS OF AMPHIBIANS IN ALTERED FOREST HABITATS by GABRIELLE JOY GRAETER B.S., University of North Carolina-Chapel Hill, 1999 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE ATHENS, GEORGIA 2005 © 2005 Gabrielle Joy Graeter All Rights Reserved HABITAT SELECTION AND MOVEMENT PATTERNS OF AMPHIBIANS IN ALTERED FOREST HABITATS by GABRIELLE JOY GRAETER Major Professor: J. Whitfield Gibbons Committee: Mary C. Freeman C. Ronald Carroll Betsie B. Rothermel Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia December 2005 ACKNOWLEDGEMENTS I thank Whit Gibbons for his constant encouragement, support, and dedication to his students. I feel honored to be one of Whit’s students and am inspired by his incredible amount of energy and enthusiasm for herpetology and education. I thank Betsie Rothermel for her continual guidance and help with all stages of my research and thesis. She provided invaluable support and information and I am very grateful for her mentorship. I also thank Mary Freeman, especially for her guidance during my on-campus year and her willingness to assist me with statistical dilemmas. I thank Ron Carroll for his support and in helping me to look at my research from a broader perspective. Many others have helped me, with field work, statistics, advice, or other support. I could not have accomplished this without their generosity: Kimberly Andrews, David Berry, Sean Blomquist, Chris Conner, Sarah Durant, Aaliyah Green, Judy Greene-McLeod, Deno Karapatakis, Mark Langley, Tom Luhring, Brian Metts, John Nestor, Leslie Ruyle, Brian Todd, Tracey Tuberville, JD Willson, Machelle Wilson, Chris Winne, Meredith Wright, and Leslie Zorn. I also want to thank my parents, John and Kathryn Graeter, brother and sister, Jesse Graeter and Amanda Miles-Graeter, and grandparents, Harry and Bess Wehrlen, for their love and encouragement. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS...........................................................................................................iv LIST OF TABLES........................................................................................................................vii LIST OF FIGURES.....................................................................................................................viii CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW.....................................................1 Background on Amphibian Ecology and Conservation Issues.................................1 Forest Management in the Southeast.........................................................................3 Summary of Previous Research on Amphibian Responses to Forest Management..5 Amphibian Population-Level Responses to Forest Management in the Southeastern Coastal Plain..............................................................................................................6 Movement Responses of Individual Amphibians to Forest Management................7 Objectives of Study.................................................................................................14 Literature Cited........................................................................................................15 2 HABITAT SELECTION AND MOVEMENT PATTERNS OF THREE AMPHIBIAN SPECIES (RANA SPHENOCEPHALA, AMBYSTOMA OPACUM, BUFO TERRESTRIS) IN ALTERED FOREST HABITATS IN THE UPPER COASTAL PLAIN OF SOUTH CAROLINA..........................................20 Introduction.............................................................................................................21 Materials and Methods............................................................................................23 v Results.....................................................................................................................34 Discussion...............................................................................................................38 Conclusions and Implications.................................................................................49 Acknowledgements.................................................................................................54 Literature Cited........................................................................................................55 3 THE USE OF FLUORESCENT POWDERED PIGMENTS AS AN EFFECTIVE TECHNIQUE FOR TRACKING AMPHIBIANS..................................................78 Introduction.............................................................................................................79 Materials and Methods............................................................................................80 Results.....................................................................................................................81 Discussion...............................................................................................................82 Acknowledgements.................................................................................................85 Literature Cited........................................................................................................86 4 CONCLUSION............................................................................................................91 vi LIST OF TABLES Page Table 2.1: Binomial probability results for R. sphenocephala, A. opacum, and B. terrestris by edge type........................................................................................................................62 Table 2.2: Binomial probability results for R. sphenocephala, A. opacum, and B. terrestris, with data condensed into two treatments, Forest v. Clearcut ...............................................63 Table 2.3: Results of multivariate analysis of variance of the effects of treatment, site, and their interaction on each species’ movement path characteristics.........................................63 Table 2.4: Ground-level openness candidate models showing fixed effects, model ∆i values, and Akaike weights..............................................................................................................64 Table 2.5: Fixed effects coefficient estimates for the highest ranked models for each composite variable..........................................................................................................................64 Table 2.6: Ground-level cover candidate models showing fixed effects, model ∆i values, and Akaike weights..............................................................................................................65 Table 2.7: Tree density candidate models showing fixed effects, model ∆i values, and Akaike weights...........................................................................................................................65 vii LIST OF FIGURES Page Figure 2.1: Diagram of a LEAP array showing the arrangement of the four forest management treatments......................................................................................................................66 Figure 2.2: Diagram of microhabitat availability transects in one quadrant..................................66 Figure 2.3: Percentage of R. sphenocephala in clearcut v. forest at selected distances from the release point on forest/clearcut edges............................................................................67 Figure 2.4: Percentage of A. opacum in clearcut v. forest at 2 m and endpoint from the release point on forest/clearcut edges........................................................................................67 Figure 2.5: Percentage of B. terrestris in clearcut v. forest at 5 m and endpoint from the release point on forest/clearcut edges........................................................................................68 Figure 2.6: Movement paths of R. sphenocephala at (A) site 1000 and (B) site 37......................69 Figure 2.7: Movement paths of B. terrestris at (A) site 37 and (B) site 119.................................70 Figure 2.8: Movement paths of A. opacum at (A) site 119 and (B) site 37...................................71 Figure 2.8C: A close-up of the A. opacum movement paths on the control/CC-removed edge at site 37............................................................................................................................72 Figure 2.9: Mean path length for each species..............................................................................73 Figure 2.10: Minimum and maximum path lengths for each species............................................73 Figure 2.11: Mean number of turns per 10 m for each species......................................................74 Figure 2.12: Mean path linearity for each species.........................................................................74 Figure 2.13: Mean path length in forests v. clearcuts for each species.........................................75 viii Figure 2.14: Mean number of turns per 10 m in forests v. clearcuts for each species...................75 Figure 2.15: Mean path linearity in forests v. clearcuts for each species......................................76 Figure 2.16: Mean values for ground-level openness availability v. ground-level openness use by R. sphenocephala by treatment type and site................................................................76 Figure 2.17: Mean values for ground-level cover availability v. ground-level cover use by R. sphenocephala by treatment type and site.....................................................................77 Figure 2.18: Mean values for tree density availability v. tree density use by R. sphenocephala by treatment type and site...................................................................................................77 Figure 3.1: Mean, minimum, maximum path lengths of A. opacum, B. terrestris, and R. sphenocephala in S.C. (this study), A. annulatum in M.O., and R. sylvatica in M.E...88 Figure 3.2: Mean path length for the four fluorescent powder colors...........................................89 Figure 3.3: Mean path length for powder color, specific to species..............................................89 Figure 3.4: Relationship between post-release precipitation and mean and maximum powder path length in (A) R. sphenocephala at three different precipitation levels and (B) in A. opacum at two different precipitation levels ................................................................90 ix