Marshall University Marshall Digital Scholar Theses, Dissertations and Capstones 1-1-2007 Ecology and Morphological Comparison between Rough Greensnakes (Opheodrys a. aestivus) and Eastern Smooth Greensnakes (Opheodrys v. vernalis) in West Virginia Timothy Earl Baldwin [email protected] Follow this and additional works at: http://mds.marshall.edu/etd Part of the Animal Sciences Commons, and the Population Biology Commons Recommended Citation Baldwin, Timothy Earl, "Ecology and Morphological Comparison between Rough Greensnakes (Opheodrys a. aestivus) and Eastern Smooth Greensnakes (Opheodrys v. vernalis) in West Virginia" (2007). Theses, Dissertations and Capstones. Paper 451. This Thesis is brought to you for free and open access by Marshall Digital Scholar. It has been accepted for inclusion in Theses, Dissertations and Capstones by an authorized administrator of Marshall Digital Scholar. For more information, please contact [email protected]. Ecology and Morphological Comparison between Rough Greensnakes (Opheodrys a. aestivus) and Eastern Smooth Greensnakes (Opheodrys v. vernalis) in West Virginia Thesis submitted to the Graduate College of Marshall University In partial fulfillment of the Requirements for the degree of Master of Science Herpetology/ Biological Sciences By Timothy Earl Baldwin Thomas K. Pauley, Committee Chair Dan K. Evans Jayme L. Waldron Marshall University Copyright 2007 Keywords: Opheodrys aestivus, Opheodrys vernalis, Habitat selection, Ecology, diet, morphology, Stomach Content Analysis ABSTRACT Ecology and Morphological Comparison between Rough Greensnakes (Opheodrys a. aestivus) and Eastern Smooth Greensnakes (Opheodrys v. vernalis) in West Virginia Timothy Earl Baldwin Since 1971, documented Rough Greensnake (Opheodrys aestivus) occurrences in West Virginia have declined from approximately 100 to less than 20 occurrences in the last 10 years. In contrast to the decline of Rough Greensnakes in WV, Smooth Greensnake (O. vernalis) populations appear to be stable over the same period of time. Historic sites from the West Virginia Biological Survey were cross referenced with habitat descriptions in published literature to establish research locations. One hundred nineteen Rough and Smooth Greensnakes were measured for snout-vent length and total body length, and of these, 78 were measured in detail for external head morphology characteristics. Stomachs of field-captured specimens were flushed to identify prey, and in preserved specimens the gastro-intestinal tracts were dissected and examined for prey items. Plant community data were collected at each research site (N=51) along 150m transects to define their habitat characteristics. Of the 6 month active period, Rough Greensnakes had the most captures in September, accounting for 30%. In comparison, Smooth Greensnakes had the most captures in June, accounting for 33%. Exponential regression showed a positive correlation between total length and weight for Smooth Greensnakes (R2 = 0.9136) and Rough Greensnakes (R2 =0.7124). Species occupied different habitats, with Rough Greensnakes found along forest edges near roadsides and Smooth Greensnakes in open fields with sparse vegetation. There was a statistically significant difference between the habitat types that were occupied by Rough and Smooth Greensnakes (p< 0.001). Only Opheodrys aestivus adults were found, while Opheodrys vernalis was represented by age groups from hatchlings to older adults. The data suggest that differences in both activity period and habitat preference may explain differences in population structure. ii ACKNOWLEDGEMENTS First and foremost I would like to thank Dr. Pauley, for being not only a great and approachable advisor, but also for being so supportive during my project planning process. We went through numerous ideas before we landed on greensnake comparisons. I thank you for taking the time to answer all of my questions. Thank you also for giving me the opportunity to work on so many projects so that I could gain more experience as well as save money to fund my project. Even though you were often busy, thank you for always taking the time to talk if I needed to talk. Thank you to Dr. John and Janett Casto for the generous award that enabled me to fund my thesis. Next, I would like to thank my family for embracing my dream to study reptiles and amphibians. Without your support I am not sure this project would’ve been completed. Thank you to my parents for listening to my powerpoint presentations over the phone. I know it was not always easy to understand a presentation without visual, but you always had feedback for me. Thank you to my mother for helping me to edit my abstracts and papers. Thank you to my brother for the late nights of listening to my rants about my frustrations with not only my statistical analysis. Thank you for always being there when I needed you. Thank you to Daniel Ware, Tristan and Emily Bond, Conor Keitzer, Matthew Graham, Keri Corely, and Amy Schneider for helping me look for greensnakes. Thank you Dan, Tristan, and Conor for letting me accompany you to study sites to look for greensnakes. Thank you both for always keeping an eye out and taking measurements for me if I was not with you. Thank you Dan for the jokes and helping things stay light in the field. It was not always an easy job, but we got through it. Thank you to Deborah Merritt and Dr. Arnold for helping me with my stomach content analysis. I did not have experience with insect identification, but you both provided me with books and took the time to help me with the identification process. Thank you to Dr. Evans and Dr. Waldron for always providing literature for me whenever I had a question. Thank you for always taking the time to meet with me about my project and possible ways I can take and analyze data. Thank you Dr. Waldron for all your help with ARCGis and for helping me to think outside of the box. Thank you to Dr. Georgel for meeting with me about my project. Thank you for always asking the tough questions. These questions helped to make me a better researcher. Thank you for all your help with my powerpoint presentations. I believe I have come a long way from my first semester, and that is thanks in large part to you. Thank you to Dr.Walz for helping me with ARCGis and advising me on classes that helped me with my thesis project. Thank you for always being patient with me even when it seemed as though I was asking the same questions over and over Thank you Dr. Burcher for helping me better organize aspects of my research. Thank you for helping me to realize that I do not always have to overfill my presentations. Thank you also for helping me realize that simple is sometimes better when I am presenting my research. Thank you Mary Jo for always listening to my thesis research updates every week. Thank you for the jokes as well as helping me to see the bright side of things. The laughter helped me more than you know. iii TABLE OF CONTENTS Page Number ABSTRACT ii ACKNOWLEDGEMENTS iii TABLE OF CONTENTS iv LIST OF FIGURES v LIST OF TABLES vi CHAPTER ONE: Literature Review 1 CHAPTER TWO: Distributions of Rough Greensnakes (Opheodrys aestivus) and Smooth Greensnakes (Opheodrys vernalis) in West Virginia Introduction 8 Methods 11 Results and Discussion 18 CHAPTER THREE: External Morphological Comparison between Opheodrys aestivus and Opheodrys vernalis Introduction 24 Methods 26 Results 27 Discussion 28 CHAPTER FOUR: Diet and Foraging Strategies of Opheodrys aestivus and Opheodrys vernalis Introduction 42 Methods 44 Results 45 Discussion 46 CHAPTER FIVE: Habitat Selection between Rough Greensnakes (Opheodrys aestivus) and Smooth Greensnakes (Opheodrys vernalis) Introduction 58 Methods 59 Results 60 Discussion 61 LITERATURE CITED 68 CURRICULUM VITAE 70 iv LIST OF FIGURES Figure 1. National Distribution of Rough Greensnakes 5 Figure 2. National Distribution of Smooth Greensnakes 6 Figure 3. Keeled Scales of Opheodrys aestivus 7 Figure 4. Smooth Scales of Opheodrys vernalis 7 Figure 5. West Virginia County Distribution of Rough Greensnakes 9 Figure 6. West Virginia County Distribution of Smooth Greensnakes 10 Figure 7. O. aestivus and O. vernalis Historic Sites 20 Figure 8. O. aestivus 2006 populations 21 Figure 9. O. vernalis 2006 populations 22 Figure 10. Total Body Length and Weight Correlation for O. aestivus 30 Figure 11. Total Body Length and Weight Correlation for O. vernalis 31 Figure 12. Snout-Vent Length and Weight Correlation for O. aestivus 32 Figure 13. Snout-Vent Length and Weight Correlation for O. vernalis 33 Figure 14. Weight Comparison of O. aestivus and O. vernalis 34 Figure 15. Total Length Comparison of O. aestivus and O. vernalis 35 Figure 16. Eye Diameter Comparison of O. aestivus and O. vernalis 36 Figure 17. Longitudinal Groove Comparison of O. aestivus and O. vernalis 37 Figure 18. Percentage Snout Attenuation of O. aestivus and O. vernalis 38 Figure 19. Cranial Length Comparison of O. aestivus and O. vernalis 39 Figure 20. Cranial Width Comparison of O. aestivus and O. vernalis 40 Figure 21. Cranial Area Comparison of O. aestivus and O. vernalis 41 Figure 22. O. aestivus Prey Item Counts 48 Figure 23. O. aestivus Prey Item Percentage 49 Figure 24. O. aestivus Total Volume Per Prey Order 50 Figure 25. O. aestivus Total Volume Per Prey Order Percentage 51 Figure 26. O. aestivus Feeding Strategy Plot 52 Figure 27. O. vernalis Prey Item Counts 53 Figure 28. O. vernalis Prey Item Percentage 54 Figure 29. O. vernalis Total Volume Per Prey Order 55 Figure 30. O. vernalis Total Volume Per Prey Order Percentage 56 Figure 31. O. vernalis Feeding Strategy Plot 57 Figure 32. Elevation Comparison of O. aestivus and O. vernalis 62 Figure 33. Air Temperature Comparison of O. aestivus and O. vernalis 63 Figure 34. Aspect Comparison of O. aestivus and O. vernalis 64 Figure 35.