ResearchOnline@JCU This file is part of the following reference: Pearcy, Ashley Grace (2007) The para grass city, where the grass is green and the snakes are pretty: the ecology of Herpetofauna in an invaded wetland. Masters (Research) thesis, James Cook University. Access to this file is available from: http://eprints.jcu.edu.au/29566/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://eprints.jcu.edu.au/29566/ The Para Grass City, Where the Grass is Green and the Snakes are Pretty: the Ecology of Herpetofauna in an Invaded Wetland Thesis submitted by Ashley Grace Pearcy BS (Tampa) in November 2007 for the research degree of Master of Science in Tropical Ecology within the School of Marine and Tropical Biology James Cook University STATEMENT OF ACCESS I, the undersigned, the author of this thesis, understand that James Cook University will make this thesis available for use within the University Library and, via the Australian Digital Theses network (unless granted an exemption), for use elsewhere. I understand that, as an unpublished work, a thesis as significant protection under the Copyright Act and; I do not wish to place any further restrictions on access to this work. ____________________ ii STATEMENT ON SOURCES DECLARATION I declare that this thesis is my own work and has not been submitted in any other form for another degree or diploma at any university or other institution of tertiary education. Information derived from the published and unpublished work of others has been acknowledged in the text and a list of references is given. ________________ iii Significant Contributions Funding Burdekin Dry Tropics Assitance in obtaining funding Lin Schwarzkopf Christopher Johnson Project done in conjunction with Queensland Parks and Wildlife Service Australian Commonwealth Scientific and Research Organization (CSIRO) Research Assistants Samantha Forbes Benedicte Eftevand Lauren Hodgson Assistance with snake regurgitation and identification data collection John Llewelyn Statistical support Leonie valentine Supervision and revisions to thesis Christopher Johnson Ivan Lawler Andi Cairns iv Acknowledgements This past year has been demanding, full of unexpected difficulties and inspiring accomplishments. I want to thank everyone that has supported me throughout this time, both those that doubted the possibilities that lay ahead and those that had full faith in what may come. To my parents: I know the stress I lay on you; thank you for taking it in stride. Thank you for supporting me in my Epicurean lifestyle and my never-ending search for happiness. “You are the wind beneath my wings.” To the rest of my family: Bro, thanks for the support despite my off kilter way of doing things. Thank you to the B’s for understanding my absence for the family gatherings and for the support during the rough times. Nic and Fen, thanks for making me laugh and for being my solid ground on the other side of the world. Pa, thanks for always offering up advice, even if I do not always take it. Neane, thanks for being interested in what I do even though it seems so far-fetched from the world in which I grew up. Thanks to everyone for supporting my adventures. To the team: Sammy Forbes, you have been an inspiration on and off this project. Your hard work leaves no doubt for the future to which you aspire and the guaranteed success you will achieve. Thank you for your dedication and heart. Thanks for the para grass runs and the para grass city. Thanks for the dancing, the music, the laughing, and the surfing. I would not have made it through this without you. Much love and peace. Benedicte Eftevand- keep racking up that CV! I cannot thank you enough for your commitment in the field. Thanks for making me laugh and continually reminding me to “chill out”. Angus McNab thanks for all the help and for being an all-around good mate. Adrian McMahon, you are my right hand man. I could not have made it through this without the long hours and you by my side to get me through them. Thanks for the technical and moral support! Emadch Beck, Chris Ryen, and Ashley Field, thanks for being supportive and listening to my crazy stories. Thanks for the much-needed distractions which have kept me sane. To the supervisors: Chris Johnson and Ivan Lawler, thanks for taking me on and helping me to accomplish what I set forth to do. Thank you to: Andi Cairns for her last minute revisions, advice, and chats; Leonie Valentine, without you I would have never had any confidence to tackle statistics; Tony Grice, Mike Nichols, and Paul Williams for advice on experimental design and working in the Town Common. A big thank you to anyone and everyone else who has supported me throughout this project and the past year: Richard Rowe, Richard Pearson, Lin Schwarzkopf, Lauren Hodgson, John Llewelyn, Rob Graham, Jason Schaffer, Brian Ross, Sam Noonan, Miwa Takahashi, Zuzu Wahab, Stephen Kolomoyjec, Curtis Lind, Stefan Walker, Dan Ryen, Gerard Wanecheck, Øyvind Syrrist, Eivind Undeheim, Ray Lloyd, Ben Pearson, Andrea Bird, Spencer Bryde v Abstract Wetlands are susceptible to invasion by both flora and fauna due to their availability of differing habitat. This induces the enactment of treatments either for prevention or management of introduced species. Many invasive management practices are done with a focus on single taxa, especially with concern to wetlands. Wetlands offer a dynamic habitat for several species, and being aware of how these habitats are used by all species can offer a beneficial knowledge base for those enacting management techniques to ensure minimal consequences. This thesis investigated the influence of invasive species on herpetofauna in a wetland. The majority of this study focused on habitat use and the effects of the para grass Urochloa mutica.. By trapping along the ecotone gradient, abundance and location were used to determine primary habitat. It is concluded that the majority of herpetofauna species are more abundant in the woodland than in the margin or floodplain. This benefits the management treatments done to the floodplain by alleviating loss through the confirmation of larger populations in adjacent woodlands. A few species, however, associated mostly with the floodplain were identified such as Lampropholis delicata and Litoria fallax. These species could face greater consequences from management techniques. QPWS/CSIRO are experimenting with management techniques to control the spread of the invasive para grass. The effect of these treatments (burning and grazing) on the keelback snake (Tropidonophis mairii) during the wet season was studied by setting up aquatic traps in the floodplain in paddocks each with a different para grass treatment. The results found that snakes are more abundant in undisturbed, or control sites. This presents questions concerning the consequences of the weed vs. those of the management practice. A final study was done on the relation between Tropidonophis mairii and cane toads Bufo marinus, finding that despite the availability of cane toads, keelbacks selectively avoid them in their diet. Keelbacks are known to consume the toxic cane toad, but this defined preference for other individuals, shows that they are not a viable biological control method for the quickly expanding cane toad population. vi Table of Contents Pg Signed statement of access ii Signed statement of sources iii Significant Contribution iv Acknowledgments v Abstract vi Table of Contents vii List of Tables ix List of Figures x I. Chapter 1: Introduction 1 A. Aims 6 II. Chapter 2: The Good, the Bad and the Ugly: Benefits and Disadvantages to Wetland Weed Management 7 A. Abstract 7 B. Introduction 7 C. Sustained Changes 8 D. Weed Management 9 1. Introduction 9 2. Types of Management 10 a. Chemical 10 b. Physical 10 c. Mechanical 11 d. Biological 11 3. Conclusion 12 E. Yay or Nay to Management: Determining the Benefits and Consequences of Weed Management 12 F. Success 16 G. Conclusion 16 III. Chapter 3: Habitat Use by Herpetofauna in a Wetland: Who Lives Where? 18 A. Abstract 18 B. Introduction 18 C. Aims 21 D. Methods 21 1. Study Site 21 2. Experimental Design 23 3. Analysis 26 a. Trap Efficiency 26 b. Habitat 26 c. Weather 27 d. QPWS/CSIRO Para Grass Treatments 27 E. Results 27 1.Trap Efficiency 29 2. Habitat 31 a. Reptiles 31 b. Amphibians 34 3. Dominant Vegetation 37 4. Effect of Weather 39 vii 5. Pre vs. Post Burn 40 F. Discussion 40 1. Habitat Preference of Reptiles and Amphibians 40 2. Dominant Vegetation 42 3. Trap Efficiency 42 4. Effects of Weather 43 5. The Effect of Para Grass Treatments 43 6. Value for Management of Para Grass 43 7. Concerns Caused by Treatments 44 G. Conclusion 45 IV. Chapter 4: Living in an Invaded Wetland: the Natural History of Tropidonophis mairii in the Townsville Town Common 46 A. Abstract 46 B. Introduction 46 C. Aims 48 D. Methods 48 1. Experimental Design 48 2. Analysis 50 E. Results 50 1. Population Size and Composition 50 2. Habitat Use 51 3. Predator-Prey Dynamics 54 F. Discussion 55 1. Population Dynamics 55 2. Floodplain Use 55 3. Feeding Habits 56 G. Conclusion 57 1. Population and Feeding Habits 57 2. Floodplain Treatment Use 57 V. Chapter 5: General Conclusion 58 VI. References 61 viii List of Tables Table Pg 2.1 Weed ecology and the effect on habitat: predicting invasiveness and effectiveness