Populations in Surrey, British Columbia
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STATUS OF RED-LEGGED FROGS (Rana aurora aurora) IN SURREY, BRITISH COLUMBIA By Lanny Englund B.Sc., University of British Columbia, 1995 B.Sc., University of Northern British Columbia, 2000 A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in ENVIRONMENT AND MANAGEMENT We accept this thesis as conforming to the required standard .......................................................... Dr. Charles Krusekopf, MEM Program Head School of Environment and Sustainability .......................................................... Dr. Vivienne Wilson, Senior Project Manager Golder Associates Ltd. .......................................................... Greg Ward, Urban Forestry and Environmental Programs Manager City of Surrey .......................................................... Dr. Tony Boydell, Director School of Environment and Sustainability ROYAL ROADS UNIVERSITY April 2007 © Lanny Englund, 2007 ISBN: 978-0-494-37709-3 Status of the Red-legged Frog (Rana aurora aurora) ii Abstract There is growing evidence of amphibian population declines around the world. Red- legged frogs (Rana aurora aurora) are one species of amphibian in decline within the Lower Fraser Basin (LFB) in British Columbia, Canada. This study gathered baseline distribution information for red-legged frogs in twelve parks in Surrey, BC. The findings suggest that red- legged frog populations are most likely found within their range in the Lower Fraser Basin on sites where wetlands have high percent cover of aquatic vegetation and forest cover within a 200 m radius of the wetland. Specific park management recommendations were developed for the twelve study sites with the goal of sustaining red-legged frog populations within Surrey’s protected area network in perpetuity. This study is the first step towards gaining the knowledge necessary to ensure the sustainability of this species in Surrey and perhaps their entire range within the LFB. Status of the Red-legged Frog (Rana aurora aurora) iii Acknowledgements I would like to first thank my supervisory committee, Dr. Vivienne Wilson and Greg Ward, for their support. Vivienne, thank you for taking me on and coming through for me even though it would have been easier to pass me off to another supervisor once you started the new job. Greg, thank you for supporting me on my thesis work and my masters degree. I would also like to acknowledge the financial contributions from the City of Surrey that made both this project and my degree possible. There are several others that have helped make this project possible. My thanks go out to Ross Vennesland for taking the time to help me develop my methodology and for providing feedback when it was most needed. Dennis Knopp who taught me a lot about amphibians and their habitat. Thanks also to Mary Doris for helping collect data when she should have been enjoying her holidays. Finally, I want to thank my family for their continued support and understanding that has always enabled me to pursue my academic goals. My greatest thanks go to my amazing wife Krista who supported me all along the way, provided valuable input on all aspects of this project and spent nearly as much time as I did in the field, even after I dropped her camera in a pond. Status of the Red-legged Frog (Rana aurora aurora) iv Table of Contents ABSTRACT................................................................................................................................... ii ACKNOWLEDGEMENTS ........................................................................................................iii TABLE OF CONTENTS ............................................................................................................ iv LIST OF TABLES ...................................................................................................................... vii LIST OF FIGURES ...................................................................................................................viii 1 INTRODUCTION AND LITERATURE REVIEW...................................................... 1 1.1 RANGE OF RED-LEGGED FROGS .........................................................................................2 1.2 BIOLOGY OF RED-LEGGED FROGS.....................................................................................4 1.3 IMPACTS TO RED-LEGGED FROG POPULATIONS ...........................................................5 1.4 CURRENT STATUS ................................................................................................................11 1.5 RESEARCH PROBLEM ..........................................................................................................13 1.6 RESEARCH HYPOTHESES....................................................................................................13 1.7 RESEARCH OBJECTIVES......................................................................................................13 2 RESEARCH METHODOLOGY .................................................................................. 14 2.1 RESEARCH SITE SELECTION ..............................................................................................14 2.2 STUDY SITES ..........................................................................................................................22 2.3 SPATIAL ANALYSIS OF HABITAT .....................................................................................24 2.4 HABITAT CLASSIFICATION ................................................................................................25 2.4.1 Terrestrial..........................................................................................................................25 2.4.2 Wetland.............................................................................................................................27 2.5 EGG MASS SAMPLING PROTOCOL....................................................................................29 2.6 WATER QUALITY ..................................................................................................................30 2.7 BULLFROG PRESENCE/ABSENCE......................................................................................32 3 RESULTS ........................................................................................................................ 33 3.1.1 Bothwell Park ...................................................................................................................33 3.1.2 Crescent Park ....................................................................................................................34 3.1.3 Green Timbers Urban Forest Park ....................................................................................35 3.1.4 Hi-Knoll Park....................................................................................................................37 3.1.5 43 Z Utility Right-of-Way ................................................................................................39 3.1.6 Elgin Heritage Park...........................................................................................................40 3.1.7 Hawthorne Park ................................................................................................................41 3.1.8 Port Kells Park..................................................................................................................42 Status of the Red-legged Frog (Rana aurora aurora) v 3.1.9 Boundary Park ..................................................................................................................44 3.1.10 Cougar Creek Park............................................................................................................45 3.1.11 Guildford Heights Park.....................................................................................................46 3.1.12 Semiahmoo Trail Park ......................................................................................................48 3.2 WATER QUALITY ..................................................................................................................49 3.3 EGG MASS PRESENCE / ABSENCE.....................................................................................51 3.4 BULLFROG PRESENCE / ABSENCE....................................................................................54 3.5 WATER QUALITY AND PRESENCE/ABSENCE CORRELATIONS .................................55 3.6 TERRESTRIAL HABITAT STRATIFICATION ....................................................................57 4 DISCUSSION .................................................................................................................. 60 4.1 CURRENT STATUS OF RED-LEGGED FROGS IN SURREY ............................................60 4.2 HABITAT REQUIREMENTS..................................................................................................60 4.3 PARK MANAGEMENT RECOMMENDATIONS .................................................................62 4.3.1 General..............................................................................................................................62 4.3.2 Bothwell Park ...................................................................................................................63 4.3.3 Crescent Park ....................................................................................................................65 4.3.4 Green Timbers Urban Forest Park ....................................................................................67