Species Occurrence and Distribution of Amphibians and Reptiles in Hells Canyon Jonathan M. Beck Charles R. Peterson Mark Gerber Idaho State University Department of Biology Natalie J. S. Turley Wildlife Technician Technical Report Appendix E.3.2-36 April 2001 Revised July 2003 Hells Canyon Complex FERC No. 1971 Copyright © 2003 by Idaho Power Company Idaho Power Company Species Occurrence and Distribution of Amphibians and Reptiles TABLE OF CONTENTS Table of Contents............................................................................................................................. i List of Tables ................................................................................................................................. iv List of Figures..................................................................................................................................v List of Appendices ......................................................................................................................... vi Executive Summary.........................................................................................................................1 1. Introduction.................................................................................................................................5 1.1. Justification........................................................................................................................5 1.2. State of Knowledge............................................................................................................5 1.3. Objectives ........................................................................................................................10 2. Study Area ................................................................................................................................11 2.1. Location ...........................................................................................................................11 2.2. Physiography....................................................................................................................12 2.3. Land Features and Geology .............................................................................................13 2.4. Soils..................................................................................................................................13 2.5. Climate.............................................................................................................................13 2.6. Vegetation........................................................................................................................14 2.7. Land Use ..........................................................................................................................17 2.8. Plant Operations...............................................................................................................17 3. Methods.....................................................................................................................................18 3.1. Historic Distribution of Reptiles and Amphibians...........................................................18 3.2. Survey Techniques...........................................................................................................18 3.2.1. Drift-Fence Trapping ..............................................................................................19 3.2.2. Wetland Surveys .....................................................................................................20 Hells Canyon Complex Page i Species Occurrence and Distribution of Amphibians and Reptiles Idaho Power Company 3.2.3. Stream Surveys .......................................................................................................21 3.2.4. Timed Reptile Surveys............................................................................................22 3.2.5. Nighttime Driving...................................................................................................22 3.2.6. Incidental Observations ..........................................................................................22 3.3. Data Analysis...................................................................................................................23 3.3.1. Relative Abundance and Species Diversity ............................................................23 3.3.2. Habitat Relationships..............................................................................................23 3.3.3. Species Distribution................................................................................................24 4. Results.......................................................................................................................................26 4.1. Historic Distribution of Reptiles and Amphibians...........................................................26 4.2. Reptiles ............................................................................................................................27 4.2.1. Relative Abundance and Species Diversity ............................................................27 4.2.2. Habitat Associations ...............................................................................................28 4.2.3. Distribution .............................................................................................................28 4.3. Amphibians......................................................................................................................29 4.3.1. Relative Abundance................................................................................................29 4.3.2. Habitat Associations ...............................................................................................30 4.3.3. Distribution .............................................................................................................30 4.4. Sensitive Species..............................................................................................................31 5. Discussion.................................................................................................................................31 5.1. Reptile Community..........................................................................................................31 5.1.1. Relative Abundance................................................................................................32 5.1.2. Habitat Associations ...............................................................................................32 5.1.3. Distribution .............................................................................................................33 5.2. Amphibian Community ...................................................................................................34 Page ii Hells Canyon Complex Idaho Power Company Species Occurrence and Distribution of Amphibians and Reptiles 5.2.1. Relative Abundance................................................................................................34 5.2.2. Habitat Associations ...............................................................................................34 5.2.3. Distribution .............................................................................................................37 5.3. Comparison of Survey Techniques..................................................................................38 5.4. Special Status Species......................................................................................................38 6. Conclusions and Management Recommendations ...................................................................41 6.1. Conclusions......................................................................................................................41 6.2. Management Recommendations......................................................................................41 7. Acknowledgments.....................................................................................................................42 8. Literature Cited .........................................................................................................................42 Hells Canyon Complex Page iii Species Occurrence and Distribution of Amphibians and Reptiles Idaho Power Company LIST OF TABLES Table 1. Historica and IPC records of amphibian and reptile species recorded in Idaho, Oregon, and the Hells Canyon Study Area. ............................................... 49 Table 2. Special status reptile and amphibian species that may occur or have been documented to occur (1995–1999, shown in bold) in the Hells Canyon Study Area............................................................................................................. 51 Table 3. Wetlands surveyed for amphibians below Hells Canyon Dam during the spring and summer of 1996–1998......................................................................... 53 Table 4. Roads driven to survey for reptiles and amphibians, including data on survey dates, and presence or absence of reptiles and amphibian. ....................... 55 Table 5. Total number of each species (amphibians and reptiles) captured using drift-fences, the percentage of all species captured, and the mean abundance for each species, spring and summer of 1996 and 1997. .................... 56 Table 6. Amphibian and reptile frequency of occurrence (constancy), relative abundance,