ii iii TABLE OF CONTENTS Executive Summary ...................................................................................................... ix Introduction to Studies ...................................................................................................1 Study 1: Release and Radio Telemetry of Head-started Western Pond Turtles at Sycuan Peak Ecological Reserve........................................................................4 Introduction .................................................................................................................. 4 Methods........................................................................................................................ 4 Study Site ................................................................................................................. 4 Head-starting ............................................................................................................ 8 Telemetry ............................................................................................................... 10 Motion and Time Lapse Cameras .......................................................................... 11 Visual Surveys ....................................................................................................... 12 Results ........................................................................................................................ 12 Telemetry ............................................................................................................... 12 Motion and Time Lapse Cameras .......................................................................... 13 Visual Surveys ....................................................................................................... 15 Discussion .................................................................................................................. 16 Milestones .............................................................................................................. 16 Recommendations .................................................................................................. 16 Study 2: Population Assessment of Western Pond Turtles at Pine Valley Creek ..17 Introduction ................................................................................................................ 17 Methods...................................................................................................................... 18 Site Description ...................................................................................................... 18 Visual Encounter Surveys ...................................................................................... 21 Results ........................................................................................................................ 22 Overview of Captures ............................................................................................ 22 Population Estimates .............................................................................................. 24 Age and Sex Structure ........................................................................................... 24 Discussion .................................................................................................................. 25 Study 3: Assessment of the Upper Watersheds of the Otay, Tijuana, San Dieguito, and San Diego Rivers for Western Pond Turtle Translocation and Donor Sites.....................................................................................................................27 Introduction ................................................................................................................ 27 Methods...................................................................................................................... 29 iv Site Descriptions .................................................................................................... 29 Methods .................................................................................................................. 53 Results ........................................................................................................................ 54 Site Identification ................................................................................................... 54 Surveys ................................................................................................................... 58 Discussion .................................................................................................................. 65 Study 4: Rancho Jamul Ecological Reserve Western Pond Turtle Translocation .67 Introduction ................................................................................................................ 67 Methods...................................................................................................................... 67 Study Area ............................................................................................................. 67 Surveys ................................................................................................................... 72 Results ........................................................................................................................ 75 Habitat Surveys ...................................................................................................... 75 Nonnative Aquatic Species Removal ..................................................................... 76 Telemetry and Monitoring ..................................................................................... 77 Discussion .................................................................................................................. 79 Literature Cited ............................................................................................................81 LIST OF FIGURES Figure 1.1. The location of Sycuan Peak Ecological Reserve, San Diego, CA. Sycuan Peak Ecological Reserve is located downstream of Loveland Reservoir along the Sweetwater River. .......................................................................... 5 Figure 1.2. Pond turtle habitat and trapping locations at Sycuan Peak Ecological Reserve, San Diego, CA. ............................................................................. 6 Figure 1.3. Photographs of trapping points in suitable pond turtle habitat at Sycuan Peak Ecological Reserve......................................................................................... 7 Figure 1.4. Photos of the pond turtle head-starting process at the San Diego Zoo.. ....... 9 Figure 1.5. Head-started pond turtles with radio-transmitters affixed to carapace.. ..... 11 Figure 1.6. Movements of head-started pond turtles at SPER. ...................................... 13 Figure 1.7. Motion triggered photos of disturbance at SPER Pool 1. ........................... 15 Figure 2.1. The Pine Valley Creek study area in southern San Diego County, CA....... 19 Figure 2.2. The Pine Valley Creek pond turtle mark recapture study site. .................... 20 Figure 2.3. Pine Valley Creek habitat. ........................................................................... 21 Figure 2.4. Visual pond turtle detections.. ..................................................................... 24 v Figure 2.5. Body size and weight relationships for the Pine Valley Creek pond turtle population compared to the Sycuan Peak Ecological Reserve (SPER) population. ................................................................................................... 25 Figure 3.1. Possible pond turtle translocation receiver and donor sites within the upper San Dieguito River watershed.. ................................................................ 30 Figure 3.2. Potential pond turtle donor site in upper Santa Ysabel Creek downstream from Witch Creek.. ................................................................................... 31 Figure 3.3. Potential pond turtle donor site in upper Santa Ysabel Creek in Pamo Valley.. ...................................................................................................... 32 Figure 3.4. Potential pond turtle donor site in upper Santa Ysabel Creek below Clevenger Canyon.. ................................................................................... 33 Figure 3.5. Potential pond turtle receiver site at the San Dieguito River Park below Lake Hodges (Santa Fe Valley).. ....................................................................... 34 Figure 3.6. Potential pond turtle donor site in Scholder Creek in upper Black Canyon. 35 Figure 3.7. Potential pond turtle donor site in lower Black Canyon.. ............................ 36 Figure 3.8. Potential pond turtle receiver site at the California Department of Fish and Wildlife Boden Canyon Ecological Reserve. ........................................... 37 Figure 3.9. Potential pond turtle donor and receiver sites in the San Diego River Watershed. ................................................................................................ 38 Figure 3.10. Potential pond turtle donor site in the San Diego River at Penin Canyon (Temescal Creek). ..................................................................................... 39 Figure 3.11. Potential pond turtle donor site in the San Diego River above Ritchie Creek.. ......................................................................................................